David T Harris

Interests

Research

Cord blood, cord tissue and adipose tissue-derived stem cellsregenerative medicinetissue engineeringstem cell clinical trials

Teaching

ImmunobiologyStem CellsRegenerative MedicineClinical Immunology

Courses

Scholarly Contributions

Chapters

• Harris, D. T. (2018). Stem cell banking: methods and clinical applications for regenerative medicine. In The Science and Clinical Applications of Stem Cells.

Journals/Publications

• Harris, D. T., Ingraham, N., & Badowski, M. (2023). Comparison of Manual versus Automated SARS-CoV-2 Rapid Antigen Testing in Asymptomatic Individuals. Journal of clinical medicine, 12(22).
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  The SARS-CoV-2 pandemic has infected more than 770 M people and killed more than 6.9 M persons worldwide. In the USA, as of August 2023, it has infected more than 103 M people while causing more than 1.1 M deaths. During a pandemic, it is necessary to rapidly identify those individuals infected with the virus so that disease transmission can be stopped. We examined the sensitivity of the Quidel Rapid Antigen test on the manual Sofia 2 platform and the Beckman-Coulter antigen test on the automated DxI-800 system for use in screening asymptomatic individuals at the University of Arizona from March through May 2021. A total of 378 asymptomatic subjects along with 176 validation sets of samples in 23 independent experiments were assessed in side-by-side antigen testing using both assays. Nasal swabs and saliva were used as viral sources. Manual testing (Quidel) was compared with automated testing (Beckman) methods for cost and efficiency. Limit dilution of viral antigen spiked samples was performed to determine sensitivity to antigen load by the tests. The results between the two tests were found to be concordant. Both tests were comparable in terms of detecting low numbers of positive subjects in the asymptomatic population. A concordance of 98% was observed between the two tests. Experiments also demonstrated that saliva specimens were an acceptable viral source and produced comparable results for each test. Overall, the two methods were interchangeable.
• Choudhery, M. S., Mahmood, R., Harris, D. T., & Ahmad, F. J. (2022). Minimum criteria for defining induced mesenchymal stem cells. Cell biology international, 46(6), 986-989.
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  Mesenchymal stem cells (MSCs) are a promising cell type for cell-based therapies. The therapeutic potential of MSCs has been verified in preclinical and clinical studies, however; low cell number in adult tissues, restricted expansion and differentiation capacity, and donor-related heterogeneity limit their use. To address these issues, there has been considerable interest in induced pluripotent stem cells (iPSCs) derived MSCs (induced mesenchymal stem cells [iMSCs]). Investigators obtain iMSCs from iPSCs of different origins, with variable methods of generation and expansion. Results of current studies have suggested iMSCs as a unique alternative source of MSCs. However, iMSCs are defined using the same criteria (proposed previously for primary MSCs by the International Society for Cellular Therapy [ISCT]) without realizing the distinct nature of iMSCs as compared to primary MSCs. To rationally define iMSCs, additional characterization is proposed along with ISCT's minimum criteria for defining primary MSCs. Minimum criteria for defining iMSCs should include (1) spindle-shaped morphology, (2) plastic adherent growth, (3) positive expression of CD29, CD44, CD73, CD90, CD105, along with negative expression of hematopoietic markers (CD45, CD34, CD14 or CD11b, CD79α or CD19, HLA-DR), (4) lack of expression of iPSCs induction factors, (5) trilineage differentiation potential, (6) lack of ability to form teratoma, and (7) release of MSC relevant paracrine factors. Defining the minimum criteria for iMSCs will be of great interest in the field and will provide a uniform description and identification of iMSCs to expedite progress in the field. Furthermore, due to increased interest in the clinical use of iMSCs, the above-mentioned additional characterization before the clinical application is important to avoid unwanted complications for recipients.
• Muise, A., White, L., Badowski, M., & Harris, D. T. (2022). Analysis of High-Throughput Processing Methods for Peripheral Blood Cell Isolation. Biopreservation and biobanking, 20(3), 302-305.
• Betancourt, W. Q., Schmitz, B. W., Innes, G. K., Prasek, S. M., Pogreba Brown, K. M., Stark, E. R., Foster, A. R., Sprissler, R. S., Harris, D. T., Sherchan, S. P., Gerba, C. P., & Pepper, I. L. (2021). COVID-19 containment on a college campus via wastewater-based epidemiology, targeted clinical testing and an intervention. The Science of the total environment, 779, 146408.
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  Wastewater-based epidemiology has potential as an early-warning tool for determining the presence of COVID-19 in a community. The University of Arizona (UArizona) utilized WBE paired with clinical testing as a surveillance tool to monitor the UArizona community for SARS-CoV-2 in near real-time, as students re-entered campus in the fall. Positive detection of virus RNA in wastewater lead to selected clinical testing, identification, and isolation of three infected individuals (one symptomatic and two asymptomatic) that averted potential disease transmission. This case study demonstrated the value of WBE as a tool to efficiently utilize resources for COVID-19 prevention and response. Thus, WBE coupled with targeted clinical testing was further conducted on 13 dorms during the course of the Fall semester (Table 3). In total, 91 wastewater samples resulted in positive detection of SARS-CoV-2 RNA that successfully provided an early-warning for at least a single new reported case of infection (positive clinical test) among the residents living in the dorm. Overall, WBE proved to be an accurate diagnostic for new cases of COVID-19 with an 82.0% positive predictive value and an 88.9% negative predictive value. Increases in positive wastewater samples and clinical tests were noted following holiday-related activities. However, shelter-in-place policies proved to be effective in reducing the number of daily reported positive wastewater and clinical tests. This case study provides evidence for WBE paired with clinical testing and public health interventions to effectively contain potential outbreaks of COVID-19 in defined communities.
• Harris, D. T., Badowski, M., Jernigan, B., Sprissler, R., Edwards, T., Cohen, R., Paul, S., Merchant, N., Weinkauf, C. C., Bime, C., Erickson, H. E., Bixby, B., Parthasarathy, S., Chaudhary, S., Natt, B., Cristan, E., El Aini, T., Rischard, F., Campion, J., , Chopra, M., et al. (2021). SARS-CoV-2 Rapid Antigen Testing of Symptomatic and Asymptomatic Individuals on the University of Arizona Campus. Biomedicines, 9(5).
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  SARS-CoV-2, the cause of COVID19, has caused a pandemic that has infected more than 80 M and killed more than 1.6 M persons worldwide. In the US as of December 2020, it has infected more than 32 M people while causing more than 570,000 deaths. As the pandemic persists, there has been a public demand to reopen schools and university campuses. To consider these demands, it is necessary to rapidly identify those individuals infected with the virus and isolate them so that disease transmission can be stopped. In the present study, we examined the sensitivity of the Quidel Rapid Antigen test for use in screening both symptomatic and asymptomatic individuals at the University of Arizona from June to August 2020. A total of 885 symptomatic and 1551 asymptomatic subjects were assessed by antigen testing and real-time PCR testing. The sensitivity of the test for both symptomatic and asymptomatic persons was between 82 and 90%, with some caveats.
• Zhao, R., Hernando, D., Harris, D. T., Hinshaw, L. A., Li, K., Ananthakrishnan, L., Bashir, M. R., Duan, X., Ghasabeh, M. A., Kamel, I. R., Lowry, C., Mahesh, M., Marin, D., Miller, J., Pickhardt, P. J., Shaffer, J., Yokoo, T., Brittain, J. H., & Reeder, S. B. (2021). Multisite multivendor validation of a quantitative MRI and CT compatible fat phantom. Medical physics, 48(8), 4375-4386.
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  Chemical shift-encoded magnetic resonance imaging enables accurate quantification of liver fat content though estimation of proton density fat-fraction (PDFF). Computed tomography (CT) is capable of quantifying fat, based on decreased attenuation with increased fat concentration. Current quantitative fat phantoms do not accurately mimic the CT number of human liver. The purpose of this work was to develop and validate an optimized phantom that simultaneously mimics the MRI and CT signals of fatty liver.
• Choudhery, M. S., & Harris, D. T. (2020). Stem cell therapy for COVID-19: Possibilities and challenges. Cell biology international, 44(11), 2182-2191.
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  Since its eruption in China, novel coronavirus disease (COVID-19) has been reported in most of the countries and territories (>200) of the world with ∼18 million confirmed cases (as of August 3, 2020). In most of the countries, COVID-19 upsurge is uncontrolled with a significant mortality rate. Currently, no treatment effective for COVID-19 is available in the form of vaccines or antiviral drugs and patients are currently treated symptomatically. Although the majority of the patients develop mild symptoms and recover without mechanical ventilation for respiratory management, severe respiratory illness develops in a significant portion of affected patients and may result in death. While the scientific community is working to develop vaccines and drugs against the COVID-19 pandemic, novel alternative therapies may reduce the mortality rate. Recent use of stem cells for critically ill COVID-19 patients in a small group of patients in China and subsequent Emergency Use Authorization of stem cells by Food and Drug Administration to Global Institute of Stem Cell Therapy and Research and Athersys has created excitement among the medical community. As a result, several clinical trials have been registered using stem cells for COVID-19 treatment that aim to use different cell sources, dosage, and importantly diverse targeted patient groups. In this brief review, the possibilities of stem cell use in COVID-19 patients and relevant challenges in their use have been discussed.
• Ripperger, T. J., Uhrlaub, J. L., Watanabe, M., Wong, R., Castaneda, Y., Pizzato, H. A., Thompson, M. R., Bradshaw, C., Weinkauf, C. C., Bime, C., Erickson, H. L., Knox, K., Bixby, B., Parthasarathy, S., Chaudhary, S., Natt, B., Cristan, E., Aini, T. E., Rischard, F., , Campion, J., et al. (2020). Detection, prevalence, and duration of humoral responses to SARS-CoV-2 under conditions of limited population exposure. medRxiv : the preprint server for health sciences.
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  We conducted an extensive serological study to quantify population-level exposure and define correlates of immunity against SARS-CoV-2. We found that relative to mild COVID-19 cases, individuals with severe disease exhibited elevated authentic virus-neutralizing titers and antibody levels against nucleocapsid (N) and the receptor binding domain (RBD) and the S2 region of spike protein. Unlike disease severity, age and sex played lesser roles in serological responses. All cases, including asymptomatic individuals, seroconverted by 2 weeks post-PCR confirmation. RBD- and S2-specific and neutralizing antibody titers remained elevated and stable for at least 2-3 months post-onset, whereas those against N were more variable with rapid declines in many samples. Testing of 5882 self-recruited members of the local community demonstrated that 1.24% of individuals showed antibody reactivity to RBD. However, 18% (13/73) of these putative seropositive samples failed to neutralize authentic SARS-CoV-2 virus. Each of the neutralizing, but only 1 of the non-neutralizing samples, also displayed potent reactivity to S2. Thus, inclusion of multiple independent assays markedly improved the accuracy of antibody tests in low seroprevalence communities and revealed differences in antibody kinetics depending on the viral antigen. In contrast to other reports, we conclude that immunity is durable for at least several months after SARS-CoV-2 infection.
• Ripperger, T. J., Uhrlaub, J. L., Watanabe, M., Wong, R., Castaneda, Y., Pizzato, H. A., Thompson, M. R., Bradshaw, C., Weinkauf, C. C., Bime, C., Erickson, H. L., Knox, K., Bixby, B., Parthasarathy, S., Chaudhary, S., Natt, B., Cristan, E., El Aini, T., Rischard, F., , Campion, J., et al. (2020). Orthogonal SARS-CoV-2 Serological Assays Enable Surveillance of Low-Prevalence Communities and Reveal Durable Humoral Immunity. Immunity, 53(5), 925-933.e4.
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  We conducted a serological study to define correlates of immunity against SARS-CoV-2. Compared to those with mild coronavirus disease 2019 (COVID-19) cases, individuals with severe disease exhibited elevated virus-neutralizing titers and antibodies against the nucleocapsid (N) and the receptor binding domain (RBD) of the spike protein. Age and sex played lesser roles. All cases, including asymptomatic individuals, seroconverted by 2 weeks after PCR confirmation. Spike RBD and S2 and neutralizing antibodies remained detectable through 5-7 months after onset, whereas α-N titers diminished. Testing 5,882 members of the local community revealed only 1 sample with seroreactivity to both RBD and S2 that lacked neutralizing antibodies. This fidelity could not be achieved with either RBD or S2 alone. Thus, inclusion of multiple independent assays improved the accuracy of antibody tests in low-seroprevalence communities and revealed differences in antibody kinetics depending on the antigen. We conclude that neutralizing antibodies are stably produced for at least 5-7 months after SARS-CoV-2 infection.
• Valori, V., Tus, K., Laukaitis, C., Harris, D. T., LeBeau, L., & Maggert, K. A. (2020). Human copy number is unstable in metastatic breast cancers. Epigenetics, 15(1-2), 85-106.
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  Chromatin-mediated silencing, including the formation of heterochromatin, silent chromosome territories, and repressed gene promoters, acts to stabilize patterns of gene regulation and the physical structure of the genome. Reduction of chromatin-mediated silencing can result in genome rearrangements, particularly at intrinsically unstable regions of the genome such as transposons, satellite repeats, and repetitive gene clusters including the rRNA gene clusters (). It is thus expected that mutational or environmental conditions that compromise heterochromatin function might cause genome instability, and diseases associated with decreased epigenetic stability might exhibit genome changes as part of their aetiology. We find the support of this hypothesis in invasive ductal breast carcinoma, in which reduced epigenetic silencing has been previously described, by using a facile method to quantify copy number in biopsied breast tumours and pair-matched healthy tissue. We found that and satellite DNA sequences had significant copy number variation - both losses and gains of copies - compared to healthy tissue, arguing that these genome rearrangements are common in developing breast cancer. Thus, any proposed aetiology onset or progression of breast cancer should consider alterations to the epigenome, but must also accommodate concomitant changes to genome sequence at heterochromatic loci.
• Badowski, M. S., Muise, A., & Harris, D. T. (2019). Long-Term Biobanking of Intact Tissue from Lipoaspirate. Journal of clinical medicine, 8(3).
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  Autologous fat grafting has now been extensively and successfully performed for more than two decades. Although most adipose grafts and adipose-derived MSC therapies are done with fresh tissue, cryopreservation of tissue allows for much greater flexibility of use. Over the course of five years, 194 cryopreserved adipose samples were thawed and then returned to the collecting physician for subsequent autologous applications. Samples were stored with a mean cryogenic storage time of 9.5 months, with some samples being stored as long as 44 months. The volumes of tissue stored varied from 12 cc to as large as 960 cc. Upon thawing, the volume of recovered whole adipose tissue averaged 67% of the original amount stored for all samples, while the samples that were stored for longer than one year averaged 71%. Recovery was not found to be a function of length of time in cryopreservation. No significant relationship was found between tissue recovery and patient age. While an average recovery of 67% of volume frozen indicates that the use of banked and thawed tissue requires a larger amount of sample to be taken from the patient initially, an experienced clinician easily accomplishes this requirement. As cryopreservation of adipose tissue becomes more commonplace, physicians will find it helpful to know the amount and quality of tissue that will be available after thawing procedures.
• Harris, D. T., & Israel, S. (2019). What will Become of the Taxpayer Investment in Public Cord Blood Stem Cell Banking?. Current stem cell research & therapy, 14(4), 367-372.
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  Cord Blood (CB) is a unique and readily available source of hematopoietic stem cells for transplantation. CB also contains other types of stem cells, including endothelial stem cells and mesenchymal stem cells, that may prove useful in non-traditional clinical uses. Genetic and molecular analyses have demonstrated that CB stem cells lie somewhere between mature stem cells like those found in Bone Marrow (BM), and fetal stem cells. After 25 years of clinical experience, CB is now used in the same fashion as BM for all typical malignant and genetic diseases treated by bone marrow transplant. Due to the establishment of CB banks in the US and abroad, more than 35,000 CB transplants have been performed over the past 25 years. An average of 700-800 CB transplants are performed annually. In addition, CB is now used more frequently for regenerative medicine and tissue engineering applications. At first glance, it seems that everything could not be better with the public cord blood banks and the use of their samples in the clinic. However, a recent report by the Rand Corp. reviewed the US national cord blood stem cell banking program and detailed many ongoing problems. However, some details were omitted from the report that would shed some light on the causes of many of the problems. This paper will summarize the status of the public cord blood stem cell banking program in the US, detail the problems associated with the program that could jeopardize its existence and suggest possible solutions to resolve these issues.
• Tus, K., Harris, D. T., Lebeau, L., Laukaitis, C. M., Valori, V., & Maggert, K. (2019). Human rDNA Copy Number Is Unstable in Developing Breast Cancers. Epigenetics.
• Harris, D. T. (2018). Biobanking and Omics. Frontiers in Biology. doi:10.1007/s11515-018-1505-3
• Harris, D. T. (2018). Biobanking and Regenerative Medicine: An Overview. Journal of Clinical Medicine, 7, 131-133. doi:10.3390/jcm7060131
• Harris, D. T. (2018). Biobanking and Regenerative Medicine: An Overview. Journal of clinical medicine, 7(6).
• Pandey, A. C., Lancaster, J. J., Harris, D. T., Goldman, S., & Juneman, E. (2017). Cellular Therapeutics for Heart Failure: Focus on Mesenchymal Stem Cells. Stem cells international, 2017, 9640108.
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  Resulting from a various etiologies, the most notable remains ischemia; heart failure (HF) manifests as the common end pathway of many cardiovascular processes and remains among the top causes for hospitalization and a major cause of morbidity and mortality worldwide. Current pharmacologic treatment for HF utilizes pharmacologic agents to control symptoms and slow further deterioration; however, on a cellular level, in a patient with progressive disease, fibrosis and cardiac remodeling can continue leading to end-stage heart failure. Cellular therapeutics have risen as the new hope for an improvement in the treatment of HF. Mesenchymal stem cells (MSCs) have gained popularity given their propensity of promoting endogenous cellular repair of a myriad of disease processes via paracrine signaling through expression of various cytokines, chemokines, and adhesion molecules resulting in activation of signal transduction pathways. While the exact mechanism remains to be completely elucidated, this remains the primary mechanism identified to date. Recently, MSCs have been incorporated as the central focus in clinical trials investigating the role how MSCs can play in the treatment of HF. In this review, we focus on the characteristics of MSCs that give them a distinct edge as cellular therapeutics and present results of clinical trials investigating MSCs in the setting of ischemic HF.
• Harris, D. T. (2016). Banking of Adipose- and Cord Tissue-Derived Stem Cells: Technical and Regulatory Issues. Advances in experimental medicine and biology, 951, 147-154.
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  Stem cells are found in all multicellular organisms and are defined as cells that can differentiate into specialized mature cells as well as divide to produce more stem cells. Mesenchymal stem cells (MSC) were among the first stem cell types to be utilized for regenerative medicine. Although initially isolated from bone marrow, based on ease and costs of procurement, MSC derived from adipose tissue (AT-MSC) and umbilical cord tissue (CT-MSC) are now preferred stem cell sources for these applications. Both adipose tissues and cord tissue present unique problems for biobanking however, in that these are whole tissues, not cellular suspensions. Although the tissues could be processed to facilitate the biobanking process, by doing so additional regulatory issues arise that must be addressed. This review will discuss the technical issues associated with biobanking of these tissues, as well as regulatory concerns when banking of utilizing MSC derived from these sources in the clinic.
• Al-Ghabani, S., Allen, M., Ussery, C., Badowski, M., Harris, D. T., & Herbst, K. (2018). Altered vasculature, increased macrophages and adipocyte hypertrophy in lipidema. Obesity.
• Ardila, D. C., Maestas, D., Liou, J., Slepian, M., Badowski, M., Harris, D. T., & Vande Geest, J. (2018). In vitro characterization of human cord blood-derived endothelial cells for vascular tissue engineering applications. Journal of Clinical Medicine.
• Choudhery, M. S., Badowski, M., Muise, A., & Harris, D. T. (2015). Effect of mild heat stress on the proliferative and differentiative ability of human mesenchymal stromal cells. Cytotherapy, 17(4), 359-68.
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  Mesenchymal stromal cells (MSCs) are an attractive candidate for autologous cell therapy, but regenerative potential can be compromised with extensive in vitro cell passaging. Development of viable cell therapies must address the effect of in vitro passaging to maintain overall functionality of expanded MSCs.
• Choudhery, M. S., Badowski, M., Muise, A., Pierce, J., & Harris, D. T. (2015). Subcutaneous Adipose Tissue-Derived Stem Cell Utility Is Independent of Anatomical Harvest Site. BioResearch open access, 4(1), 131-45.
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  One of the challenges for tissue engineering and regenerative medicine is to obtain suitably large cell numbers for therapy. Mesenchymal stem cells (MSCs) can easily be expanded in vitro to obtain large numbers of cells, but this approach may induce cellular senescence. The characteristics of cells are dependent on variables like age, body mass index (BMI), and disease conditions, however, and in the case of adipose tissue-derived stem cells (ASCs), anatomical harvest site is also an important variable that can affect the regenerative potential of isolated cells. We therefore had kept the parameters (age, BMI, disease conditions) constant in this study to specifically assess influence of anatomical sites of individual donors on utility of ASCs. Adipose tissue was obtained from multiple anatomical sites in individual donors, and viability and nucleated cell yield were determined. MSC frequency was enumerated using colony forming unit assay and cells were characterized by flow cytometry. Growth characteristics were determined by long-term population doubling analysis of each sample. Finally, MSCs were induced to undergo adipogenic, osteogenic, and chondrogenic differentiation. To validate the findings, these results were compared with similar single harvest sites from multiple individual patients. The results of the current study indicated that MSCs obtained from multiple harvest sites in a single donor have similar morphology and phenotype. All adipose depots in a single donor exhibited similar MSC yield, viability, frequency, and growth characteristics. Equivalent differentiation capacity into osteocytes, adipocytes, and chondrocytes was also observed. On the basis of results, we conclude that it is acceptable to combine MSCs obtained from various anatomical locations in a single donor to obtain suitably large cell numbers required for therapy, avoiding in vitro senescence and lengthy and expensive in vitro culturing and expansion steps.
• Corenblum, M. J., Flores, A. J., Badowski, M., Harris, D. T., & Madhavan, L. (2015). Systemic human CD34(+) cells populate the brain and activate host mechanisms to counteract nigrostriatal degeneration. Regenerative medicine, 10(5), 563-77.
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  Here we investigated the neuroprotective potential of systemic CD34(+) human cord blood cells (hCBCs) in a 6-hydroxydopamine rat model of Parkinson's disease.
• Harris, D. T. (2018). What will become of the taxpayer investment in public cord blood stem cell banking?. Current Stem Cell Research and Therapy.
• Harris, D. T., Badowski, M., Allen, M., Ussery, C., Cromer, W., AL-Ghadban, S., & Herbst, K. L. (2018). Dilated blood and lymphatic micro-vessels, angiogenesis, increased macrophages and adipocyte hypertrophy in lipedema thigh skin and fat tissue. Journal of Obesity.
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  Background: Lipedema is a common painful subcutaneous adipose tissue (SAT) disorder characterized by enlargement of fat primarily in the legs of women. Case reports of lipedema tissue samples demonstrate fluid and fibrosis in the interstitial matrix, increased macrophages and adipocyte hypertrophy. The aims of this project are to investigate blood vasculature, immune cells and structure of lipedema tissue in a cohort of women. Methods: Forty-nine participants, 19 controls and 30 with lipedema, were divided into groups based on body mass index (BMI): Non-Obese (BMI 20 to
• Lensch, M., Muise, A., White, L., Badowski, M., & Harris, D. T. (2018). Comparison of synthetic media for expansion of adipose-derived mesenchymal stromal cells. Biomedicines, 6, 54. doi:10.3390/biomedicines6020054
• Badowski, M., Muise, A., & Harris, D. T. (2014). Mixed effects of long-term frozen storage on cord tissue stem cells. Cytotherapy, 16(9), 1313-21.
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  Cord tissue (CT) storage is promoted as an opportunity to preserve a source of mesenchymal stromal cells (MSCs) for future use. We analyzed maximal MSC yields from fresh and frozen CT including functional capacity after long-term cryopreservation as a means of assessing potential utility.
• Badowski, M., Shultz, C. L., Eason, Y., Ahmad, N., & Harris, D. T. (2014). The influence of intrinsic and extrinsic factors on immune system aging. Immunobiology, 219(6), 482-5.
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  Sex and age-matched wild-type and TCR transgenic mice were infected with cytomegalovirus (CMV) at 6 months of age and followed for 12 additional months to examine aging of the immune system. It was found that viral infection of C57Bl/6 mice resulted in accelerated aging of the immune system as shown by a loss of CD8(+)28(+) cells and an accumulation of KLRG1(+) T cells. CMV infection of OT-1 transgenic mice had no influence on immune aging of these mice which nonetheless demonstrated an accumulation of CD8(+)28(-) and KLRG1(+) T cells with time. CD4(+) T cells were unaffected in either strain of mice. Thus, immunological aging was found to be due to both cell-intrinsic and cell-extrinsic factors. Persistent viral infections may accelerate immunological aging but consideration must be given to individual variation in the aging process.
• Badowski, M., Shultz, C., & Harris, D. T. (2014). WITHDRAWN: Effect of anti-coagulant choice on cord blood processing results. Cytotherapy.
• Choudhery, M. S., & Harris, D. T. (2014). Cryopreservation can be used as an anti-aging strategy. Cytotherapy, 16(12), 1771-3.
• Choudhery, M. S., Badowski, M., Muise, A., Pierce, J., & Harris, D. T. (2014). Cryopreservation of whole adipose tissue for future use in regenerative medicine. The Journal of surgical research, 187(1), 24-35.
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  Human adipose tissue (AT) is an ideal stem cell source for autologous cell-based therapies. The preferred setting for tissue engineering and regenerative medicine applications is the availability of clinically acceptable off-the-shelf cells and cell products. As AT is not always available for use, cryopreserved tissue represents an alternative approach. The aim of the present study was to compare the different properties of mesenchymal stem cells (MSCs) isolated from cryopreserved AT. We have measured cell recovery, viability, phenotype, proliferative potential, and differentiation into mesenchymal (adipogenic, osteogenic, chondrogenic) and nonmesenchymal (neuron-like cells) lineages.
• Choudhery, M. S., Badowski, M., Muise, A., Pierce, J., & Harris, D. T. (2014). Donor age negatively impacts adipose tissue-derived mesenchymal stem cell expansion and differentiation. Journal of translational medicine, 12, 8.
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  Human adipose tissue is an ideal autologous source of mesenchymal stem cells (MSCs) for various regenerative medicine and tissue engineering strategies. Aged patients are one of the primary target populations for many promising applications. It has long been known that advanced age is negatively correlated with an organism's reparative and regenerative potential, but little and conflicting information is available about the effects of age on the quality of human adipose tissue derived MSCs (hAT-MSCs).
• Harris, D. T. (2014). Stem Cell Banking for Regenerative and Personalized Medicine. Biomedicines, 2(1), 50-79.
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  Regenerative medicine, tissue engineering and gene therapy offer the opportunity to treat and cure many of today's intractable afflictions. These approaches to personalized medicine often utilize stem cells to accomplish these goals. However, stem cells can be negatively affected by donor variables such as age and health status at the time of collection, compromising their efficacy. Stem cell banking offers the opportunity to cryogenically preserve stem cells at their most potent state for later use in these applications. Practical stem cell sources include bone marrow, umbilical cord blood and tissue, and adipose tissue. Each of these sources contains stem cells that can be obtained from most individuals, without too much difficulty and in an economical fashion. This review will discuss the advantages and disadvantages of each stem cell source, factors to be considered when contemplating banking each stem cell source, the methodology required to bank each stem cell source, and finally, current and future clinical uses of each stem cell source.
• Harris, D. T., & Badowski, M. (2014). Long term human reconstitution and immune aging in NOD-Rag (-)-γ chain (-) mice. Immunobiology, 219(2), 131-7.
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  Aging of the human immune system is characterized by a gradual loss of immune function and a skewing of hematopoiesis toward the myeloid lineage, a reduction in the lymphocytic lineage, and progressive increases in senescent memory T cells at the expense of naïve T cells. Both the innate and the adaptive branches of the immune system are affected, including neutrophils, macrophages, dendritic cells and lymphocytes. Mice, the most common research model, although inexpensive, do not necessarily reflect the human immune system in terms of its interaction with infectious agents of human origin or environmental factors. This study analyzed whether a human immune system contained within the NOD-Rag (-)-γ chain (-) mouse model could realistically be used to evaluate the development and therapy of aging-related diseases. To that end lightly irradiated NOD-Rag (-)-γ chain (-) mice were injected intra-hepatically on day 1 of life with purified cord blood-derived CD34(+) stem and progenitor cells. Multiple mice were constructed from each cord blood donor. Mice were analyzed quarterly for age-related changes in the hematopoietic and immune systems, and followed for periods up to 18-24 months post-transplant. Flow cytometric analyses were performed for hematopoietic and immune reconstitution. It was observed that NOD-Rag (-)-γ chain (-) mice could be "humanized" long-term using cord blood stem cells, and that some evidence of immune aging occurred during the life of the mice.
• Li, H., Feng, Z., Tsang, T. C., Tang, T., Jia, X., He, X., Pennington, M. E., Badowski, M. S., Liu, A. K., Chen, D., Harris, D. T., Martinez, J., & Meade-Tollin, L. C. (2014). Fusion of HepG2 cells with mesenchymal stem cells increases cancer‑associated and malignant properties: an in vivo metastasis model. Oncology reports, 32(2), 539-47.
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  In the present study, we have tested the hypothesis that fusion between an altered cell and a mesenchymal stem cell produces a hybrid cell with enhanced characteristics associated with metastatic cancer cells, and we have developed a flexible model for investigating the mechanisms of metastasis. Human HepG2 cells with low metastatic potential were induced to fuse with rat bone marrow mesenchymal stem cells, and the progeny were compared with the parental cells for possession of enhanced in vitro and in vivo characteristics of malignant cells. Compared to the parental cells, the fused cells exhibited enhanced expression of E-cadherin, vimentin, Twist, Snail, matrix metalloproteinase 2 and 9 activities, aneuploidy and enhanced in vitro invasion and migration. In an in vivo xenograft assay, the fused cells generated increased numbers of metastatic liver and lung lesions. This model system is a flexible tool for investigation of the mechanisms of stem cell fusion in carcinogenesis and metastasis and for the discovery of new therapeutic targets to inhibit metastasis.
• Choudhery, M. S., Badowski, M., Muise, A., & Harris, D. T. (2013). Comparison of human mesenchymal stem cells derived from adipose and cord tissue. Cytotherapy, 15(3), 330-43.
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  Stem cell therapies can provide an alternative approach for repair and regeneration of tissues and organs. Mesenchymal stem cells (MSCs) are promising candidates for cell-based therapies. Although bone marrow-derived MSCs have multi-lineage differentiation potential, bone marrow is not an optimal source because of the isolation process and low yield. The goal of this study was to investigate comparatively for the first time the in vitro regenerative potential of human MSCs from two other sources: umbilical cord tissue and adipose tissue.
• Harris, D. T. (2013).

  Autologous cord blood infusions for the treatment of pediatric neurological conditions

  . Journal of Cell Science and Therapy. doi:10.4172/2157-7013.s1.002
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  C palsy (CP) is a devastating brain disorders that affects many children worldwide. In addition, for unexplained reasons many children suffer strokes both in and ex utero. Stem cells have the capacity to generate new cells to replace those lost through injury, and have shown promise in animal models of CP and stroke. This presentation will summarize the pre-clinical data for use of cord blood (CB) stem cells for the treatment of these conditions. In addition, case studies will be presented of multiple pediatric patients that have undergone autologous CB stem cell infusions to treat these conditions (CP and stroke), as well as drowning and neurological-based hearing loss. Conditions affecting beneficial outcome will be discussed as well as uses of CB stem cells for other regenerative medicine applications.
• Harris, D., & Harris, D. T. (2013). Alterations in target cell membrane phospholipids alter T cell but not NK cell killing. Immunobiology, 218(1).
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  The ability of tumor cells to grow progressively in vivo despite the host immune response remains a major conundrum in tumor immunology. Various mechanisms have been proposed to explain how tumors evade immune destruction. The work presented herein shows that simple alterations in plasma membrane phospholipid composition can alter susceptibility to immune lysis. The phospholipid composition of target cells was specifically altered by growth in medium containing choline analogs. Manipulation of membrane phospholipids was observed to alter cell susceptibility to murine CTL but not NK cell lysis. The effects of such changes in phospholipid composition on CTL-mediated lysis appeared to occur during the recognition phase of lysis. This mechanism could be a means by which tumor cells, as well as other pathogenic organisms, escape immune detection and destruction.
• Harris, D., & Harris, D. T. (2013). Umbilical cord tissue mesenchymal stem cells: characterization and clinical applications. Current stem cell research & therapy, 8(5).
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  Umbilical cord tissue (CT) can provide a virtually unlimited source of multipotent mesenchymal stem cells (MSC) that can potentially be used in a variety of regenerative medicine and tissue engineering applications. Cord tissue segments can be frozen and preserved in liquid nitrogen dewars for prolonged periods of time, having been frozen in time at the peak of biological activity. CT stem cells are capable of giving rise to various mesenchymal and non-mesenchymal cell lineages including bone, cartilage, fat and neurons. Thus, CT stem cells are candidates to develop stem cell-based therapies for a wide variety of diseases including cardiovascular, ophthalmic, orthopedic and neurological applications. CT is currently being used in several regenerative medicine clinical studies, examples of which include treatment of graftversus- host disease and non-healing bone fractures. CT represents an additional source of stem cells that have both immediate and future applications for the individual donor.
• Harris, D., Choudhery, M. S., Badowski, M., Muise, A., & Harris, D. T. (2013). Utility of cryopreserved umbilical cord tissue for regenerative medicine. Current stem cell research & therapy, 8(5).
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  MSCs can be isolated from adult sources such as bone marrow and adipose tissue. In contrast to these adult tissue sources, harvesting MSCs from cord tissue is a non-invasive procedure and poses no risk to the donor. Stem cell banks offer the opportunity to cryopreserve cord tissue as a source of MSCs for future autologous or allogeneic stem cell based regenerative medicine applications. There is little published data however, characterizing MSCs isolated from cryopreserved cord tissue. The goal of this study was to determine if MSCs isolated from cryopreserved cord tissue are functionally equivalent to MSCs isolated from fresh cord tissue. Umbilical cords were collected from 10 donors. Cords were segmented into 4-6 inch pieces and either cryopreserved or used immediately. Fresh and thawed cord segments were cultured in 7-14 days for outgrowth of MSCs. MSCs were analyzed by FACS for CD45, CD73, CD90 and CD105 expression. FACs analysis confirmed cells isolated from both fresh and frozen tissue expressed MSC markers. Adherent cells were obtained from both fresh and cryopreserved cord tissue segments at a similar plating efficiency. There was no difference in either the number or time of population doublings. MSCs isolated from fresh and frozen tissue were capable of differentiating along adipogenic, chondrogenic, osteogenic and neurogenic pathways, as confirmed by histology and RT-PCR analysis of tissue specific mRNAs. No significant functional differences were observed between MSCs from frozen cord tissue as compared to fresh cord tissue. Cryopreserving cord tissue allows for isolation of MSCs at the point of care when the specific clinical application is known. This may be advantageous as MSC isolation protocols continue to be optimized dependent on intended use.
• Harris, D. T. (2012). Is volume the only factor that impacts cord blood processing efficiency?. Cytotherapy, 14(8), 1022-3.
• Harris, D. T., Hilgaertner, J., Simonson, C., Ablin, R. J., & Badowski, M. (2012). Cell-based therapy for epithelial wounds. Cytotherapy, 14(7), 802-10.
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  Bone marrow-derived cells (BMDC) form a significant portion of regenerating epithelial tissue. The purpose of this study was to determine whether exogenous BMDC (containing stroma, stem and progenitor cells), introduced systemically or within the injury site, could enhance the injury repair response.
• Harris, D., & Harris, D. T. (2012). Changes in plasma membrane phospholipids inhibit antibody-mediated lysis. Biochemical and biophysical research communications, 417(1).
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  A variety of mechanisms have been proposed to explain how tumors evade immune destruction. This work has identified one such mechanism that determines susceptibility to immune lysis; membrane phospholipid composition altered susceptibility to antibody plus complement (Ab+C)-mediated lysis. Effects on antibody plus complement-mediated lysis were correlated with levels of major histocompatibility complex (MHC) molecules but not inherent resistance to complement damage. This cellular mechanism could be a means by which tumor cells escape immune detection and destruction.
• Harris, D., & Harris, D. T. (2012). Optimizing cord blood sample cryopreservation. Cytotherapy, 14(3).
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  Cord blood (CB) banking is becoming more and more commonplace throughout the medical community, both in the USA and elsewhere. It is now generally recognized that storage of CB samples in multiple aliquots is the preferred approach to banking because it allows the greatest number of uses of the sample. However, it is unclear which are the best methodologies for cryopreservation and storage of the sample aliquots. In the current study we analyzed variables that could affect these processes.
• Harris, D., Badowski, M. S., & Harris, D. T. (2012). Collection, processing, and banking of umbilical cord blood stem cells for transplantation and regenerative medicine. Methods in molecular biology (Clifton, N.J.), 879.
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  Collection and banking of umbilical cord blood can provide a virtually unlimited source of ethnically diverse stem cell donors. It can be used in place of bone marrow or peripheral blood stem cells for hematologic transplants as well as in a variety of regenerative medicine applications. In this study, we review the latest developments in cord blood banking. We have banked over 300,000 collections at our facility, which were processed by either Ficoll or AXP methodologies. An average 95-99% processing efficiency was obtained. Processed samples can be frozen in either cryovials or bags and banked in the vapor phase of a liquid nitrogen dewar for prolonged periods of time. In conclusion, it is possible to simply and reproducibly harvest, process, and bank cord blood samples using currently available technology.
• Harris, D., Ahmad, N., Mehta, R., & Harris, D. T. (2011). HIV-1 replication and gene expression occur at higher levels in neonatal blood naive and memory T-lymphocytes compared with adult blood cells. Virology, 413(1).
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  Our previous study has shown that HIV-1 replicated at higher levels in neonatal (cord) blood monocytes/macrophages and T-lymphocytes compared with adult blood cells. However, it is not known whether this differential HIV-1 replication also occurs in naive and/or memory T-lymphocytes. We, therefore, compared HIV-1 replication in CD3(+) and CD4(+) naive (CD45RA(+)) and memory (CD45RO(+)) T-lymphocytes isolated from five cord and adult blood donors. We found that HIV-1 replicated at higher levels in both CD3(+) and CD4(+) CD45RA(+) and CD45RO(+) T-lymphocytes isolated from cord blood compared with adult blood. In addition, there was no difference in the cell surface expression of CD4, CXCR4 and CCR5 on cord blood CD45RA(+) and CD45RO(+) T-lymphocytes compared with adult blood cells. Furthermore, we found that there was an increase in HIV-1 gene expression in cord blood CD45RA(+) and CD45RO(+) T-lymphocytes compared with adult blood cells by using a single-cycle replication competent HIV-1-NL4-3-Env(-)R(+) luciferase amphotropic virus, which measures HIV-1 transcriptional activity independent of CD4 and CXCR4 or CCR5 expression. In summary, HIV-1 replicated at higher levels in cord blood CD45RA(+) and CD45RO(+) T-lymphocytes compared with adult blood cells and this differential replication is influenced at the level of HIV-1 gene expression.
• Harris, D., Hilgaertner, J. W., He, X., Camacho, D., Badowski, M., Witten, M., & Harris, D. T. (2011). The influence of hydrocarbon composition and exposure conditions on jet fuel-induced immunotoxicity. Toxicology and industrial health, 27(10).
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  Chronic jet fuel exposure could be detrimental to the health and well-being of exposed personnel, adversely affect their work performance and predispose these individuals to increased incidences of infectious disease, cancer and autoimmune disorders. Short-term (7 day) JP-8 jet fuel exposure has been shown to cause lung injury and immune dysfunction. Physiological alterations can be influenced not only by jet fuel exposure concentration (absolute amount), but also are dependent on the type of exposure (aerosol versus vapor) and the composition of the jet fuel (hydrocarbon composition). In the current study, these variables were examined with relation to effects of jet fuel exposure on immune function. It was discovered that real-time, in-line monitoring of jet fuel exposure resulted in aerosol exposure concentrations that were approximately one-eighth the concentration of previously reported exposure systems. Further, the effects of a synthetic jet fuel designed to eliminate polycyclic aromatic hydrocarbons were also examined. Both of these changes in exposure reduced but did not eliminate the deleterious effects on the immune system of exposed mice.
• Nietfeld, J. J., & Harris, D. T. (2010). Cost-effectiveness of private umbilical cord blood banking. Obstetrics and gynecology, 115(5), 1090.
• Sundaravaradan, V., Mehta, R., Harris, D. T., Zack, J. A., & Ahmad, N. (2010). Differential expression and interaction of host factors augment HIV-1 gene expression in neonatal mononuclear cells. Virology, 400(1), 32-43.
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  We have previously shown a higher level of HIV-1 replication and gene expression in neonatal (cord) blood mononuclear cells (CBMC) compared with adult blood cells (PBMC), which could be due to differential expression of host factors. We performed the gene expression profile of CBMC and PBMC and found that 8013 genes were expressed at higher levels in CBMC than PBMC and 8028 genes in PBMC than CBMC, including 1181 and 1414 genes upregulated after HIV-1 infection in CBMC and PBMC, respectively. Several transcription factors (NF-kappaB, E2F, HAT-1, TFIIE, Cdk9, Cyclin T1), signal transducers (STAT3, STAT5A) and cytokines (IL-1beta, IL-6, IL-10) were upregulated in CBMC than PBMC, which are known to influence HIV-1 replication. In addition, a repressor of HIV-1 transcription, YY1, was down regulated in CBMC than PBMC and several matrix metalloproteinase (MMP-7, -12, -14) were significantly upregulated in HIV-1 infected CBMC than PBMC. Furthermore, we show that CBMC nuclear extracts interacted with a higher extent to HIV-1 LTR cis-acting sequences, including NF-kappaB, NFAT, AP1 and NF-IL6 compared with PBMC nuclear extracts and retroviral based short hairpin RNA (shRNA) for STAT3 and IL-6 down regulated their own and HIV-1 gene expression, signifying that these factors influenced differential HIV-1 gene expression in CBMC than PBMC.
• Harris, D., & Harris, D. T. (2009). Non-haematological uses of cord blood stem cells. British journal of haematology, 147(2).
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  Embryonic stem (ES) cell therapies are often promoted as the optimal stem cell source for regenerative medicine applications because of their ability to develop into any tissue in the body. Unfortunately, ES cell applications are currently limited by ethical, political, biological and regulatory hurdles. However, multipotent non-ES cells are available in large numbers in umbilical cord blood (CB). CB stem cells are capable of giving rise to hematopoietic, epithelial, endothelial and neural tissues both in vitro and in vivo. Thus, CB stem cells are amenable to treat a wide variety of diseases including cardiovascular, ophthalmic, orthopaedic, neurological and endocrine diseases. In addition, the recent use of CB in several regenerative medicine clinical studies has demonstrated its pluripotent nature. Here we review the latest developments in the use of CB in regenerative medicine. Examples of these usages include cerebral palsy and type I diabetes. The numbers of individuals affected with each of these diseases are estimated at 10 000 infants diagnosed with cerebral palsy annually and 15 000 youths diagnosed with type 1 diabetes annually. A summary of the initial results from such clinical studies using autologous cord blood stem cells will be presented.
• Harris, D., Badowski, M. S., Zhang, T., Tsang, T. C., & Harris, D. T. (2009). Chimeric antigen receptors for stem cell based immunotherapy. Journal of experimental therapeutics & oncology, 8(1).
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  The retargeting of lymphocytes is an important new strategy in immunotherapy of cancer. One can currently isolate naturally refined, high affinity specificities from antibodies and T-cell receptors (TCRs) to use in engineered applications. We have developed two new molecules that have specificity for the overexpressed tumor antigen HER2/neu. The specificity derived from an anti-HER2 antibody variable fragment was used to create a single chain Fv (scFv). A HER2 reactive TCR was also used to develop a single chain TCR (scTCR). The HER2 binding elements were linked to an intracellular signaling module, active only in the T cell signaling pathway, providing a novel molecule to retarget lymphocytes. We demonstrate here that these molecules can be expressed in several cell lines as well as in hematopoietic stem cells (HSCs). In a transplant setting, these new receptors can be expressed in multiple cells types derived from repopulating HSCs. These new chimeric receptors will be valuable tools for further research of immune function of retargeted hematopoietic cells.
• Wellensiek, B. P., Ramakrishnan, R., Sundaravaradan, V., Mehta, R., Harris, D. T., & Ahmad, N. (2009). Differential HIV-1 integration targets more actively transcribed host genes in neonatal than adult blood mononuclear cells. Virology, 385(1), 28-38.
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  We have recently shown an increased HIV-1 replication and gene expression in neonatal (cord) blood mononuclear cells compared with adult cells, which could be due to HIV-1 integration as it targets active host genes. Here we have characterized 468 HIV-1 integration sites within cord and adult blood T-lymphocytes and monocyte-derived macrophages (MDM) from five donors. Several functional classes of genes were identified by gene ontology to be over represented, including genes for cellular components, maintenance of intracellular environment, enzyme regulation, cellular metabolism, catalytic activity and cation transport. Numerous potential transcription factor binding sites at the sites of integration were identified. Furthermore, the genes at the site of integration, transcription factors which potentially bind upstream of the HIV-1 promoter and factors that assist HIV-1 integration were found to be expressed at higher levels in cord than adult cells. Taken together, these results suggest HIV-1 integration occurred in a more actively transcribed genes in neonatal cells compared with adult cells, which may help explain a higher level of HIV-1 gene expression and replication in neonatal compared with adult cells.
• Harris, D. T. (2008). Cord blood stem cells: worth the investment. Nature reviews. Cancer, 8(10), 823; author reply 823.
• Harris, D., & Harris, D. T. (2008). Cord blood stem cells: a review of potential neurological applications. Stem cell reviews, 4(4).
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  It is estimated that as many as 128M individuals in the United States, or 1 in 3 people, might benefit from regenerative medicine therapy. Many of these usages include applications that affect the nervous system, including cerebral palsy, stroke, spinal cord injury and neurodegenerative disease such as Parkinson's. The numbers of such individuals affected range from 10,000 (for cerebral palsy) to 700,000 annually (for stroke) at a cost of more than $65B. For the foreseeable future, regenerative medicine entrée to the clinic will depend upon the development of adult or non-embryonic stem (ES) cell therapies. Currently, non-ES cells easily available in large numbers from affected individuals can be found in the bone marrow, adipose tissue and umbilical cord blood (CB). It is our belief that CB stem cells are the best alternative to ES cells as these stem cells can be used to derive tissues from the mesodermal, endodermal and ectodermal germ lineages. CB contains a mixture of different types of stem cells in numbers not seen in any other location including embryonic-like stem cells, hematopoietic stem cells, endothelial stem cells, epithelial stem cells, mesenchymal stem cells and unrestricted somatic stem cells. This review will summarize the findings reported in the literature with regards to the use of CB stem cells to neurological applications including in vitro work, pre-clinical animal studies, and patient clinical trials.
• Cohen-Barak, O., Erickson, D. T., Badowski, M. S., Fuchs, D. A., Klassen, C. L., Harris, D. T., & Brilliant, M. H. (2007). Stem cell transplantation demonstrates that Sox6 represses epsilon y globin expression in definitive erythropoiesis of adult mice. Experimental hematology, 35(3), 358-67.
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  Sox6, a member of the Sox transcription factor family, is essential for the silencing of epsilon y globin gene expression in definitive erythropoiesis of mice. Homozygous Sox6-null mice are neonatally lethal, precluding analysis at later stages. We created adult mice that are deficient in Sox6 specifically in hematopoietic tissues by transplanting embryonic liver stem cells from Sox6-deficient mice into lethally irradiated congenic wild-type adult mice. The mice receiving mutant stem cells (mutant engrafted) showed high expression levels of epsilon y in bone marrow, spleen, and circulating blood compared with mice receiving wild-type and heterozygous stem cells (control engrafted). The level of expression of epsilon y in circulating blood was directly correlated with the percentage of successful mutant donor cell engraftment. Additionally, the mutant engrafted adult mice showed an increase in erythroid precursor cells in bone marrow, spleen, and blood. Thus, Sox6 continues to function as a major regulator of epsilon y in adult definitive erythropoiesis and is required for normal erythrocyte maturation. Therefore, Sox6 may provide a novel therapeutic target by reactivating epsilon y in patients with hemoglobinopathies such as sickle cell anemia and beta-thalassemia.
• Harris, D. T., & Rogers, I. (2007). Umbilical cord blood: a unique source of pluripotent stem cells for regenerative medicine. Current stem cell research & therapy, 2(4), 301-9.
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  It is estimated that almost 1 in 3 individuals in the United States might benefit from regenerative medicine therapy. Unfortunately, embryonic stem (ES) cell therapies are currently limited by ethical, political, biological and regulatory hurdles. Thus, for the foreseeable future, the march of regenerative medicine to the clinic will depend upon the development of non-ES cell therapies. Current sources of non-ES cells easily available in large numbers can be found in the bone marrow, adipose tissue and umbilical cord blood. Each of these types of stem cells has already begun to be utilized to treat a variety of diseases. This review will show that cord blood (CB) contains multiple populations of ES-like and other pluripotential stem cells, capable of giving rise to hematopoietic, epithelial, endothelial, and neural tissues both in vitro and in vivo. Cumulatively, the identification and isolation of these populations of pluripotent stem cells within cord blood represents a scientific breakthrough that could potentially impact every field of medicine, via their use in regenerative medicine. Thus, CB stem cells are amenable to treatment of a wide variety of diseases including cardiovascular, hepatic, ophthalmic, orthopaedic, neurological and endocrine diseases.
• Harris, D. T., Badowski, M., Ahmad, N., & Gaballa, M. A. (2007). The potential of cord blood stem cells for use in regenerative medicine. Expert opinion on biological therapy, 7(9), 1311-22.
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  It is estimated that up to 128 million individuals might benefit from regenerative medicine therapy, or almost 1 in 3 individuals in the US. If accurate, the need to relieve suffering and reduce healthcare costs is an enormous motivator to rapidly bring stem cell therapies to the clinic. Unfortunately, embryonic stem (ES) cell therapies are limited at present by ethical and political constraints and, most importantly, by significant biologic hurdles. Thus, for the foreseeable future, the march of regenerative medicine to the clinic will depend on the development of non-ES cell therapies. At present, non-ES cells easily available in large numbers can be found in the bone marrow, adipose tissue and umbilical cord blood (CB). Each of these stem cells is being used to treat a variety of diseases. This review shows that CB contains multiple populations of pluripotent stem cells, and can be considered the best alternative to ES cells. CB stem cells are capable of giving rise to hematopoietic, epithelial, endothelial and neural tissues both in vitro and in vivo. Thus, CB stem cells are amenable to treat a wide variety of diseases including cardiovascular, ophthalmic, orthopedic, neurologic and endocrine diseases.
• Harris, D. T., Sakiestewa, D., Titone, D., & Witten, M. (2007). JP-8 jet fuel exposure rapidly induces high levels of IL-10 and PGE2 secretion and is correlated with loss of immune function. Toxicology and industrial health, 23(4), 223-30.
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  The US Air Force has implemented the widespread use of JP-8 jet fuel in its operations, although a thorough understanding of its potential effects upon exposed personnel is unclear. Previous work has demonstrated that JP-8 exposure is immunosuppressive. In the present study, the potential mechanisms for the effects of JP-8 exposure on the immune system were investigated. Exposure of mice to JP-8 for 1 h/day resulted in immediate secretion of two immunosuppressive agents; namely, interleukin-10 (IL-10) and prostaglandin E2 (PGE2). JP-8 exposure rapidly induced a persistently high level of serum IL-10 and PGE2 at an exposure concentration of 1000 mg/m3. IL-10 levels peaked at 2 h post-JP-8 exposure and then stabilized at significantly elevated serum levels, while PGE2 levels peaked after 2-3 days of exposure and then stabilized. Elevated IL-10 and PGE2 levels may at least partially explain the effects of JP-8 exposure on immune function. Elevated IL-10 and PGE2 levels, however, cannot explain all of the effects due to JP-8 exposure (e.g., decreased organ weights and decreased viable immune cells), as treatment with a PGE2 inhibitor did not completely reverse the immunosuppressive effects of jet fuel exposure. Thus, low concentration JP-8 jet fuel exposures have significant effects on the immune system, which can be partially explained by the secretion of immunosuppressive modulators, which are cumulative over time.
• Harris, D., Davis, A. H., Jianhua Wang, ., Tsang, T. C., & Harris, D. T. (2007). Direct sequencing is more accurate and feasible in detecting single nucleotide polymorphisms than RFLP: using human vascular endothelial growth factor gene as a model. Biological research for nursing, 9(2).
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  Since the sequencing of the human genome, there has been increased interest in understanding the distribution and effects of genetic variations among individuals. Restriction fragment length polymorphism (RFLP) is a well-established and frequently used method for genotyping. This method, however, is indirect and has a number of limitations. It is thus important to reevaluate the use of RFLP in light of more contemporary methods of genotyping. The specific aims of this study are to (a) compare genotyping methods of traditional RFLP with contemporary direct sequencing for accurate identification of polymorphisms within the human vascular endothelial growth factor (VEGF) gene and (b) describe distribution of a known single nucleotide polymorphism (SNP) in the VEGF gene in a sample composed of 50 healthy volunteers. Polymerase chain reaction (PCR) was used to amplify the initial sample of DNA. Genotypes of a G-to-A substitution (GG, AG, AA) at -1154 were analyzed by RFLP and direct sequencing. RFLP was unable to discriminate among the three possible genotypes, whereas direct sequencing clearly identified genotype for all 50 samples. Observed genotype frequencies were comparable with the Hardy-Weinberg principle. This comparative study provides justification for selecting direct sequencing instead of RFLP for detecting SNPs in selected genes.
• Lister, J., Gryn, J. F., McQueen, K. L., Harris, D. T., Rossetti, J. M., & Shadduck, R. K. (2007). Multiple unit HLA-unmatched sex-mismatched umbilical cord blood transplantation for advanced hematological malignancy. Stem cells and development, 16(1), 177-86.
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  We investigated the effect of multiple-unit umbilical cord blood (UCB) transplantation on engraftment in the setting of severe human leukocyte antigen (HLA) mismatch. Ten poor-risk adult patients with hematological malignancy received multiple unit, HLA-unmatched, sex-mismatched, unrelated UCB transplantation after a reduced intensity-conditioning regimen (RICR) with engraftment as the primary endpoint. The median age of the patients was 55 years with a range of 28-67. Patients received one unit of UCB per 10 kg of recipient body weight (5-7 units). The median number of nucleated cells and CD34(+) cells per kilogram of recipient body weight infused was 6.3 x 10(7) (range 3.8-10.0) (NC/kg) and 5.7 x 10(5) (range 1.1-11.9) (CD34/kg), respectively. Three patients expired before day 28 and were not evaluable for engraftment. Five of the remaining 7 patients showed increasing neutrophil counts. Fluorescent in situ hybridization (FISH) for the Y chromosome or HLA-typing showed only donor cells in the peripheral blood. After engraftment, HLA typing was done on 3 patients and their infused UCB units. All revealed the presence of a single HLA type concordant with one of the infused units. Moreover, the order of infusion did not influence which UCB unit engrafted. The engrafting UCB units were infused first or second in one case and fourth in the other two. One patient transplanted for refractory acute lymphoblastic leukemia (ALL) survives in continuous complete remission 4 years after transplant. He engrafted with one UCB unit, is fully hematologically reconstituted, has no evidence of graft-versus-host disease (GVHD), and takes no immunosuppressive medication. HLA typing reveals that the recipient and the engrafted cord blood match at only one HLA-B locus using conventional 6 antigen typing (A, B, and DR). Although engraftment was not accelerated, it did occur in the majority of evaluable patients. Long-term disease-free survivorship without debilitating GVHD is possible in patients with refractory hematological malignancy who receive unmatched multiple unit UCB.
• Harris, D., Dammeyer, P., Jaramillo, M. C., Pipes, B. L., Badowski, M. S., Tsang, T. C., & Harris, D. T. (2006). Heat-inducible amplifier vector for high-level expression of granulocyte-macrophage colony-stimulating factor. International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group, 22(5).
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  In cytokine immunotherapy of cancer it is critical to deliver sufficiently high local cytokine concentrations in order to reach the therapeutic threshold needed for clinical efficacy. Simultaneously, for optimal clinical safety adverse effects caused by high systemic cytokine levels must be minimized. One of the most promising anti-cancer therapeutic cytokines, granulocyte-macrophage colony-stimulating factor (GM-CSF), has elicited anti-tumour immune responses in animal studies and clinical trials. However, the clinical efficacy has been limited, with local GM-CSF levels being therapeutically insufficient and systemic toxicity being a limiting factor.
• Harris, D., Pipes, B. L., Tsang, T., Peng, S., Fiederlein, R., Graham, M., & Harris, D. T. (2006). Telomere length changes after umbilical cord blood transplant. Transfusion, 46(6).
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  The establishment of donor-derived hematopoiesis in the recipients of hematopoietic stem cell (HSC) transplants involves extensive proliferation and differentiation of HSCs. Data from long-term survivors of HSC transplants suggest that these transplanted HSCs may experience a debilitating replicative senescence. A significant posttransplant shortening of peripheral blood mononuclear cell (PBMNC) telomeres has been observed in both marrow transplant and peripheral blood progenitor cell transplant recipients. Similar studies have not been performed for umbilical cord blood (UCB) HSC transplants, which might be expected to exhibit increased posttransplant replicative potential due to their inherently greater telomere length.
• Sundaravaradan, V., Saxena, S. K., Ramakrishnan, R., Yedavalli, V. R., Harris, D. T., & Ahmad, N. (2006). Differential HIV-1 replication in neonatal and adult blood mononuclear cells is influenced at the level of HIV-1 gene expression. Proceedings of the National Academy of Sciences of the United States of America, 103(31), 11701-6.
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  The majority of HIV-1-infected neonates and infants have a higher level of viremia and develop AIDS more rapidly than infected adults, including differences seen in clinical manifestations. To determine the mechanisms of HIV-1 infection in neonates vs. adults, we compared the replication kinetics of HIV-1 in neonatal (cord) and adult blood T lymphocytes and monocyte-derived macrophages (MDM) from seven different donors. We found that HIV-1 replicated 3-fold better in cord blood T lymphocytes compared with adult blood T lymphocytes and 9-fold better in cord MDM than adult MDM. We also show that this differential HIV-1 replication did not depend on differences in cell proliferative capabilities, cell surface expression of CD4, CXCR4, and CCR5, or in the amount of PCR products of reverse transcription, DNA synthesis, and translocation of preintegration complex into the nucleus in cord and adult T lymphocytes and MDM. Furthermore, using a single-cycle replication competent HIV-1-NL4-3-Env(-) luciferase amphotropic virus, which measures HIV-1 transcriptional activity independent of receptor and coreceptor expression, we found there was a 3-fold increase of HIV-1 LTR-driven luciferase expression in cord T lymphocytes compared with adult T lymphocytes and 10-fold in cord MDM than in adult MDM. The HIV-1 LTR-driven luciferase expression correlated with HIV-1 LTR transcription, as measured by ribonuclease protection assay. These data suggest that the increased replication of HIV-1 in cord blood compared with adult blood mononuclear cells is regulated at the level of HIV-1 gene expression, resulting in a higher level of viremia and faster disease progression in neonates than adults.
• Harris, D., He, X., Gonzalez, V., Tsang, A., Thompson, J., Tsang, T. C., & Harris, D. T. (2005). Differential gene expression profiling of CD34+ CD133+ umbilical cord blood hematopoietic stem progenitor cells. Stem cells and development, 14(2).
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  Umbilical cord blood (CB)-derived primitive hematopoietic stem progenitor cells (HSPC) are a promising source for stem cell-based gene therapy due to the reduced incidence and severity of graftversus- host disease (GVHD) after human leukocyte antigen (HLA)-disparate CB transplantation. Cell-surface markers such as CD34 and CD133 have been used in combination to enrich primitive HSPC for research and clinical applications. To understand the molecular characteristics of the CB HSPC, we compared the global gene expression of freshly isolated CB CD34+ CD133+ cells with their progenies using a cDNA microarray containing 22,000 human cDNA clones printed on a single chip. A total of 139 genes were differentially expressed between CB HSPC and their progenies. These transcripts included a number of known genes that might play roles in key functions of CB HSPC as well as many genes of unknown function. Among the genes showing the greatest differential expression levels in HSPC were: psoriasin 1, CRHBP, HDAC3, MLLT3, HBEX2, SPINK2, c-kit, H2BFQ, CD133, HHEX, TCF4, ALDH1A1, and FHL1. These data provide more information on the molecular phenotype of CB HSPC and may lead to the identification of new genes critical to stem cell function.
• Harris, D., He, X., Luo, P., Tsang, T. C., Zhang, T., & Harris, D. T. (2005). Immuno-gene therapy of melanoma by tumor antigen epitope modified IFN-gamma. Cancer immunology, immunotherapy : CII, 54(8).
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  Cytokine-based vaccines play a major part in tumor immuno-gene therapy. However, down-regulated antigen expression on tumor cells may diminish the immuno-potentiating aspects of cellular vaccines. In this study, we coexpressed a tumor antigen epitope with IFN-gamma in the same gene by replacing the IFN-gamma signal peptide with an antigen epitope-expressing signal peptide. We then investigated the effect of the antigen epitope-incorporated IFN-gamma on the immunotherapy of murine melanoma B16 tumors. Results showed that TRP-2 epitope-expressing IFN-gamma decreased B16 tumorigenicity and enhanced its immunogenicity after gene transfer. Protective immunity against wild type B16 tumors was induced by vaccination with IFN-gamma transiently gene-modified tumor cells. These data suggest that cellular vaccines engineered to express an antigen epitope within an immunostimulatory cytokine could potentiate the immunization effect.
• Harris, D., He, X., Tsang, T. C., Pipes, B. L., Ablin, R. J., & Harris, D. T. (2005). A stem cell fusion model of carcinogenesis. Journal of experimental therapeutics & oncology, 5(2).
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  The origin of cancer remains enigmatic. Current models of carcinogenesis based on the gene mutation hypothesis have limitations in explaining many aspects of cancer. We put forward a new model of multistage carcinogenesis and propose that cancer development involves gene mutations and cell fusions. Specifically, cancer can result from a fusion between an "altered" pre-malignant cell and a bone marrow-derived stem cell (BMDSC). "Aneuploidy", which is a hallmark of malignancy, is a direct consequence of this cell fusion. The "stem cell fusion" model explains the remarkable similarities between malignant cells and BMDSC. This model also explains why non-mutagens can be carcinogens, and why non-mutagenic processes, such as wound healing and chronic inflammation, can promote malignant transformation. This model is readily testable. Cancer has been difficult to treat because of tissue heterogeneity and gene instability. However, if the malignant characteristics of cancer cells are derived from BMDSC, new conserved targets such as homing receptors for designing novel therapies may emerge.
• Harris, D., He, X., Tsang, T. C., Zhang, T., Luo, P., & Harris, D. T. (2005). Antigen epitope-expressing cytokines for DNA immunization. Vaccine, 23(16).
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  Strategies to enhance the efficacy of DNA vaccination against malignancy remain to be established. In this study, a plasmid expressing a tumor antigen incorporated into the signal peptide of human IL-2 was tested as a DNA vaccine in a murine model system. Results showed that antigen-specific CTL responses were elicited by intramuscular injection of these plasmids. Importantly, compared with a minigene vector expressing the same epitope, the OVA epitope-incorporated, IL-2 expression plasmid vaccination was more effective in protecting mice from OVA-expressing tumor challenge. The improved efficacy appears to result from enhanced antigen presentation as well as the immunostimulatory activity of IL-2. This approach may provide new perspectives in designing cytokine-adjuvant DNA vaccines for clinical applications.
• Harris, D., Pipes, B. L., Vasanwala, F. H., Tsang, T. C., Zhang, T., Luo, P., & Harris, D. T. (2005). Brief heat shock increases stable integration of lipid-mediated DNA transfections. BioTechniques, 38(1).
• Lebsack, T. W., Kreulen, C., Deever, D. B., Harris, D. T., & Witten, M. L. (2005). Substance P effects on developing thymocytes in hindlimb unloaded rats. Aviation, space, and environmental medicine, 76(1), 11-8.
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  The purpose of this study was to examine the effects of substance P (SP) on the immune system in a condition similar to microgravity. We analyzed immune disturbances caused by subjecting Fischer 344 rats to a 45 degrees antiorthostatic suspension technique, otherwise known as the hindlimb unloading (HU) model.
• Harris, D., Luo, P., He, X., Tsang, T. C., & Harris, D. T. (2004). A novel inducible amplifier expression vector for high and controlled gene expression. International journal of molecular medicine, 13(2).
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  Safety and efficacy are both required for successful gene therapy. In this regard, our laboratory has created a novel expression system, pHi-Hot that combines inducible and amplifier strategies in one construct. In pHi-Hot, the first transcriptional unit contains an inducible heat shock protein (hsp70B) promoter controlling the expression of a transcriptional factor, Tat, which transactivates a second promoter, the HIV2 LTR, located downstream on the same construct. The second promoter drives the gene of interest. The magnitude of the amplified second gene expression can be regulated through manipulating the activity of the hsp promoter driving the Tat gene. Using the human interleukin-2 (IL-2) cytokine gene as the reporter gene, we demonstrated that moderate heat shock at 42 degrees C for 30 min, the pHi-Hot vector could achieve high gene expression levels while maintaining its inducibility. The induced IL-2 levels were 35- to 70-fold higher than achieved by using the hsp promoter alone, and 10- to 35-fold higher than achieved by using the CMV promoter. Using inducible and amplifier strategies, we can achieve high and controlled gene expression levels from a single construct. Finally, we discuss the advantages of using these strategies in developing new targeting and inducible vectors for genetic research and gene therapy.
• Harris, D., Zhang, T., He, X., Tsang, T. C., & Harris, D. T. (2004). SING: a novel strategy for identifying tumor-specific, CTL-recognized tumor antigens. FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 18(3).
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  Traditional methods for identifying T cell-recognized tumor antigens (Ags) are laborious and time-consuming. In an attempt to simplify the procedure, a novel strategy, SING (SIgnal transduction molecule-mediated, NFAT-controlled, GFP expression) was established as a direct approach for cloning T cell-recognized tumor Ags. In the SING system, a mouse T cell line (BW5147) was transduced with a chimeric H-2Kb construct containing T cell-signaling domains and a green fluorescent protein (GFP) reporter gene under the transcriptional control of nuclear factor of activated T cells (NFAT). The resultant BW5147 cells were named BS cells. This cell line could "sense" TCR stimulation through the T cell-signaling domains after coculture with Ag-specific T cells and then become fluorescent (expressing green fluorescence protein, GFP+) in the presence of Ag peptides. The interaction between BS cells and Ag-specific T cells could be enhanced by addition of costimulatory signals. Currently, BS cells have been optimized to "sense" TCR stimulation after being pulsed with the relevant peptides at concentrations as low as 10(-9) M. Endogenous Ag-expressing BS cells could also become fluorescent after coculture with Ag-specific T cells. Our results provide a proof of principle for using the SING system to directly isolate Ag-expressing BS cells from BS cell repertoires, which are retrovirally transduced with tumor-derived cDNA libraries. Once tumor Ag-marked BS cells are identified, the sequences encoding tumor Ags could be easily retrieved by PCR amplification of the genomic DNA using vector-specific primers.
• Harris, D., Zhang, T., He, X., Tsang, T. C., & Harris, D. T. (2004). Transgenic TCR expression: comparison of single chain with full-length receptor constructs for T-cell function. Cancer gene therapy, 11(7).
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  Genetic modification of T lymphocytes with T-cell receptor (TCR) genes provides a novel tool for adoptive immunotherapy. However, the efficiency of full-length TCR (flTCR)-transduced T cells could be limited by factors such as incorrect pairing between exogenous and endogenous TCR chains and downregulation of the CD3 complex. To overcome these hurdles, one promising strategy is to use three-domain single-chain TCRs (3D-scTCR), in which TCR Valpha and Vbeta chains are joined by a linker with signal transduction domains fused at the carboxyl termini as signal transducers and amplifiers. Our results showed that surface expression of scTCRs on T cells after retroviral transduction was affected by the origin of the transmembrane (TM) region and placement of signaling domains. scTCR-modified T cells were functional as shown by cytokine (IL-2 and IFN-gamma) release in response to antigen stimulation and cytolytic activity against specific target cells. CD8 and CD28, but not the complete CD3 complex, could enhance the scTCR-induced T cell activation. Compared with flTCR-modified T cells and native CTLs, scTCR-modified T cells require higher thresholds of antigen stimulation (approximately 10(-8) M peptide) to be functional. Despite the low efficiency of scTCRs, our data provide insight into further improvements in generating efficient scTCRs for in vivo applications.
• Harris, D., He, X., Tsang, T. C., Luo, P., Zhang, T., & Harris, D. T. (2003). Enhanced tumor immunogenicity through coupling cytokine expression with antigen presentation. Cancer gene therapy, 10(9).
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  The density of tumor antigen in conjunction with major histocompatibility complex (MHC) class I molecules on the cell surface affects cytotoxic T cell (CTL) function in an active antitumor immune response. Thus, methods to enhance antigen expression/presentation could augment the effect of cancer immune therapy. In the present study, we investigated the feasibility of modifying a cytokine signal peptide with a tumor antigenic epitope. We inserted the genes encoding the MHC class I-restricted antigenic epitope of chicken ovalbumin and tyrosinase-related protein 2 into the signal sequence of the interleukin-2 gene, replacing part of the signal sequence at different positions. Our results showed that these modified signal peptides still functioned, as indicated by cytokine secretion. The antigenic epitope within the modified signal peptide could be processed properly and presented on tumor cell surface. Tumor cells demonstrated enhanced immunogenicity as indicated by increased susceptibility to CTL lysis in vitro and decreased tumor grow in vivo after gene modification. These data provide potential perspectives in designing therapeutic or vaccine strategies in immuno-gene therapy of cancer.
• Harris, D., Zhang, T., Tsang, T. C., & Harris, D. T. (2003). Efficient transduction of murine primary T cells requires a combination of high viral titer, preferred tropism, and proper timing of transduction. Journal of hematotherapy & stem cell research, 12(1).
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  Retroviral vectors have been used exclusively for genetic modification of primary T cells. Most T cell infection protocols have been developed for human T cells, whereas systematic investigations of the optimal conditions for transduction of murine primary T cells are limited. In this study, ecotropic and 10A1-pseudotyped retroviral vectors were compared for their efficiency in infecting murine primary T cell cells, as well as T cell lines. Various factors that affect transduction efficiency were also explored, including virus titer, times of exposure, timing of infection, low-speed centrifugation, and use of fibronectin fragment. Our results showed that up to 80% of murine primary T cells could be infected after a single exposure. Successful infection required a combination of high virus titer (>10(7) CFU/ml), proper timing of infection (within 24 h after mitogen stimulation), and preferred tropism (ecotropic vectors). These optimization results may help to establish a standard protocol for infection of murine primary T cells and provide some insight into the obstacles to retroviral infection of T cells.
• Harris, D. T., Sakiestewa, D., Titone, D., Young, R. S., & Witten, M. (2002). JP-8 jet fuel exposure results in immediate immunotoxicity, which is cumulative over time. Toxicology and industrial health, 18(2), 77-83.
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  The US Air Force has implemented the widespread use of JP-8 jet fuel in its operations, although a thorough understanding of its potential effects upon exposed personnel is unclear. In the present study, the immediate effects of JP-8 exposure on the immune system were analyzed. Exposure of mice once to a single 1000 mg/m3 concentration of JP-8 for one hour resulted in significant immune organ weight loss and loss of viable immune cells from the spleen within two hours post-exposure. Although a similar exposure had no effect on thymus organ weight, it did result in significant losses of viable immune cells at one hour post-exposure. It was also observed that a loss of viable bone marrow cells could be seen at four hours post-exposure, with a return to baseline levels by 24 hours post-exposure. In terms of peripheral blood immune cells, a significant loss of viable immunecells was observed within one hour post-exposure, which became more pronounced with time. Further, it was observed that a single one-hour JP-8 exposure resulted in an immediate loss of immune function at one hour post-exposure that did not recover within 24 hours. An extension of the above experiments revealed that each additional one hour/day of exposure to 1000 mg/m3 of JP-8 promulgates the significant immunotoxicity described above. That is, spleenic organ weights, as well as viable cell numbers, continued to decline with additional days of short-term exposure. Thymic organ weights were significantly reduced at three to four days of one-hour exposures, with a continuing loss of viable cell numbers. Significantly, functional immune responses continued to deteriorate with each additional day of JP-8 exposure. Thus, low concentration JP-8 jet fuel exposures have significant effects on the immune system, these effects occur rapidly and these effects are cumulative over time.
• Harris, D., Zhang, T., Tsang, T. C., & Harris, D. T. (2002). Comparison of cis and trans tat gene expression in HIV LTR-based amplifier vectors. BioTechniques, 33(5).
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  The long terminal repeat (LTR) of the human immunodeficiency virus (HIV) drives highly efficient gene expression in the presence of the transactivator, Tat. Thus, tat-containing vectors may be very useful tools in gene therapy. However information about the optimal way of delivering the tat gene is limited. In this study, we compared the effects of cis and trans expressions of the tat gene and its effects on HIV LTR-driven gene expression in different cell lines using non-viral vectors. The human interleukin-2 (IL-2) gene was used as a reporter gene under the control of the HIV2 LTR (pHIV2-IL-2). The tat gene, driven by a cytomegalovirus (CMV) promoter, was either co-transfected separately (pCMV-Tat) or inserted downstream of the IL-2 gene (pHIV2-IL-2-neo-C-Tat). Our results showed that HIV2 LTR-Tat-based vectors were much more potent than CMV promoter-based vectors in transient expression. The co-transfection of both plasmids was comparable to a single transfection of pHIV-IL-2-neo-C-Tat in both high and low transfection efficiency cells. In conclusion, the co-placement of HIV2 LTR and tat genes on a single plasmid allows for gene expression as efficiently as a two-plasmid system, suggesting that HIV2 LTR-Tat-based vectors may be attractive tools for gene therapy.
• Shibata, A., Harris, D. T., & Billings, P. R. (2002). Concentrations of estrogens and IGFs in umbilical cord blood plasma: a comparison among Caucasian, Hispanic, and Asian-American females. The Journal of clinical endocrinology and metabolism, 87(2), 810-5.
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  It has been hypothesized that exposure to elevated levels of estrogens and IGFs before birth may increase breast cancer risk in female offspring. We examined whether the concentrations of estrone, E2, IGF-I, IGF-II, and IGF-binding protein-1 (IGFBP-1), -2, and -3 in umbilical cord blood plasma differed in female neonates of three racial/ethnic groups with contrasting breast cancer risk. The study included 57 Caucasian, 22 Hispanic, and 22 Asian-American subjects. Relative contribution of race/ethnicity to the analyte level variability was the largest for IGFBP-1 (P = 0.06). The only statistically significant (P < 0.05) mean difference was the lower IGFBP-3 levels in Asian than in Caucasian subjects. Adjusted mean levels of estrone and E2 for Asian subjects were 128% and 109% of the Caucasian means, respectively, whereas the Hispanic group showed lower means (85% and 84% of the Caucasian means). IGF-I, IGFBP-1, and IGFBP-3 showed lower adjusted means for both Hispanics and Asians compared with Caucasians. However, these differences were not statistically significant. In summary, we have shown that concentrations of estrogens, IGF-I, IGF-II, and IGFBPs are not different in cord blood samples from Caucasian, Hispanic, and Asian-American subjects. These data do not support a link between antenatal exposure to elevated levels of estrogens and IGFs and breast cancer.

Presentations

• Vedantam, G., Chi, T., Harris, D. T., Jernigan, B., Badowski, M., Anwar, F., & Tzou, D. (2022, May). Kidney Stone Endotoxin Concentration Correlates with Post-Operative Sepsis Following Percutaneous Nephrolithotomy. 117th Annual Meeting of the American Urological Association/Podium Session. New Orleans, LA: American Urological Association.
• Ghishan, F. K., Harris, D. T., Lee, B. R., Chaus, F., Jernigan, B., Badowski, M., & Tzou, D. (2019, Nov./Fall). Feasibility of Detecting Both Superficial and Intra-renal Stone Endotoxin Concentrations.. 95th Annual Western Section American Urological Association Annual Conference. Monterey, CA: Western Section American Urological Association.
• Ghishan, F. K., Harris, D. T., Lee, B. R., Chaus, F., Jernigan, B., Badowski, M., & Tzou, D. (2019, Nov./Fall). Feasibility of Detecting Both Superficial and Intra-renal Stone Endotoxin Concentrations.. Western Section American Urological Association Annual Conference. Monterey, CA: Western Section American Urological Association.

Poster Presentations

• AL-Ghadban, S., Herbst, K. L., Badowski, M., Harris, D. T., Badowski, M., Harris, D. T., AL-Ghadban, S., & Herbst, K. L. (2017, January/Spring). Insight into Fat Disorders: Biology of Subcutaneous Adipose Tissue.. First Annual DoM Research Poster Session. College of Medicine: University of Arizona.
• AL-Ghadban, S., Herbst, K. L., Ussery, C., Allen, M., Badowski, M., Harris, D. T., Badowski, M., Harris, D. T., Allen, M., Ussery, C., AL-Ghadban, S., & Herbst, K. L. (2017, November/Winter). Altered vasculature, Inflammation, and Angiogenesis in Lipedema.. Junior Investigator Poster Session. Tucson, Arizona: University of Arizona.
• AL-Ghadban, S., Herbst, K. L., Ussery, C., Allen, M., Badowski, M., Harris, D. T., Badowski, M., Harris, D. T., Allen, M., Ussery, C., AL-Ghadban, S., & Herbst, K. L. (2017, Winter). Altered vasculature, angiogenesis and adipocyte hypertrophy in subcutaneous adipose tissue (SAT) Disorders.. iFATS conference. Miami, Florida.