Systemic lupus erythematosus (SLE) is a complex autoimmune disease. Genetic factors playing an important role in disease susceptibility have long been suggested. Transforming growth factor-beta (TGF-beta) regulates differentiation and proliferation of T cells. Therefore, it could be a candidate gene for the development of systemic lupus erythematosus. Allelic polymorphisms in TGF-beta promoter region (-988, -800, -509) and in exon 1 (codon 10 and codon 25) have been suggested to associate with SLE susceptibility. Allelic polymorphisms at positions -988, -800, -509, codon 10 and codon 25 on TGF-beta gene in 138 SLE patients and 182 healthy controls were analyzed in this study. TGF-beta polymorphisms were determined by PCR amplification and sequencing. With the previous polymorphic data of interleukin-4 (IL-4) -590 and interleukin-10 (IL-10) -819, associations of cytokine genotyoe and allele frequencies were analyzed. Results showed that there were differences in the genotype distribution of TGF-beta promoter region at position -509 and in the signal sequence at codon 10 (Leu¡÷Pro) between case and control groups in this study. However, no significant differences were found for all the TGF-beta polymorphisms. Allele frequency of IL-10 -819 was significantly associated with the susceptibility of SLE (p = 0.011). No significant associations were found between lupus nephritis with all the cytokine polymorphisms, but CNS involvement and lung involvement were associated with the polymorphisms studied in this research.

Lübeck, Med. Universität, Habilitation, 2000.

Thesis (Ph. D.)--York University, 2000. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 153-184). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ67888.

Thesis (M. Sc.)--York University, 2001. / Typescript. Includes bibliographical references (leaves 69-89). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ67745.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Surgery / Master / Master of Philosophy

A major challenge facing the tissue engineering discipline is cartilage tissue repair and engineering, because of the highly specialized structure and limited repair capacity that cartilage possesses. Dental pulp stem cells (DPSCs) were identified about a decade ago as a potential candidate for cell based therapy and tissue engineering applications. The present study aimed to utilize gene therapy with isolated DPSCs to induce chondrogenic transgene expression and chondrogenic lineage differentiation, with the ultimate goal of engineering cartilage tissue-like constructs. We isolated DPSCs from human teeth extracted for orthodontic treatment. We further enriched the isolated population using immunomagnetic bead selection, which increased stem cell markers: Stro-1 and CD146, compared to unselected population. The DPSCs showed the ability to differentiate into the chondrogenic lineage when induced with recombinant hTGFβ-3 and when transduced with hTGFβ-3 transgene. We successfully constructed the recombinant adeno-associated viral vector encoding the human TGFβ-3, and determined the best multiplicity of infection for DPSCs. The transduced DPSCs highly expressed hTGFβ-3 for up to 60 days. Expression of chondrogenic markers; Collagen IIa1, Sox9, and aggrecan was verified by immunohistochemistry and mRNA. We successfully fabricated an electrospun nano-fiber scaffold upon which morphology, proliferation and viability of the DPSCs were examined. DPSCs attached and proliferated on nano-fiber scaffolds demonstrating better viability compared to micro-fiber scaffolds. Transduced cells expressed hTGFβ-3 protein up to 48 days. Cells seeded on nanofiber scaffolds showed higher expression levels compared to micro-fiber scaffolds or culture plate. Scaffolds seeded with DPSCs were implanted in nude mice. Immunohistochemistry for TGFβ-3 DPSCs constructs (n=5/group) showed cartilage-like matrix formation with glucoseaminoglycans as shown by Alcian blue. Immunostaining showed positivity for Collagen IIa1, Sox9 and aggrecan. Semi-thin sections of the transduced DPSCs constructs examined by transmission electron microscopy (TEM) showed chondrocytic cellular and intra-cellular features, as well as extracellular matrix formation (n=2/group). In vivo constructs with the TGFβ-3 DPSCs showed higher collagen type II and Sox9 mRNA expression relative to non-transduced DPSCs constructs (n=5/group). Western blot analysis confirmed this expression pattern on the protein level (n=3/group). Engineered constructs mechanical properties were examined and compared to patellar bovine cartilage to assess functionality (n=5/group). TGFβ-3 transduced DPSCs constructs showed a higher equilibrium elastic modulus compared to nontransduced constructs. Micro-fiber scaffolds constructs showed a higher elastic modulus (0.11 MPa, 18% of bovine cartilage), compared to nano-fiber constructs modulus (0.032 MPa, 6% of bovine cartilage). Nano-fiber based constructs showed a similar Poisson‘s ration to bovine cartilage, while that of micro-fiber scaffolds was lower. As an alternative gene delivery method, electroporation parameters for DPSCs transfection were optimized, and compared to commonly used chemical transfection methods. TGFβ-3 transfected DPSCs showed a significantly higher relative TGFβ-3 mRNA and protein expression compared to non transfected control and to eGFP transfected DPSCs. Transfected DPSCs showed increased relative expression of chondrogenic markers; Collagen II, Sox9 and aggrecan, compared to non transfected DPSCs. Successful chondrogenic differentiation of DPSCs gene therapy with TGFβ-3 transgene, and seeding them on PLLA/PGA scaffolds makes it a potential candidate for cartilage tissue engineering and cell based therapy. / published_or_final_version / Dentistry / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / toc / Zoology / Doctoral / Doctor of Philosophy

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