Shalini Vellasamy

Generation of mesenchymal stem cell from human umbilical cord tissue using a combination enzymatic and mechanical disassociation method

MSCs (mesenchymal stem cells) promise a great potential for regenerative medicine due to their unique properties of self‐renewal, high plasticity, modulation of immune response and the flexibility for genetic modification. Therefore, the increasing demand for cellular therapy necessitates a larger‐scale production of MSC; however, the technical and ethical issues had put a halt on it. To date, studies have shown that MSC could be derived from human UC (umbilical cord), which is once considered as clinical waste. We have compared the two conventional methods which are classic enzymatic digestion and explant method with our newly tailored enzymatic—mechanical disassociation method to generate UC‐MSC. The generated UC‐MSCs from the methods above were characterized based on their immunophenotyping, early embryonic transcription factors expression and mesodermal differentiation ability. Our results show that enzymatic—mechanical disassociation method increase the initial nucleated cell yield greatly (approximately 160‐fold) and maximized the successful rate of UC‐MSC generation. Enzymatic‐mechanical disassociation‐derived UC‐MSC exhibited fibroblastic morphology and surface markers expression of CD105, CD73, CD29, CD90 and MHC class I. Furthermore, these cells constitutively express early embryonic transcription factors (Nanog, Oct‐4, Sox‐2 and Rex‐1), as confirmed by RT‐PCR, indicating their multipotency and high self‐renewal capacity. They are also capable of differentiating into osteoblasts and adipocytes when given an appropriate induction. The present study demonstrates a new and efficient approach in generating MSC from UC, hence serving as ideal alternative source of mesenchymal stem cell for clinical and research use.

Basic fibroblast growth factor modulates cell cycle of human umbilical cord-derived mesenchymal stem cells

Mesenchymal stem cells (MSC) have great potential in regenerative medicine, immunotherapy and gene therapy due to their unique properties of self‐renewal, high plasticity, immune modulation and ease for genetic modification. However, production of MSC at sufficient clinical scale remains an issue as in vitro generation of MSC inadequately fulfils the demand with respect to patients.

Imatinib induces demethylation of miR-203 gene : An epigenetic mechanism of anti-tumor effect of imatinib

MicroRNA (miRNA) is an important regulator of cellular proliferation, differentiation and death. Leukemia-specific signature of miRNAs suggests that epigenetic dysregulation of miRNAs is important for leukemogenesis. We focused on the role of DNA methylation of miR-203 which targets BCR-ABL1 mRNA. The microarray analysis showed that 48 miRNAs of CpG-rich 212 miRNAs were upregulated over 2-fold after imatinib treatment. Imatinib induced the demethylation of the miR-203 promoter region, resulting in low expression of targeted BCR-ABL1 gene, and loss of proliferation of leukemic cells. In conclusion, demethylation of miR-203 is one of the molecular mechanisms of imatinib-induced inhibition of BCR-ABL1-positive leukemic cells.

Mesenchymal stem cells of human placenta and umbilical cord suppress T-cell proliferation at G0 phase of cell cycle.

Mesenchymal stem cells (MSC) generated from human umbilical cord (UC‐MSC) and placenta (PLC‐MSC) were assessed and compared for their immunomodulatory function on T cells proliferation by analysis of the cell cycle. Mitogen stimulated or resting T cells were co‐cultured in the presence or absence of MSC. T‐cell proliferation was assessed by tritiated thymidine (3H‐TdR) assay and the mechanism of inhibition was examined bycell cycle and apoptosis assay. Both UC‐MSC and PLC‐MSC profoundly inhibited the proliferation of T‐cell, mainly via cell‐to‐cell contact. MSC‐mediated anti‐proliferation does not lead to apoptosis,but prevented T cells from entering S phase and they therefore accumulated in the G0/G1 phases. The anti‐proliferative activity of MSC was related to this cell cycle arrest of T‐cell. UC‐MSC produced a greater inhibition than PLC‐MSC in all measured parameters.

Evaluation of metabolic and immunological changes in streptozotocin-nicotinamide induced diabetic rats

Type 2 diabetes is a chronic disease with growing public health concern globally. Finding remedies to assist this health issue requires recruiting appropriate animal model for experimental studies. This study was designated to evaluate metabolic and immunologic changes in streptozotocin-nicotinamide induced diabetic rats as a model of type 2 diabetes. Male rats were induced diabetes using nicotinamide (110 mg/kg) and streptozotocin (65 mg/kg). Following 42 days, biochemical and immunological tests showed that diabetic rats had higher levels of blood glucose, WBC, certain abnormalities in lipid profile and insufficient mitogenic responses of lymphocytes (p<0.05). However, the status of the total antioxidant, inflammatory biomarkers and other parameters of full blood count (except HCT) were not significantly altered. Phenotyping assay indicated insignificant lymphocyte subtype imbalances excluding a significant rise in the level of CD4+CD25+ marker (p<0.05). This model of diabetic animals may represent some but not all symptoms of human type 2 diabetes.