tgf-breceptor2 knocked down by sirna increases cord blood cd34+ hscs self-renewal

objective: nowadays, cord blood hematopoietic stem cells (hscs) are known as a valuable source for bone marrow transplantation but unfortunately their insufficient number is a limiting factor for using them in adult bone marrow transplantation. cord blood hcss expansion is an approach to overcome this problem, by inducing their self-renewal. tgf-b signaling pathway is a key inhibitory agent for hscs self-renewal. in this study, we tried to enhance self-renewal of long term culture initiating cell by inhibiting tgfbr2 expression. materials and methods: cd34+ hscs were isolated from cord blood units with macs column. sirna against tgfbr2 was transfected by lipofectamine™ rnaimax as transfection reagent. hscs were cultured in imdm medium containing 10% fbs and early acting cytokines (flt3l, scf, tpo) for 8 days. then we evaluated tgfbr2 expression by qrt-pcr. the cd34+ subpopulation of cultured cells were examined by flow cytometry on the 8th day. finally the expanded cells were evaluated for the presence of early hematopoietic stem cells by lt-cic and clonogenic assays. results: according to our results, tgfbr2 down regulation increases cd34+ subpopulation of hscs. in addition, lt-cic assay showed an enhancement in primitive hematopoietic stem cell capable of self-renewal. conclusion: all in all, it seems that positive regulators have attracted more attention in the field of hscs expansion while negative regulators have same importance in self-renewal process of hscs and their inhibition can be a beneficial tool for enhancement of hscs self-renewa.