Tarbiat Modares University Pathobiology Research 2538-3000 14 1 2011 01 01 TGF-bReceptor2 knocked down by SiRNA increases cord blood CD34+ HSCs self-renewal افزایش فعالیت خود تجدید شوندگی سلول‏های بنیادی خون‏ساز بند ناف CD34+ با استفاده از سرکوب بیان ژن گیرنده نوع دو TGF-b 1 15 19091 EN Mehdi Allahbakhshian Farsani Department of Hematology and Blood Banking, Faculty of Medical Science, Tarbiat Modares University, Tehran, Iran Naser Amirizadeh Assistant Professor, Department of Hematology, Research Center of Iranian Blood Transfusion Organization, Tehran, Iran Mehdi Forouzandeh Associated Professor, Department of Biotechnology, Faculty of Medical Science, Tarbiat Modares University, Tehran, Iran Masoud Soleimani Assistant Professor, Department of Hematology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Ali Akbar Pourfatholah Professor, Department of Immunology, Faculty of Medical Science, Tarbiat Modares University, Tehran, Iran Journal Article 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. https://mjms.modares.ac.ir/article_19091_d26f2e40e165eba24032e5767061c60c.pdf