Adipose Stem Cells as a Feeder Layer Reduce Apoptosis and p53 Gene Expression of Human Expanded Hematopoietic Stem Cells Derived from Cord Blood

Human hematopoietic stem cells (hHSCs) have been used for transplantation in hematologic failures. Because the number of hHSCs per cord blood unit is limited, the expansion of these cells is important for clinical application. It has been reported that cytokines and feeder layer provide a perspective to in vitro expansion of hHSCs. In this regard, cord blood CD34+ cells expanded after co-culture with adipose-derived stem cells (ADSCs) feeder layer and cytokine conditions were analyzed in terms of apoptosis and the expression level of p53, a tumor suppressor gene. Three cultures of cord blood CD34+ cells were prepared ex-vivo for 7 days, including cytokines stem cell factor (SCF), thrombopoietin (TPO), and fetal liver tyrosine kinase 3 ligand (Flt3L) with ADSCs feeder layer, cytokines without feeder layer, and a culture on micro porous membrane with cytokines. Apoptosis rate and the expression level of P53 gene in all groups were analyzed by real-time PCR. The data showed that p53 expression and apoptosis rate in CD34+ fresh cells were higher than other culture systems. P53 gene expression in the expanded cells at both cytokine cultures with and without ADSCs feeder layer decreased, but it was lower than other culture systems at co-culture system with cytokines (P < 0.05). Apoptosis rate in expanded cord blood CD34+ with feeder layer was significantly lower than the group without ADSCs feeder layer. It could be concluded that direct culture of CD34+on feeder layer ADSCs affects the expansion of HSCs.