Bachgroun: Hematopoietic stem cell derived from umbilical cord blood (UCB) has been used for regenerative medicine in hematological abnormalities. MicroRNAs are important regulators of gene expression that control both physiological and pathological processes such as development of tissue and cancer. Some studies have shown that miR-33, has a critical role in control of self-renewal cells. Here to understand the role of adipose derived mesenchymal stem cells (ASCs) as a feeder layer on expansion of hematpoietic stem cells (HSCs), the expression of p53 and miR-33a were evaluated.

Material and methods: Isolated human ASCs in passage 3 were cultured as a feeder layer. Ex vivo cultures ofcord bloodCD34+ cells that expand in three culture conditions for 7 days were performed in following groups: fresh CD34+ cells, in the present of cytokines, directly cultured on feeder layer,indirectly cultured on feeder layer(cultured on thincert plate with 0.4 µm pore size). Expression of genes p53 and Mir-33a were analyzed by real-time PCR.

Result: The expression of p53 was significantly (p<0.05) down regulated in HSCs directly cultured on ADSCs feeder layer compared to without feeder layer.  The expression of miR-33a was significantly (p>0.05) up regulated in HSCs directly cultured on feeder layer compare to without feeder layer.

Conclusion: Defining the role of ADSCs in controlling the HSC self-renewal through mir33 and p53may lead to the prevention  and treatment of hematopoietic disorders.