Platelet Growth Factors Suppress the Expansion, but Promote the Differentiation of Cord Blood CD133+ Stem Cells to Megakaryocyte Progenitors

Noroozi Aghideh A *, Kheirandish M , Abolghasemi H , Gharabaghian A , Khalaf Adeli E , Siadat S.D , Haghbin S ,


Objective: Umbilical cord blood (UCB) is a rich source of hematopoietic cells as a valuable source for hematopoietic stem cell transplantation (HSCT). In addition, cord blood megakaryocytic progenitor cells are more immature than other sources such as bone marrow (BM) that result in delayed platelet recovery in the recipients of UCB transplants. Platelet rich plasma (PRP) is a concentrate of platelet growth factors and many studies have shown the effects of these factors on the expansion and function of different cell types. In this study, we surveyed the effects of platelet growth factors including the platelet supernatant (PS), platelet lysate (PL) and activated PRP (AP) on the expansion and differentiation of cord blood CD133+ stem cells into megakaryocytic progenitor cells. Materials and Methods: UCB 133+ cells were separated by MACS method and counted using improved neubauer hemocytometer. their viability was determined using dye exclusion assay and 7-AAD method. AP was prepared by PRP activation by thrombin and calcium chloride. PS and PL preparation was performed by high speed centrifugation (900 g) of PRP and freezing and thawing of PRP, respectively. The growth factors and protein concentrations in these platelet products were measured by ELISA and Bradford methods, respectively. Mean expression rate of CD133, CD41, CD61 and CD42b in day 0 and CD41, CD61 and CD42b at the end of culture period were assayed by flow cytometry. Results: The results showed that PDGF and TGF-β concentrations are higher than other platelet growth factors. Further, protein concentrations in PS, PL and AP were 460, 490 and 480 mg/ml, respectively (p