Background and Objectives:Adult bone marrow (BM) is the major source of mesenchymal stem cells (MSCs) for celltherapy. However, aspiration of BM involves invasive procedures. We isolated MSCs fromhuman full term umbilical cord blood (UCB).MSCs have been suggested to provide a suitable cellular environment for in vitro expansion ofhaematopoietic progenitor cells (HPCs) from umbilical cord blood.In this study, we have analyzed the immunophenotypic differentiation of HPC. Co-culture withMSC greatly enhanced proliferation of human HPC, especially of the more primitiveCD34+CD38- fraction.Design and Methods:MSCs were isolated from UCB collected from full term vaginal deliveries and cultured inappropriate growth medium. The hematopoiesis–supportive function of UC-MSCs was examinedby co culture of cord blood mononuclear cells with MSCs as a feeder layer or with theirsupernatant.Results:MSCs were successfully isolated from 5 of the 20 UCB collected. UCB-MSCs shared thecharacteristic of BM-MSC, including fibroblastic-like morphology, immunophenotype,hematopoiesis-supportive function through the maintainance of CD34+38- and CD34+ CD38+cells.Interpretation and Conclusions:We were able to isolate MSCs from human full term umbilical cord blood with a 25% successrate, and we studied their support of HSCs upon co culture and found the preferred maintenanceof CD 34+ cells upon co culture on a feeder layer of MSCs in comparison to the use ofmesenchymal stem cells supernatant.