Introduction: Expanding stem cell precursors usingdifferent culture media and supporting endothelial cells has beenshown in previous studies to result in grafts that are capable ofhematopoiesis in myeloablated host. The use of xenogenicendothelium or cell lines is not applicable to humans withoutconcern. Patients and methods: We investigated the feasibilityof ex vivo expansion of cord blood stem cells by co-culturingwith autologus HUVEC or placenta in the presence of 3 or 5growth factor cytokine cocktails. We compared the fold increasein expansion to the control arm of the study; the cord stem cells inliquid cultures with added cytokine cocktail. HPC, CD34+ cells,placenta and HUVEC were all isolated from the same umbilicalcord. Results: Total cells, CD34 and CFU were significantlyincreased when cultured with the HUVEC or placenta comparedto the liquid cultures. In the liquid cultures, five growth factorcytokine cocktails lead to an expansion that was significantlymore than that observed using three cytokines only but less thanthe co culture arms. Conclusion: The use of autologus derivedHUVEC or placenta provides an exciting and potentiallyclinically applicable approach to expand the umbilical cord stem cells for multiple uses in both the pediatric and adult patient,superior to the cytokine supplemented liquid cultures.