Ex Vivo Production of Cord Blood CD34+Derived Myeloid Precursors After Serum-Free Static Culture

Cord blood (CB) transplantation is an increasingly used source of hematopoietic progenitor cells for allogeneic stem cell transplantation (1 ). At birth, blood sequestered into placental vessels can be recovered by draining the cord vein into a closed system. A mean recovery of 90 mL of placental blood is obtained, containing an average of 4 x 106 cells expressing the CD34 antigen. The clinical series published analyzing this transplant modality showed potential advantages in comparison with other sources (2 -3 ). CB has demonstrated higher allogeneic tolerance across HLA barriers, with lower incidence of graft-versus-host disease maintaining the antitumoral effects. Moreover, the easy procurement of the blood without donor risk and the storage in banks of large quantities of products, fully characterized and ready to use, make it attractive for clinical application. However, the appearance of early events related to the delay of myeloid engraftment has resulted in a higher transplant-related mortality during the first month after infusion. This delayed engraftment is related to the limit number of myeloid progenitors contained in a common CB donation. Nevertheless, the overall survival in the global series is comparable between CB transplants and those using postnatal bone marrow as a source of stem cells (4 ).