Recovery and characterization of CD34+ cord blood cells after cryopreservation

Hematopoietic stem and progenitor cell transplantation is an important therapy for certain hematological and malignant disorders, and these cells are being used as vehicles for potential gene therapy approaches to treatment. Umbilical cord blood is a rich source of stem and progenitor cells, which can be efficiently transduced by viral vectors with new genetic material, and these cells have been used in both allogeneic and autologous transplant settings, the latter setting used by others for gene transfer as a possible means of gene therapy. Since cord blood banking is increasingly being considered as an adjunct for allogeneic and autologous transplantation, the present studies were done in order to evaluate the consequences of cryopreserving highly purified CD34+ cells from cord blood. The results demonstrate that CD34+ cord blood cells can be frozen in cryopreserved form and recovered efficiently with cell cycle, proliferative and cell expansion characteristics equivalent to the pre-freeze samples of cells. This information complements previous studies from our group demonstrating the efficient freezing of relatively unseparated populations of cord blood cells, and should be of practical use for future studies involving banking and use of cord blood stem and progenitor cells.