Retrovirus receptor mRNA expression correlates with gene transfer efficiency in pluripotent hematopoietic stem cells

Hematopoietic stem cells (HSC) from bone marrow, peripheral blood and cord blood are important in clinical transplantation. However, their use in gene therapy protocols is still limited by a low level of transduction efficien cy. In addition to the cell cycling block to retrovirus transduction, we re cently demonstrated that the low level of retrovirus receptor mRNA in mouse HSC correlated with the low level of amphotropic retrovirus transduction i n these cells. Similarly, we found low levels of mRNA encoding the amphotro pic retrovirus receptor in human hone marrow Lin(-) CD34(+) CD38(-) HSC. In an effort to identify an alternative population of human HSC that might be more efficiently transduced, we assayed HSC populations from cord blood fo r mRNA encoding the amphotropic retrovirus receptor. High levels of recepto r mRNA were present in HSC from previously cryopreserved cord. blood compar ed with HSC from fresh bone marrow and fresh cord blood. The HSC from cryop reserved cord blood are excellent candidates for gene therapy protocols.