Superior transduction of mouse hematopoietic stem cells with 10A1 and VSV-G pseudotyped retrovirus vectors

The inefficient transduction of human hematopoietic stem cells (HSC) with amphotropic retroviral vectors has been an obstacle to gene therapy for hematopoietic diseases. We have previously reported low levels of amphotropic retrovirus receptor (Pit-2) mRNA and higher levels of gibbon ape leukemia virus (GALV) or 10A1 retrovirus receptor (Pit-1) mRNA in mouse and human HSC. The vesicular stomatitis virus (VSV-G) uses an abundant membrane phospholipid as a receptor. We hypothesized that transduction of HSC requires relatively high levels of retrovirus receptor molecules. Because mouse HSC can be efficiently transduced by ecotropic virus through the abundant ecotropic receptor, the mouse is an ideal model to compare receptor levels and transduction. We have developed a cotransduction assay where ecotropic retrovirus transduction is a positive internal control for downstream steps in retrovirus transduction. A comparison of mouse HSC transduction with amphotropic, 10A1, and VSV-G envelopes showed that the level of amphotropic and 10A1 receptor mRNA in HSC correlated with the frequency of transduction. Transduction with VSV-G vectors was similar to that with 10A1 vectors. We conclude that the level of retrovirus receptor on HSC is critical for HSC transduction and that GALV or VSV-G vectors would be better for human HSC transduction.