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 a mphotropic retroviral vectors has been an obstacle to gene therapy for hema topoietic diseases. We have previously reported low levels of amphotropic r etrovirus receptor (Pit-2) mRNA and higher levels of gibbon ape leukemia vi rus (GALV) or 10A1 retrovirus receptor (Pit-1) mRNA in mouse and human HSC. The vesicular stomatitis virus (VSV-C) uses an abundant membrane phospholi pid as a receptor. We hypothesized that transduction of HSC requires relati vely high levels of retrovirus receptor molecules. Because mouse HSC can be efficiently transduced by ecotropic virus through the abundant ecotropic r eceptor, the mouse is an ideal model to compare receptor levels and transdu ction. We have developed a cotransduction assay where ecotropic retrovirus transduction is a positive internal control for downstream steps in retrovi rus transduction. A comparison of mouse HSC transduction with amphotropic, 10A1, and VSV-C envelopes showed that the level of amphotropic and 10A1 rec eptor mRNA in HSC correlated with the frequency of transduction. Transducti on with VSV-C vectors was similar to that with 10A1 vectors. We conclude th at 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.