Submitted March 3, 2008
Accepted July 17, 2008
Unaltered repopulation properties of mouse hematopoietic stem cells transduced with lentiviral vectors
Africa Gonzalez-Murillo, M. Luz Lozano, Eugenio Montini, Juan A. Bueren, and Guillermo Guenechea*
Hematopoiesis and Gene Therapy Division, CIEMAT and Center for Biomedical Research on Rare Diseases, (CIBERER), Madrid, Spain
Ospedale San Raffaele-Telethon Institute for Gene Therapy, (HSR-TIGET), Milano, Italy
* Corresponding author; email: g.guenetxea{at}ciemat.es.
Recent studies of retroviral-mediated gene transfer have shown that retroviral integrations themselves may trigger nonmalignant clonal expansion of hematopoietic stem cells (HSCs) in transplanted recipients. These observations suggested that previous conclusions of HSCs dynamics based on gamma-retroviral gene marking should be confirmed with improved vectors having a more limited capacity to transactivate endogenous genes. Because of the low trans-activation activity of self-inactivating lentiviral vectors (LV), we have investigated whether the LV-marking of mouse HSCs induces a competitive repopulation advantage in serially transplanted recipients. As deduced from analyses conducted in primary and secondary recipients we concluded that lentivirally transduced HSCs have no competitive repopulation advantages over untransduced HSCs. By means of LAM-PCR analysis we characterized LV- targeted genes in HSC clones that engrafted up to quaternary recipients. While nine clones harboured integrations close to defined Retroviral Insertion Sites, none of them was characterized as a Common Integration Site, and none of them was present in HSC clones repopulating quaternary recipients. Taken together, our results show unaltered repopulation properties of HSCs transduced with LVs, and confirm early studies suggesting the natural capacity of a few HSC clones to generate a mono or oligoclonal hematopoiesis in transplanted recipients.
