An Improved Mouse Sca-1+ Cell-Based Bone Marrow Transplantation Model for Use in Gene- and Cell-Based Therapeutic Studies

This study sought to develop a murine bone marrow transplantation strategy that would yield consistently high levels of long-term engraftment without significant morbidity and mortality. Hematopoietic stem cell (HSC)-enriched Sca-1+ cells were used for transplantation because of their propensity of homing to bone marrow. Green fluorescent protein (GFP)-expressing transgenic mice were used as donors. Murine Sca-1+ cells were enriched 13-fold from whole bone marrow with immunomagnetic column chromatography. Retroorbital injections yielded highly reproducible and higher levels of engraftment compared with tail vein injections. The combination of W41/W41 recipient mice and sublethal irradiation preconditioning produced long-term engraftment with minimal morbidity and mortality. A 24-hour delay between the sublethal irradiation and transplantation did not affect the efficiency and level of engraftment, but provided flexibility with respect to the timing of transplantation. Based on these findings, a mouse Sca-1+ cell-based strategy, involving the retroorbital injection of Sca-1+ cells into sublethally irradiated, myelosuppressed W41/W41 recipient mice within 24 h after irradiation, was developed. Transplantation of lentiviral vector-transduced wild-type Sca-1+ cells expressing GFP by this strategy led to consistently high levels of long-term engraftment. In summary, this murine Sca-1+ cell-based strategy could be used in studies of HSC-based gene or cell therapies.