Bone marrow stromal cells as a vehicle for gene transfer

Adoptive transfer of genetically modified somatic cells is playing an incre asingly important role in the management of a wide spectrum of human diseas es. Hematopoietic stem cells and lymphocytes have been used to transfer a v ariety of genes, however, they have limitations. In this study, the feasibi lity of retroviral gene transduction of bone - marrow stromal cells, and th e engraftment characteristics of these cells following infusion, was invest igated in a murine transplantation model. Stromal cells derived from Balb/c mouse bone marrow were transduced with a replication-defective retrovirus containing the LacZ gene. Following three rounds of transduction, between 5 and 40% of the cells were positive for the LacZ gene. A total of 2 x 10(6) cells were infused into the same mouse strain. After : the infusion, the L acZ gene was detected by PCR in the bone marrow, spleen, liver, kidney and lung; however, only the spleen and bone marrow samples were strongly positi ve. Quantitative PCR demonstrated that between 3 and 5% of spleen and bone marrow cells, and 1% of liver cells contained the LacZ gene at 3 weeks afte r infusion; <0.2% transduced cells were found in other organs. No differenc e was noted in engraftment between mice with or without irradiation before transplantation, suggesting that engraftment occurred without myeloablation . The infused transduced cells persisted for up to 24 weeks. Self-renewal o f transplanted stromal cells was demonstrated in secondary transplant studi es. Ease of culture and gene transduction and tissue specificity to hematop oietic organs (bone marrow, spleen, liver) is demonstrated, indicating that stromal cells may be an ideal vehicle for gene transfer.