Increased HSC activity in the bone marrow, AGM, and liver of Bcl-2-overexpressing transgenic animals. (A) HSC activity in the BM of Bcl-2-overexpressing mice. Whole BM from a male Ln 479 transgenic (tg) and a nontrangenic (wt) littermate was injected at different limiting doses (103, 104, and 105 cells) together with 105 female BM cells into irradiated female recipients. At 4 months after transplantation, the peripheral blood of the recipient was analyzed in a semiquantitative manner for male donor hematopoietic cells. Black triangles represent individual recipients engrafted with Bcl-2 BM, and gray circles indicate individual recipients engrafted with wt BM. Results of competitive repopulation experiments for Ln 479 transgenic and nontransgenic littermates are shown. A greater than 10% engraftment level in the peripheral blood was used as the criterion for positive HSC repopulation. Ln2 transgenic BM gave similar results (not shown). (B-C) Transplantations were performed with E11 AGM, E12 AGM Ln 479 transgenic (▪; panel B), and E12 liver cells (▪; panel C), as well as nontransgenic control cells (▦). The combined results of 2 independent transplantation experiments show the percentage repopulated recipients (y-axis) and the number of mice positive/the number of total mice injected for each group. ee indicates embryo equivalents injected; and ND, not done. All recipients considered positive at more than 4 months after transplantation showed donor-derived cell engraftment levels exceeding 10% by semiquantitative PCR. In general, a higher percentage of repopulated recipients is seen with Bcl-2 transgenic midgestation AGM and liver cells than with wild-type littermate cells. Results of secondary transplantations are shown on the right. BM cells from primary recipients injected with E11 AGM, E12 AGM, and E12 liver were transplanted in limiting dilutions into irradiated adult secondary recipients. The percentage of repopulated recipients and the number of mice positive/the number of total mice injected are shown for each group. The BM cells of the primary recipients injected with E11 AGM, E12 AGM, and E12 liver cells that were used for secondary transplantation were 75% to 100% repopulated by donor-derived cells. Results were obtained at more than 4 months after transplantation by PCR analysis of peripheral blood DNA. Again, a higher percentage of repopulated recipients is seen with Bcl-2 transgenic as compared with wild-type littermate cells.
