In vivo repopulating activity of cells generated in vitro.

(A) To analyze HSC activity in vivo, hematopoietic cells generated in vitro under various culture conditions were transplanted into lethally irradiated adult mice. Donor contribution in peripheral blood of recipient mice was analyzed by FACS at 2 months after transplantation. Donor cells used are as follows: (lane a) cells derived from AGM culture originating from 6 embryo equivalents (see Figure 1); (lanes b-d) cells from AGM/FL coculture originating from one-third embryo equivalent of whole AGM cells (approximately 1 × 10⁵ cells); and (lanes e-g) CD34⁺/c-Kit⁺ cells (2 × 10³) derived from AGM (one-third embryo equivalent). Data shown are the mean ± SD of 3 to 5 experiments. (B) LTR activity of cells either freshly isolated from the E11.5 AGM region or generated in vitro. Mice were killed at various times, and peripheral blood cells were analyzed for donor contribution by FACS. Data are the mean ± SD values of 3 to 5 experiments.