AA4.1⁺ day 14 fetal liver cells (Ly5.2) were further purified for a lin^−/lo, Sca-1⁺, c-kit⁺ stem cell surface phenotype. Fresh purified control cells (10³) were transplanted with 10⁶ Ly5.1 competitor marrow (n = 6 mice). From the same purification, 10⁴ cells were cocultured with stromal cell lines for 4 weeks. Subsequently, 10% of each culture was transplanted per mouse (n = 8 mice/stroma) together with 10⁶ competitor BM cells. The contribution to each lineage in peripheral blood is expressed as the percent of the total specific lineage population that was Ly5.2⁺. CRU/10⁵, relative enrichment of competitive repopulating units. Data are the mean ± SEM.

The lineage and CRU content of low numbers of enriched fetal liver stem cells maintained on AFT024 and 2012 were determined. 500 stem cells were maintained in Dexter LTC for 4 to 7 weeks over irradiated monolayers. 20% of each culture was used to transplant groups of 4 mice (ie, each mouse received the equivalent of 100 stem cells that initially seeded the cultures) combined with 4 × 10⁵ competitor BM cells. Data are the mean ± SEM.

Ly5.1 BM cells with a lin^−/lo, Sca-1⁺, and c-kit⁺ cell surface phenotype were purified. 100 fresh cells per mouse (control) were transplanted with 10⁵ Ly5.2 competitor BM cells. One thousand of the same purified cells were cocultured with stromal cell lines for 6 weeks. The cultures were then harvested, and 10% of each culture was transplanted per mouse with competitor. Data are from peripheral blood samples taken 4 months after transplant and are the mean ± SEM.