Human cell engraftment following intrafemoral delivery of noncultured and cultured cells. Human engraftment was measured at 3 and 6 weeks after transplantation as the percentage of nonerythroid CD45⁺ (▤, □) plus erythroid CD45^–CD36⁺ (▨) human cells in the injected right femur (I), the right tibia (T), the left femur (F), the blood (B), and the spleen (S). Each bar represents the mean data (± SE) from the mice given transplants of day-0 (n = 24) or day-4 cells (n = 24) from 4 experiments.