Titration of BM CD34⁺Thy-1⁺Lin⁻ cells in the SCID-hu bone model. Bone grafts were injected with a range of doses of CD34⁺Thy-1⁺ Lin⁻ cells (1,000 to 30,000) per graft. Data are the mean of four separate experiments from 4 different BM donors. Donor reconstitution means that greater than 1% of hematopoietic cells were positive for donor HLA antigen.