Engraftment after varying numbers of washes.

Fresh male marrow suspensions were inoculated onto pre-established stromal layers and allowed to adhere for 1 hour; then the layers were washed once, 3 times, 5 times, or 10 times before cells were harvested for transplantation. The percentage of male chimerism in irradiated female recipients 6 weeks after transplantation in 2 experiments (4 to 5 recipients per group per experiment) is shown. There is no significant difference among the groups; however, there appears to be a trend toward decreased adhesion of engraftable HSCs after 10 washes.