Bone marrow-derived CD45+ and CD45- cells reside in skeletal muscle.

In this report we examined the kinetics of accumulation in muscle tissue of donor-derived CD45+ and CD45- cells from one to several weeks post-bone marrow transplantation. Only after hemopoiesis is fully reconstituted are CD45+ cells recovered from muscle tissue in proportions similar to ones we reported earlier in non-transplanted mice. Furthermore, using marked donor bone marrow cells, we document that in addition to CD45+ cells, donor-derived CD45- cells with certain phenotypic characteristics progressively accumulate in muscle post-transplantation. The turnover rate and physiologic roles of these populations in muscle are unclear and require further study.