Fig. 1. Bone marrow cells fully replace the skeletal-muscle CD45⁺-fraction following i.v. transplantation. Whole BM from GFP mice was i.v. transplanted into sub-lethally irradiated NOD/SCID mice (10x10⁶ cells per mouse). After 6 to 8 weeks, skeletal muscle was removed from transplanted mice and sibling mice that had not received GFP BM cells. (A) (i) The proportion of skeletal muscle CD45⁺ cells expressing GFP was determined using flow cytometry (n=12) and gated based on light side-scatter (SSC) properties. (ii) Skeletal muscle cells were also examined for the presence of CFU (n=2). GFP-expressing hematopoietic colonies were detected by fluorescent microscopy. (B) Skeletal muscle from non-transplanted and GFP BM transplanted mice were further examined by flow cytometry for the frequency of CD45⁺ cells. (C) The proportion of Sca-1⁺ cells within the CD45⁺ fraction of skeletal muscle from transplanted and non-transplanted mice and within the BM-derived CD45⁺ cells of donor GFP mice was also compared (n=8). (D) NOD/SCID mice were (i.v.) transplanted with varying doses of Sca-1⁺CD45⁺ GFP⁺ cells. The proportion of GFP-expressing CD45⁺ cells in the skeletal muscle and BM compartments were compared using linear regression analysis.