FIGURE 3.

Human BM mesenchymal stem and progenitor cells primarily reside in CD44⁻ stromal cell fraction. The data are from five analysis experiments with four healthy donors. A, FACS profiles show CD44, CD271, and CD146 expression in human BM CD45⁻CD235⁻CD31⁻ cells and sorting of the CD44^+/− cells. The stromal cells were first enriched by magnetic-activated cell sorting prior to staining of the antibodies. B, percentages of the CD44⁺ and CD44⁻ cells within stromal cells in BM. C, expressions of CD146 and CD271 in the CD44⁺ and CD44⁻ cells. D, the frequencies of CD146⁺CD271⁺ cells and CD44⁺ and CD44⁻ cells in BM. E, limiting dilution of CFU-Fs in the CD44^+/− cells. The cell doses yielding 37.5% negative wells are indicated by dashed lines on the x axis. F, CFU-F recovery from the CD44^+/− cells of BM. G, morphology of Giemsa-stained CFU-Fs. H, in vitro differentiation of the CD44⁻ cells. The adipocytes were identified by oil red stainings. The osteoblasts were confirmed by both Alizarin red and von Kossa stainings. The chondrocytes were identified by both toluidine blue and Alcian blue. PI, propidium iodide.