Mononuclear cells from BM chimeras were replated in MAPC medium at a density of 106 cells/cm2. (A) After 1 week, large GFP-negative cells (arrows) and small GFP-positive and GFP-negative cells were seen. (B) After 2 weeks, colonies of the small GFP-positive cells began to be observed adjacent to larger cells. (C) After 3 weeks, colonies of small, MAPC-like cells were seen (arrowheads). (D) Staining for CD73-PE, a marker for mesenchymal cells. (E) Staining for smooth muscle actin-Cy-3, which is a marker for activated stromal cells. (F) Staining for CD14-PE, a marker for macrophages. Notice the presence of small GFP-positive spindle-shaped cells that resemble MAPCs, which were negative for the above markers. (G) MAPC colony seen after 5 weeks. (H) MAPC immunophenotype: negative for CD45, CD105, CD44, CD73, but positive for Flk-1, Sca-1, CD13. Original magnification, ×20 for panels A-G. Arrowheads indicate MAPC-like cells; arrows, large GFP-negative cells.
