Nestin expression in endothelial progenitor cells (EPCs). Mouse bone marrow mononuclear cells (MNCs) were cultured in endothelial growth medium supplemented with growth factors. After 21 days in vitro (DIV), cells were fixed and stained to detect nestin (A,D,G, red). (B) A proliferation marker, Ki67 (green). Endothelial markers CD31 (E, green) and von Willebrand Factor (vWF) (H, green) of the same images shown in A,D,G. (C,F,I) Merged images. Double-positive cells expressed nestin and Ki67, or nestin and CD31. (A–I) Nuclei were stained with Hoechst (blue). Bar = 100 μm.