Fig. 2

Osteogenic, adipogenic, and chondrogenic differentiation assays. a Differentiation assays were performed in Tie2– cells and Tie2+ cells (i.e., NPPC) after sorting and a mixed cell population (unsorted NPC). Top panel Macroscopic and microscopic images of osteogenesis (Alizarin red staining). Middle panel Adipogenic differentiation (Oil red O staining), arrows highlighting the formation of fat droplets. Lower panel Chondrogenic differentiation: Safranin-O staining and proteoglycans (PG, green) immunohistochemistry counterstained with 4′,6-diamidino-2-phenylindole (DAPI, blue). Results of one representative experiment of at least three repeats are shown. Scale bars are indicated on the images. b Quantification of Alizarin red staining (ARS), Oil red O fat droplet-positive cells, and GAG/DNA content. Individual cell populations were cross-compared to determine significance with *p < 0.05. Bars represent mean ± SD (N = 5). GAG glycosaminoglycans, Tie2 angiopoietin-1 receptor (Color figure online)