Differentiation potential of CPC. Cells were cultured with basal medium as control (left column) or with differentiation medium (adipogenic, osteogenic, chondrogenic) for up to four weeks. Chondrogenic progenitor cells (CPC) are A: Oil Red O positive after adipogenic differentiation (red: stained lipid droplets) and positive after osteogenic differentiation for B: von Kossa (black: mineral deposition) and C: alkaline phosphatase (AP) activity (red dye deposit). The chondrogenic differentiation was performed as 3D micromass culture (D-E). Immunohistochemical staining with cartilage oligomeric matrix protein (COMP; D) and collagen II (Col II; E) were positive. The bar indicates 100 μm unless otherwise noted.
Joos et al. Arthritis Research & Therapy 2013 15:R119 doi:10.1186/ar4299