Fig. 2

Multi-differentiation of mCPCs derived from paired grade 1–2 and grade 3–4 OA cartilage. a–c Representative photomicrographs of ALP (a), Von Kossa (b), and Oil Red O (c) staining of mCPCs. d Histochemical staining of HE, toluidine blue, Safranin O, and immunohistochemical staining of Col-II and Sox-9 for cartilage pellets that developed with paired grade 1–2 and grade 3–4 cartilage-derived mCPCs. e Histological scores of pellets. f–h The relative mRNA expression of osteogenesis (RUNX2 and OCN), adipogenesis (CEBP/α and PPARγ), and chondrogenesis genes (Col-II and Sox-9). Data were normalized to β-actin and RPL13a (housekeeping genes for Sox-9 and Col-II only). n = 6 donors, with each repeated in triplicates, error bars denote the means ± SD, *p < 0.05, ***p < 0.001. Scale bars represent 200 μm (a–c) and 100 μm (d), respectively. ALP, alkaline phosphatase; HE, hematoxylin and eosin; RUNX2, runt-related transcription factor 2; OCN, osteocalcin; CEBP/α, CCAAT/enhancer-binding protein alpha; PPARγ, peroxisome proliferator-activated receptor gamma; Col-II, collagen type II; Sox-9: sex-determining region Y-box 9