Fig. 4

Chondrogenic differentiation of normal and osteoarthritic (OA) synovial membrane-derived cMSCs. A Evaluation of glycosaminoglycan (GAG) deposition and collagen content. 5 µm sections of pellets cultured for 21 weeks in chondrogenic differentiation medium containing 10 ng/ml TGF-β1 and 100 ng/ml BMP-2 were stained with toluidine blue (scale bar = 100 µM). A representative image of every donor is shown. One donor (X) was lost during processing. Additionally, immunohistochemical analysis of collagen (COL) content was performed for COL type I and II using DAB (3, 3'-diaminobenzidine, orange/brown staining) (scale bar = 200 µm). The donor numbers of clinically normal (N) and OA (O) donors correspond to the donor numbers and information in Additional file 1: Table S1. Biochemical evaluation of the GAG (B) and DNA (C) content in µg. Each dot represents an individual donor. *p < 0.05; **p < 0.01