Gene expression analysis via quantitative real time RT-PCR. mRNA gene expression analysis via SYBR Green detection was used to evaluate gene expression of: (A) aggrecan, (B) sox9, (C) collagen I (COL1A2), (D) collagen II (COL2A1), (E) collagen X (COL10A1) (F) matrix metalloproteinase-1 (MMP-1), (G) matrix metalloproteinase −3 (MMP3), (H) matrix metalloproteinase-13 (MMP13), and (I) interleukin 1 receptor antagonist (IL1Ra) in pellets from MCs, MC:BMSCs and BMSCs after 17 days of culture in serum free chondrogenic medium containing TGF-β3, dexamethasone and ascorbate. In the last 3 days of pellet culture, pellets were either cultured in the presence (signified by +) or absence of IL-1β. Each data point represents the mean ± SEM. One-way analysis of variance (ANOVA) with Tukey’s multiple comparison post-tests was performed using SPSS version 20 and statistical significance level indicators are: *p <0.05, **p <0.01; *** p <0.0001. No significant (ns) difference. All marker gene expression data was normalized to expression of human β-actin; y-axis.