Fig. 1.

IMRCs activated by synovial fluid enhanced chondrocytes proliferation and differentiation. a Schematic illustration of the cell model stimulated by synovial fluid in vitro. b Morphology of UCMSCs and IMRCs before and after synovial fluid stimulation. c PCA of gene expression values derived from whole transcriptome sequencing data of IMRCs and UCMSCs before and after synovial fluid treatment. d GO biological process (GOBP) analysis of differentially upregulated genes for IMRCs versus UCMSCs after being treated by synovial fluid. e Heatmap illustrating the gene expression in UCMSCs and IMRCs, before and after synovial fluid stimulation. ELISA analysis of biologically relevant chemokines and cytokines in the supernatant of IMRCs and UCMSCs with and without synovial fluid stimulation. Proinflammatory (f), immunomodulatory (g), and pro-regenerative (h), cytokines. *P < 0.05, **P < 0.01, ***P < 0.001, NS, not significant; data are represented as the mean ± SEM. Scale bar: 100 μm