Fig. 6

The potential protein mediators participated in re-organization of cytoskeleton in chondrocytes in response to PDMS substrates with different stiffnesses. a, b Immunofluorescence by CLSM showing the formation and distribution of microfilaments (F-actin bundle) in chondrocytes after reduction of FAK by siRNA interference. White arrows indicated formation of microfilaments near the nucleus. Grayscale images were used to indicate the changes of microfilaments in chondrocytes in response to stiff and soft substrates. Purple boxed areas indicated the differences in microfilament bundle. c Pheatmap by RNA sequencing indicating the mRNA changes of protein mediators in chondrocytes in response to stiff and soft substrates. Cell layste samples were collected at 72 h after being seeded onto stiff and soft substrates. Data were presented as FPKM (Fragments Per Kilobase of transcript per Million fragments mapped) by online R-package from RNA sequencing data. Three independent pairs of samples, i.e., Sample 1 and 1’, Sample 2 and 2’, and Sample 3 and 3’, were from the same mother cells, respectively. d qPCR confirming the mRNA down-regulation of protein mediators in chondrocytes in response to soft substrates relative to the stiff group. e qPCR confirming the mRNA up-regulation of protein mediators in chondrocytes in response to soft substrates relative to the stiff group. All experiments by qPCR in (d) & (e) are based on three independent experiments (n = 3). All significant data presented in (d) & (e) are based on two-tailed Student’s t-tests.