Fig. 5

The Secretome of Aged MSCs affects the viability and differentiation of primary Chondrocytes. A Phase contrast images of rat chondrocytes after YCM, ACM, and PTP-ACM treatment in comparison to their control are illustrated. B Live/dead staining of rat chondrocytes after YCM, ACM and PTP-ACM treatment. C Percent viability of rat chondrocytes after YCM, ACM, and PTP-ACM treatment in comparison to control is graphically illustrated. D Immunofluorescence staining of control (i), YCM (ii), ACM (iii), and PTP-ACM (iv) treated chondrocytes with an antibody to Collagen 2A (COL2A). PTP-ACM (iv) treated chondrocytes showed increased expression and proper organization of Col2A. E qRT-PCR analysis of chondrocytes treated or not with YCM, ACM, and PTP-ACM for the relative expression of Col2A (a), SOX9 (b). F The representative blot shows the expression of acid phosphatase type V (ACP5) their corresponding densitometry graphs [F(a, b)] in young, aged, and PTP inhibitor-treated aged MSCs. The band intensity of ACP5 was normalized with respect to housekeeping protein (Beta-actin), and the normalized values were plotted. The qRT-PCR data represent the relative expression of transcripts normalized to GAPDH and expressed as the Mean ± SEM for three biologically independent experiments (n = 3). For statistical analysis, One-way ANOVA followed by Bonferroni post hoc test in Graphpad Prism 6 version 6.0 (GraphPad Software Inc, La Jolla, CA) was used. All the data are represented as mean ± SD. *p < 0.05; **p < 0.01; ***p < 0.001, ****p < 0.0001; ns not significant. MSCs mesenchymal stem cells, PTP protein tyrosine phosphatase, CM conditioned medium, YCM young MSC-derived-CM, ACM aged MSC-derived CM, PTP-ACM PTP inhibitor treated aged MSC-derived CM