PTN increases cartilage specific protein and gene expression during hBMSC chondrogenic differentiation.

<p>hBMSC from 3 independent patients were cultured in micromass with chondrogenic medium in absence or with increasing doses of PTN (0 pg/ml white boxes, 50 pg/ml grey boxes and 500 pg/ml black boxes) for 21 days. All conditions were performed in triplicate per patient. (<b>A</b>): Collagen 2 immunostaining of chondrogenic pellets. Side box shows an enlargement (x3) of the black square. Bars represent 100 µm. (<b>B</b>): Real-time polymerase chain reaction analysis of cartilage related genes expression. RNA were purified from hBMSC at day 0 and after 7 and 14 days of culture without or with PTN. Expression levels of cartilage genes: SRY-box9 (Sox9), Cartilage Oligomeric Matrix Protein (COMP) and Collagen9A1 (Col9) are normalized to Glyceraldehyde 3-Phosphate Dehydrogenase (GAPDH). Values are the mean±SEM. The gene expression values at day 0 are represented by straightened lines. Statistical analysis were performed, with a one way anova Kruskal-Wallis test, between values from free-PTN conditions (white boxes) at day 0, 7 and 14 (##: p<0.01; ###: p<0.001), and between values from increasing PTN doses from the same day (**: p<0.01; ***: p<0.001).