کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2515077 | 1118500 | 2006 | 14 صفحه PDF | دانلود رایگان |
Expansion of articular chondrocytes in monolayer culture leads to loss of the unique chondrocyte phenotype and the cells’ redifferentiation capacity. Dedifferentiation of chondrocytes in monolayer culture is a challenging problem for autologous chondrocyte transplantation (ACT). It is well established that Igf-I exerts positive anabolic effects on chondrocytes in vivo and in vitro. Accordingly, in this study, we examined whether the anabolic insulin-like growth factor-I (Igf-I) is capable of extending the chondrogenic potential of dedifferentiated chondrocytes in vitro. Chondrocyte monolayers were cultured up to 10 passages. At each passage chondrocytes were stimulated with Igf-I (10 ng/ml) and introduced to high-density cultures for up to 7 days. Expression of collagen type II, cartilage-specific proteoglycans, activated caspase-3, integrin β1, extracellular signal-regulated kinase (Erk) and Sox9 was examined by Western blotting, immunoprecipitation and immunomorphological techniques. Monolayer chondrocytes rapidly lost their differentiated phenotype. When introduced to high-density cultures, only chondrocytes from P1–P4 redifferentiated. In contrast, Igf-I treated cells from P1 up to P7 redifferentiated and formed cartilage-like tissue in high-density culture. P8–P10 cells exhibited apoptotic alterations and produced significantly less matrix. Igf-I markedly increased expression of integrin β1, Erk and Sox9. Immunoprecipitation revealed that phosphorylated Erk1/2 physically interacts with Sox9 in chondrocyte nuclei, suggesting a previously unreported functional association which was markedly enhanced by Igf-I. Treatment of chondrocyte cultures with Igf-I stabilizes chondrogenic potential, stimulates Sox9 and promotes molecular interactions between Erk and Sox9. These effects appear to be regulated by the integrin/MAPK signaling pathways.
Journal: Biochemical Pharmacology - Volume 72, Issue 11, 30 November 2006, Pages 1382–1395