Bone Abstracts

Background: Bone metabolic disorders, such as osteoarthritis (OA), osteopenia and osteoporosis have been associated to iron overload, both in humans and animal models. In the case of hereditary hemochromatosis (HH), arthropathy represents one of the most prevalent and disabling symptoms. This work aims at investigating the roles of HH-related HFE mutation and iron accumulation on chondrocyte metabolism.

Materials and methods: Primary cultures of articular chondrocytes were developed from WT and hfe KO mice based on the methodology described by Gosset (Nature Protocols, 2008). These cultures were subjected to three iron citrate treatments at several concentrations (0–300 mM) and characterized by analysis of i) gene expression of molecular markers through qPCR and ii) glycosaminoglycan production by Alcian Blue Staining, and presence of collagen II by immunofluorescence assay.

Results: Primary cultures of Hfe KO chondrocytes were established and analysis of cell morphology, alcian blue staining and collagen II protein accumulation were consistent with a chondrocyte phenotype. Expression of genes associated to cartilage metabolism including collagen II and X, aggrecan, and Sox9 were shown to be upregulated in chondrocytes from Hfe KO relatively to WT mice. Expression of Hfe and Ferroportin was strongly upregulated upon iron overload while expression of Transferrin receptor-2 was low and did not respond to iron overload.

Conclusions: We have established for the first time primary cultures of articular chondrocytes from Hfe KO mice and showed that all cartilage metabolism genes analysed were significantly upregulated in the mutant cells, indicating changes in normal chondrocyte metabolism. Furthermore, when exposed to iron overloads, primary chondrocytes showed an absence of response of Transferrin-receptor 2 but a clear response of Hfe and Ferroportin, indicating the presence of a regulatory mechanism in response to iron.