INFLUENCE OF MECHANICAL STRESS ON EXTRACELLULAR MATRIXES SYNTHESIZED BY CHONDROCYTES SEEDED ONTO ALGINATE AND HYALURONATE-BASED 3D BIOSYSTEMS

Articular cartilage is an hydrated tissue that withstands and distributes mechanical stresses. The chondrocytes respond to mechanical signals by regulating their metabolic activity through complex biological and biophysical interactions with the extracellular matrix (ECM). The objective of this work was to compare, under mechanical stress, the ECMs synthesized by rat chondrocytes seeded onto biosystems based on alginate (Alg), hyaluronic acid (HA) and a HA amphiphilic derivative. The mechanical stress simulates the traumatisms resulting from accidental shocks or intensive physical exercise by knocking the biosystems together. The investigation of ECMs neosynthesized by chondrocytes was carried out according to various criteria: proliferation, proteoglycans synthesis activity, expression of type I and type II collagens and the expression of alpha 5/beta 1 integrin. The results obtained for the stress applied on neosynthesized matrixes of 3, 10, 17 and 24 days evidenced a high proliferation and proteoglycans synthesis activity for cells submitted to a knocking process. For all biosystems, the neosynthesized matrix contained an important level of collagen, which was in part of type II, whatever the biosystems. Finally, the chemical modification of HA by long hydrophobic alkyl chains, affords an amphiphilic derivative with viscoelastic properties perfectly mimicking those of matricial environment of chondrocytes. This study showed that the HA amphiphilic derivative induced biological effects similar to those of parent HA containing no hydrophobic modifications.