Effect of increasing hyaluronic acid content in collagen scaffolds on the maintenance of chondrogenic phenotype in chondrocytes and mesenchymal stem cells

Abstract

IntroductionIn articular cartilage, hyaluronic acid (HA) has been shown to increase adhesion, differentiation, and proliferation of cartilage cells, and its addition to three-dimensional (3D) scaffolds has been shown to improve chondrocyte phenotype in vitro. ObjectivesThe purpose of this study was to determine (1) whether increasing the HA levels in collagen scaffolds leads to better maintenance of the chondrogenic phenotype in chondrocytes in a dose-dependent manner and (2) whether collagen scaffolds infused with HA promote the differentiation of mesenchymal stem cells (MSCs) into chondrocytes within 3D collagen/HA scaffolds. MethodsBovine chondrocytes and rat MSCs were seeded onto 2% or 6% collagen/HA scaffolds, or no scaffold for controls. Cells were harvested at days 6, 12 and 18. Real-time polymerase chain reaction was used to measure expression of Type I and Type II collagen, SOX-9, and aggrecan. ResultsExpression of Type I and II collagen was increased at day 18 in the chondrocytes of both groups. For the MSCs, at day 18 there was increased expression of Type I collagen and increased expression of aggrecan in both the 2 and 6% scaffold groups, plus increased SOX-9 expression in the 2% HA group. ConclusionsThough there was no significant dose-dependent change between the HA groups in their effects on Type II collagen production, both HA scaffold groups showed significantly increased expression of Type II collagen as compared to monolayer controls at 18 days. Future experiments should extend timepoints to elucidate these effects and human chondrocytes and MSCs should be used to determine biological applicability.