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Bone marrow-derived mesenchymal stem cells (BMSCs) are a good cell source for regeneration of cartilage as they can migrate directly to the site of cartilage injury and differentiate into articular chondrocytes. Articular cartilage defects do not heal completely due to the lack of chondrocytes or BMSCs at the site of injury. In this study, the chemotaxis of BMSCs toward chemokines, which may give rise to a complete regeneration of the articular cartilage, was investigated. CCR2, CCR4, CCR6, CXCR1, and CXCR2 were expressed in normal BMSCs and were increased significantly upon treatment with proinflammatory cytokines. BMSC migration was increased by MIP-3α and IL-8 more than by MCP-1 or SDF-1α. IL-8 and MIP-3α significantly enhanced the chemotaxis of BMSCs compared with MCP-1, SDF-1α, or PBS. Human BMSC recruitment to transplanted scaffolds containing either IL-8 or MIP-3α significantly increased in vivo compared to scaffolds containing PBS. Furthermore, IL-8- and MIP-3α-containing scaffolds enhanced tissue regeneration of an osteochondral defect site in beagle knee articular cartilage. Therefore, this study suggests that IL-8 and MIP-3α are the candidates that induce the regeneration of damaged articular cartilage.

In this study, the high pressure phase behaviour of poly( l -lactic acid) (M = 312,000), dichloromethane and carbon dioxide ternary mixtures was studied using a variable volume view cell at temperatures ranging from 313.15 K to 363.15 K and pressures of up to 30.0 MPa as functions of temperature and the CO2/dichloromethane mass ratio at poly( l -lactic acid) weight fractions of 1.0%, 2.5% and 3.0%. The experimental results were correlated with the hybrid equation of state for the CO2-polymer system using the van der Waals one-fluid mixing rule with three adjustable binary interaction parameters.