The effect of stress and tissue fluid microenvironment on allogeneic chondrocytes in vivo and the immunological properties of engineered cartilage

Engineered implants derived from neonatal rabbit chondrocytes and collagen type I hydrogel, were loaded in dialyzer pockets and implanted in muscle and articular cavity of rabbits to simulate different stress and tissue fluid micro-environments. After 4 and 12 weeks, the expressions of main histocompatibility complex (MHC) molecules as well as the mixed lymphocyte chondrocytes reactions (MLChR) levels of the seeded cells were detected. The results indicated that with stress and synovial fluid microenvironment, the formation of chondroid tissue was prominently promoted in articular cavity. It gave the seeded chondrocytes lower and gradually decreasing levels of allogeneic lymphocytes activation, however, with the higher cell mortality, the MHC molecules expression, especially MHC-I were up-regulated obviously in early stage. These results are very different to those seen in muscle and prove that stress and tissue fluid micro-environments can greatly impact the differentiation and immunological properties of the engineered cartilage. From the perspective of avoiding severe rejection, to promote the formation of the matrix as fast and select scaffold with higher "isolation" ability may be meaningful. Furthermore, the suitably treated dialyzer pockets model can be used for the study of the differentiation and immunological properties of the tissue engineered cartilage.