gms | German Medical Science

Objectives: The meniscus is located between the femoral condyle and tibial plateau of the knee that aids in the force transmission, shock absorption, joint stability, lubrication and proprioception of the joint. It is composed of an inner avascular region and a vascularized outer zone. Treatment of meniscus tears within the avascular region is a significant challenge, particularly in an early osteoarthritis situation. cell based tissue engineering approaches have shown promising in vitro results However, in vivo studies have not found a consensus on the appropriate autologous cell source in a clinical situation. This study sought to evaluate the appropriate cell source for autologous meniscal repair within the avascular region in an early osteoarthritis situation.

Methods: Bone marrow and medial meniscus were harvested New Zealand white rabbits and then cultured for isolation and expansion of bone marrow mesenchymal stem cells (MSCs) and meniscal cells. Cells were seeded onto collagen-hyaluronan scaffolds and implanted into the defect site without pre-culture. A punch defect model was performed on the lateral meniscus of the rabbit and then a cell-seeded scaffold was press-fit into the defect. Rabbits were sacrificed after 6 or 12 weeks (n = 6 per time point and treatment), gross joint morphology was assessed and menisci were harvested for histological and immunohistochemical processing. Evaluation of macroscopic, histological and immunohistochemical results were evaluated using a validated meniscus scoring system. In an in vitro model, human meniscal cells isolated from non-repairable bucket handle tears and human MSCs were expanded. Using a pellet culture model, both cell types were assessed for their meniscus-like potential through collagen type I and II immunostaining, collagen type II ELISA and gene expression analysis.

Results and Conclusion: Following resections of medial menisci, all knees showed early osteoarthritic changes. However, successful repair of meniscus punch defects was performed using either meniscal cells or MSCs in an animal model. Gross joint assessment demonstrated donor site morbidity for meniscal cell treated defects. Furthermore, MSCs had significantly increased collagen type II gene expression and collagen type I immunostaining compared to meniscal cells (p < 0.05).

Thus, regenerative potential of the meniscus by an autologous cell-based tissue engineering approach was demonstrated in an early osteoarthritis situation. MSCs were found to have improved meniscal healing in an autologous setting compared to meniscal cells, thus demonstrating its feasibility in a clinical setting. The reason for this intrinsic repair may be related to the differentiation of progenitor cells or the secretion of bioactive factors by MSCs in a cell therapeutic manner. Furthermore, this model may also be used to test other autologous cell sources to test their feasibility for cell-based meniscal repair.