Bone marrow mesenchymal stem cells combined with biomimetic hydrogel for repair of articular cartilage defect in porcine

Abstract

Objective To investigate the feasibility of bone marrow mesenchymal stem cells (BMSCs) combined with type Ⅱ collagen- hyaluronic acid- oxidized chondroitin sulfate (Col Ⅱ-HA-OCS) biomimetic hydrogel to repair articular cartilage defect in porcine and the role of the transplanted cells played in the process of cartilage repair. Methods A articular cartilage defect model which remaining cartilage calcified zone was created in the knee of Bama minipigs, the autologous BMSCs was used as seeds for transplantation and was labeled by the 5, 6-carboxyfluorescein diacetate succinimidyl ester (CFDA SE). Animals were randomly divided into three groups: Group A (blank group) was left untreated, group B (cell-free biomimetic hydrogel group) was filled with biomimetic hydrogel and group C (BMSCs combined with biomimetic hydrogel group) was filled with the CFDA SE labeled autologous BMSCs combined with biomimetic hydrogel. One month after the operation, BrdU labeled liquid was injected intravenously into the animals 24 h and 48 h before specimens were taken from the executed animals. Partial cartilage repaired tissue in Group C was taken, cryosectioned and stained with DAPI and BrdU immunofluorescence. Confocal laser scanning microscope was used to observe and count the cells. Specimens of the three groups were analyzed through gross observation and histological staining, and scored according to the international cartilage repair society (ICRS) gross morphological score and ICRS histological score. Results Laser scanning confocal microscopy showed (97.3±2.6)% of the cells were derived from the implanted BMSCs in repaired tissue and that the ratio of these cells with proliferative capacity was (76.6±2.5)%. Gross observation suggested most of the cartilage defect areas in Group C were filled with ivory tissue, but those in Group A and B were still obvious depression. Histological staining showed the cartilage defect areas in Group C were filled with cartilage like tissue, which was well integrated with the surrounding normal cartilage, presented a few cartilage lacunas could be seen, and had contents of Col Ⅱ and glycosaminoglycan similar with the adjacent normal cartilage. There was almost no filler in the defect area in Group A. There was little fibrous tissue in the defect area in Group B. ICRS gross score was (8.3±1.0)points in Group C, higher than that in Group A [(0.5±0.6)points] and Group B [(2.3±0.5)points] (P<0.05). ICRS histological score was (10.3±2.4)points in Group C, higher than that in Group A [(0.5±0.6)points] and Group B [(4.5±1.0)points] (P<0.05). Conclusions BMSCs combined with Col Ⅱ-HA-OCS biomimetic hydrogel for repairing porcine articular cartilage defects can achieve satisfactory results. Implanted BMSCs are the main component of the cell composition in the repaired tissue and gradually differentiated into chondrocytes. Key words: Cartilage; Mesenchymal stem cells; Collagen type Ⅱ; Bone regeneration