Regulation of mesenchymal cell differentiation and biological cartilage repair using cell supplementation

我们已经确定了BMP信号相关因子SF3b4和Gas6。这些因子调节未分化间充质细胞的软骨分化。然后，我们在体外分析了分化调节间充质细胞对退变软骨的影响，并证明了细胞可以附着和嵌入表面基质。为了进一步将细胞疗法扩展到软骨修复，我们尝试了大量软骨细胞的无支架移植；关节内注射补充细胞。在裸鼠股骨髌骨沟处建立全层关节软骨缺损。使用未分化软骨祖细胞表型的N1511细胞作为细胞补充。骨形态发生蛋白(BMP)/胰岛素处理N1511细胞诱导成软骨分化。用荧光染料短暂标记未分化的N1511细胞或BMP/胰岛素处理的软骨细胞N1511细胞，并将等比1 × 107/ml的细胞注射到膝关节。18周后对注射细胞的定位和缺损的修复进行组织学评价。注射细胞大多附着在滑膜表面，然后移植到滑膜下组织。这些细胞也分散在填补骨软骨缺损的修复组织中，而在正常关节软骨表面未检测到。没有组织学证据表明滑膜炎症或异位软骨增生。在没有细胞注射的对照组中，没有观察到缺陷的自发透明再生。然而，关节内细胞注射增强了缺损的修复，BMP/胰岛素处理的软骨细胞N1511比未分化的N1511细胞表现出更好的软骨修复。因此，关节内补充固定的软骨细胞可能是一种潜在的基于细胞的治疗关节软骨病变的方法。

We have identified BMP signal related factor, SF3b4, and also Gas6. These factors regulated chondrogenic differentiation of undifferentiated mesenchymal cells. We, then analyzed the effect of differentiation-regulated mesenchymal cells on the degenerated cartilage in vitro and demonstrated that the cells could attach and embedded into surface matrix. To further extend the cell-based therapy to the cartilage repair, we have attempted scaffold-free transplantation of large numbers of chondrocytic cells ; cell supplementation by intra-articular injection. A full-thickness articular cartilage defect was created in the femoral patellar groove of the nude rat. N1511 cells with undifferentiated chondroprogenitor phenotype were used for cell supplementation. N1511 cells were treated with bone morphogenetic protein (BMP)/insulin to induce chondrogenic differentiation. Undifferentiated N1511 cells or BMP/insulin treated chondrocytic N1511 cells were briefly labeled with fluorescent dye and a aliquot of 1x107/ml of cells was injected into the knees. Localization of the injected cells and the repair of the defect were evaluated histologically by 18 weeks. Injected cells were mostly attached to the synovial surface and then engrafted into sub-synovial tissue. The cells were also scattered among the repaired tissue that filled the osteochondral defect, whereas they were not detected on the surface of normal articular cartilage. There was no histological evidence of synovial inflammation or ectopic chondroplasia. Spontaneous hyaline regeneration of the defect was not observed in the controls without cell injection. However, intra-articular cell injection enhanced the repair of the defect and BMP/insulin-treated chondrocytic N1511 cells showed better cartilage repair than undifferentiated N1511 cells. Thus, intra-articular supplementation of committed chondrocytic cells may be a potential cell-based therapy for articular cartilage lesions.