Chondrocytes from Different Zones Exhibit Characteristic Differences in High Density Culture

Superficial and middle/deep zone chondrocytes were isolated from goat femoral cartilage by a zonal abrasion method. The cells were expanded 100-fold through two passages, then seeded into agarose wells to form high-density constructs through a self-assembling process. After 4 weeks in culture, the superficial zone constructs contracted into a dense cell mass, while middle/deep zone chondrocytes formed constructs with four distinct regions. Middle/deep zone chondrocytes produced 250% more glycosaminoglycans per dry weight and more collagen per dry weight than superficial zone chondrocytes. The superficial and middle/deep zone chondrocytes were found to retain characteristic differences even after 100-fold expansion, as evidenced by construct morphology and extracellular matrix content. This study uniquely demonstrated the ability of expanded superficial and middle/deep zone chondrocytes to form constructs of distinct characteristics without a scaffold. The goal of tissue engineering different zones of cartilage is to eventually replicate the specific function of each zone.     

A Cell-Free Collagen Type I Device for the Treatment of Focal Cartilage Defects

The purpose of this study was to evaluate the potential value of a cell-free collagen type I gel plug for the treatment of focal cartilage defects. Cellular migration and proliferation was addressed in vitro, and the formation of repair tissue in a nude mouse-based defect model. A cell-free plug made of collagen type I was placed in the center of an incubation plate. Surrounding space was filled with a collagen type I gel (Arthro Kinetics, Esslingen, Germany) seeded with 2 × 10⁵ human articular chondrocytes/mL gel. After cultivation for up to 6 weeks in vitro, samples were subject to histological and immunohistochemical staining and gene expression analysis. Subsequently, chondral defects of human osteochondral blocks were treated with the plug, and specimens were cultivated subcutaneously in nude mice for 6 weeks. The repair tissue was evaluated macroscopically, and collagen type II production was investigated immunohistochemically. In vitro, morphology of immigrated cells did not show any differences, as did collagen type II gene expression. After 4 weeks, the plug was homogeneously inhabited. After 6 weeks of cultivation in nude mice, collagen gel plug treatment led to a macroscopically excellent repair tissue. Histological staining revealed a tight bonding, and the collagen gel plug started to be remodeled. We conclude that the novel collagen gel plug device offers an environment favorable for the migration of articular chondrocytes and leads to a good-quality repair tissue in the nude mouse model. The arthroscopic transplantation of a collagen gel plug may be one option in the treatment of focal cartilage defects.     

膝关节股骨远端软骨硬化前后力学性能分析

目的建立膝关节有限元模型,研究正常及软骨硬化情况下膝关节的应力、应变变化,为临床治疗膝关节骨性关节炎提供参考。方法通过Mimics、ANSYS等软件结合正常膝关节CT扫描图像数据,建立膝关节三维有限元模型,并施加350 N压力载荷,设定软骨硬化前后相关的材料参数,分析膝关节主要组织的应力、应变改变情况。结果膝关节股骨远端软骨硬化后,关节软骨的减震和传递负荷等作用基本消失;股骨应力、应变变化量最大,受力分布极不均匀,股骨前端应力、应变较内、外侧髁明显,整体受力也有明显增加;半月板的应力、应变值最大。结论长期的软骨破坏会影响关节软骨营养代谢,导致骨性关节炎疾病进一步恶化。研究结果可以较好阐释骨性关节炎发病过程和机理,同时为建立参数化研究系统提供相关数据。