Sharma Garima, Saxena R K, Mishra Prashant
Centre for Biomedical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110 016, India.
Clin Biomech (Bristol). 2007 Feb;22(2):248-55. doi: 10.1016/j.clinbiomech.2006.09.008. Epub 2006 Nov 15.
Mechanical stresses are known to play important role on articular cartilage functions in vivo and also on cartilage explants and chondrocytes monolayer culture. This study examined the differential effect of cyclic and static pressures on chondrocytes cultured in alginate matrix, which is physiologically closer to the in vivo environment of cells in cartilage.
Goat knee joint articular cartilage chondrocytes cultured in alginate beads were exposed to 1.2 and 2.4 MPa cyclic and static loadings via a custom-made cam/follower based machine. Biochemical contents (glycosaminoglycan, collagen, DNA) and protease activity of cells were analyzed separately in cellular matrix, further removed matrix and in culture medium. Morphology of chondrocytes was studied under transmission electron microscopy.
Compared with controls (unloaded cells), cyclic loading increased the glycosaminoglycan content of cells at 1.2 and 2.4 MPa in cellular matrix and further removed matrix (P<0.001) whereas it decreased at similar static loads (P<0.001). In alginate matrix, chondrocytes released a metalloprotease, which required Mn(2+) for activity. Both cyclic load levels inhibited its specific activity in cellular matrix but increased it at static loading (P<0.001). The protease specific activity in further removed matrix increased at both cyclic and static loadings (P<0.001). Transmission electron microscopy data showed improved cells ultrastructure and cell-matrix interactions under cyclic load whereas these deteriorated under static loadings.
The study suggests that cyclic load has a positive effect on chondrocytes metabolism and morphology whereas static load has a degenerative effect.
机械应力在体内对关节软骨功能以及软骨外植体和软骨细胞单层培养中都起着重要作用。本研究考察了循环压力和静态压力对在藻酸盐基质中培养的软骨细胞的不同影响,藻酸盐基质在生理上更接近软骨中细胞的体内环境。
将培养在藻酸盐珠中的山羊膝关节软骨细胞通过定制的基于凸轮/从动件的机器分别暴露于1.2和2.4兆帕的循环和静态负荷下。分别在细胞基质、进一步去除的基质和培养基中分析细胞的生化成分(糖胺聚糖、胶原蛋白、DNA)和蛋白酶活性。在透射电子显微镜下研究软骨细胞的形态。
与对照组(未加载细胞)相比,循环加载在1.2和2.4兆帕时增加了细胞基质和进一步去除的基质中细胞的糖胺聚糖含量(P<0.001),而在类似的静态负荷下则降低(P<0.001)。在藻酸盐基质中,软骨细胞释放一种金属蛋白酶,其活性需要锰离子。两种循环负荷水平均抑制其在细胞基质中的比活性,但在静态负荷下增加(P<0.001)。在进一步去除的基质中,蛋白酶比活性在循环和静态负荷下均增加(P<0.001)。透射电子显微镜数据显示,循环负荷下细胞超微结构和细胞-基质相互作用得到改善,而在静态负荷下则恶化。
该研究表明,循环负荷对软骨细胞代谢和形态有积极影响,而静态负荷有退行性影响。