Faculty of Biomedical Engineering, Technion - Israel Institute of Technology, Technion City, Haifa 32000, Israel.
Biomaterials. 2011 Feb;32(6):1508-16. doi: 10.1016/j.biomaterials.2010.10.017. Epub 2010 Nov 19.
Primary bovine chondrocytes and PEG-based hydrogels were used to investigate the effects of scaffold composition and architecture on the cellular response to large dynamic compressive strain stimulation. Proteins and proteoglycans were conjugated to functionalized poly(ethylene glycol) (PEG) and immobilized in PEG hydrogels to create bio-synthetic scaffolds. Second passage articular chondrocytes were encapsulated into four different scaffold compositions: PEG-Proteoglycan (PP), PEG-Fibrinogen (PF), PEG-Albumin (PA), and PEG only and subjected to 15% dynamic compressive strain at 1-Hz frequency. Cellular response was evaluated in terms of cell number, glycosaminoglycans (GAGs), collagen type II and collagen type I accumulation in the constructs following 24h and 28 days of stimulated and static culture. Stimulation of the constructs resulted in an increase in the cell number in all scaffolds, with no statistical difference measured among them. Dynamic stimulation of PP, PF, PA and PEG constructs resulted in a respective increase in the GAGs by 33%, 53.4%, 240.5%, and 284.5%, compared to their static controls. The permissive PEG and PA scaffolds showed a significantly larger relative increase in the GAGs in comparison to the other scaffolds tested. Collagen type II content in the PF, PA and PEG constructs increased by 78%, 1266% and 896% respectively, compared to their static controls. Permissive constructs showed a significantly larger relative increase and final absolute values of GAGs and type II collagen, compared to the PF constructs. Immunostaining for collagen type I, an indicator for chondrocyte de-differentiation, indicated that stimulation inhibited its production. Correlation maps between scaffold properties highlighted the major differences between permissive and instructive scaffolds. These results support the hypothesis that both compressive strain and scaffold bioactivity have an important effect on the chondrocyte metabolic response to mechanical stimulation, and that the 3-D environment surrounding chondrocytes can actively participate in translating mechanical stimulation to the resident cells.
原代牛软骨细胞和 PEG 水凝胶被用于研究支架组成和结构对细胞对大动态压缩应变刺激的反应的影响。蛋白质和蛋白聚糖被共轭到功能化的聚乙二醇（PEG）上，并固定在 PEG 水凝胶中以创建生物合成支架。第二通道关节软骨细胞被包封在四种不同的支架组成中：PEG-蛋白聚糖（PP）、PEG-纤维蛋白原（PF）、PEG-白蛋白（PA）和仅 PEG，并在 1-Hz 频率下接受 15%的动态压缩应变。细胞反应根据细胞数量、糖胺聚糖（GAGs）、构建体中的 II 型胶原和 I 型胶原的积累来评估，在刺激和静态培养 24 小时和 28 天后。所有支架中的构建体的刺激导致细胞数量增加，其中没有统计学差异。与静态对照相比，PP、PF、PA 和 PEG 构建体的动态刺激分别导致 GAGs 增加 33%、53.4%、240.5%和 284.5%。允许的 PEG 和 PA 支架与测试的其他支架相比，GAGs 的相对增加明显更大。与静态对照相比，PF、PA 和 PEG 构建体中的 II 型胶原含量分别增加了 78%、1266%和 896%。允许的构建体与 PF 构建体相比，GAGs 和 II 型胶原的相对增加和最终绝对值明显更大。胶原蛋白 I 的免疫染色，作为软骨细胞去分化的指标，表明刺激抑制了其产生。支架特性之间的相关图谱突出了允许和指令性支架之间的主要差异。这些结果支持了这样的假设，即压缩应变和支架生物活性对软骨细胞对机械刺激的代谢反应都有重要影响，并且围绕软骨细胞的 3-D 环境可以积极参与将机械刺激转化为驻留细胞。
