Dimicco M A, Kisiday J D, Gong H, Grodzinsky A J
Center for Biomedical Engineering and Biological Engineering Division, Massachusetts Institute of Technology, Cambridge, MA, USA.
Osteoarthritis Cartilage. 2007 Oct;15(10):1207-16. doi: 10.1016/j.joca.2007.03.023. Epub 2007 May 23.
Determine whether the structure of the type VI collagen component of the chondrocyte pericellular matrix (PCM) generated by agarose-embedded chondrocytes in culture is similar to that found in native articular cartilage.
Confocal microscopy, quick-freeze deep-etch electron microscopy, and real-time polymerase chain reaction (PCR) were used to investigate temporal and spatial patterns of type VI collagen protein deposition and gene expression by bovine chondrocytes during 4 weeks of culture within a 2% agarose hydrogel. Similar analyses were performed on chondrocytes within samples of intact cartilage obtained from the same joint surfaces as those used for cell isolation for comparison.
Type VI collagen accumulated uniformly around cells embedded in agarose, with the rate of deposition slowing after the second week. After 1 week, PCM fibrils were observed to be oriented perpendicular to the cell surface, in contrast with the primarily tangential fibrillar arrangement observed in native articular cartilage. Expression of col6 in agarose-embedded cells was initially much higher ( approximately 400%) than that in chondrocytes within cartilage. Expression of col6 in the cultured chondrocytes declined by approximately 60% after 1 week, and remained stable thereafter.
PCM structure and composition around cells in a hydrogel scaffold may be different than that in native cartilage, with potential implications for mass transport, mechanotransduction, and ultimately, the success of tissue engineering approaches.
确定培养的琼脂糖包埋软骨细胞产生的软骨细胞周细胞外基质（PCM）中VI型胶原蛋白成分的结构是否与天然关节软骨中的结构相似。
使用共聚焦显微镜、快速冷冻深蚀刻电子显微镜和实时聚合酶链反应（PCR）研究牛软骨细胞在2%琼脂糖水凝胶中培养4周期间VI型胶原蛋白的沉积和基因表达的时空模式。对从与用于细胞分离相同关节表面获取的完整软骨样本中的软骨细胞进行类似分析以作比较。
VI型胶原蛋白在琼脂糖包埋的细胞周围均匀积累，第二周后沉积速率减慢。1周后，观察到PCM纤维垂直于细胞表面排列，这与天然关节软骨中主要为切向纤维排列形成对比。琼脂糖包埋细胞中col6的表达最初比软骨中的软骨细胞高得多（约400%）。培养的软骨细胞中col6的表达在1周后下降约60%，此后保持稳定。
水凝胶支架中细胞周围的PCM结构和组成可能与天然软骨不同，这对物质运输、机械转导以及最终组织工程方法的成功可能具有影响。
