Taylor Drew W, Ahmed Nazish, Parreno Justin, Lunstrum Gregory P, Gross Allan E, Diamandis Eleftherios P, Kandel Rita A
1 BioEngineering of Skeletal Tissues Team, CIHR , Ottawa, Ontario, Canada .
Tissue Eng Part A. 2015 Feb;21(3-4):683-93. doi: 10.1089/ten.TEA.2014.0103. Epub 2014 Dec 16.
Current approaches to cartilage tissue engineering require a large number of chondrocytes. Although chondrocyte numbers can be expanded in monolayer culture, the cells dedifferentiate and unless they can be redifferentiated are not optimal to use for cartilage repair. We took advantage of the differential effect of culture conditions on the ability of passaged and primary chondrocytes to form cartilage tissue to dissect out the extracellular matrix (ECM) molecules produced and accumulated in the early stages of passaged cell cartilage tissue formation as we hypothesized that passaged bovine cells that form cartilage accumulate a pericellular matrix that differs from cells that do not form cartilage. Twice passaged bovine chondrocytes (P2) (cartilage forming), or as a control primary chondrocytes (P0) (which do not generate cartilage), were cultured on three-dimensional membrane inserts in serum-free media. P2 redifferentiation was occurring during the first 8 days as indicated by increased expression of the chondrogenic genes Sox9, collagen type II, aggrecan, and COMP, suggesting that this is an appropriate time period to examine the ECM. Mass spectrometry showed that the P2 secretome (molecules released into the media) at 1 week had higher levels of collagen types I, III, and XII, and versican while type II collagen and COMP were found at higher levels in the P0 secretome. There was increased collagen synthesis and retention by P2 cells compared to P0 cells as early as 3 days of culture. Confocal microscopy showed that types XII, III, and II collagen, aggrecan, versican, and decorin were present in the ECM of P2 cells. In contrast, collagen types I, II, and III, aggrecan, and decorin were present in the ECM of P0 cells. As primary chondrocytes grown in serum-containing media, a condition that allows for the generation of cartilage tissue in vitro, also accumulate versican and collagen XII, this study suggests that these molecules may be necessary to provide a microenvironment that supports hyaline cartilage formation. Further study is required to determine if these molecules are also accumulated by passaged human chondrocytes and their role in promoting hyaline cartilage formation.
目前的软骨组织工程方法需要大量的软骨细胞。尽管软骨细胞数量可在单层培养中扩增,但细胞会去分化,除非它们能重新分化,否则用于软骨修复并非最佳选择。我们利用培养条件对传代软骨细胞和原代软骨细胞形成软骨组织能力的不同影响,来剖析传代细胞软骨组织形成早期产生和积累的细胞外基质(ECM)分子,因为我们推测形成软骨的传代牛细胞会积累一种不同于不形成软骨的细胞的细胞周围基质。将传代两次的牛软骨细胞(P2)(形成软骨)或作为对照的原代软骨细胞(P0)(不产生软骨)在无血清培养基中的三维膜插入物上培养。如软骨生成基因Sox9、II型胶原蛋白、聚集蛋白聚糖和软骨寡聚基质蛋白表达增加所示,P2在培养的前8天发生重新分化,这表明这是检查ECM的合适时间段。质谱分析表明,P2在1周时的分泌蛋白组(释放到培养基中的分子)中I型、III型和XII型胶原蛋白以及多功能蛋白聚糖水平较高,而II型胶原蛋白和软骨寡聚基质蛋白在P0分泌蛋白组中的水平较高。早在培养3天时,与P0细胞相比,P2细胞的胶原蛋白合成和保留就有所增加。共聚焦显微镜显示,XII型、III型和II型胶原蛋白、聚集蛋白聚糖、多功能蛋白聚糖和核心蛋白聚糖存在于P2细胞的ECM中。相比之下,I型、II型和III型胶原蛋白、聚集蛋白聚糖和核心蛋白聚糖存在于P0细胞的ECM中。由于在含血清培养基中生长的原代软骨细胞(一种允许在体外产生软骨组织的条件)也会积累多功能蛋白聚糖和XII型胶原蛋白,这项研究表明这些分子可能是提供支持透明软骨形成的微环境所必需的。需要进一步研究以确定这些分子是否也会被传代的人软骨细胞积累以及它们在促进透明软骨形成中的作用。