Background In vitro chondrocyte expansion is a major challenge in cell-based therapy for human articular cartilage repair. Classical culture conditions usually use animal serum as a medium supplement, which raises a n...Background In vitro chondrocyte expansion is a major challenge in cell-based therapy for human articular cartilage repair. Classical culture conditions usually use animal serum as a medium supplement, which raises a number of undesirable questions. In the present study, two kinds of defined, serum-free media were developed to expand chondrocytes in monolayer culture for the purpose of cartilage tissue engineering. Methods Bovine chondrocytes were expanded in serum-free media supplemented with fibroblast growth factor-2 and platelet-derived growth factor or fibroblast growth factor-2 and insulin-like growth factor. Expansion culture in a conventional 10% fetal bovine serum （FBS） medium served as control. Fibronectin coating was used to help cell adhesion in serum-free medium. Next, in vitro three-dimensional pellet culture was used to evaluate the chondrocyte capacity. Cell pellets were expanded in different media to re-express the differentiated phenotype （re-differentiation） and to form cartilaginous tissue. The pellets were assessed by glycosaminoglycans contents, collagen II, collagen I and collagen X immunohistological staining. Results Chondrocytes cultured in serum-free media showed no proliferation difference than cells grown with 10% FBS medium. In addition, chondrocytes expanded in both serum-free media expressed more differentiated phenotypes at the end of monolayer culture, as indicated by higher gene expression ratios of collagen type II to collagen type I. Pellets derived from chondrocytes cultured in both serum-free media displayed comparable chondrogenic capacities to pellets from cells expanded in 10% FBS medium. Conclusion These findings provide alternative culture approaches for chondrocytes in vitro expansion, which may benefit the clinical use of autologous chondrocytes implantation.展开更多
目前,移动流媒体系统存在网络链路不稳定,带宽有限,移动终端呈现微课视频的高时延,数据缓冲频繁,用户体验差等问题,提出了动态码率自适应的微课移动流媒体系统.详细分析了构建方案系统实现的关键技术,通过服务器端应用Direct Show技术和...目前,移动流媒体系统存在网络链路不稳定,带宽有限,移动终端呈现微课视频的高时延,数据缓冲频繁,用户体验差等问题,提出了动态码率自适应的微课移动流媒体系统.详细分析了构建方案系统实现的关键技术,通过服务器端应用Direct Show技术和FFmpeg程序实现微课视频的内容准备,应用Nginx服务器技术实现微课视频流内容分发系统,在客户端应用HTTP Live Streaming技术方案的Client组件实现播放功能上,提供适合当下带宽的最平滑播放的流式文件,尽最大可能为移动终端提供最佳用户体验.展开更多
文摘Background In vitro chondrocyte expansion is a major challenge in cell-based therapy for human articular cartilage repair. Classical culture conditions usually use animal serum as a medium supplement, which raises a number of undesirable questions. In the present study, two kinds of defined, serum-free media were developed to expand chondrocytes in monolayer culture for the purpose of cartilage tissue engineering. Methods Bovine chondrocytes were expanded in serum-free media supplemented with fibroblast growth factor-2 and platelet-derived growth factor or fibroblast growth factor-2 and insulin-like growth factor. Expansion culture in a conventional 10% fetal bovine serum （FBS） medium served as control. Fibronectin coating was used to help cell adhesion in serum-free medium. Next, in vitro three-dimensional pellet culture was used to evaluate the chondrocyte capacity. Cell pellets were expanded in different media to re-express the differentiated phenotype （re-differentiation） and to form cartilaginous tissue. The pellets were assessed by glycosaminoglycans contents, collagen II, collagen I and collagen X immunohistological staining. Results Chondrocytes cultured in serum-free media showed no proliferation difference than cells grown with 10% FBS medium. In addition, chondrocytes expanded in both serum-free media expressed more differentiated phenotypes at the end of monolayer culture, as indicated by higher gene expression ratios of collagen type II to collagen type I. Pellets derived from chondrocytes cultured in both serum-free media displayed comparable chondrogenic capacities to pellets from cells expanded in 10% FBS medium. Conclusion These findings provide alternative culture approaches for chondrocytes in vitro expansion, which may benefit the clinical use of autologous chondrocytes implantation.
文摘目前,移动流媒体系统存在网络链路不稳定,带宽有限,移动终端呈现微课视频的高时延,数据缓冲频繁,用户体验差等问题,提出了动态码率自适应的微课移动流媒体系统.详细分析了构建方案系统实现的关键技术,通过服务器端应用Direct Show技术和FFmpeg程序实现微课视频的内容准备,应用Nginx服务器技术实现微课视频流内容分发系统,在客户端应用HTTP Live Streaming技术方案的Client组件实现播放功能上,提供适合当下带宽的最平滑播放的流式文件,尽最大可能为移动终端提供最佳用户体验.
