Rivera Alexander L, Baskaran Harihara
Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
Department of Chemical and Biomolecular Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
Micromachines (Basel). 2015 Mar;6(3):330-346. doi: 10.3390/mi6030330. Epub 2015 Mar 2.
Tissue engineering is viewed as a promising option for long-term repair of cartilage lesions, but current engineered cartilage constructs fail to match the mechanical properties of native tissue. The extracellular matrix of adult human articular cartilage contains highly organized collagen fibrils that enhance the mechanical properties of the tissue. Unlike articular cartilage, mesenchymal stem cell (MSC) based tissue engineered cartilage constructs lack this oriented microstructure and therefore display much lower mechanical strength. The goal of this study was to investigate the effect of biomolecular gradients and shear stress on MSCs undergoing chondrogenesis within a microfluidic device. Via poly(dimethyl siloxane) soft-lithography, microfluidic devices containing a gradient generator were created. Human MSCs were seeded within these chambers and exposed to flow-based transforming growth factor β1 (TGF-β1) gradients. When the MSCs were both confluent and exposed to shear stress, the cells aligned along the flow direction. Exposure to TGF-β1 gradients led to chondrogenesis of MSCs, indicated by positive type II collagen staining. These results, together with a previous study that showed that aligned MSCs produce aligned collagen, suggest that oriented cartilage tissue structures with superior mechanical properties can be obtained by aligning MSCs along the flow direction and exposing MSCs to chondrogenic gradients.
组织工程被视为软骨损伤长期修复的一种有前景的选择，但目前的工程化软骨构建体未能匹配天然组织的力学性能。成年人类关节软骨的细胞外基质包含高度有序的胶原纤维，这些纤维增强了组织的力学性能。与关节软骨不同，基于间充质干细胞（MSC）的组织工程软骨构建体缺乏这种定向微观结构，因此显示出低得多的机械强度。本研究的目的是研究生物分子梯度和剪切应力对在微流控装置中经历软骨形成的间充质干细胞的影响。通过聚二甲基硅氧烷软光刻技术，创建了包含梯度发生器的微流控装置。将人类间充质干细胞接种在这些腔室内，并暴露于基于流动的转化生长因子β1（TGF-β1）梯度中。当间充质干细胞汇合并暴露于剪切应力时，细胞沿流动方向排列。暴露于TGF-β1梯度导致间充质干细胞软骨形成，Ⅱ型胶原染色阳性表明了这一点。这些结果，连同先前一项表明排列的间充质干细胞产生排列的胶原的研究，表明通过使间充质干细胞沿流动方向排列并使间充质干细胞暴露于软骨形成梯度，可以获得具有优异力学性能的定向软骨组织结构。
