Black Lauren D, Meyers Jason D, Weinbaum Justin S, Shvelidze Yevgeniya A, Tranquillo Robert T
Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Tissue Eng Part A. 2009 Oct;15(10):3099-108. doi: 10.1089/ten.TEA.2008.0502.
A high-potential therapy for repairing the heart post-myocardial infarction is the implantation of tissue-engineered myocardium. While several groups have developed constructs that mimic the aligned structure of the native myocardium, to date no one has investigated the particular functional benefits conferred by alignment. In this study we created myocardial constructs in both aligned and isotropic configurations by entrapping neonatal rat cardiac cells in fibrin gel. Constructs were cultured statically for 2 weeks, and then characterized. Histological staining showed spread cells that express typical cardiac cell markers in both configurations. Isotropic constructs had higher final cell and collagen densities, but lower passive mechanical properties than aligned constructs. Twitch force associated with electrical pacing, however, was 181% higher in aligned constructs, and this improvement was greater than what would be expected from merely aligning the cells in the isotropic constructs in the force measurement direction. Our hypothesis was that this was due to improved gap junction formation/function facilitated by cell alignment, and further analyses of the twitch force data, as well as Western blot results of connexin 43 expression and phosphorylation state, support this hypothesis. Regardless of the specific mechanism, the results presented in this study underscore the importance of recapitulating the anisotropy of the native tissue in engineered myocardium.
一种用于心肌梗死后心脏修复的高潜力疗法是植入组织工程心肌。虽然有几个研究小组已经开发出模仿天然心肌排列结构的构建体，但迄今为止，还没有人研究过这种排列所带来的特定功能益处。在本研究中，我们通过将新生大鼠心肌细胞包埋在纤维蛋白凝胶中，创建了排列和各向同性两种构型的心肌构建体。构建体静态培养2周，然后进行表征。组织学染色显示，两种构型中均有表达典型心肌细胞标志物的铺展细胞。各向同性构建体最终的细胞和胶原蛋白密度较高，但被动力学性能低于排列构建体。然而，与电起搏相关的收缩力在排列构建体中高出181%，这种改善大于仅仅将各向同性构建体中的细胞在力测量方向上排列所预期的效果。我们的假设是，这是由于细胞排列促进了缝隙连接的形成/功能改善，对收缩力数据的进一步分析以及连接蛋白43表达和磷酸化状态的蛋白质印迹结果支持了这一假设。无论具体机制如何，本研究结果强调了在工程心肌中重现天然组织各向异性的重要性。
