Division of Cardiac Surgery, The Johns Hopkins Hospital, Baltimore, Maryland, USA.
Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA.
J Tissue Eng Regen Med. 2021 May;15(5):503-512. doi: 10.1002/term.3188. Epub 2021 Apr 2.
Current efforts to engineer a clinically relevant tissue graft from human-induced pluripotent stem cells (hiPSCs) have relied on the addition or utilization of external scaffolding material. However, any imbalance in the interactions between embedded cells and their surroundings may hinder the success of the resulting tissue graft. Therefore, the goal of our study was to create scaffold-free, 3D-printed cardiac tissue grafts from hiPSC-derived cardiomyocytes (CMs), and to evaluate whether or not mechanical stimulation would result in improved graft maturation. To explore this, we used a 3D bioprinter to produce scaffold-free cardiac tissue grafts from hiPSC-derived CM cell spheroids. Static mechanical stretching of these grafts significantly increased sarcomere length compared to unstimulated free-floating tissues, as determined by immunofluorescent image analysis. Stretched tissue was found to have decreased elastic modulus, increased maximal contractile force, and increased alignment of formed extracellular matrix, as expected in a functionally maturing tissue graft. Additionally, stretched tissues had upregulated expression of cardiac-specific gene transcripts, consistent with increased cardiac-like cellular identity. Finally, analysis of extracellular matrix organization in stretched grafts suggests improved remodeling by embedded cardiac fibroblasts. Taken together, our results suggest that mechanical stretching stimulates hiPSC-derived CMs in a 3D-printed, scaffold-free tissue graft to develop mature cardiac material structuring and cellular fates. Our work highlights the critical role of mechanical conditioning as an important engineering strategy toward developing clinically applicable, scaffold-free human cardiac tissue grafts.
目前，从人诱导多能干细胞（hiPSCs）工程化制备具有临床相关性的组织移植物的努力依赖于添加或利用外部支架材料。然而，嵌入细胞与其周围环境之间的相互作用的任何不平衡都可能阻碍所得组织移植物的成功。因此，我们的研究目标是从 hiPSC 衍生的心肌细胞（CM）中创建无支架、3D 打印的心脏组织移植物，并评估机械刺激是否会导致移植物成熟度的提高。为了探索这一点，我们使用 3D 生物打印机从 hiPSC 衍生的 CM 细胞球状体中生产无支架的心脏组织移植物。通过免疫荧光图像分析，与未刺激的自由漂浮组织相比，这些移植物的静态机械拉伸显著增加了肌节长度。拉伸组织的弹性模量降低，最大收缩力增加，形成的细胞外基质排列增加，这在功能成熟的组织移植物中是预期的。此外，拉伸组织中心脏特异性基因转录本的表达上调，与增加的心脏样细胞身份一致。最后，对拉伸移植物中细胞外基质组织的分析表明，嵌入的心脏成纤维细胞的重塑得到了改善。总之，我们的结果表明，机械拉伸刺激 3D 打印无支架组织移植物中的 hiPSC 衍生 CM 发育成熟的心脏材料结构和细胞命运。我们的工作强调了机械条件作为开发临床适用的无支架人类心脏组织移植物的重要工程策略的关键作用。
