Institute of Pharmacology and Toxicology, University Medical Center Göttingen, 37075, Göttingen, Germany; DZHK (German Center for Cardiovascular Research), partner site Göttingen, 37075, Göttingen, Germany.
DZHK (German Center for Cardiovascular Research), partner site Göttingen, 37075, Göttingen, Germany; University of Göttingen, Institute for Nonlinear Dynamics, 37077, Göttingen, Germany; Max Planck Institute for Dynamics and Self-Organization, 37077, Göttingen, Germany.
Prog Biophys Mol Biol. 2019 Jul;144:51-60. doi: 10.1016/j.pbiomolbio.2018.11.011. Epub 2018 Dec 12.
Cardiomyocyte and stroma cell cross-talk is essential for the formation of collagen-based engineered heart muscle, including engineered human myocardium (EHM). Fibroblasts are a main component of the myocardial stroma. We hypothesize that fibroblasts, by compacting the surrounding collagen network, support the self-organization of cardiomyocytes into a functional syncytium. With a focus on early self-organization processes in EHM, we studied the molecular and biophysical adaptations mediated by defined populations of fibroblasts and embryonic stem cell-derived cardiomyocytes in a collagen type I hydrogel. After a short phase of cell-independent collagen gelation (30 min), tissue compaction was progressively mediated by fibroblasts. Fibroblast-mediated tissue stiffening was attenuated in the presence of cardiomyocytes allowing for the assembly of stably contracting, force-generating EHM within 4 weeks. Comparative RNA-sequencing data corroborated that fibroblasts are particularly sensitive to the tissue compaction process, resulting in the fast activation of transcription profiles, supporting heart muscle development and extracellular matrix synthesis. Large amplitude oscillatory shear (LAOS) measurements revealed nonlinear strain stiffening at physiological strain amplitudes (>2%), which was reduced in the presence of cells. The nonlinear stress-strain response could be characterized by a mathematical model. Collectively, our study defines the interplay between fibroblasts and cardiomyocytes during human heart muscle self-organization in vitro and underscores the relevance of fibroblasts in the biological engineering of a cardiomyogenesis-supporting viscoelastic stroma. We anticipate that the established mathematical model will facilitate future attempts to optimize EHM for in vitro (disease modelling) and in vivo applications (heart repair).
心肌细胞和基质细胞的相互作用对于基于胶原蛋白的工程心肌的形成至关重要，包括工程化人类心肌（EHM）。成纤维细胞是心肌基质的主要成分。我们假设成纤维细胞通过压缩周围的胶原网络，支持心肌细胞自我组织成功能性合胞体。我们关注 EHM 中早期的自我组织过程，研究了在胶原 I 水凝胶中，通过定义的成纤维细胞和胚胎干细胞来源的心肌细胞群体介导的分子和生物物理适应。在细胞独立的胶原凝胶化（30 分钟）的短阶段后，组织压实逐渐由成纤维细胞介导。在存在心肌细胞的情况下，成纤维细胞介导的组织变硬减弱，允许在 4 周内组装稳定收缩、产生力的 EHM。比较 RNA 测序数据证实，成纤维细胞对组织压实过程特别敏感，导致支持心肌发育和细胞外基质合成的转录谱快速激活。大振幅振荡剪切（LAOS）测量显示，在生理应变幅度（>2%）下存在非线性应变硬化，而在存在细胞的情况下则降低。非线性应力-应变响应可以通过数学模型来描述。总的来说，我们的研究定义了在体外人类心肌自我组织过程中成纤维细胞和心肌细胞之间的相互作用，并强调了成纤维细胞在心肌生成支持的粘弹性基质的生物工程中的重要性。我们预计，所建立的数学模型将有助于未来尝试优化 EHM 用于体外（疾病建模）和体内应用（心脏修复）。
