Mechanobiology of Myofibroblast Behavior in Health and Disease

心脏由不同类型的细胞组成。肌成纤维细胞是由正常的成纤维细胞转化而来的。肌成纤维细胞在心脏瓣膜发育、纤维化心脏组织的形成和钙化主动脉瓣结节的形成等生理和病理生理事件中发挥重要作用。这些被激活的细胞能够增殖，分泌炎症和组织降解的化学因子，并重塑周围环境，如细胞外基质(ECM)。内皮细胞向间充质细胞转化(EndMT)是内皮细胞向间充质样细胞转化的过程，是肌成纤维细胞的来源之一。EndMT最先在胚胎心脏瓣膜发育中被观察到，但最近的研究表明，EndMT也出现在组织水平的修复过程中--如伤口愈合--以及成人疾病的发展--包括癌症、心脏纤维化和钙化性主动脉瓣疾病(CAVD)。内皮细胞机械和化学环境的变化可以促进EndMT，但关于这些转化的细胞为什么可以促进组织再生或疾病进展的了解较少。这个结合了实验和计算建模方法的项目的主要研究目标是确定在正常生理环境中看到的联合机械和化学力量是否以及如何引导间充质转化的主动脉瓣内皮细胞走向疾病。研究成果将被纳入旨在增进K-12科学技术理解的研讨会中，该奖项还将为研究生和本科生提供教育和职业发展机会。该项目将测试细胞外环境的组成和由于血液流动而在体内发生的剪应力如何影响实验室实验(体外)中间充质转化细胞的行为。此外，该项目将使用数学建模和计算机模拟来研究EndMT来源的肌成纤维细胞重建周围组织的能力，它们与常驻瓣膜间质细胞的相互作用，指导这些行为的分子机制，以及这些多尺度机制的潜在反馈回路。本研究结合了利用主动脉瓣微流控细胞培养模型的实验和对细胞在不同机械和化学环境条件下的转化、相互作用和迁移的计算模拟。实验和计算模型都将模拟体内细胞-细胞和细胞-细胞外基质的相互作用，包括细胞的生长、迁移、增殖和在健康和患病的主动脉瓣中的相互作用。计算模型模拟将能够更详细地检查对疾病进展最关键的机械和化学因素，并提供一种手段来探索EndMT和组织修饰的反馈回路，这只能在实验中以有限的方式进行。总之，体外实验和计算模拟将为CAVD的分子机制提供新的见解，阐明导致再生或病理组织重塑的机械条件，并为新的治疗策略提供试验台。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The heart is made up of different types of cells. Myofibroblasts develop through a transformation from normally occurring fibroblasts. Myofibroblasts play a critical role in physiological and pathophysiological events such as heart valve development, the generation of fibrotic heart tissue, and the formation of calcified aortic valve nodules. These activated cells are able to proliferate, secrete inflammatory and tissue-degrading chemical factors, and remodel the surrounding environment such as the extracellular matrix (ECM). Endothelial to mesenchymal transformation (EndMT), which is the transition of endothelial cells to mesenchymal-like cells, is one source of myofibroblasts. EndMT was first observed in embryonic heart valve development, but more recent studies have shown that EndMT is also observed in tissue-level repair processes -- such as wound healing -- and in adult disease development -- including cancer, cardiac fibrosis, and calcific aortic valve disease (CAVD). Changes in the endothelial cell mechanical and chemical environment can promote EndMT, but less is known about why these transformed cells can promote tissue regeneration or progression of disease. A primary research goal of this project, which combines experimental and computational modeling methods, is to determine if and how combined mechanical and chemical forces seen in the normal physiological environment direct mesenchymally transformed aortic valve endothelial cells toward disease. The research results will be incorporated into workshops that are designed to enhance K-12 scientific and technological understanding, and this award will also provide graduate and undergraduate educational and professional development opportunities.The project will test how the composition of the extracellular environment and shear stresses, which occur in vivo due to blood flow, affect mesenchymally-transformed cell behavior in laboratory experiments (in vitro). Additionally, the project will use mathematical modeling and computer simulation to study the ability of EndMT-derived myofibroblasts to restructure the surrounding tissue, their interaction with resident valve interstitial cells, the molecular mechanisms directing these behaviors, and the potential feedback loop of these multiscale mechanisms. This research combines experiments using microfluidic cell culture models of the aortic valve with computational simulation of the transformation, interaction, and migration of cells under different mechanical and chemical environmental conditions. Both the experimental and computational models will mimic cell-cell and cell-ECM interactions in the body, including cell growth, migration, proliferation, and interaction in both healthy and diseased aortic valves. The computational model simulations will enable a more detailed examination of the mechanical and chemical factors most critical to disease progression and provide a means to probe the feedback loop of EndMT and tissue modification, which can only be performed in a limited manner experimentally. Together, the in vitro experiments and computational simulations will provide new insight into the molecular mechanisms of CAVD, illuminate the mechanical conditions that lead to regenerative or pathological tissue remodeling, and provide a test-bed for new therapeutic strategies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.