The Mechanical Phenotype of Fetal Fibroblasts as a Model for Regenerative Repair

 描述（由申请人提供）：在出生后或“成人”皮肤伤口愈合中，成纤维细胞机械感知（“机械感知”）在肉芽组织中发育并分化成肌成纤维细胞的刚度和张力。肌成纤维细胞产生大的收缩 过度收缩和重塑ECM的力，导致瘢痕形成和纤维化。相比之下，哺乳动物胎儿的受损皮肤愈合无瘢痕，没有肌成纤维细胞参与，这表明较小的细胞力量有助于再生修复。体内和体外研究表明，胎儿成纤维细胞具有可能有助于无瘢痕愈合的独特特征，包括对ECM刚性和缺陷信号通路的反应改变。然而，目前尚不清楚为什么胎儿成纤维细胞保留这种独特的表型，并表现出不同的反应，如ECM刚性，诱导成纤维细胞分化的成人成纤维细胞的环境因素。因此，我们的总体假设是胎儿成纤维细胞不会在生理生物力学刚性的反应中变成肌成纤维细胞。我们将通过以下具体目标来检验这一假设：（1）测试胎儿成纤维细胞具有内在改变的机械感应的特定假设，其导致无效的肌成纤维细胞分化，（2）确定基质组合物如何影响肌成纤维细胞分化，因为成人和胎儿伤口愈合的特征在于不同类型的胶原，和（3）使用测序方法来鉴定胎儿成纤维细胞基因表达中的分子差异，其可用于靶向成人成纤维细胞中的肌成纤维细胞分化。我们正在采取一种创新的方法，利用胎儿成纤维细胞的机械表型作为理解再生修复的模型，因为这些细胞似乎缺乏产生更大的细胞力的能力，以响应基质刚性，这有助于肌成纤维细胞分化和纤维化愈合。我们将通过使用模拟伤口愈合的不同机械阶段的合成基质来测试我们的新概念，所述合成基质逐步诱导肌成纤维细胞分化以隔离生理刚性和不同ECM组分的影响。总的来说，我们的目标是通过量化与真皮组织修复相关的细胞生物力学特性来描述胎儿成纤维细胞差异机械感知ECM刚度的潜在分子和物理机制。此外，我们的研究计划旨在发现潜在的分子靶点，用于产后伤口愈合中皮肤瘢痕和纤维化的新治疗策略。这些研究具有特别的临床重要性，因为目前不存在可接受的抗纤维化疗法，并且皮肤瘢痕形成和纤维化每年花费数十亿美元用于医疗护理和管理。此外，我们提出的研究的预期结果与其他纤维化相关的病理学以及组织工程和再生医学领域有关。

 DESCRIPTION (provided by applicant): In post-natal or "adult" dermal wound healing, fibroblasts mechanically sense ("mechanosense") rigidity and tension that develop in granulation tissue and differentiate into myofibroblasts. Myofibroblasts generate large contractile forces that excessively contract and remodel the ECM resulting in scarring and fibrosis. In contrast, injured skin in the mammalian fetus heals scarlessly without myofibroblast involvement suggesting that smaller cellular forces contribute to regenerative repair. In vivo and in vitro studies have shown that fetal fibroblasts have unique characteristics that may contribute to scarless healing including altered responses to ECM rigidity and defective signaling pathways. However, it remains unclear why fetal fibroblasts retain this distinct phenotype and exhibit differential responses to environmental factors such as ECM rigidity that induce myofibroblast differentiation in adult fibroblasts. Therefore, our overall hypothesis is that fetal fibroblasts d not become myofibroblasts in response to physiologic biomechanical rigidities. We will test this hypothesis with the following Specific Aims: (1) to test the specific hypothesis that fetal fibroblasts have intrinsically altered mechanosensing which leads to ineffective myofibroblast differentiation, (2) to determine how matrix composition influences myofibroblast differentiation since adult and fetal wound healing are characterized by different types of collagen, and (3) to use a sequencing approach to identify molecular differences in fetal fibroblast gene expression that can be used to target myofibroblast differentiation in adult fibroblasts. We are taking an innovative approach by utilizing the mechanical phenotype of fetal fibroblasts as a model for understanding regenerative repair since these cells appear to lack the ability to produce larger cellular forces in response to matrix rigidity which contribute to myofibroblast differentiation an fibrotic healing. We will test our novel concept by using synthetic substrates that mimic the different mechanical stages of wound healing that progressively induce myofibroblast differentiation to isolate the effects of physiologic rigidities and different ECM components. Overall, our goal is to delineate the underlying molecular and physical mechanisms by which fetal fibroblasts differentially mechanosense ECM rigidity by quantifying cellular biomechanical properties relevant to dermal tissue repair. Furthermore, our research plan is designed to uncover potential molecular targets for novel treatment strategies for dermal scarring and fibrosis in post-natal wound healing. These studies are of particular clinical importance since no acceptable anti-fibrotic therapies currently exist and dermal scarring and fibrosis costs billions f dollars of year in medical care and management. In addition, the expected outcomes of our proposed studies are relevant to other fibrosis-related pathologies as well as to the fields of tissue engineering and regenerative medicine.