CAREER: Regulation of Stem Cell Migration by Extracellular Matrix Plasticity

干细胞迁移是骨折和伤口愈合的关键方面，许多新兴的治疗系统需要干细胞迁移到植入的生物材料中或从植入的生物材料中迁移出来。在组织中迁移的过程中，干细胞必须爬过细胞外基质，这些细胞外基质上的毛孔有时比细胞本身小100到1000倍。生理组织及其细胞外基质通常表现出机械可塑性，在机械力的作用下经历不可逆的变形。在这些组织中，细胞产生的力量可以永久性地--或可塑性地--扩张基质中的毛孔。因此，细胞外基质的机械性能，包括基质的机械可塑性或永久变形程度，可能在调节干细胞迁移方面发挥关键作用。细胞外基质可塑性在调节干细胞迁移中的作用将在这个教师早期职业发展计划(CALEAR)研究项目中进行研究。这项研究将与教育和外展活动相结合，这些活动涉及对研究生、本科生和高中教师的培训。研究成果将纳入本科生和研究生课程。将开发适合高中课堂和更广泛公众的教学模块，包括动手活动，主题为生物材料、僵硬、可塑性和活组织的工程模型。这一综合努力将扩大对组织力学和干细胞迁移的理解。这个项目将研究组织的机械可塑性如何调节干细胞的迁移。研究人员假设，通过力的产生，细胞可以在基质中以可塑性的方式打开毛孔，从而促进迁移。使用3D培养、2D培养和基于微通道的迁移分析的生物材料，该奖项将通过三个研究目标来验证这一假设。目的1研究由海藻酸盐和透明质酸-胶原共聚物制成的可调三维水凝胶基质中基质机械可塑性对干细胞迁移的影响。将跟踪细胞迁移，并量化HA-COL基质中胶原结构的变化。目标2将利用共聚焦荧光显微镜来评估迁移测量以及细胞和核的形态，以确定机械可塑性对干细胞在2D表面和微通道中迁移的影响。目标3将阐明干细胞在具有不同机械可塑性的基质中迁移的生物物理和分子机制。特别是，基质应变将在迁移过程中进行测量，并与肌动蛋白动态、细胞形态和体积以及核形态相关。最后，3D迁移分析将在扰动分子的同时重复进行，以确定它们如何影响迁移。这些研究将揭示干细胞迁移的基本新见解，这将促进对自然再生过程的了解，然后可应用于先进的再生医学。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。

Stem cell migration is a critical aspect of fracture and wound healing, and many emerging treatment systems require the migration of stem cells to or from implanted biomaterials. During migration through tissues, stem cells must crawl through an extracellular matrix with pores that are sometimes 100 to 1,000 times smaller than the cells themselves. Physiological tissues and their extracellular matrix often exhibit mechanical plasticity, undergoing irreversible deformations in response to mechanical force. In these tissues, cell generated forces can permanently -- or plastically -- expand pores in the matrix. Thus, the mechanical properties of the extracellular matrix, including how mechanically plastic or permanently deformable the matrix is, could play a critical role in regulating stem cell migration. The role of extracellular matrix plasticity in regulating stem cell migration will be investigated in this Faculty Early Career Development Program (CAREER) research project. The research will be integrated with both educational and outreach activities that involve the training of graduate students, undergraduates, and high school teachers. Research results will be incorporated into both undergraduate and graduate level courses. Teaching modules, including hands-on activities, suitable for high school classrooms and the broader public will be developed on the topics of biomaterials, stiffness, plasticity, and engineering models of living tissues. This integrated effort will broaden understanding regarding tissue mechanics and stem cell migration. This project will investigate how tissue mechanical plasticity regulates stem cell migration. The researcher hypothesizes that cells, through the generation of forces, can plastically open up pores in the matrix to facilitate migration. Using biomaterials for 3D culture, 2D culture, and microchannel-based migration assays, this award will test this hypothesis through three research objectives. Objective 1 will examine the impact of matrix mechanical plasticity on stem cell migration in tunable 3D hydrogel matrices developed from both alginate and hyaluronic acid-collagen copolymers. Cell migration will be tracked and changes to the collagen architecture in the HA-col matrices will be quantified. Objective 2 will establish the impact of mechanical plasticity on stem cell migration on 2D surfaces and in microchannels using confocal fluorescence microscopy to assess measurements of migration as well as cellular and nuclear morphology. Objective 3 will elucidate the biophysical and molecular mechanisms that stem cells utilize to migrate through matrices with different levels of mechanical plasticity. In particular, matrix strains will be measured during migration and correlated with actin dynamics, cell morphologies and volume, and nuclear morphologies. Finally, 3D migration assays will be repeated while perturbing molecules to determine how they affect migration. These studies will reveal fundamental new insights into stem cell migration, which will advance knowledge of natural regenerative processes that can then be applied to advance regenerative medicineThis 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.