Measurement of Forces and Their Role in Stem Cell Differentiation Using Suspended Fiber Networks

干细胞是连接胚胎和成人生命的重要桥梁，通过无限自我更新和承诺成为（分化为）代表组织和器官的专门细胞的惊人能力。此外，它们是修复机制的关键参与者，因为干细胞功能的损伤与包括癌症在内的疾病模型直接相关。细胞在其自然环境中不断受到生化和生物物理信号的影响。虽然生物化学线索对干细胞行为的作用有很好的记载，但直到最近我们才开始了解生物物理线索的作用。在这种情况下，对细胞在分化过程中不断感受到或施加的无处不在的力的作用知之甚少。该奖项资助了确定这些力量及其在干细胞分化中的作用的基础研究。这一新知识将允许开发能够同时提供特定细胞类型的生化和生物物理因子的支架，从而影响发育和疾病生物学。这项研究涉及多个学科，包括工程（机械、生物医学）、聚合物物理、生物学和数学，在快速发展的机械生物学的保护下。这项研究的知识将有利于美国的经济和社会，同时也为未被充分代表的群体更多地参与研究和工程提供了途径。这项研究计划构建模拟细胞外基质（ECM）的纳米纤维支架，称为“纳米网”，作为力测量探针。纳米网由排列和悬浮的纳米纤维组成，它们的直径、长度和间距在双层结构中混合在一起。此外，纳米网络包含熔融纤维交叉点，允许迁移的单个细胞偏转纤维段，从而提供使用反方法的力测量。这种多尺度方法将允许同时研究生物物理（曲率、结构刚度（N/m））和生化（生长因子浓度）线索对附着在悬浮纳米上的单个人骨髓间充质干细胞（h-MSCs）分化的作用。这将允许开发一套力分化（F-D）主曲线，校准间充质干细胞分化的最佳生物物理和生化贡献。这些基础知识将通过在单细胞水平上揭示细胞- ecm机械生物学相互作用的作用，并为组织再生、伤口愈合缝合、用于早期诊断的单细胞力测量分析和包括癌症在内的各种疾病的药物测试的可植入平台的开发提供见解。

Stem cells are the essential bridge connecting embryos to the adult life span through amazing capability of unlimited self-renewal and commitment to become (differentiate into) specialized cells representing tissues and organs. In addition, they are key players in repair mechanisms as impairment of stem cell functionality is directly related to disease models including cancer. Cells in their native environment are constantly subjected to both biochemical and biophysical signals. While the role of biochemical cues on stem cell behavior is well documented, only recently have we begun to understand the role of biophysical cues. In this context, very little is known on the role of ubiquitous forces cells feel or exert constantly during differentiation. This award funds fundamental research in determining these forces and their role in stem cell differentiation. The new knowledge will allow development of scaffolds capable of providing simultaneous biochemical and biophysical factors specific to a cell type, thus impacting both developmental and disease biology. This research involves multiple disciplines including engineering (mechanical, biomedical), polymer physics, biology and mathematics under the umbrella of rapidly growing mechanobiology. The knowledge from this research will benefit the U.S. economy and society, while also providing pathways for increased participation of underrepresented groups in research and engineering.This research plans to build extracellular matrix (ECM)-mimicking nanofiber-based scaffolds called 'nanonets' as force measurement probes. Nanonets are composed of aligned and suspended nanofibrous assemblies of a mix of diameters, lengths, and spacing in double layer configuration. Furthermore, nanonets contain fused fiber intersections, which allow migrating single cells to deflect fiber segments, thus providing a measure of forces using inverse methods. This multiscale approach will permit simultaneous investigations on the role of biophysical (curvature, structural stiffness (N/m)) and biochemical (growth factor concentrations) cues on differentiation of single human bone-marrow derived mesenchymal stem cells (h-MSCs) attached to suspended nanonets. This will allow development of a set of force-differentiation (F-D) master curves calibrating the optimal biophysical and biochemical contributions to mesenchymal stem cell differentiation. The fundamental knowledge will contribute significantly by unraveling the role of cell-ECM mechanobiological interactions at the single-cell level and provide insights in development of implantable platforms for tissue regeneration, wound healing sutures, single cell force measurement assays for early diagnosis and drug testing for a wide variety of diseases including cancer.