Collaborative Research: Biomechanics of Epithelial Tissue Homeostasis, Collapse, and Eversion

细胞组装和组织成功能组织对发育和伤口愈合至关重要。不规则或不受控制的细胞生长和组装导致肿瘤形成和癌症等病理。此外，在培养中生长成功能性细胞簇的模型组织被称为类器官，已广泛用于药物开发和再生医学，以及形态发生、宿主-病原体相互作用和组织修复的体外研究。该奖项支持一个结合实验和计算的项目，该项目将通过研究球形细胞单层（称为腺泡）来揭示控制上皮组织中细胞组装和组织的生物力学原理，当诱导变得更收缩时，它们会自发地塌陷并改变极性（即腺泡将自己翻过来）。最后的外翻状态与类器官的应用有关，其中需要顶端表面的外部暴露，并且它也类似于癌症中的腺泡异常。从这项研究中获得的知识将对组织发育的基本理解以及培养的类器官结构的控制有价值。因此，该项目对促进人类健康具有广泛的潜在影响，因为研究结果将与建立组织组织和发育的机械原理直接相关。它也与药物测试、再生医学或疾病模型的类器官生物制造高度相关。该项目将支持各种研究生和本科生的培训和指导，包括佛罗里达大学数字艺术专业的学生，他们将从三维成像的腺泡动态中绘制动画，以实现推广和教育目的。该项目的目标是利用实验和计算方法的协同结合来了解腺泡稳定性和外翻的生物力学。第一个目标是确定导致腺泡机械平衡的细胞应力的贡献，测试表面张力和/或管腔压力被调节以维持腺泡在稳定和不稳定平衡状态之间的临界点的假设。基于顶点的三维数学模型将用于模拟单层中相互作用的细胞群，考虑到顶端和基底细胞表面的表面张力和曲率以及细胞-细胞界面张力。该模型还将考虑细胞-细胞和细胞-基质粘附在表面力和界面能中的作用。当通过高分辨率共聚焦显微镜跟踪腺泡表面的三维形态时，这些参数将在实验中被扰动。第二个目标是了解腺泡是如何从平衡状态受到干扰，并被驱动收缩和evert到一个evert极性的状态，测试一个假设，即顶端和底部表面张力之间的差异是evert的机械驱动力。将使用考虑细胞收缩力和粘性力的动态顶点/有限元模型模拟外倾过程，并通过化学扰动（例如，肌动球蛋白激活，抑制ECM粘附）和激光烧蚀触发外倾，对其进行实验测试。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Assembly and organization of cells into functional tissues is essential to development and wound healing. Irregular or uncontrolled growth and assembly of cells leads to pathologies such as tumor formation and cancer. Additionally, model tissues grown in culture into functional cell clusters called organoids have been widely used in drug development and regenerative medicine, as well as in vitro studies of morphogenesis, host-pathogen interactions, and tissue repair. This award supports a combined experimental and computational project that will reveal the biomechanical principles that govern the assembly and organization of cells in epithelial tissue by studying spherical cell monolayers (called acini), which spontaneously collapse and evert polarity (i.e., where the acinus turns itself inside out) when induced to become more contractile. The final everted state is relevant to organoid applications where outer exposure of the apical surface is desired, and it also resembles acinar gland abnormalities in cancer. The knowledge gained from this study will be valuable to fundamental understanding of tissue development as well as control of the structure of cultured organoids. Thus, this project has broad potential impact on advancing human health, as the findings will be directly relevant to establishing the mechanical principles of tissue organization and development. It is also highly relevant to the biomanufacturing of organoids for drug testing, regenerative medicine, or models of disease. This project will support the training and mentorship of diverse graduate and undergraduate students, including students in the University of Florida Digital Arts program, who will render animations from three-dimensional imaging of acinus dynamics for outreach and education purposes. The goal of this project is to understand the biomechanics of acinus stability and eversion using a synergistic combination of experimental and computational approaches. The first objective is to determine the contributions to cellular stresses that lead to mechanical equilibrium of the acinus, testing the hypothesis that surface tensions and/or the lumen pressure are regulated to sustain the acinus at the critical point between stable and unstable equilibrium states. A three-dimensional vertex-based mathematical model will be used to model the interacting cell population in the monolayer, accounting for the surface tensions and curvatures of the apical and basal cell surfaces and the cell-cell interfacial tension. The model will also account for the roles of cell-cell and cell-matrix adhesion in the surface forces and interfacial energies. These parameters will be perturbed experimentally while tracking the 3D morphology of the acinus surfaces via high resolution confocal microscopy. The second objective is to understand how the acinus is perturbed from the equilibrium state and driven to contract and evert to a state of everted polarity, testing the hypothesis that the difference between and apical and basal surface tensions is the mechanical driving force for eversion. The eversion process will be simulated using a dynamic vertex/finite element model accounting for cell contractile and viscous forces, and it will be experimentally tested by triggering eversion via chemical perturbations (e.g. actomyosin activation, inhibition of ECM adhesion) and by laser ablation.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.