Tissue Engineered Model of Aging to Study the Role of Cellular Interdependence in Failing Tissues

虽然已经取得了进展，但衰老仍然是现代生物学中一个尚未解决的问题。已经确定了导致细胞破坏的许多机制，但生物体，即活的动物和植物，可能不是因为它们的细胞耗尽而死亡，而是因为更大规模的失败。细胞的失败扩散到组织、器官的失败，最终导致有机体的失败。这个项目的重点是这种有序崩溃的第一个中间步骤：失败从细胞到组织的传播。为此，该项目将从理论和实验上确定细胞之间复杂的相互作用在衰老组织中的作用，使用组织工程策略独立控制年龄和细胞相互作用。实验将得到数学模型和计算机模拟的补充，这些模型和计算机模拟将输出这些组织的死亡曲线(死亡概率随年龄增长的曲线)和预期寿命。此外，该项目将能够量化细胞规模老化过程与由更大规模相互作用产生的过程相比的相对重要性。从更广泛的影响来看，老龄化对每个人都有影响。随着预期寿命的稳步增长，迫切需要更好地了解衰老背后的原理，以找到减少与年龄相关的疾病的方法。该项目将在涉及老龄化的多个方面向科学界和医学界提供一个新的视角，为延缓或逆转老龄化的新方法铺平道路，并帮助实现更健康的老年。研究结果将向广大受众传播，从中学到本科生和研究生，以及当地社区，特别强调STEM领域中代表性不足的群体。活动包括为中学女生举办的研讨会，为高中生举办的地区性科学博览会项目，以及在当地医学中心举行的研讨会。尽管有许多关于细胞损伤的理论，但对于微观失效如何级联到组织、器官乃至最终有机体的宏观失效，我们知之甚少。该项目的目标是通过理论和实验确定细胞之间复杂的相互依赖和相互作用在衰老组织中的作用，将微观细胞失效与衰老的宏观表现联系起来。根据来自研究人员实验室的强有力的初步数据，假设衰老是由于通过相互依赖的细胞网络级联的故障，而不是一系列孤立的细胞故障。衰老的定义是随着年龄的增长死亡概率增加。为了验证这一假设，该项目的目标是：1)构建由不同密度的(老年人和年轻人)单一和多种细胞类型的心脏组织(心脏成纤维细胞、心肌细胞和内皮细胞)的不同密度组成的3D工程化心脏组织；2)在有和没有氧化应激的情况下对组织老化一个月，同时测量其中一组组织和细胞的存活统计数据；以及3)使用详细的分析理论来推断相互作用的作用。具体地说，计算模型研究空间相互依赖网络，其边权重由扩散方程和一级反应动力学确定。在类似渗流的扩散中，节点根据它们与其他节点的相互作用而随机失效。计算框架将为拟议的实验生成可验证的假设，作为回报，实验测量将限制模型参数。该项目的发现有可能改变衰老研究，因为它引入了一种全新的观点，即衰老是任何(有生命的或无生命的)系统的普遍属性，这些系统具有足够数量的组件，这些组件彼此强烈依赖于彼此来执行其微观功能。此外，这一观点首次能够量化和模拟老龄化的进程，给定某种相互依赖的网络结构，以预测相互依赖的系统应该如何以及何时预期灾难性的崩溃。这一奖项反映了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。

Though progress has been made, aging remains an unsolved problem in modern biology. A number of mechanisms that lead to cell damage have been identified, but organisms, i.e., living animals and plants, presumably die not because they run out of cells, but because of failures of much larger scale. Cellular failures spread into failure of tissues, organs and ultimately the organism. This project focuses on the first intermediate step of this ordered collapse: the spread of failure from cells to tissues. To this end, the project will theoretically and experimentally establish the role of complex interactions between cells in aging tissues, using tissue engineering strategies to independently control both age and cell interactions. Experiments will be supplemented by mathematical models and computer simulations that will output mortality curves (plots of probability of death with increasing age) and life expectancies of these tissues. Furthermore, the project will be able to quantify the relative importance of cellular scale aging processes compared to those stemming from larger scale interaction effects. In view of broader impacts, aging affects everyone. With steadily increasing life expectancy, there is an immediate need to better understand principles underlying aging to find ways to decrease age-related diseases. This project will offer a fresh view to the scientific and medical community on the multiple scales involved in aging, paving the way for new approaches to delay or reverse aging and help attain healthier old ages. The research findings will be disseminated to a broad audience, from middle school to undergraduate and graduate students, and to the local community, with specific emphasis on underrepresented groups in STEM fields. Activities include workshops for middle school girls, regional science fair projects for high school students and seminars at a local medical center.Although there exist a number of theories on cell damage, very little is known about how microscopic failures cascade to macro scale failure of tissues, organs and ultimately the organism. The goal of this project is to bridge microscopic cell failure to macroscopic manifestations of aging, by theoretically and experimentally establishing the role of complex interdependence and interactions between cells in aging tissues. Based on strong preliminary data from the investigators' labs, it is hypothesized that aging, defined in terms of an increased probability of death with chronological age, is due to failures cascading through an interdependent network of cells, rather than a series of isolated cell failures. To test this hypothesis, the aims of this project are to 1) Fabricate 3D engineered heart tissues consisting of varying densities of (aged and young) single and multiple cell types of the heart tissue (cardiac fibroblasts, cardiomyocytes and endothelial cells); 2) Age the tissue for a month, both with and without oxidative stress, while measuring the survival statistics of a population of tissues and cells within; and 3) Make inferences regarding the role of interactions using a detailed analytical theory. Specifically, the computational model studies spatial interdependence networks whose edge weights are determined by the diffusion equation and first order reaction kinetics. The nodes fail stochastically depending on their interaction with others, in a percolation-like spread. The computational framework will generate testable hypotheses for the proposed experiments, and in return, experimental measurements will constrain the model parameters. Project findings have the potential to transform aging research by introducing an entirely new view that aging is a universal attribute of any (living or non-living) system that has a sufficient number of components that strongly depend on one other to carry out their microscopic functions. Furthermore, this view enables, for the first time, the ability to quantify and simulate the progression of aging, given a certain interdependence network structure to predict how and when an interdependent system should be expected to catastrophically collapse.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.