EAGER: Exploring Cell-Cell Gap as a Critical Parameter in Biological Phase Changes

EAGER：探索细胞间间隙作为生物相变的关键参数

• 批准号: 1742908
• 负责人: Taher Saif
• 金额: $ 29.72万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1742908&HistoricalAwards=false
• 关键词: EAGER; Exploring; Cell; Gap; Critical

Biological systems sometimes rapidly change behavior when the number of cells becomes large enough. This EArly-concept Grant for Exploratory Research (EAGER) project is based on preliminary data showing that for one type of mammalian cell, that it is the distance between the cells that triggers the different behavior. This was observed for a particular type of muscle cell. When the cells are 100 micrometers apart, the form into muscle "fibers" automatically. When they are further than 100 micrometers apart, they do not. This observation will be further examined in fibroblasts. The compression of extracellular matrix by fibroblasts is fundamental to the healing of wounds and also to the original morphogenesis of organs. The project will determine whether this threshold of 100 micrometers is also true for fibroblasts from mice, monkeys and humans. As a test of the breadth of the observation, the 100 micrometer threshold will also be tested using the Protista Dictyostelium that has the property of aggregating into larger structures under some conditions. If the results of the experiments are comparable among the different cell types, the project will have developed significant support for the existence of a threshold distance for the activation of a tissue "phase change" in the aggregation of fibroblasts and of Dictyostelium. This could improve our understanding of a variety of conditions where tissues apparently show a phase change in behavior including embryogenesis, cancer tumorigenesis, in vitro tissue formation, bacterial biofilm formation and a variety of collective phenomena in the microbial world. Identification of critical distance conditions will help with predicting the path of morphogenesis of 3D printed tissues with cells and extracellular matrix. The research will be carried out by a graduate and two undergraduate students. One of the UG students will be from the Department of Biology, the others from Engineering. Thus, the students will be trained in multidisciplinary fields. Special effort will be made to recruit students from minorities and under-represented groups to conduct the research.The project is inspired by recent experimental findings suggesting that muscle cells within 100 micrometers of each other in 3D culture compact the ECM and form myotubes (PI's lab), endothelial cells within 100 micrometers of each other form vasculature, fibroblasts in collagen within 100 micrometers of each other compact the collagen. When the cell-cell gap exceeds 100 micrometers, none of these processes occur. The hypothesis of a critical distance will be tested using fibroblasts from multiple species (mouse, monkey and human) in a collagen matrix mixed with fluorescent beads for optically tracking compaction and cluster formation by slime mold cells (Dictyostelium). In order to gain insight on the experimental observations of the threshold cell-cell gap, a mathematical model will be created to simulate the experimental observations. Each cell remodels the matrix around them by adhering to the matrix and by pulling the fibers as the cell filopodia generate contractile forces. Each cell forms a zone of remodeled matrix with higher stiffness under tension. If cells are far apart, their zones remain independent of each other. In a system with many cells, such non-interacting zones maintain global symmetry. When the cells are close to each other, their zones overlap, and symmetry is broken. The stiffness between the cells becomes higher, and the cells form a stiffer fibrous bridge between them. More filopodia tend to extend along the bridge compared to other directions, the cells become polarized and elongated while remaining contractile. This results in an attractive interaction between the cells that will compact the matrix. Three types of fibroblasts from mouse (embryonic fibroblast, NIH/3T3), monkey (kidney fibroblasts) and human (lung) will be used to test hypothesis on matrix compaction, and slime mold cells (Dictyostelium discoideum) will be used to test for generality. All of these cell types have comparable size, ~ 10 micrometer in diameter. Hence, we predict similar critical distances for all cell types.

当细胞数量足够大时，生物系统有时会迅速改变行为。 探索性研究（急切）项目的早期概念授予基于初步数据，表明对于一种哺乳动物细胞，是细胞之间触发不同行为的距离。 对于特定类型的肌肉细胞观察到了这一点。当细胞分开100微米时，形式会自动进入肌肉“纤维”。 当它们相距超过100微米时，它们就不会。 该观察结果将在成纤维细胞中进一步检查。 成纤维细胞对细胞外基质的压缩是伤口愈合以及器官的原始形态发生的基础。 该项目将确定对小鼠，猴子和人类的成纤维细胞的100微米的阈值是否也是如此。 作为观察的广度测试，还将使用Protista dictyostelium测试100千分尺阈值，该protista dictyostelium具有在某些条件下汇总成较大结构的特性。 如果实验的结果在不同的细胞类型之间是可比性的，则该项目将在成纤维细胞和dictyostelium的聚集中激活组织“相变”的阈值距离的存在显着支持。这可以提高我们对各种条件的理解，在这些条件下，组织显然表现出行为的相变，包括胚胎发生，癌症肿瘤发生，体外组织形成，细菌生物膜形成以及微生物世界中各种集体现象。临界距离条件的识别将有助于预测带有细胞和细胞外基质的3D印刷组织形态发生的路径。 这项研究将由研究生和两名本科生进行。其中一位UG学生将来自生物学系，其他学生则来自工程学。因此，学生将接受多学科领域的培训。 Special effort will be made to recruit students from minorities and under-represented groups to conduct the research.The project is inspired by recent experimental findings suggesting that muscle cells within 100 micrometers of each other in 3D culture compact the ECM and form myotubes (PI's lab), endothelial cells within 100 micrometers of each other form vasculature, fibroblasts in collagen within 100 micrometers of each other compact the collagen.当细胞细胞间隙超过100微米时，这些过程均未发生。 临界距离的假设将使用来自多个物种（小鼠，猴子和人类）与荧光珠混合的成纤维细胞（小鼠，猴子和人）进行测试，以通过粘液霉菌（dictyostelium）进行光学跟踪压实和簇形成。 为了了解阈值细胞间隙的实验观察结果，将创建一个数学模型来模拟实验观察。 每个细胞通过粘附在基质上并将纤维拉动作为丝状产生收缩力来重塑它们周围的基质。每个细胞形成一个重塑矩阵的区域，在张力下较高刚度。如果细胞相距很远，它们的区域将保持彼此独立。在具有许多细胞的系统中，这种非相互作用区域保持全局对称性。当细胞彼此靠近时，它们的区域重叠，对称性被打破。细胞之间的刚度变得更高，并且细胞形成它们之间的纤维桥。与其他方向相比，更多的丝状疾病倾向于沿桥梁延伸，细胞在剩余收缩的同时变得极化和伸长。这会导致细胞之间有吸引力的相互作用，从而压实基质。来自小鼠（胚胎成纤维细胞，NIH/3T3），猴子（肾成纤维细胞）和人类（肺）的三种类型的成纤维细胞将用于测试基质压实的假设，并且将使用粘液霉菌细胞（dictyostelostelium discoideum）来测试生成性。所有这些细胞类型的大小可比，直径约为10微米。 因此，我们预测所有细胞类型的临界距离相似。