Intercellular interactions define cell migrations and transitions that maintain fetal membrane homeostasis

胎膜（羊膜）在怀孕期间保护胎儿。在足月，衰老（老化）和炎症导致膜细胞功能和机械不稳定，有助于分娩。过早衰老和膜功能障碍与早产（PTB）和胎膜早破（pPROM）有关。然而，细胞水平的变化对妊娠期膜稳定性的影响及其导致分娩和分娩的功能障碍仍不清楚。最近对衰老足月和早产儿膜的研究发现了“微骨折”（MFs），这是细胞重塑的部位。MFs在妊娠期间被重新密封以保持膜的完整性。与对照组相比，足月产程、pPROM和PTB膜中MFs的数量和形态（深度和宽度）的增加表明MFs的再密封受到损害。羊膜上皮细胞发生上皮间充质转化（epithelial mesenchymal transition， EMT）。此外，这些细胞在深度上皮化（裸细胞/无细胞）区域表现出增殖和再密封特性，以稳定膜。在MFs愈合边缘，羊膜间充质细胞表现出相反的现象，即间充质-上皮转化（MET）。根据这些发现，我们假设细胞转化对于维持胎膜完整性是必不可少的。我们

Fetal membranes (amniochorion) protect the fetus during pregnancy. At term, senescence (aging) and inflammation cause functional and mechanical instability to membrane cells, contributing to parturition. Premature senescence and membrane dysfunctions are associated with preterm birth (PTB) and preterm premature rupture of the membranes (pPROM). However, cellular-level changes contributing to membrane stability during gestation and its dysfunction leading to labor and delivery are still unclear. Recent studies of senescent term and preterm membranes revealed “microfractures” (MFs), sites of cellular remodeling. MFs are resealed during gestation to maintain membrane integrity. Higher numbers of MFs and their increased morphometry (depth and width) in term labor, pPROM, and PTB membranes compared to respective controls suggest MFs' resealing is compromised. Amnion epithelial cells in MFs have been observed undergoing epithelial mesenchymal transition (EMT). Further, these cells showed proliferative and resealing properties of deepithelialized (nude/cell free) areas to stabilize membranes. At the healing edge of MFs, amnion mesenchymal cells exhibited a reverse phenomenon, mesenchymal-epithelial transition (MET). From these findings, we postulate that cellular transitions are essential for maintaining fetal membrane integrity. We hypothesize that MFs are areas of membrane remodeling and their increased number and morphometry are associated with failure to remodel and dysfunctional membranes. Understanding intercellular and cell-matrix interactions causing MFs' development and their resealing will help us to determine how oxidative stress (OS) and inflammation can contribute to the persistence of MFs and dysfunctional membrane status in PTB and pPROM. Two specific aims to be tested are Specific Aim 1: To investigate the dynamic remodeling of the fetal membrane epithelium in an in vitro model of cell-free (nude) membranes during OS and infection / inflammation compared to normal conditions; Specific Aim 2: To determine cell migration, matrix degradation, and cellular transition associated with MFs' formation using a fetal membrane organ-on-a-chip approach. This multidisciplinary proposal combines cell and molecular biological and bioengineering approaches designed to overcome the limitations of classic 2D cell cultures by developing a fetal membrane-on-a-chip using organ-on-chip technologies. This model system will maintain multiple cell types in close proximity with constant dynamic interactions, similar to the conditions in utero. We will elucidate causative molecular mechanisms of (normal and abnormal) biologic MFs' formation and how they contribute to PTB and pPROM. Understanding cellular-level mechanisms will allow us to design strategies to minimize MFs' development to strengthen intrauterine cavities and reduce the risk of PTB and pPROM.