Cell Mechanosensing in 3D Confinement in Health and Diseases

Abstract

In vivo, cells are physically confined in all three dimensions by the extracellular matrix (ECM) and/or neighboring cells. This three-dimensional (3D) confinement can regulate cell behavior and viability. Much of what is known about cell function stems from experiments on two-dimensional (2D) surfaces that lack key physical and topographical cues. Various models and mechanisms have been used to trigger 3D confinement in the cells. However, long-term 3D confinement has not been studied in depth regarding how it affects cell biological functions. This dissertation investigates how long-term 3D confinement can regulate cell behavior and gene expression. In project 1, I created and modified a single-cell PDMS-based platform with a geometrically defined microenvironment. Using this device, I have shown that long-term 3D confinement through confining microchannels activates intracellular signaling pathways, leading to cell apoptosis in very confined microenvironments. In project 2, I explored how long-term 3D confinement affects Smooth Muscle Cells’ (SMCs) behavior and gene expression, as they are essential for controlling blood pressure by contracting or relaxing. I observed that entrapment in confined channels leads to an increase in SMCs contractile gene expression and contractility. In project 3, I examined the translocation of Anillin (one of the scaffolding proteins) from the nucleus to the cytoplasm in response to long-term 3D confinement. To elaborate on our data, Tissue Engineered Vessels (TEVs) as well as aorta from normotensive and hypertensive young or old rats were also used to localize Anillin in health and disease. Collectively, these projects contribute to uncovering previously unidentified molecular mechanisms governing cell function in (patho) physiologically significant microenvironments, which pave the way for the creation of novel interventions intended to slow the progression of pathologic conditions.