Mitosis in confining microenvironments

Physiologically, many types of cells divide in mechanically confining microenvironments, including dense extracellular matrices (ECMs) with distinct viscoelastic, viscoplastic, and non-linear elastic characteristics. The mechanically confining microenvironment provides a barrier that cells must overcome to achieve cell growth and mitotic elongation for successful cell division, but how cells overcome this barrier in highly confining microenvironments remains largely unclear. We employed a computational model to study the mechanism of cell growth and mitotic elongation occurring within ECMs. We found that a dividing cell is encapsulated by an envelope structure formed by interconnected matrix fibers, and the envelope structure was deformed when the cell underwent mitotic elongation. This deformation was opposed mainly by high tensile forces developed in the matrix near the cell equator. Depending on how fast the tensile forces relaxed in the matrix over time, the rate and extent of mitotic elongation varied significantly. Our findings provide insights into understanding the mechanism of mitosis in highly confining microenvironments.