Calcium oscillations in wounded fibroblast monolayers are spatially regulated through substrate mechanics

Abstract

The maintenance of tissue integrity is essential for the life of multicellular organisms. Healing of a skin wound is a paradigm for how various cell types localize and repair tissue perturbations in an orchestrated fashion. To investigate biophysical mechanisms associated with wound localization, we focus on a model system consisting of a fibroblast monolayer on an elastic substrate. We find that the creation of an edge in the monolayer causes cytosolic calcium oscillations throughout the monolayer. The oscillation frequency increases with cell density, which shows that wound-induced calcium oscillations occur collectively. Inhibition of myosin II reduces the number of oscillating cells, demonstrating a coupling between actomyosin activity and calcium response. The spatial distribution of oscillating cells depends on the stiffness of the substrate. For soft substrates with a Young's modulus E ~ 360 Pa, oscillations occur on average within 0.2 mm distance from the wound edge. Increasing substrate stiffness leads to an average localization of oscillations away from the edge (up to ~0.6 mm). In addition, we use traction force microscopy to determine stresses between cells and substrate. We find that an increase of substrate rigidity leads to a higher traction magnitude. For E < ~2 kPa, the traction magnitude is strongly concentrated at the monolayer edge, while for E > ~8 kPa, traction magnitude is on average almost uniform beneath the monolayer. Thus, the spatial occurrence of calcium oscillations correlates with the cell-substrate traction. Overall, the experiments with fibroblasts demonstrate a collective, chemomechanical localization mechanism at the edge of a wound with a potential physiological role.

Traction force microscopy with optimized regularization and automated Bayesian parameter selection for comparing cells

“…During the last decade, traction force microscopy has become one of the most popular techniques for studying mechanobiology on the cellular level. The technique has found broad use for studying sub-cellular structures, 66,[84][85][86][87] single cell dynamics, [88][89][90][91] and collective cellular behavior, [92][93][94][95][96][97] , and there are far too many applications to be reviewed here appropriately.…”

From Integration to Marginalization

“…It is said that this rule is intended for foreign nationals, while for the Chinese who have become Indonesian citizens, the term Tionghoa can be maintained. In fact, due to the high level of anti-Chinese sentiment, the use of the term Cina has spread everywhere (Lembong, 2011). Included in the writing of history textbooks, the authors follow this change of designation.…”

“…Even the term Cina is often referred to with a certain unpleasant accent. Since September 1966, almost all newspapers have switched from using the term Tionghoa to Cina (Lembong, 2011;Suryadinata, 2002). Moreover, in subsequent developments, the New Order suppressed all things related to the Chinese including Chinese historical narratives in textbooks since 1975 has been completely lost.…”

Comparative wound healing potential of Mitracarpus hirtus ointment and honey in diabetic albino rats by collagen assessment

“…Wound healing in treated and non-treated STZ-induced diabetic albino rats as indicated by solubility of collagen in acid The higher percentage closure observed in the treated wounds of the diabetic rats can be attributed to increased deposition of total collagen and reduction in oxidative stress arising from the infliction of wounds to the rats. Close interaction of cells is necessary for synthesis and deposition of collagen facilitated by contracture of the skin tissue (Lembong et al 2017). Cardiac glycosides have been implicated for contraction in tissues by inhibiting the Na + -K + ATPase pump in the sarcolemmal membrane of the myocyte and other cells (Cunningham et al 2018).…”

“…Cardiac glycosides have been implicated for contraction in tissues by inhibiting the Na + -K + ATPase pump in the sarcolemmal membrane of the myocyte and other cells (Cunningham et al 2018). This inhibition causes intracellular accumulation of Na + , which makes the Na + -Ca 2+ pump extrude less Ca 2+ , causing Ca 2+ to accumulate inside the cell resulting in increased force of contraction necessary for wound closure (Lembong et al 2017). In addition to excellent water-absorbing quality, biodegradability, biocompatibility and outstanding filmforming properties, interactions of Ca 2+ ions with the cells to facilitate contractions are the basis for using calcium alginate in wound dressing (Wang et al 2015).…”