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

TitleCalcium oscillations in wounded fibroblast monolayers are spatially regulated through substrate mechanics.
Publication TypeJournal Article
Year of Publication2017
AuthorsLembong, J, Sabass, B, Stone, HA
JournalPhys Biol
Date Published2017 06 28
KeywordsAnimals, Biomechanical Phenomena, Calcium Signaling, Cell Count, Elastic Modulus, Mice, Myosin Type II, NIH 3T3 Cells, Skin, Wound Healing

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.

Alternate JournalPhys Biol
PubMed ID28378710