Timescale of hole closure during plasma membrane repair estimated by calcium imaging and numerical modeling

Plasma membrane repair is essential for eukaryotic cell life and is triggered by the influx of calcium through membrane wounds. Repair consists of sequential steps, with closure of the membrane hole being the key event that allows the cell to recover, thus identifying the kinetics of hole closure as important for clarifying repair mechanisms and as a quantitative handle on repair efficiency. We implement calcium imaging in MCF7 breast carcinoma cells subject to laser damage, coupled with a model describing the spatio-temporal calcium distribution. The model identifies the time point of hole closure as the time of maximum calcium signal. Analysis of cell data estimates the closure time as: tc=5.45 +/- 2.25 s and tc=6.81 +/- 4.69 s using GCaMP6s-CAAX and GCaMP6s probes respectively. The timescale was confirmed by independent time-lapse imaging of a hole during sealing. Moreover, the analysis estimates the characteristic time scale of calcium removal, the penetration depth of the calcium wave and the diffusion coefficient. Probing of hole closure times emerges as a strong universal tool for quantification of plasma membrane repair

Automated summary

Cell membrane repair is crucial for cell survival, with closure of the membrane hole identified as a key event that allows the cell to recover. By implementing calcium imaging in damaged breast carcinoma cells and using a spatio-temporal calcium distribution model, the time point of hole closure was determined. Additionally, the analysis estimated the characteristic time scale of calcium removal, penetration depth of the calcium wave, and diffusion coefficient. Studying hole closure times proves to be a useful tool for quantifying plasma membrane repair efficiency.