The cellular biomechanics of wound resistance in the giant ciliate protozoa Stentor coeruleus

The ability to heal wounds and regenerate is critical for single-cell organisms to seal membrane wounds in a timely manner to prevent loss of important cellular organelles. The giant single-cell ciliate protozoa Stentor coeruleus is known for its wound healing and regenerative abilities, having one of the highest healing rates among living organisms and being capable of healing large wounds. In this work, we hypothesize that the plasma membrane, the cytoskeleton and the osmotic pressure work together to resist mechanical stresses thereby preventing wounds. We imparted mechanical stresses on the cells by flowing them through microfluidic constrictions. Reduction in osmotic pressure inside the cell was found to drastically reduce wounding probability. Drug induced inhibition of the cell microtubule network increased the wounding probability while decreasing the transit time of the cells at the constriction. Stabilizing the microtubules, on the other hand, appeared to make the cells stiffer and inhibited cell shape recovery. The regime map for Stentor wounding as a function of cell velocity and size showed diverging phase boundaries. We identified a scaling relationship based on the cell velocity and size to determine an empirical relationship for the cell wounding probability. Our findings have helped us understand how the different components of Stentor interact with each other to help the cell resist mechanical stresses and prevent wounding.