The Effects of Cellular Alignment on the Velocity of Scratch-Induced Calcium Waves in RPE-1 Cell Monolayers

RPE-1 (Human Retinal Pigment Epithelial) cells are spindle-shaped epithelial cells that have been shown to exhibit nematic liquid crystal behavior at high densities. Specifically, when RPE-1 cells are densely packed together, they tend to orient themselves with neighboring cells along their long axis. Mechanical stimulation of epithelial tissues through scratch wounds results in calcium waves that emanate perpendicularly from the wound edge. These waves play a crucial role in intercellular signaling, but the relationship between cellular alignment and calcium wave propagation is not well understood. In order to investigate this matter, we confined RPE-1 cells in grooves and measured the degree of cellular alignment within the tissue using a nematic order parameter (Q). Subsequently, we created scratch wounds in the monolayer, with wounds oriented either parallel or perpendicular to the director field of the cells. Finally, we measured the velocity of scratch-induced calcium waves. Our results show that scratch wounds made perpendicular to the director field of the cells resulted in faster calcium wave propagation than scratch wounds made parallel to the director field. By measuring the velocity of scratch-induced calcium waves and quantifying the alignment of cells in the tissue layer, we can gain insight into how physical cues in the cellular environment affect cellular behavior and intercellular communication. Ultimately, this research may lead to new insights into the development of tissue engineering and regenerative medicine strategies by allowing us to design more effective approaches that promote tissue regeneration and repair.