Non-localized Increase in Lipid Content and Striation Pattern Formation Characterize the Sonoporated Plasma Membrane

Eukaryotic cells can survive sonoporation and repair their plasma membrane wounds. However, it is not clear how the repaired plasma membranes will differ from the intact ones. To answer this question, we used high-resolution confocal microscopy and scanning electron microscopy to study plasma membrane lipid alterations induced by sonoporation. First, we found that the wound-induced increase in membrane lipid content was not limited to the sonoporation sites. The degree of lipid increase was dependent on pore distance, calcium influx and pore size. Second, we observed interesting lipid striation patterns on the sonoporated plasma membranes. This patterning effect was reversible in the cell subjected to small-scale sonoporation and could be recognized using digital image orientation analysis. Third, we showed that actin stress fibers underneath the plasma membrane hindered the addition and the protrusion of lipids to produce the patterning effect. Our findings demonstrated that the sonoporated and repaired plasma membranes have distinct lipid distribution characteristics.