A human red blood cell is a dimpled ballerina, ceaselessly spinning, tumbling, bending, and squeezing through openings narrower than its width to dispense life-giving oxygen to every corner of the body. In a paper published in the October issue of Annals of Biomedical Engineering, which was made available online on Oct. 21, a team of UCSD researchers describe a mathematical model that explains how a mesh-like protein skeleton gives a healthy human red blood cell both its rubbery ability to stretch without breaking, and a potential mechanism to facilitate diffusion of oxygen across its membrane. “Red cells are one of the few kinds of cells in the body with no nucleus and only a thin layer of protein skeleton under their membrane: they are living bags of hemoglobin,” said Amy Sung, a professor of bioengineering at UCSD’s Jacobs School of Engineering and coauthor of the study. “Very little is known about how the elements of the membrane skeleton behave when red blood cells deform, and we were amazed at what our simulation revealed.” Scientists have been mystified for years by the human red blood cell membrane skeleton, a network of roughly 33,000 protein hexagons that looks like a microscopic geodesic dome. Unfortunately, neither the architecture of the dome nor the structures of individual proteins that make up the hexagons reveal the details of how the remarkably regular organization actually works.
