Negative Effect of High Calcium Levels on Schwann Cell Survival

Abstract

Our previous studies showed that the functional recovery of an injured nerve correlates with calcium absorption, and that acceleration of this absorption can greatly improve regeneration. In our study, we examined effects of the calcium concentration on cultured Schwann cells obtained from the rat sciatic nerve. Using published methods and simple calculations, we measured the calcium concentration inside normal and injured (crushed) nerve fibers and found that the injured-nerve internal calcium concentration is 16.8 mM, on average. The cells, including Schwann cells, were isolated from an intact sciatic nerve and cultured with various Ca2+ concentrations of calcium-spiked media, from the normal (1.8 mM) to 5.0–16.8 mM. The cells were fixed, blocked, and incubated with Anti-S-100, Goat-Anti-Mouse, and Propidium Iodide. They were viewed under fluorescent conditions to identify the Schwann cells. All the cells in the control dishes were viable, and there were large numbers of Schwann cells present. All the experimental dishes showed the profound concentration-dependent harmful effect of excessive calcium on the number and type of cells present. The high level of calcium corresponding to nerve injury severely affected Schwann and all other cell survival and growth in this cell culture study. Thus, Schwann cell survival and growth are very sensitive to and negatively affected by higher calcium levels than that in the normal media.