Cellular mechanisms of plasmalemmal sealing and axonal repair by polyethylene glycol and methylene blue
Article first published online: 3 FEB 2012
Copyright © 2012 Wiley Periodicals, Inc.
Journal of Neuroscience Research
Volume 90, Issue 5, pages 955–966, May 2012
How to Cite
Spaeth, C.S., Robison, T., Fan, J.D. and Bittner, G.D. (2012), Cellular mechanisms of plasmalemmal sealing and axonal repair by polyethylene glycol and methylene blue. J. Neurosci. Res., 90: 955–966. doi: 10.1002/jnr.23022
- Issue published online: 7 MAR 2012
- Article first published online: 3 FEB 2012
- Manuscript Accepted: 15 DEC 2011
- Manuscript Revised: 4 DEC 2011
- Manuscript Received: 2 NOV 2011
- Lone Star Paralysis Foundation
- axonal severance;
- nerve repair
Mammalian neurons and all other eukaryotic cells endogenously repair traumatic injury within minutes by a Ca2+-induced accumulation of vesicles that interact and fuse with each other and the plasmalemma to seal any openings. We have used uptake or exclusion of extracellular fluorescent dye to measure the ability of rat hippocampal B104 cells or rat sciatic nerves to repair (seal) transected neurites in vitro or transected axons ex vivo. We report that endogenous sealing in both preparations is enhanced by Ca2+-containing solutions and is decreased by Ca2+-free solutions containing antioxidants such as dithiothreitol (DTT), melatonin (MEL), methylene blue (MB), and various toxins that decrease vesicular interactions. In contrast, the fusogen polyethylene glycol (PEG) at 10–50 mM artificially seals the cut ends of B104 cells and rat sciatic axons within seconds and is not affected by Ca2+ or any of the substances that affect endogenous sealing. At higher concentrations, PEG decreases sealing of transected axons and disrupts the plasmalemma of intact cells. These PEG-sealing data are consistent with the hypothesis that lower concentrations of PEG directly seal a damaged plasmalemma. We have considered these and other data to devise a protocol using a well-specified series of solutions that vary in tonicity, Ca2+, MB, and PEG content. These protocols rapidly and consistently repair (PEG-fuse) rat sciatic axons in completely cut sciatic nerves in vivo rapidly and dramatically to restore long-lasting morphological continuity, action potential conduction, and behavioral functions. © 2012 Wiley Periodicals, Inc.