(157b) Axonal Growth and Myelination on Pre-Stretch Induced Anisotropic Surface

Spinal cord injury (SCI) has been shown to result in devastating consequences including temporary or permanent deficit in sensory as well as motor function. After acute SCI, axons sprout briefly, but soon undergo growth arrest and retraction. The regeneration is found to be a chaotic process due to unorganized axon alignment. Therefore, in order to persuade sufficient regenerated axons to bridge the lesion site, properly organized axonal alignment is necessary. Since demyelination after SCI strongly impairs the conductive capacity of surviving axons, remyelination is critical for successful functioning of regenerated nerves. In this study, we discuss how an anisotropic surface arising from mechanical pre-stretch impacts axonal alignment and myelination.

We previously demonstrated that mesenchymal stem cells aligned on pre-stretch induced anisotropic surface because the cells can sense a larger effective stiffness in the stretched direction than in the perpendicular direction. Thus we questioned whether our pre-stretched surface could similarly affect axonal alignment and growth. In order to test this hypothesis, we cultured dorsal root gangalia (DRG) neuron cells on poly-L-lysine (PLL) coated 16% pre-stretched PDMS membrane for 6 days. After three days of culture axons were found to align in the direction of the pre-stretch, but aligned randomly on the unstretched surface. Further, we found the thickness of the axons on the pre-stretched surface is greater than that on the unstretched surface. This should better promote myelination of the axons on the pre-stretched surface, since myelination has been shown to depend highly on the thickness of the axon, i.e. thicker axons are preferably myelinated.