Department of Neurology, University of Regensburg, Universitätsstr. 84, 93053 Regensburg, Germany.
Acta Biomater. 2011 Jul;7(7):2826-34. doi: 10.1016/j.actbio.2011.04.006. Epub 2011 Apr 16.
Substantial recovery of function following peripheral and central nervous system (CNS) injury critically depends on longitudinally directed axon regeneration across the injury site, which requires a mechanical guidance providing scaffold. We have previously shown that anisotropic alginate-based hydrogels with a defined capillary diameter (25 μm), which form via a self-organizing process driven by unidirectional diffusion of divalent cations into sodium alginate sols, promoted longitudinally oriented elongation of CNS axons in vitro and in vivo. In the present study the influence of various capillary diameters and the incorporation of gelatin to promote directed axon outgrowth and Schwann cell migration were assessed in a dorsal root ganglion outgrowth assay in vitro. Superimposing an alginate sol with Cu(2+), Sr(2+), or Zn(2+) ion containing solutions allowed the creation of hydrogels with capillaries 18, 25 and 55 μm in diameter, respectively. Axon outgrowth and Schwann cell migration were analyzed in terms of axon length/density and Schwann cell density within the capillary structures. Axon ingrowth into capillary hydrogels, which was always accompanied by Schwann cells, was enhanced with increasing capillary diameter. The incorporation of gelatin did not influence overall axon density, but promoted the length of axon outgrowth within the hydrogels. The longitudinal orientation of axons decreased in wider capillaries, which suggests that medium-sized capillaries are the optimal substrate to elicit substantial axon growth and longitudinal orientation after axon injury.
外周和中枢神经系统 (CNS) 损伤后的功能实质性恢复严重依赖于损伤部位的长轴突再生，这需要一种机械导向提供支架。我们之前已经表明，具有定义的毛细直径（25μm）的各向异性藻酸盐基水凝胶通过由二价阳离子单向扩散到海藻酸钠溶胶中驱动的自组织过程形成，促进了 CNS 轴突的体外和体内的长轴定向伸长。在本研究中，我们在体外背根神经节突起测定中评估了各种毛细直径的影响以及掺入明胶以促进定向轴突生长和施万细胞迁移。将含有 Cu(2+)、Sr(2+)或 Zn(2+)离子的藻酸盐溶胶叠加在一起，可以分别形成直径为 18、25 和 55μm 的水凝胶毛细结构。通过轴突长度/密度和毛细结构内施万细胞密度来分析轴突生长和施万细胞迁移。轴突进入总是伴随着施万细胞的毛细水凝胶的生长得到增强，随着毛细直径的增加而增强。明胶的掺入不会影响总的轴突密度，但会促进水凝胶内轴突生长的长度。在更宽的毛细血管中，轴突的纵向取向减少，这表明中等大小的毛细血管是在轴突损伤后引发大量轴突生长和纵向取向的最佳基质。
