Dubey N, Letourneau P C, Tranquillo R T
Department of Chemical Engineering & Materials Science, The Biomedical Engineering Institute, Minneapolis, Minnesota, 55455, USA.
Exp Neurol. 1999 Aug;158(2):338-50. doi: 10.1006/exnr.1999.7095.
High-strength magnetic fields were used to align collagen gel formed into 4-mm-diameter rods during the self-assembly of type I collagen monomers into fibrils. We developed an in vitro assay to study neurite elongation into the magnetically aligned collagen gel rods from dorsal root ganglia (DRG) explants placed onto one end of the rods. The depth of neurite elongation from chick embryo DRG neurons into these rods was found to be substantially greater than that observed in controls and increased with an increase in magnetic field strength, as did the collagen gel rod birefringence, indicative of collagen fibril alignment along the rod axis. Moreover, the axial bias of neurite elongation became more pronounced with an increase in magnetic field strength, presumably due to a contact guidance response of growth cones at the neurite tips. Coinvasion of Schwann cells from neonatal rat DRG was also studied in these assays using double immunolabeling. In the absence of serum, Schwann cells were highly associated with, and often trailed, elongating neurites. In the presence of serum, Schwann cells showed significantly higher rates of invasion and formed axially aligned chords reminiscent of bands of Büngner. These results may translate into an improved method of entubulation repair of transected peripheral nerves by directing and stimulating axonal growth through a tube filled with magnetically aligned collagen gel.
在I型胶原单体自组装成原纤维的过程中，使用高强度磁场使形成直径为4毫米棒状的胶原凝胶排列整齐。我们开发了一种体外试验，以研究从置于棒一端的背根神经节（DRG）外植体中长出的神经突向磁性排列的胶原凝胶棒内的延伸情况。发现鸡胚DRG神经元的神经突向这些棒内延伸的深度明显大于对照组，并且随着磁场强度的增加而增加，胶原凝胶棒的双折射也随之增加，这表明胶原原纤维沿棒轴排列。此外，随着磁场强度的增加，神经突延伸的轴向偏向变得更加明显，这可能是由于神经突尖端生长锥的接触导向反应所致。在这些试验中，还使用双重免疫标记研究了新生大鼠DRG中雪旺细胞的共同侵入情况。在无血清的情况下，雪旺细胞与伸长的神经突高度相关，并且常常尾随其后。在有血清的情况下，雪旺细胞显示出明显更高的侵入率，并形成了轴向排列的索带，类似于Büngner带。这些结果可能转化为一种改进的方法，通过引导和刺激轴突生长穿过充满磁性排列胶原凝胶的管子，来修复横断的周围神经。
