Development of biodegradable matrix, which promotes axonal regenerations

具有共价键的冻干海绵已被证明可以促进周围神经和脊髓的神经再生。本研究观察了幼年大鼠脊髓横断后早期再生轴突的生长和星形胶质细胞的反应。切除两个节段(Th7-8)，并植入海藻酸盐。作为对照，植入胶原凝胶代替海藻酸盐，或不植入病变。术后2周和4周取材，观察神经生长和星形胶质细胞反应。许多再生轴突被发现从残端延伸到藻酸盐植入的损伤处，其中一些伴随着星形细胞突起。在所有未植入的动物中，在两个界面上都形成了巨大的囊腔，没有明确的轴突延伸到病变中。在植入胶原的动物中，在一些大鼠身上发现了空洞的形成，一旦在残端形成再生轴突，就不会进一步延伸到病变中。延伸到藻酸盐植入损伤的星形细胞突起没有基底板，而在对照实验中发现的星形细胞突起被基底板覆盖。这些发现表明，藻酸盐有助于减少由结缔组织和反应性星形细胞突起组成的屏障，并为再生轴突的生长和星形细胞突起的延长提供支架。

Freeze-dried alginate sponge cross-linked with covalent bonds has been demonstrated to enhance nerve regeneration in peripheral nerves and spinal cord. The present study examined at early stages after surgery the outgrowth of regenerating axons and reactions of astrocytes at the stump of transected spinal cord in young rats. Two segments (Th7-8) were resected, and alginate was implanted in the lesion. As controls, collagen gel was implanted in place of alginate or the lesion was left without implantation. Two and 4 weeks after surgery, nerve outgrowth and astrocyte reactions were examined. Many regenerating axons, some of which were accompanied by astrocytic processes, were found to extend from the stump into the alginate-implanted lesion. In the all non-implanted animals, large cystic cavities were formed at both interfaces with no definite axonal outgrowth into the lesion. In collagen-implanted animals, cavity formation was found in some rats, and regenerating axons once formed at the stumps did not extend further into the lesion. Astrocytic processes extending into alginate-implanted lesion had no basal laminae, whereas those found in control experiments were covered by basal laminae. These findings suggest that alginate contributed to reducing the barrier composed of connective tissues and reactive astrocytic processes, and served as a scaffold for the outgrowth of regenerating axons and elongation of astrocytic processes.