Intensification of motor regeneration with HNK-1 mimetic peptide after avulsion and reimplantation of medullary ventral roots in C57BL/6J mice

Abstract

Spinal cord injuries generate significant degeneration of motoneurons, loss of synapses, formation of glial scar and chronic inflammation, hampering functional recovery. In order to provide neuroprotection and regeneration, early surgical interventions and treatments that positively modify the neuronal microenvironment are necessary. In this sense, the use of neuroprotective and chemotactic molecules opens new therapeutic perspectives, with an important translational potential. The carbohydrate HNK-1 has been gaining prominence for possessing such characteristics. However, such a polysaccharide is difficult to obtain, in addition to having a short half-life, which was overcome by the synthesis of HNK-1 mimetic peptides. Such molecules maintain the potential to stimulate the growth of neurites, with possible relevant biological effect after spinal cord injuries at the interface of the central nervous system (CNS) and peripheral nervous system (PNS). Thus, the present study will use an association between the L2 / HNK-1 mimetic peptide (pm-L2 / HNK-1) and the reimplantation of avulsed nerve roots. The SNC/SNP repair will be performed with the use of fibrin sealant (SF), taking into account previous studies from our laboratory. It is expected to optimize neuronal plasticity, synaptic preservation, and motor functionality after injury. For this purpose, 50 female mice of the C57BL/6J isogenic strain will be submitted to motor root avulsion surgical procedure (L4-L6) followed by reimplantation, with the application of SF. For that, three experimental groups will be set (n = 15 / group): G1 = Avulsion only, G2 = Avulsion + replantation with SF and G3 = Avulsion + replantation with SF + pm-L2 / HNK-1. The experimental groups will be evaluated 2, 4 and 12 weeks after surgery. Spinal cord changes, neuronal survival, molecular aspects will be studied by transmission electron microscopy, Nissl staining and immunofluorescence. Functional recovery will be assessed by the Walking Track Test, using the CatWalk platform (Noldus). (AU)