Nerve regeneration after crushing of ventral roots at the interface of the CNS and PNS and treatment with mesenchymal stem cells

Author(s)

Aline Barroso Spejo

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2013-02-27

Examining board members

Alexandre Leite Rodrigues de Oliveira; Valéria Paula Sassoli Fazan; Renata Graciele Zanon

• Advisor: Alexandre Leite Rodrigues de Oliveira

Abstract

Recent studies have shown promising results in the treatment of nervous system injuries through stem cells implantation, attributing this functional improvement to the production of trophic factors by these cells. In this study, the neuroprotective and neurorregenerative effects of mesenchymal stem cells (MSC) from Lewis-EGFP mice was investigated after crushing the motor roots L4, L5 and L6. Five female rats Lewis were used in each of the following groups: G1 - motor roots crushing; G2 - motor roots crushing and DMEM (Dulbeco's Modified Eagle Medium) injection in the white/gray matter interface; G3 - motor roots crushing and MSC injection in the white/gray matter interface. At 4 weeks after injury, neuronal survival was evaluated by Nissl staining, and revealed, by the neuronal count, increased survival in the group treated with MSC. The technique of immunohistochemistry was used to evaluate the expression of synaptophysin, synapsin, VGLUT1 (Vesicular Glutamate Transporter-1) and GAD65 (Glutamate decarboxylase 65). The expression of synaptophysin and synapsin on the surface of lesioned motoneurons, showed a smaller decrease of inputs in animals treated with MSC, suggesting a possible reduction in synaptic elimination process. To detect possible changes in the balance of excitatory / inhibitory inputs reaching the cell body of the motoneurons, antibodies for VGLUT1 (marker of glutamatergic terminals) and GAD 65 (marker of GABAergic terminals) were used. The reduction of glutamatergic terminals was similar in all groups. While the reduction of GABAergic terminals was in greater extent in G1 and G2 with respect to the group treated with MSC. The data indicate that MSC can protect neurons against excitotoxicity, resulting in decreased cell loss. With survival of 12 weeks after the injury, nerve regeneration was assessed by morphological analysis of the sciatic nerve (nerve size, number and morphology of myelinated fibers) and motor function recovery (walking track test). The group treated with DMEM showed nerve with smaller area and fewer myelinated fibers than treated with MSC, however, the group treated with cells was not better than the group that only suffered crushing. Morphometry revealed fibers with less myelination in the three injured groups, compared to the contralateral side, but there was no difference between treatments. Motor function appeared better in MSC-treated group in comparison to the DMEM-treated, but not in relation to the group which only suffered crushing. The effect of MSC in motor function was acute, demonstrating efficiency between 4 to 6 weeks after injury. Thus, the MSC shown to be neuroprotective and contributed to regeneration, but the form of administration of such cells, by direct injection into spinal cord, has to be improved or substituted by another method (AU)

• FAPESP's process: 10/14210-9 - Nerve regeneration after crushing of ventral roots at the interface of the CNS and PNS and treatment with mesenchymal stem cells
• Grantee: Aline Barroso Spejo
• Support Opportunities: Scholarships in Brazil - Master