Neuroprotective effects of sildenafil in experimental spinal cord injury in rabbits

Enhancement of neural regeneration after spinal cord injury using muscle graft in experimental dogs

AIMS

Spinal cord injuries (SCIs) can cause severe disability or death. The principal treatments for traumatic SCI include surgical stabilization and decompression. Using muscle as a scaffold is a new approach. The aim of this work is to evaluate the clinical efficacy of muscle graft as a scaffold for the growing axons organizing their growth, preventing gliosis in the damaged area and enhancing neural recovery in canine model of traumatic spinal cord injury.

METHODS

14 dogs were divided into group I (Control group) 4 control dogs subjected to Sham operation, group II (Trauma control group) 5 dogs subjected to dorsal laminectomy with excision of 1 cm segment of the spinal cord and group III (Muscle graft group) 5 dogs subjected to dorsal laminectomy then muscle graft was taken from the longissimus thoraces and inserted into the spinal cord gap. The animals of all groups were euthanatized after 8 weeks. Olby and modified Tarlov scores were used to clinically evaluate the therapeutic effects. Spinal cord specimens were subjected to histological, morphometric and statistical studies.

RESULTS

Olby and modified Tarlov scores revealed significant clinical improvement in the muscle graft group. Histological sections showed overgrowth of axons on the muscle graft and the sections started to organize as central gray matter and peripheral white matter. CD44 & CD105 stains were positive for endogenous stem cells.

CONCLUSIONS

This study proved the clinical efficacy of muscle grafting as a tool for induction of neuroregeneration after traumatic spinal cord injury.

Exendin-4 Enhances Motor Function Recovery via Promotion of Autophagy and Inhibition of Neuronal Apoptosis After Spinal Cord Injury in Rats

Autophagy occurs prior to apoptosis and plays an important role in cell death regulation during spinal cord injury (SCI). This study aimed to determine the effects and potential mechanism of the glucagon-like peptide-1 (GLP-1) agonist extendin-4 (Ex-4) in SCI. Seventy-two male Sprague Dawley rats were randomly assigned to sham, SCI, 2.5 μg Ex-4, and 10 μg Ex-4 groups. To induce SCI, a 10-g iron rod was dropped from a 20-mm height to the spinal cord surface. Ex-4 was administered via intraperitoneal injection immediately after surgery. Motor function evaluation with the Basso Beattie Bresnahan (BBB) locomotor rating scale indicated significantly increased scores (p < 0.01) in the Ex-4-treated groups, especially 10 μg, which demonstrated the neuroprotective effect of Ex-4 after SCI. The light chain 3-II (LC3-II) and Beclin 1 protein expression determined via western blot and the number of autophagy-positive neurons via immunofluorescence double labeling were increased by Ex-4, which supports promotion of autophagy (p < 0.01). The caspase-3 protein level and neuronal apoptosis via transferase UTP nick end labeling (TUNEL)/NeuN/DAPI double labeling were significantly reduced in the Ex-4-treated groups, which indicates anti-apoptotic effects (p < 0.01). Finally, histological assessment via Nissl staining demonstrated the Ex-4 groups exhibited a significantly greater number of surviving neurons and less cavity (p < 0.01). To our knowledge, this is the first study to indicate that Ex-4 significantly enhances motor function in rats after SCI, and these effects are associated with the promotion of autophagy and inhibition of apoptosis.