[Protective effect of olfactory ensheathing cells in combination with intrathecal injection of vascular endothelial growth factor on injured spinal cord in rats].

OBJECTIVE

To investigate the synergistic effect of a combination of grafted olfactory ensheathing cells (OECs) from the olfactory bulbs and intrathecal injection of vascular endothelial growth factor (VEGF) on repairing spinal cord injury, and to explore the neuroprotection on both neurons and nerve fibers.

METHODS

OECs from neonatal rats were cultured, purified, and collected with 0.25% trypsin after 9 days. A total of 75 adult female Wistar rats (weighing 200-250 g) were randomly divided into 5 groups: group A was sham-surgery group receiving laminectomy; the spinal cord injury model was established with weight-dropped apparatus in the rats of groups B, C, D, and E. Then group B was injected with 10 microL DMEM-F12 medium without serum at injury site on the 1 day and was intrathecally administrated with 10 microL saline solution twice a day during the following 1 week; group C was injected with 10 microL DMEM-F12 medium and 25 ng recombined rat VEGF165 (rrVEGF165); group D was injected with 10 microL DMEM-F12 medium containing 1 x 10(5) OECs and 10 microL saline solution; group E was injected with 10 microL DMEM-F12 medium containing 1 x 10(5) OECs and 25 ng rrVEGF165. The functional recovery of hindlimb was evaluated by the Basso-Beattie-Bresnahan (BBB) score at 1 day and each week from 1 to 8 weeks. The histological changes and the changes of ultrastructure were observed at 8 weeks after operation by HE and electron microscope, and the immunohistochemistry staining was used for p75 nerve growth factor receptor (p75NGFR), Caspase-3, and von Willebrand factor (vWF).

RESULTS

The function of hindlimb recovered rapidly in group E; the BBB score reached the peak at 8 weeks, and it was significantly higher than those in other groups (P < 0.05). The histology and ultrastructure observation showed that nerve fibers and neurons were damaged seriously in group B, moderately in groups C and D, and slightly in group E. Numerous spared tissue between nerve stumps, fibers with regular myelination, and neurons with little vacuolar mitochondria were observed in group E. The immunohistochemistry staining revealed that Caspase-3 positive cells in groups B, C, D, and E were significantly more than that in group A (P < 0.05); more Caspase-3 positive cells were found in groups B and D than in groups C and E (P < 0.05), while no significant difference was found between groups C and E (P > 0.05). And more vessels per high field were examined in groups C and E than in groups A, B, and D (P < 0.05), while no significant difference was found between groups C and E (P > 0.05). The p75NGFR positive results showed the survival of OECs in groups D and E at 8 weeks after OECs transplantation.

CONCLUSION

Grafted OECs combined with intrathecal injection of VEGF has significant promotive effects on restoration of spinal cord injury in rats, can improve part function of nerve fibers, and shows neuroprotection on damaged cells and fibers, which have a synergistic effect.