Sciatic nerve grafting and inoculation of FGF-2 promotes improvement of motor behavior and fiber regrowth in rats with spinal cord transection

Abstract

Purpose: Failure of severed adult central nervous system (CNS) axons to regenerate could be attributed with a reduced intrinsic growing capacity. Severe spinal cord injury is frequently associated with a permanent loss of function because the surviving neurons are impaired to regrow their fibers and to reestablish functional contacts. Peripheral nerves are known as good substrate for bridging CNS trauma with neurotrophic factor addition. We evaluated whether fibroblastic growth factor 2 (FGF-2) placed in a gap promoted by complete transection of the spinal cord may increase the ability of sciatic nerve graft to enhance motor recovery and fibers regrow. Methods: We used a complete spinal cord transection model. Rats received a 4 mm-long gap at low thoracic level and were repaired with saline (control) or fragment of the sciatic nerve (Nerve) or FGF-2 was added to nerve fragment (Nerve+FGF-2) to the grafts immediately after complete transection. The hind limbs performance was evaluated weekly for 8 weeks by using motor behavior score (BBB) and sensorimotor tests-linked to the combined behavior score (CBS), which indicate the degree of the motor improvement and the percentage of functional deficit, respectively. Neuronal plasticity were evaluated at the epicenter of the injury using MAP-2 and GAP-43 expression. Results: Spinal cord treatment with sciatic nerve and sciatic nerve plus FGF-2 allowed recovery of hind limb movements compared to control, manifested by significantly higher behavioral scores. Higher amounts of MAP-2 and GAP-43 immunoreactive fibers were found in the epicenter of the graft when FGF-2 was added. Conclusions: FGF-2 added to the nerve graft favored the motor recovery and fiber regrowth. Thus, these results encourage us to explore autologous transplantation as a novel and promising cell therapy for treatment of spinal cord lesion.