Lentivirus-siNgR199 Promotes Axonal Regeneration and Functional Recovery in Rats

Abstract

ABSTRACTBackground: The limited regenerative capability of central neurons and inhibitory factors are the main causes of axonal regeneration failure after spinal cord injury (SCI). Nogo receptors (NgR) are a family of receptors shared by three factors that inhibit axon outgrowth. In a previous study, siNgR199, an effective lentiviral siRNA vector of NgR1, was constructed and transfected into cortical neurons in vitro, and it effectively promoted axon outgrowth. The present study focused on the therapeutic effect of delivery of a recombinant lentivirus containing siNgR199 in vivo in rats. Methods: Rat models of traumatic SCI were constructed according to the method developed by Allen. The animals were randomly divided into three groups: group 1, injected with physiological saline; group 2, injected with empty lentivirus vehicle; and group 3, injected with lentivirus carrying siNgR199. The Basso, Beattie, and Bresnahan (BBB) scale was used for assessing hindlimb locomotor function after SCI. The neural tracer biotinylated dextran amine (BDA) and immunohistochemical methods were employed to study axon outgrowth. Results: After injection for 8 weeks, BBB locomotion scores showed that the motor function of the hindlimb recovered better in animals in group 3 (injected with lentivirus carrying siNgR199) than those in groups 1 and 2, which were injected with saline and empty lentivirus vehicle, respectively. In group 3, regenerative nerve fibers were observed at and across the injury site, while very few axonal sprouts were observed in groups 1 and 2. Conclusions: Injection with lentivirus carrying siNgR199 into the sensorimotor cortex improved axonal regeneration and functional recovery of hindlimb after SCI in rats.