Overexpression of Rictor in the injured spinal cord promotes functional recovery in a rat model of spinal cord injury.

ABSTRACT

Rictor is an essential component that directly activates the mammalian target of rapamycin (mTOR) activity, which contributes to the intrinsic axon growth capacity of adult sensory neurons after injury. However, whether its action also applies to regeneration after spinal cord injury (SCI) remains unknown. In this study, rats were given spinal cord contusion at the T9-10 level to establish the SCI model and were subsequently treated with intraspinal cord injection of a Rictor overexpression lentiviral vector to locally upregulate the Rictor expression in the injured spinal cord. Thereafter, we investigated the therapeutic effects of Rictor overexpression in the injured spinal cords of SCI rats. Rictor overexpression not only significantly attenuated the acute inflammatory response and cell death after SCI but also markedly increased the shift in macrophages around the lesion from the M1 to M2 phenotype compared to those of the control lentiviral vector injection-treated group. Furthermore, Rictor overexpression dramatically increased neurogenesis in the lesion epicenter, subsequently promoting the tissue repair and functional recovery in SCI rats. Interestingly, the mechanism underlying the beneficial effects of Rictor overexpression on SCI may be associated with the Rictor overexpression playing a role in the anti-inflammatory response and driving macrophage polarization toward the M2 phenotype, which benefits resident neuronal and oligodendrocyte survival. Our findings demonstrate that Rictor is an effective target that affects the generation of molecules that inhibit spinal cord regeneration. In conclusion, localized Rictor overexpression represents a promising potential strategy for the repair of SCI.