Transspinal temporal interference stimulation enhances neuroplasticity-associated responses and facilitates motor recovery after spinal cord injury in mice

Abstract

Spinal cord injury (SCI) causes substantial motor impairment, driven by neuronal loss, axonal disruption, and impaired synaptic connectivity. Temporal interference (TI) stimulation is capable of modulating neural activity, but its therapeutic potential in SCI remains largely unexplored. We explored the influence of TI stimulation on functional recovery and neuroplasticity-associated responses following SCI. Thirty-two C57BL/6J mice were randomly allocated to four groups: sham, SCI, sham stimulation, and TI stimulation. Mice underwent T8 spinal cord hemisection, followed by daily TI stimulation from day 4 to day 21 post-injury. Locomotor recovery was evaluated using the Basso Mouse Scale (BMS). At 21 days after injury, neuronal-associated changes, glial responses, and neuroplasticity-associated molecular changes were assessed by immunofluorescence staining and western blot analysis. Compared with sham-operated mice, SCI mice exhibited impaired locomotor function, reduced NeuN-positive neuronal density, and decreased expression of neuroplasticity-associated proteins, including GAP43, NF-L, SYN, and PSD95. In contrast, TI stimulation significantly improved BMS scores and increased NeuN-positive neuronal density, accompanied by enhanced expression of axonal growth-associated proteins (GAP43 and NF-L) and synaptic plasticity-associated markers (SYN and PSD95). These findings indicate that TI stimulation improves functional recovery after SCI and is associated with enhanced neuroplasticity-related responses, including axonal growth-associated and synaptic plasticity-associated changes. This study provides evidence supporting TI stimulation as a promising neuromodulation strategy for promoting neuroplasticity-associated recovery processes after spinal cord injury.