Local Immunomodulation with Anti-inflammatory Cytokine-Encoding Lentivirus Enhances Functional Recovery after Spinal Cord Injury

Abstract

Trauma to the spinal cord and associated secondary inflammation can lead to permanent loss of sensory and motor function below the injury level, with the resulting environment serving as a barrier that limits regeneration. In this study, we investigate the localized expression of anti-inflammatory cytokines IL-10 and IL-4 via lentiviral transduction in multichannel bridges. Porous multichannel bridges provide physical guidance for axonal outgrowth with the cytokines hypothesized to modulate the neuroinflammatory microenvironment and enhance axonal regeneration. Gene expression analyses indicated that induced IL-10 and IL-4 expression decreased expression of pro-inflammatory genes and increased pro-regenerative genes relative to control. Moreover, these factors led to increased numbers of axons and myelination, with approximately 45% of axons myelinated and the number of oligodendrocyte myelinated axons significantly increased by 3- to 4-fold. Furthermore, the combination of a bridge with IL-10 and IL-4 expression improved locomotor function after injury to an average score of 6 relative to an average score of 3 for injury alone. Collectively, these studies highlight the potential for localized immunomodulation to decrease secondary inflammation and enhance regeneration that may have numerous applications.

Lentiviral interleukin-10 gene therapy preserves fine motor circuitry and function after a cervical spinal cord injury in male and female mice

“…A number of groups have reported that IL10 treatment after a thoracic SCI can lead to intraspinal sparing of neurons, axons, and lesion size that is associated with improved locomotor function [23][24][25][26][27][28][29]. We have also previously demonstrated in a left-sided, thoracic SCI that IL10 can shift the inflammatory milieu toward a pro-regenerative phenotype, which was associated with significantly improved locomotor function [37,38] and consistent with the results here in the cervical model. Thoracic injuries that employ behavioral tests such as the basso mouse scale for locomotion, which is controlled by central pattern generators (CPGs) that can be unilaterally activated to initiate bilateral locomotor behavior, may not fully capture the deficit from the unilateral injury.…”

“…After 48hrs, the supernatant was collected and the virus was precipitated using PEG-It (Systems Biosciences, Palo Alto, CA, #LV825A-1) and stored at -80°C until use. Prior to surgery, 4e7 IFU of virus was loaded onto each PLG scaffold, which were fabricated as previously described using the gas foaming technique to fuse PLG particles into a matrix [20,38,40]. Using the particulate leaching technique, 63-106 µm NaCl served as sacrificial templates for pores to allow cell infiltration into the scaffold and a sugar mixture pulled into nine 150-250 µm diameter A-P parallel strands served as sacrificial templates for conduits to guide nerve growth [36,41].…”

“…Lentivirus delivery has previously been shown to induce localized and sustained transgene expression [36]. Lentiviral IL10 expression can shift post-SCI gene expression towards an anti-inflammatory profile [37,38]. We initially analyzed behavioral recovery using a ladder beam at 2 and 12 weeks postinjury (wpi).…”

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

“…M2 macrophage activation facilitates spinal cord repair in SCI, which is associated with the promotion of neuronal survival 37 . Integrating the previous findings, the current observations that Rictor overexpression reduced apoptosis in host neurons and oligodendrocytes in the injured lesion may benefit the neurite outgrowth and synaptic plasticity after traumatic SCI 38 …”

PLG Bridge Implantation in Chronic SCI Promotes Axonal Elongation and Myelination

“…2A peptides can lead to high levels of downstream protein expression compared to other strategies for multi gene co-expression and are small enough to not negatively interfere with the function of the coexpressed genes 21 . IL-10 can alter the phenotype of invading macrophages towards a pro-regenerative phenotype and lead to improved spinal cord regeneration 22,23 , while NT-3 expression can promote neuron survival and axonal elongation 19 . Herein, we investigated the potential for co-expression to influence macrophage phenotypes, axonal elongation and myelination, and source of the myelination at 12 weeks post injury, with subsequent studies assessing the functional benefits of co-delivery.…”