Modulation of Neuroinflammation via Selective Nanoparticle-Mediated Drug Delivery to Activated Microglia/Macrophages in Spinal Cord Injury

Inflammation after spinal cord injury (SCI) is characterized by immune cell invasion and activation, combined with inflammatory mediator release that worsens outcomes following primary trauma. Effective therapies targeting neuroinflammation remain an unmet need, and modulation of the injury microenvironment to induce a comprehensive pro-regenerative response is an attractive therapeutic approach. Given its crucial role in cell stress and inflammation after SCI, the potential of pharmacologically targeting MAPK-activated protein kinase-2 (MK2) to modulate the response of microglia/macrophages after injury is focused. Nanoparticles (NPs) containing an MK2 inhibitor for specific targeting of microglia/macrophages is developed. NPs selectively target and modulate activated microglia/macrophages in vitro and in a rat model of SCI. NPs in the acute injury setting reduce the pro-inflammatory cytokine IL-6 and increase the anti-inflammatory cytokine IL-10. Importantly, NPs have a significant effect on microglia/macrophage distribution and accumulation, leading to ≈65% reduction of immune cells around the injury. Last, microglia/macrophage populations with activated morphology are significantly reduced compared to resting or ramified cells around the lesion site. This strategy exhibits potential therapeutic efficiency and specificity for local, pharmacologic manipulation of activated microglia/macrophages, and is a versatile tool to manage acute inflammation and glia plasticity after central nervous system trauma.