Enhanced neuronal transfection in the injured brain following systemic delivery of peptide-targeted lipid nanoparticles

The consequence of traumatic brain injury (TBI) is significant loss of nervous tissue that leads to long-term neurological deficits. Nucleic acid payloads offer potential treatments that can address the complex pathophysiology that unfolds after injury. TBI causes a transient disruption of the blood-brain barrier, allowing access of systemically administered nanoparticles to the affected nervous tissue. In this work, we evaluated the dosing window post-injury in which lipid nanoparticles (LNPs) carrying mRNA can access and transfect the injured brain after systemic administration and identified 24 h post-injury as a delivery time that achieves both LNP access and transfection activity. We observed that transfected cell types were majorly astrocytes and endothelial cells with no appreciable transfection of neurons. To increase neuronal transfection, we functionalized LNPs with the peptide RVG and were able to increase the proportion of neurons transfected 6.4-fold over untargeted LNPs. These results identify timelines in which LNPs can access the injured brain parenchyma to mediate gene expression and strategies to achieve neuron-specific gene delivery.