Targeted delivery of polypeptide nanoparticle for treatment of traumatic brain injury

Background and purpose: Traumatic brain injury (TBI) is a major disease without effective treatment. Recently, Tat-NR2B9c peptide emerged as a promising neuroprotective agent, but limited in clinical translation by it low brain penetrability. We synthesized Tat-NR2B9c loaded self-assembled activatable protein nanoparticles, termed TN-APNPs, and demonstrated that TN-APNPs enhanced the delivery of Tat-NR2B9c to the brain lesion in stroke. Herein we developed a novel approach to further engineering TN-APNPs for targeted delivery of Tat-NR2B9c to the injured brain with enhanced efficiency through conjugation of CAQK or CCAQK, a short peptide. Methods: Short peptide-conjugated TN-APNPs were synthesized by conjugated with CAQK or CCAQK via a click condensation reaction with CBT, then analyzed by dynamic light scattering, transmission electron microscopy and thrombin responsive assay. Characterization of short peptide-conjugated TN-APNPs were investigated by using cell excitotoxicity assay and transwell blood-brain-barrier model in vitro, and pharmacokinetics, IVIS imaging system and confocal analysis in TBI-bearing mice. Evaluation of therapeutic effects were analyzed by H&E staining, Elevated Plus Maze analysis and Rotarod test. Results: CAQK-conjugated TN-APNPs (C-TN-APNPs) and CCAQK-conjugated TN-APNPs (CC-TN-APNPs) were spherical in morphology and 30 nm in diameter. In vitro studies revealed that TN-APNPs, C-TN-APNPs and CC-TN-APNPs were responsive to thrombin cleavage, reduced the cytotoxicity of Tat-NR2B9c, and increased BBB permeability of Tat-NR2B9c. CC-TN-APNPs demonstrated the better circulation time, better targeting ability and penetrating efficiency to the injured brain, and better therapeutic benefits in vivo studies. Conclusion: This study demonstrated CC-TN-APNPs as a promising therapeutic for clinical management of TBI.