Detailed study of the molecular mechanism behind the pathogenesis of Huntington's disease (HD) suggests that polyglutamine aggregation is one of the fundamental reasons for HD. Despite the discovery of many potential molecules, HD therapy is still limited to symptomatic relief. Among these molecules, few mechanism based peptide inhibitors of polyglutamine aggregation (QBP1, NT17 and PGQ9P2) have shown promising activity; however, poor blood-brain barrier (BBB) penetration, low bioavailability, and low half-life may hinder their therapeutic potential. Hence, to deliver them to the brain for assessing their efficacy, we have designed and synthesized peptide loaded poly-d,l-lactide- co-glycolide (PLGA) nanoparticles of less than 200 nm in size by carbodiimide chemistry and nanoprecipitation protocols. For brain delivery, PLGA nanoparticles were coated with polysorbate 80 which aids receptor mediated internalization. Using the in vitro BBB model of Madin-Darby canine kidney cells and healthy mice, the translocation of polysorbate 80 coated fluorescent nanoparticles was confirmed. Moreover, QBP1, NT17, and PGQ9P2 loaded PLGA nanoparticles showed dose dependent inhibition of polyglutamine aggregation in cell models of HD (Neuro 2A and PC12 cells) and improved motor performance in Drosophila model of HD. Additionally, no toxicity in cells and animals confirmed biocompatibility of the nanoparticulate formulations. Based on this work, future studies can be designed in higher animal models to test peptide loaded nanoparticles in HD and other polyglutamine expansion related diseases.
Keywords: Huntington’s disease; PLGA nanoparticles; blood-brain barrier; carbodiimide chemistry; peptide inhibitors; polyglutamine aggregation.