Functional Protein Delivery Using Polymeric Nanoparticles: A Novel Therapeutic Approach to Alpha-Synuclein Aggregation and Parkinson's Disease

Abstract

203 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008.An efficient route for delivering specific proteins and peptides into neurons could greatly accelerate the development of therapies for various diseases, especially those involving intracellular defects such as Parkinson's disease (PD). Synthetic nanoparticles made from polybutylcyanoacrylate (PBCA) have been previously shown to deliver otherwise impermeable drugs to therapeutic levels in vivo across the blood-brain barrier (BBB). It was not yet known, however, whether such particles could also be taken up by neurons and other brain cells. Here we report the novel use of polybutylcyanoacrylate nanoparticles (NPs) for delivery of intact, functional proteins into neurons and neurogenic cell lines. Uptake of these particles is primarily dependent on endocytosis via the low-density lipoprotein receptor. The nanoparticles are rapidly turned over and display minimal toxicity to cultured neurons. Delivery of three different functional cargo proteins is demonstrated. When primary neuronal cultures are treated with recombinant E. coli beta-galactosidase as nanoparticle cargo, persistent enzyme activity is measured beyond the period of nanoparticle degradation. Delivery of the small GTPase rhoG induces neurite outgrowth and differentiation in PC12 cells. In addition, a monoclonal antibody (H3C) directed against the C-terminus of synuclein is capable of interacting with endogenous alpha-synuclein (alpha-syn) in neurons following transport via polybutylcyanoacrylate NPs.Alpha-synuclein (alpha-syn) aggregation has been linked to the pathogenesis of PD and other related conditions. Targeting this protein using synuclein-specific antibodies has thus emerged as a promising strategy for treatment development, but is limited by the need for rigorous protein expression in neuronal cells. We therefore explore the effects of treatment with H3C-loaded NPs in a cell-based model of Parkinson's disease. H3C reduces alpha-syn aggregate levels and cytotoxicity during oxidative stress. This process is dependent on lysosomal activity and is abolished by lysosomal inhibition. Binding to H3C also increases degradation of mutant forms of alpha-synuclein by purified lysosomes in vitro. H3C-loaded nanoparticles may thus aid in our understanding of abnormal protein turnover in cells, and offer a novel therapeutic approach to alpha-syn misfolding diseases such as PD.Finally, we examine the regional distribution and cellular uptake of PBCA nanoparticles in vivo following intravenous administration in mice. The particles are most strongly localized to the cerebellum, midbrain, entorrhinal cortex, hippocampus, subventricular zone, and striatum. Cell-specific staining was also observed in Purkinje neurons of the cerebellum. Positive enzyme activity was furthermore detected in the olfactory bulb of animals injected with beta-galactosidase loaded NPs. Future studies are necessary, however, in order to achieve more concentrated and targeted delivery of cargo to brain regions specifically affected by Parkinson's disease, and for optimizing neuronal internalization of the nanoparticles following passage across the BBB. Polybutylcyanoacrylate nanoparticles are thus useful for intracellular protein delivery in vitro, and have potential as carriers of therapeutic proteins for treatment of neuronal disorders in vivo .U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD