Cerebral Amyloid Angiopathy (CAA), a microvasculopathy in which beta-amyloid (A?) accumulates in the walls of cerebral blood vessels, is associated with vascular fragility and bleeding secondary to blood vessel wall breakdown. CAA is especially deleterious to vascular smooth muscle cells (VSMC). CAA is found in 70-90% of Alzheimer's disease (AD) cases, increases hemorrhagic stroke risk, and is exacerbated by active amyloid immunotherapy thereby compromising this promising AD therapeutic. There is no effective therapy for CAA. Despite the prevalence of CAA in AD and the fact that AD and CAA are different diseases, CAA is often overlooked in AD studies as A? has been widely presumed to be responsible for the VSMC loss in the walls of A?-laden vessels. VSMC loss in CAA occurs due to formation of the complement system's cytolytic membrane attack complex (MAC) in the tunica media of A?-laden CAA blood vessels. Based on this discovery by our scientific team, our goal is to develop a first-ever therapeutic for CAA based on inhibition of MAC formation which we hypothesize will prevent CAA-induced vascular fragility. We plan to target inhibition of MAC formation in the walls of A?-laden CAA blood vessels, as opposed to systemic MAC inhibition, due to the importance of MAC for immune protection against microbial infection. We propose a nose-to-brain nanoparticle therapy made of depyrogenated chitosan modified with diethylethylamine (DEAE) that delivers an encapsulated CD59 plasmid whose expression abrogates the formation of MAC. We have developed a technique to depyrogenate chitosan that enables internal placement since commercially available chitosans are contaminated with endotoxins. These contaminants interfere with plasmid transfection and gene expression. Our chitosan depyrogenation technique is based on the application of nitrogen plasma ? the same technology employed to decontaminate potential anthrax letters sent to Congress after 9/11. We completed a Phase I SBIR in which we established successful transfection of primary human VSMCs with chitosan gene-containing nanoparticles, induced surface expression of CD59 in VSMCs via nanoparticle transfection, and established successful protection of CD59 transfected cells from MAC-initiated cell lysis. In this Phase II SBIR, we intend to (1) improve production of uniform, reproducible DEAE chitosan nanoparticles that are stable over time so as to achieve consistent, predictable in vivo transfection of brain microvasculature and provide parenchymal protection, (2) characterize the therapeutic efficacy of our nose-to-brain CS-CD59 nanoparticle CAA therapy in a relevant transgenic mouse model of CAA, and (3) determine histologic, physiologic, and cognitive effects in the transgenic CAA mouse model of enhanced CD59 expression. Successful completion of this project will help enable informed translation of our DEAE chitosan nanoparticle therapy for CAA into the clinic.
Our goal is to develop a therapy for the microvasculopathy Cerebral Amyloid Angiopathy (CAA) based on intranasal delivery of nanoparticles carrying a gene for the complement-regulator CD59. There is increasing evidence that a complement-mediated attack on brain microvascular cells plays a significant role in the pathogenesis of CAA. Optimization of our chitosan-mediated gene delivery system and determination of the CD59 protective effect will be studied in vivo in a relevant CAA mouse model.
