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 AD cases, increases hemorrhagic stroke risk, and is exacerbated by 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, 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 ?smart? nanoparticle (SNP) made of depyrogenated chitosan that selectively targets cerebrovascular A? deposits to deliver an encapsulated CD59 plasmid whose expression abrogates the formation of MAC. We have developed a technique to depyrogenate chitosan that enables internal placement since previous 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. We are asking for a two year phase I SBIR grant since six months is too short of a time to accomplish our three specific aims.
These aims are: 1) To establish successful transfection of primary human cerebral vascular smooth muscle cells (HCVSMCs) with chitosan gene-containing microparticles, 2) Induce surface expression of CD59 in HCVSMCs via microparticle transfection and 3) Establish successful protection of CD59 transfected cells from MAC-initiated cell lysis.
Our goal is to develop a therapy for the microvasculopathy Cerebral Amyloid Angiopathy (CAA) based on microparticle gene delivery of 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 the chitosan-mediated gene delivery system and determination of the CD59 protective effect will be studied with in vitro cell cultures.
