Targeted Hsp as a Therapeutic for Central Retinal Artery Occlusion

It is estimated that in people will experience a central retinal artery occlusion CRAO accompanied by acute monocular vision loss Even when resolved by reperfusion of patients have a visual acuity of or worse The body s natural response to ocular trauma is the induction of heat shock protein Hsp to combat the acute effects of protein denaturation and aggregation and the chronic effects of apoptosis and secondary necrosis Unfortunately Hsp induction can require several valuable hours while a patient is in jeopardy of permanent vision loss A cell penetrating antibody mAb E is proposed as an intracellular transporter to deliver Hsp into cells Previous work with this E Hsp fusion Fv Hsp has shown cytoprotection against apoptotic cell death in vitro and in vivo Our long term goal is to determine the clinical effectiveness of this targeted Hsp in countering cell death in the retina following a CRAO The objective here is to show our Fv Hsp administered intravitreally blocks cell death using a cerebral artery occlusion method to generate the CRAO in mice The central hypothesis for the proposed research is that E can deliver Hsp directly into energy deficient cells to minimize protein denaturation and aggregation as well as inhibit both ATP dependent and independent apoptosis thus preventing significant retinal damage particularly to the sensitive retinal ganglion cells The rationale for the proposed research is that the cell penetrating antibody E binds extracellular DNA and nucleosides targets that are quite accessible where there are damaged cells and it penetrates still viable cells through an equilibrative nucleoside salvage pathway E is unique in that it penetrates cells without apparent harm and has been administered to humans without evidence of toxicity Fv Hsp has already been created and shown to be an effective cytoprotectant in vivo minimizing by the infarct volume in brain tissue when administered to rats after a stroke It has also resulted in less cardiomyocyte death at the heart apex of post reperfusion treated rabbits versus different sham controls We are requesting funding to achieve the following specific aims Characterize the Fv Hsp s pharmacokinetics and pharmacodynamics delivered to the vitreous humor Fv Hsp will be formulated in suitable ophthalmological solutions Evaluate Fv Hsp efficacy at the maximum tolerated dose MTD by intravitreal delivery to mice in a CRAO model Evaluate the Fv Hsp efficacy at the MTD at several time points after reperfusion to determine a maximal window of administration that measurably improves retinal cell survival and can be implemented in a clinical setting such as the ER The proposed research is innovative because it utilizes a unique antibody mediated energy independent intracellular delivery system for protein therapeutics Inducing heat shock proteins in vivo takes time whereas the impact of our product is the rapid delivery of Hsp into damaged cells to prevent cell death Project Narrative Relevance of the proposed project to public health The research proposal is relevant to the NEI because the development of ocular cytoprotectants to help prevent loss of vision from a central retinal artery occlusion is an unmet medical need Thus the proposed research is relevant to the mission of NEI to reducing the incidence of vision loss even blindness by developing a novel intravitreally administered cytoprotectant that prevents significant retinal cell death following a central retinal artery occlusion Ultimately the treatment proposed by Rubicon Biotechnology will be the first of its kind to target vulnerable retinal cells and help them survive