The central, long term objective of this project is to determine the contribution of relevant genes/mechanisms to outflow facility and, consequently, to develop the best possible regimen to regulate intraocular pressure (IOP) by the use of gene transfer. Our general hypothesis is that targeting cells of the outflow pathway with specific cDNAs/siRNAs will allow the modulation of relevant genes'expression (overexpressing, silencing, and/or inducing targeted promoters), and thus control elevated IOP in a more specific and prolonged manner that the currently available IOP-reducing pharmacological drugs. During the past cycle, we have identified potential IOP-lowering genes in perfused human organ cultures, and identified eukaryotic promoters targeting the human trabecular meshwork (TM). Most important, we have determined mechanisms for the lack of transduction of the non-immunogenic adeno-associated viruses (AAV) in the TM and bypass them with a new generation self-complementary AAV vector (scAAV). Specifically, and based on these findings, we now hypothesize that gene transfer to the trabecular meshwork would require a built-in mechanism that would allow the controlled turning on and off of the gene drug;that any potentially therapeutic gene and mechanism would need tissue-targeted and non-immunogenic delivery systems;and that, because of the difficulty of assaying TM gene drugs on normotense animals, we would need a living animal model that will exhibit elevated IOP without the physical and functional disruption of the resistance tissue. To test these new hypotheses, here we propose to study the effect of inducible expression and siRNA silencing on extracellular matrix (ECM) remodeling and outflow facility of the human TM perfused cultures. To transfer the selected transgenes to non immunogenic scAAV vectors under the control of the identified promoters, and to investigate their IOP-lowering ability in living rats and monkeys. And finally, we propose to begin using gene transfer technology to develop a functional TM rat model of elevated IOP.
Glaucoma is the second leading cause of irreversible blindness and the most common cause among African- Americans. Currently, there is no cure for glaucoma. The goal of our project is to search for alternative, long- term treatments of glaucoma by the use of gene transfer/gene therapy. In the short term we seek to investigate the potential of three strong candidate genes and to develop the best vector possible to carry them into the trabecular meshwork tissue. To avoid unwanted secondary effects, we are designing strategies which would allow a targeted, inducible delivery of the transgenes. Finally, to properly assay these vectors before translational research can occur, we are beginning to create an elevated pressure animal model using the inverse strategy of delivering a detrimental, clogging gene to the draining tissue.
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