Lowering intraocular pressure (IOP) slows or stops the loss of vision in primary open-angle glaucoma (POAG) patients, including in those with normal IOP. Unfortunately, current medical treatments are usually inadequate and do not target the conventional outflow pathway; the main route of aqueous humor egress and the site of extra resistance in POAG patients with elevated IOP. Presently in clinical trials are two new classes of drugs that inhibit the contractile machinery of conventional outflow pathway cells, effectively lowering IOP. Although promising, such drugs have limitations: they are disruptive, non-specific, do not restore tissue function, and are dependent on patient compliance for daily administration. An attractive therapeutic alternative for POAG are molecular therapeutics such as microRNAs (miRNAs) that achieve prolonged modulation of various biological functions such as cell contractility because of their ability to regulate entire networks of genes. Our group has recently identified miR-200c as a strong candidate to control IOP based on its ability to inhibit contractio of trabecular meshwork cells and lower IOP in vivo. To improve delivery of miRNAs in vivo, we have developed a new class of viral vectors, including influenza-associated-virus viral-like-particles (IAV-VLP) that overcome the limitation for effective in vivo delivery of miRNAs that result from overloading of the miRNA biogenesis components. Thus, we hypothesize that miR-200c regulates conventional outflow via modification of contractile state of trabecular and/or Schlemm's canal cells. We also hypothesize that over expression of miR-200c using IAV- VLP decreases IOP in normotensive animals and prevents the pathologic increase in IOP in experimental models of glaucoma. To test our hypothesis we have constructed three specific aims designed to (i) Assess the role of miR-200c on the regulation of cellular contractility of HTM and SC cells; (ii) Examine the effects of miR-200c on aqueous humor outflow function and IOP in perfused human anterior segments and living rat eyes; (iii) Test whether increased expression of miR-200c in the cells of the outflow pathway can prevent or restore the increase in IOP in experimental models of glaucoma. Taken together, results obtained from these investigations will establish feasibility of miRNA therapy for ocular hypertension in glaucoma, optimize delivery of miRNAs to conventional outflow tissues, identify new genes regulated by miRNA-200c responsible for IOP lowering and generate novel animal models for studying glaucoma.
The objective of this project is to evaluate the therapeutic potential of a new class of regulatory elements (microRNAs, specifically miR-200c) for the treatment of elevated intraocular pressure (IOP), the major causative risk factor in glaucoma. Although active efforts exist to develop microRNA therapeutics for multiple diseases, their potential for the treatment of glaucoma has not been investigated. Moreover, a novel method for sustained delivery of microRNAs in vivo, that overcomes some of the major current limitations for the practical use of miRNAs as therapeutic agents, will be tested. Taken together, results obtained from these investigations will determine advantages and limitations of miRNA therapy for ocular hypertension in glaucoma, identify genes regulated by miR-200c responsible for IOP lowering, optimize delivery of miRNAs to conventional outflow tissues, and generate novel animal models for studying glaucoma.
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