Nanotechnology for Treatment of Diabetic Retinopathy

DESCRIPTION (provided by applicant): Diabetic retinopathy (DR) is a common complication of diabetes and a leading cause of blindness in the world. Diabetic macular edema (DME) and retinal neovascularization (NV) are the two major pathological alternations leading to vision loss in patients with DR. Over-expression of vascular endothelial growth factor (VEGF) in the retina is a major causative factor for vascular leakage in DR (2-4). Currently, there is no satisfactory therapy to treat DME and retinal NV but most certainly, a dire need exists. Charlesson, LLC and its wholly-owned subsidiary LifeTrees, LLC are Oklahoma City-based companiesthat are leading the discovery and development of drug products to treat severe eye disease. The company is developing the first eyedrop-based therapy for treatment of the aforementioned conditions, and has achieved significant commercial milestones in the past 12 months. Charlesson recently added a founder of Atomic Venture Partners to its executive management team on a part-time basis. AVP is an early-stage VC fund that invests in pharmaceutical companies and has offices in the Silicon Valley, Boston, and OKC. Additionally, the company has a strong R&D partnership with the University of Oklahoma Health Sciences Center (OUHSC), and relationships with the Dean McGee Eye Institute and the OK Medical Research Foundation. The market size for neovascularization, diabetic retinopathy, and macular degeneration treatments is estimated to be greater than $9 billion, growing in excess of 20% per year. Diabetes, including diabetic retinopathy, is quickly becoming an epidemic in the industrialized world. About 18.2 million Americans have diabetes, with 2.7 million new cases in the U.S. each year. All people with diabetes, both type 1 and type 2, are at risk to develop DR. Diabetic retinopathy is the leading cause of new cases of blindness among American adults between 20 and 74 years, causing 12,000 to 24,000 new cases of blindness each year. Plasminogen kringle 5 (K5) is a proteolytic fragment of plasminogen. It is an endogenous angiogenic inhibitor. Plasminogen contains 5 kringle domains, each consisting of 80 amino acids. Angiostatin consists of the first 4 kringles (K1-4) of plasminogen. K5 has a more potent anti-angiogenic activity than angiostatin. Our previous studies have shown that intravitreal injection of K5 prevents the development and arrests the progression of retinal vascular leakage in the oxygen-induced retinopathy (OIR) and streptozotocin (STZ)-induced diabetic models. K5 injection also effectively ameliorates the retinal NV in the OIR model. K5 down-regulates the VEGF expression in cultured retinal M
ller cells, the major producer of VEGF in the retina and in the retina of OIR rats. K5 also inhibits endothelial cell migration, which is a critical process in angiogenesis. The goal of this phase I project is to develop a novel, non-viral K5 gene delivery system that is safe, has strong tissue specificity and long-term expression of K5 in the retina. The M
ller cells are the major producer of VEGF which is a potent mediator of vascular permeability and angiogenesis. In order to achieve a tissue-specific expression, human K5 has been constructed under the control of a M
ller cell-specific promoter, the glial fibrillary acidic protein (GFAP) promoter. Our preliminary study has demonstrated that the intravitreal administration of these GFAP-K5 nanoparticles (GFP-K5-NP) reduces the retinal vascular leakage and atenuates retinal NV in OIR rats. This project will extend these studies by defining 1) if GFAP-K5-NP mediates K5 expression in M
ller cells in the retina, 2) if the K5 expression has long-term effects on reducing retinal VEGF levels and vascular leakage STZ-diabetic animal models, and attenuates retinal NV and reduces retinal vascular leakage in the OIR model. Therefore, in this phase I project, we will prove the concenpt that the GFAP-K5-NP mediates the retina-specific expression of K5 and has therapeutic effects on retinal NV and vascular leakage. These studies will lay a solid ground for the further characterization of these non-viral therapies in Phase II. Diabetic macular edema (DME) and retinal neovascularization (NV) are the major pathological alternations leading to the vision loss in DR. Kringle 5 has potent anti-angiogenic effect on retinal vascular leakge and neovascularization. We plan to develop a non-viral and tissue specific gene therapy by combining the nanotechnology and natural angiogenic inhibitors, which may attenuate vascular leakage and retinal NV. These novel nanoprticles may have the therapeutic potential in the treatment of diabetic vascular complications.