Primary open angle glaucoma is a major blinding disease, with elevated intraocular pressure (IOP) as a key risk factor. Cells of the trabecular meshwork (TM) are responsible for maintaining IOP homeostasis. In glaucoma, reduced TM cellularity due to genetic and/or environmental factors may compromise IOP homeostatic capabilities. Current treatments aid many, but not all patients respond appropriately to them, or respond only for a limited time. Adding TM-like cells to replenish the remaining TM cells may facilitate restoration of function. We propose to evaluate two candidate stem cell types as replacements for absent/diseased TM cells. These two potentially autologous cell types, human mesenchymal stem cells (hMSC), and induced pluripotent stem cells (iPS cells), have been used to repopulate other tissues. The purpose of these replacements would be to restore normal IOP homeostasis. In this proposal, the central hypothesis is that one or both stem cell types can be induced to grow, expand, and replace diseased TM cells. We contend that they will adopt many or all of the structural, physiological, and biochemical, and functional attributes of TM in the proper microenvironment. With a multi- pronged approach, we will investigate the therapeutic potential of both stem cell types in the model ocular perfusion system by transplanting them as substitutes for diseased TM cells.
In Aim #1 we will compare TM cell biomarkers to those of hMSC, iPS cells, and the differentiated stem cells. By following the progress of these markers, we will test the working hypothesis that we can use them to assess the similarities of the two stem cell types to TM cells. By culturing with aqueous humor, ECM components, different media preparations, and/or other agents, we will alter the local milieu of the stem cells. With the markers as a partial guide, differentiation of the stem cells to TM-like cells will be tracked by immunohistochemistry, confocal microscopy, qRT-PCR, and Western immunoblots. Using this approach, we can determine the best stem cell candidate for differentiation and for regenerative therapy in TM.
In Aim #2 we will evaluate the functionality of transplanted cells from undifferentiated and differentiated hMSC and iPS cells. Human eyes will be experimentally partially denuded of TM cells, to test the working hypothesis that we can mimic the decreased TM cellularity of the glaucomatous eye, and then assess function of transplanted replacement cells in a model ocular perfusion system. Replacement cells will be analyzed for the capacity to restore TM-like IOP homeostasis and for phagocytotic digestion of debris. This approach has considerable promise as a novel inroad for glaucoma patients to an era of regenerative medicine.

Public Health Relevance

Nearly 80 million people worldwide are estimated to suffer from glaucoma, resulting in severe vision impairment or blindness, diminished productivity, and loss of independence when untreated, or unsuccessfully treated. With aging and glaucoma, fewer healthy cells are present in the eye for proper functioning, and current therapies are inadequate to treat many cases on a long term basis. This application seeks to remedy a deficiency in long-term glaucoma treatment with pioneering treatments using transplanted stem cells from the patient's own body.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
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Special Emphasis Panel (DPVS)
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Chin, Hemin R
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Oregon Health and Science University
Schools of Medicine
United States
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Vranka, Janice A; Kelley, Mary J; Acott, Ted S et al. (2015) Extracellular matrix in the trabecular meshwork: intraocular pressure regulation and dysregulation in glaucoma. Exp Eye Res 133:112-25
Abu-Hassan, Diala W; Li, Xinbo; Ryan, Eileen I et al. (2015) Induced pluripotent stem cells restore function in a human cell loss model of open-angle glaucoma. Stem Cells 33:751-61
Acott, Ted S; Kelley, Mary J; Keller, Kate E et al. (2014) Intraocular pressure homeostasis: maintaining balance in a high-pressure environment. J Ocul Pharmacol Ther 30:94-101
Abu-Hassan, Diala W; Acott, Ted S; Kelley, Mary J (2014) The Trabecular Meshwork: A Basic Review of Form and Function. J Ocul Biol 2:
Keller, Kate E; Vranka, Janice A; Haddadin, Ramez I et al. (2013) The effects of tenascin C knockdown on trabecular meshwork outflow resistance. Invest Ophthalmol Vis Sci 54:5613-23