Glaucoma is a leading cause of irreversible blindness throughout the world and the second leading cause of blindness overall in the USA. Elevated intraocular pressure (IOP) and aging are the most important risk factors for most forms of glaucoma. IOP level is highly dependent on the rate at which the aqueous humor is filtered through the conventional outflow pathway including the trabecular meshwork (TM). Reduced cellularity within the TM and abnormal extracellular matrix (ECM) turnover occur in glaucomatous conditions and correlate with increased outflow resistance and elevated IOP. The goal of this project is to define the mechanisms of stem cell homing and engrafting to the TM tissue, stimulating regeneration of the TM tissue, and hence restoring outflow facility and reducing IOP. In advance of this project, we have already isolated and characterized trabecular meshwork stem cells (TMSCs) from human and mouse TM tissues. These stem cells are multipotent with the abilities to differentiate into phagocytic TM cells and to home to the normal mouse TM tissue after intracameral injection. They can home and engraft to the TM region damaged by laser photocoagulation. This project is designed to test specific hypotheses about the mechanisms of TMSC homing and engrafting as well as remodeling pathological ECM of the TM for TM regeneration.
Specific Aim 1 tests the hypothesis that TMSCs home and engraft to the TM tissue via specific chemokines. We will test the role of CXCR4/CXCL12 axis by knockdown or overexpression of these genes in TMSCs and TM cells.
Specific Aim 2 tests the hypothesis that engrafted exogenous TMSCs can reconstruct the trabecular meshwork ECM and thus improve aqueous outflow to reduce IOP. We will test the ability of TMSCs to degrade abnormal collagens and to secrete organized ECM in vitro and in vivo. The scientific impact of this study will be the elucidation of the cellular and molecular mechanisms of regeneration potential of the TM by stem cells. The results may also directly lead to the design of stem cell-based therapy or adjunctive treatments that prevent blindness from glaucoma.
Glaucoma is a leading cause of irreversible blindness. Current therapies for control of intraocular pressure include surgery and medications that are effective but are imperfect because of regression, side effects, and patient non-compliance. The proposed studies will unveil the mechanisms of stem cell homing and regeneration for trabecular meshwork which will lead to stem cell-based therapies for controlling intraocular pressure and prevent glaucomatous vision loss.
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