A Porcine Organ-Culture Glaucoma Model Mimicking Trabecular Meshwork Damage Using Oxidative Stress

Abstract

Re-cellularization of the trabecular meshwork (TM) using stem cells is a potential novel treatment for ocular hypertension associated with glaucoma. To assess the therapeutic efficacy of this approach, improved in vivo and ex vivo models of TM pathophysiology are needed. Here, we investigate whether oxidative stress, induced by hydrogen peroxide (H 2 O 2), can model glaucomatous ocular hypertension in the readily available porcine anterior segment organ culture model. METHODS. The impact of H 2 O 2 on TM cell viability and function was first evaluated in vitro using primary porcine TM cells. Oxidative stress was then induced by H 2 O 2 infusion into perfused porcine anterior segments. Trabecular meshwork function was assessed by tracking matrix metalloproteinase (MMP) activity and the ability of the preparation to maintain intraocular pressure (IOP) homeostasis after a flow challenge (doubled fluid infusion rate). Finally, the TM was evaluated histologically. RESULTS. H 2 O 2 treatment resulted in a titratable reduction in cellularity across multiple primary TM cell donor strains. In organ culture preparations, H 2 O 2-treated eyes showed impaired IOP homeostasis (i.e., IOPs stabilized at higher levels after a flow challenge vs. control eyes). This result was consistent with reduced MMP activity and TM cellularity; however, damage to the TM microstructure was not histologically evident in anterior segments receiving H 2 O 2. CONCLUSIONS. Titrated H 2 O 2 infusion resulted in TM cellular dysfunction without destruction of TM structure. Thus, this porcine organ culture model offers a useful platform for assessing trabecular meshwork therapies to treat ocular hypertension associated with glaucoma.

Therapeutic Drugs and Devices for Tackling Ocular Hypertension and Glaucoma, and Need for Neuroprotection and Cytoprotective Therapies

“…Other mechanistic aspects such as the potential involvement of released substances/proteins (e.g., MMPs) can also be ascertained by sampling the effluent from these perfused segments. Such data has been reported using partially intact ex-vivo ANC eye segments of numerous different species (Llobet et al, 1999;Crosson et al, 2005;Webb et al, 2006;Keller et al, 2017;Mao et al, 2012;Boussommier-Calleja et al, 2012;Ren et al, 2016;Snider et al, 2021), and also using a whole perfused eye models (Shahidulla et al, 2005;Zhou et al, 2017). Figure 16B depicts example data obtained for two IOP-lowering agents, cabergoline and FR-190997, which enhanced outflow of perfused media in a time-dependent manner from such ex-vivo models.…”

Matrix Metalloproteinases and Glaucoma

“…Increasing MMP activity causes an elevated AH outflow rate, whereas inhibiting MMP activity decreases the AH outflow rate [ 71 ]. A recent study using a porcine model showed similar results, indicating that reduced MMP-2 and -9 activity is related to elevated IOP [ 72 ]. ECM composition changes can be observed when the AH outflow rate is pushed from equilibrium [ 73 ].…”

“…Increased matrix metalloproteinase (MMP) activity in the trabecular meshwork elevates AH outflow, which in turn reduces intraocular pressure (IOP). However, decreased MMP activity in the trabecular meshwork decreases AH outflow, which causes elevated IOP [ 63 , 65 , 71 , 72 , 73 ].…”

The correlation between primary open-angle glaucoma (POAG) and gut microbiota: a pilot study towards predictive, preventive, and personalized medicine

“…In this study, we utilized a hydrogen peroxide (H 2 O 2 ) model to mimic glaucomatous ocular hypertension in vitro. H 2 O 2 induces acute oxidative stress to TM which leads to the pathogenesis of POAG [ 68 ], this model was proved to be a useful platform which resulted in TM cellular dysfunction without the destruction of the TM structure [ 69 ], which made this model suitable for the hypothesis that gut microbiota dysbiosis regulates TM cellularity through innate immune response.…”