CRISPR-Cas9–based treatment of myocilin-associated glaucoma

Abstract

Primary open-angle glaucoma (POAG) is a leading cause of irreversible vision loss worldwide, with elevated intraocular pressure (IOP) a major risk factor. Myocilin (MYOC) dominant gain-offunction mutations have been reported in ∼4% of POAG cases. MYOC mutations result in protein misfolding, leading to endoplasmic reticulum (ER) stress in the trabecular meshwork (TM), the tissue that regulates IOP. We use CRISPR-Cas9-mediated genome editing in cultured human TM cells and in a MYOC mouse model of POAG to knock down expression of mutant MYOC, resulting in relief of ER stress. In vivo genome editing results in lower IOP and prevents further glaucomatous damage. Importantly, using an ex vivo human organ culture system, we demonstrate the feasibility of human genome editing in the eye for this important disease.myocilin | CRISPR | glaucoma | trabecular meshwork | genome editing

Gene therapy and the adeno‐associated virus in the treatment of genetic and acquired ophthalmic diseases in humans: Trials, future directions and safety considerations

“…Adenovirus encoding parts of the CRISPR/Cas9 system have been used to target the myocilin mutations in a murine model and it was found that by targeting the myocilin mutation, the IOP decreased in affected mice and this prevented further damage to the rodent eyes. The same laboratory also looked at the effects of the vector on the trabecular network of ex vivo eyes and reported a decrease in myocilin mRNA . These reports open avenues for translation into clinical trials of early‐onset glaucoma caused by myocilin mutations.…”

“…The same laboratory also looked at the effects of the vector on the trabecular network of ex vivo eyes and reported a decrease in myocilin mRNA. 139 These reports open avenues for translation into clinical trials of early-onset glaucoma caused by myocilin mutations.…”

“…Monogenic forms of glaucoma are uncommon and mostly present earlier in life than the typical adult‐onset glaucoma. Myocilin‐dominant gain of function mutations which affect the functioning of the trabecular meshwork, which is responsible for draining aqueous humour from the eye, leads to elevated IOP and have been reported in 10%‐33% of early‐onset glaucoma . Adenovirus encoding parts of the CRISPR/Cas9 system have been used to target the myocilin mutations in a murine model and it was found that by targeting the myocilin mutation, the IOP decreased in affected mice and this prevented further damage to the rodent eyes.…”

“…Myocilin-dominant gain of function mutations which affect the functioning of the trabecular meshwork, which is responsible for draining aqueous humour from the eye, leads to elevated IOP and have been reported in 10%-33% of early-onset glaucoma. [139][140][141] Adenovirus encoding parts of the CRISPR/Cas9 system have been used to target the myocilin mutations in a murine model and it was found that by targeting the myocilin mutation, the IOP decreased in affected mice and this prevented further damage to the rodent eyes. The same laboratory also looked at the effects of the vector on the trabecular network of ex vivo eyes and reported a decrease in myocilin mRNA.…”

Trabecular meshwork cells are a valuable resource for cellular therapy of glaucoma

“…Only until recently, two significant mouse models have been established for studies of TM cell therapies. 83,84 Zhu et al reported that aqueous humour out-flow was restored following transplantation of iPSC-derived TM cells in a transgenic mouse model of glaucoma. 84 Their results suggest that transplantation of iPSC-TM may restore out-flow facility and IOP in aged mice.…”