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A cure for blindness: treating glaucoma with genes

Colin Chu

Dr Colin Chu

Colin Chu research image

Histological section through the ciliary body of a mouse eye

23 July 2019

Glaucoma is the leading cause of irreversible blindness worldwide; it affects roughly 2% of all people over 40. Researchers at the University of Bristol are pioneering a new way of treating glaucoma using gene therapy.

The underlying causes are varied and no cure exists, but studies have shown that high pressure in the eye (intraocular pressure, or IOP) is a key feature, and deceasing this pressure can largely prevent progression and further visual loss by halting damage to the optic nerve. At present, there is no definitive treatment - and what treatments there are risk sudden loss of vision, or arduous lifelong repeated administration.

Thanks to the Elizabeth Blackwell Institute MRC Confidence in Concept scheme, Dr Colin Chu and Professor Andrew Dick at the School of Clinical Sciences, University of Bristol have developed a system which potentially halts the elevated IOP which causes so many problems with just one injection. The injection contains a viral vector; essentially a virus with all the pathogenic material removed. In its place Dr Chu has inserted fragments of Ribonucleic acid (RNA), a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. The virus transports these to the cells in the eye’s ciliary body, a tissue which produces the aqueous humour. Here, these RNA fragments interrupt the production of some of the cellular machinery that’s responsible for maintaining the pressure in the eye, and thus lower the IOP.

Initially, Dr Chu investigated a number of methods to reduce the IOP, before settling on disrupting the Aqp1 gene, which is responsible for making Aquaporin water channels that the eye uses to maintain IOP. He demonstrated a reproducible 22% reduction in IOP in a mouse model, before then determining that the gene Aqp1 is also expressed in human ciliary bodies, and that the same viral vector he used in the mouse model can also be used.

Dr Chu said, “We initially tried disrupting a variety of cellular mechanisms involving different pathways that maintain IOP, but we identified targeting Aqp1 provided the most robust effects. We were also able to disrupt Aqp1 in human ciliary body donor tissue and so our further research is focusing on preparing the treatment for clinical trials.”

“We are excited as this approach has the potential to halt the progress of glaucoma for great numbers of people, following a single minimally invasive injection, and of course provide huge long-term savings to healthcare systems.”

“The Confidence in Concept scheme has been extremely useful in allowing us to get this far, putting us in a strong position to secure follow-on funding and generating interest from potential industrial partners." 

Further information

Molecular Therapy: the journal of the American Society of Gene Therapy, 10 Jan 2020

Gene Therapy for Glaucoma by Ciliary Body Aquaporin 1 Disruption Using CRISPR-Cas9.



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