A small patch of cells that protects the eye from age-related blindness could begin trials in patients within two years in the UK.
The pioneering treatment could be one of the first successful applications originating from embryonic stem cells (ESC), the cells in embryos that can grow into all tissues of the body.
Because embryos are destroyed when ESCs are obtained, anti-abortion groups have opposed development of treatments based on them. More recently, they鈥檝e claimed that ESC research is unnecessary because it鈥檚 now possible to make ordinary tissue into embryonic-like cells called 鈥渋nduced pluripotent鈥� stem cells (iPS). Success of the eye patch would demonstrate that ESCs can indeed lead to valuable treatments, in this case to prevent blindness.
Advertisement
In a major boost for the treatment today, the pharmaceutical company announced that it would be funding clinical development of the treatment and helping to win permission from regulatory authorities to proceed with trials.
鈥淭his offers such an opportunity for patients, and it鈥檚 time to start mapping that regulatory pathway towards trials,鈥� says Ruth McKernan, chief scientific officer of Pfizer Regenerative Medicine.
Vital for sight
Pfizer will be taking forward the work in collaboration with (pdf), head of the team at University College London that has pioneered the work.
He and his colleagues have found a way to change the ESCs into retinal pigment epithelium (RPE) cells, which are vital for sight but deteriorate with age, leading to blindness caused by a condition called age-related macular degeneration (AMD).
Coffey鈥檚 team makes the cells into a single-layered RPE 鈥渃arpet鈥�, which underlays and nourishes the photoreceptor cells that actually process light and generate images. The RPE also 鈥渧acuums up鈥� debris produced by retinal cells.
Coffey says that the cells are only needed to protect a very small area of the eye called the macula, which is the point at which the eye focuses. 鈥淵ou end up with a carpet, or patch, that鈥檚 just 3 millimetres by 6, a monolayer of 40,000 to 60,000 cells,鈥� says Coffey.
鈥淚t sounds like a lot, but it鈥檚 actually a very small number in cellular terms,鈥� says Coffey. He says that a single flask of the RPE cells in a murky brown liquid contains enough cells to treat as many as 1000 patients.
Superior cells
Already, Coffey and his colleagues have demonstrated that they can use the patches to save the sight of rats.
More recently, they鈥檝e demonstrated that the patches can be transplanted safely into pigs, which have eyes about the same size as ours. Until the patches are tried out in humans, however, researchers cannot claim that the technology will save sight.
Coffey says that given successful regulatory approval and successful scale-up of RPE patch production by Pfizer, trials could begin within about two years.
Coffey says that at present, the only treatment for AMD is regular injections of a drug called , but it only works for a 鈥渨et鈥� form of the disease, which affects 10 per cent of patients. The patch, by contrast, repairs 鈥渄ry鈥� AMD, which accounts for 90 per cent of AMD cases, but is untreatable.
He also said that his team attempted first to make the RPEs from adult stem cells, but found that RPEs from embryonic stem cells were far superior, both in consistency and function.
