Sunday, January 29, 2012

Embryonic cells to treat diseases of the eye: ethical or not?

Early results from the world's first human trial using embryonic stem cells to treat diseases of the eye suggest the method is safe.

The trial was carried out on two patients with different conditions of the eye: One elderly patient in her 70s with dry age-related macular degeneration - the leading cause of blindness in the developed world - and another female patient in her 50s with Stargardt's disease.

Stargardt's disease
ABCA4 is the gene associated with stargardt’s disease. It produces a protein involved in energy transport to and from photoreceptor cells in the retina. Mutations in the ABCA4 gene, produce a dysfunctional protein that cannot perform its transport function. The non-functional ABCA4 protein permits the accumulation of yellow fatty material to accumulate in the retina. This material causes flecks and, ultimately, loss of vision. 

It has been reported in The Lancet that the two patients who received the retinal implants were doing well four months on. London's Moorfields Eye Hospital is now conducting a similar trial. Although these preliminary results seem promising, it could be years before the treatments are proven.

The treatment involves taking healthy immature cells from a human embryo, which are then manipulated to grow into the cells that line the back of the eye - the retina.
Researchers hope injecting these cells into a diseased eye will be able to restore vision for people with currently incurable conditions such as Stargardt's disease. The injection contained 50,000 of the retinal pigment epithelium cells.

After surgery, it was confirmed that the cells had attached to the eye's membrane as hoped, and continued to survive throughout the next 16 weeks of the study. Therefore, the procedure appeared to be safe, causing no signs of rejection or abnormal cell growth.

Despite the initial positive results of this trial, we can’t turn a “blind eye” to the ethical questions it poses.  

Professor Clynes, director of the National Institute of Cellular Biotechnology, recently stated: “It comes fundamentally to the question: is anything that is technologically possible acceptable if it cures a disease – and I’d say not.” I would tend to agree with the professor, but what are your views?

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