Stem cells restore sight in children with cataracts

Scientists have shown that stem cells found in the eye can restore vision in children with cataracts.

The study demonstrates a novel surgical method of cataract removal that preserves surrounding stem cells and allows them to regenerate functional lenses.

'The success of this work represents a new approach in how new human tissue or organs can be regenerated and human disease can be treated, and may have a broad impact on regenerative therapies by harnessing the regenerative power of our own body,' said Professor Kang Zhang, who led the study at the Shiley Eye Institute, University of California, San Diego.

The researchers, who published their results in Nature, demonstrated a minimally invasive surgical technique that removes the lens without harming a structure in the eye known as the lens capsule. This structure preserves lens epithelial stem cells, which were shown to regenerate functional lenses.

'The basic science research led to the hypothesis that preserving and stimulating autologous stem cells in the eye might promote regeneration of a surgically removed lens. And indeed, their hypothesis was true,' said Dr Dusko Ilic, reader in Women's Health at King's College London, who was not involved in the study.

Initially, the researchers proved their hypothesis by testing the new surgical approach in rabbits and primates before testing in patients. Then as part of a clinical trial they treated 12 children under the age of two with the new method and 25 children with the conventional technique, which involves replacing the cataractous lens with an artificial lens. This method is considered more destructive to the stem cell populations in the eye.

The children who received the conventional treatment experienced higher incidence of post-surgery inflammation, early-onset of high blood pressure in the eye and increased lens clouding compared with those who received the new treatment.

For the children who underwent stem cell treatment 'the lens regenerated remarkably well', said Professor Zhang. 'We restored visual function and that implies that a clear lens has regenerated.

'This illustrates that there can be a new approach. We can turn on our own dormant stem cells. Just imagine how powerful this could be if we can do it for heart attacks, or turn on neuronal stem cells in the brain?' said Professor Zhang.

Congenital cataracts affect between three and four in every 10,000 children in the UK, causing cloudy patches to develop in the lens resulting in deteriorating vision and eventually blindness, if left untreated.

Professor Graham McGeow, the deputy head of the School of Medicine, Dentistry and Biomedical Sciences at Queen's University, Belfast, who was not involved with the study, said the work was a clear 'proof of principle' for an important new treatment for cataracts in children.

Professor McGeow also mentioned that it was 'unclear' whether this treatment would benefit adult patients with cataracts since the conventional technique is usually successful.