China will begin trialling the use of embryonic stem-cells (ES) to treat Parkinsons disease and macular degeneration, in a move that has met with criticism from international experts.

The trials, which come in the wake of new stem-cell regulations introduced in China in 2015, will test the efficacy of injecting ES-derived cells into damaged areas of the brain and eyes.

In one trial, ES-derived neuronal-precursor cells will be injected into the areas of the brain affected by Parkinsons disease in attempt to regenerate dopamine-producing tissue. In another trial, the ES-derived retinal cells will be injected into eyes of people with age related macular degeneration. It is believed that the retinal cells may be able to replace cells damaged as a result of epithelial tissue degeneration.

It will be a major new direction for China, Pei Xuetao, a stem-cell scientist at the Beijing Institute of Transfusion Medicine who is on the central-government committee that approved the trials, told Nature.

Other researchers who work on Parkinsons disease, however, worry that the trials might be misguided.

Jeanne Loring, a stem-cell biologist at the Scripps Research Institute in La Jolla, California, who is also planning stem-cell trials for Parkinsons, is concerned that the Chinese trials use neural precursors and not ES-cell-derived cells that have fully committed to becoming dopamine-producing cells. Precursor cells can turn into other kinds of neurons, and could accumulate dangerous mutations during their many divisions, says Loring. Not knowing what the cells will become is troubling.

Lorenz Studer, a stem-cell biologist at the Memorial Sloan Kettering Cancer Center in New York City, says that support is not very strong for the use of precursor cells. I am somewhat surprised and concerned, as I have not seen any peer-reviewed preclinical data on this approach, he told Nature.

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Embryonic stem cell trials to launch in China - BioEdge