A man has developed serious swelling in his eye after receiving a pioneering stem cell treatment for blindness, but this was probably the result of the surgery itself rather than the stem cell implant.
The treatment was developed by Masayo Takahashi of the Riken Center for Developmental Biology in Kobe, Japan, and her team. Induced pluripotent stem (iPS) cells produced from a person鈥檚 own skin cells or a tissue-matched donor are turned into a patch of eye cells ready for transplant. The recipient is someone with a progressive form of blindness called age-related macular degeneration.
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In 2014, a woman in her 80s was the first to receive a patch made in this way. Last year, the team reported that the technique had improved her vision, raising hopes that it would work for others.
But the team announced in a press conference on 16 January that the second person to be treated this way 鈥� a man in his 70s 鈥� had developed serious retinal swelling. The same day, he had surgery to remove an 鈥撀� scar-like tissue that had formed since he was treated in June 2017.
Surgery effect
In response, some reports in the media suggest that the stem cells may have triggered this swelling. But the swelling was probably the result of last year鈥檚 surgery, rather than the stem cells, says at University College London.
鈥淚t鈥檚 a glial scar on top of the retina, and it moves and pulls the retina,鈥� says Cheetham. 鈥淚t鈥檚 probably the patient鈥檚 native cells doing this, and a reaction to the surgery,鈥� he says.
Takahashi said that although the adverse reaction was 鈥渟erious鈥�, it was 鈥渘ot a matter of great urgency or life-threatening鈥�.
Nor was the swelling caused by the man鈥檚 immune system reacting to the transplant 鈥� a potential risk after receiving an implant developed from donor cells. While the first woman鈥檚 iPS cells were made from her own skin, the man got his iPS cells from a matched donor, the first person to receive this treatment.
Flagship trial
This isn鈥檛 the only setback the team has faced. In between treating the woman and the second patient, the team had to suspend their trial when some iPS cells grown in the lab developed mutations.
But the trial was able to resume and Takahashi said this week that the man鈥檚 adverse reaction wouldn鈥檛 alter her team鈥檚 plans to continue transplanting iPS-derived cells into the eyes of people with severe eye disease.
This news will come as a big relief to those hoping iPS cells will be suitable for treating a range of diseases. These stem cells were developed a decade ago by Shinya Yamanaka at Kyoto University and earned him a Nobel prize. Takahashi鈥檚 programme is the first and, so far, only clinical trial of these cells in the world.
Read more: Mutation alert halts stem-cell trial to cure blindness
