'Miracle' stem cells help burns victims to see clearly again
Dozens of people whose eyes were severely damaged in chemical accidents have had their sight restored with transplants of their own stem cells.
Researchers say the technique returned normal vision to nearly 100 people. They said one of the patients could see clearly for the first time in more than 60 years.
'They were incredibly happy. Some said it was a miracle,' study leader Graziella Pellegrini of the University of Modena's Center for Regenerative Medicine said. 'It was not a miracle. It was simply a technique.'
“他们乐疯了。有人说这是一个奇迹。” 研究小组组长、摩德纳大学再生医学中心的Graziella Pellegrini说，“我说呢，这并非奇迹，技术而已。”
Stem cell transplants offer hope to the thousands of people worldwide every year who suffer chemical burns on their corneas from heavy-duty cleansers or other substances at work or at home.
In the study researchers took a small number of stem cells from a patient's healthy eye, multiplied them in the lab and placed them into the burned eye, where they were able to grow new corneal tissue to replace what had been damaged.
Since the stem cells are from their own bodies, the patients do not need to take anti-rejection drugs.
Currently, people with eye burns can get an artificial cornea, a procedure that carries such complications as infection and glaucoma, or they can receive a transplant using stem cells from a cadaver, but that requires taking drugs to prevent rejection.
The Italian study involved 106 patients treated between 1998 and 2007. Most had extensive damage in one eye, and some had such limited vision that they could only sense light, count fingers or perceive hand motions. Many had been blind for years and had had unsuccessful operations to restore their vision.
The cells were taken from the limbus, the rim around the cornea, the clear window that covers the colored part of the eye. In a normal eye, stem cells in the limbus are like factories, churning out new cells to replace dead corneal cells. When an injury kills off the stem cells, scar tissue forms over the cornea, clouding vision and causing blindness.
In the study, published by the New England Journal of Medicine, the doctors removed scar tissue over the cornea and glued the laboratory-grown stem cells over the injured eye.
Researchers followed the patients for an average of three years and some as long as a decade. More than three-quarters regained sight after the transplant. An additional 13 per cent were considered a partial success. Though their vision improved, they still had some cloudiness in the cornea.
治疗后的研究者对患者进行了随访。随访时间为：其中一些患者平均三年，另一些患者多达十年。 随访发现，超过四分之三的患者在移植后重新获得了视力。另外有13% 的患者被认为部分治愈，即其视力虽然得到改善，但角膜上仍然有一些云翳妨碍视力。
Patients with superficial damage were able to see within one to two months. Those with more extensive injuries took several months longer.
The approach would not help people with damage to the optic nerve or macular degeneration, which involves the retina. Nor would it work in people who are completely blind in both eyes, because doctors need at least some healthy tissue that they can transplant.
Adult stem cells, which are found around the body, are different from embryonic stem cells, which come from human embryos and have stirred ethical concerns because removing the cells requires destroying the embryos.
Dr Sophie Deng, a cornea expert at the UCLA's Jules Stein Eye Institute, said the biggest advantage was that the Italian doctors were able to expand the number of stem cells in the lab. This technique is less invasive than taking a large tissue sample from the eye and lowers the chance of an eye injury.
加州大学洛杉矶分校Jules Stein眼研究所角膜专家Sophie Deng博士说本研究最大的优势是：意大利的医生们能够在实验室里繁殖干细胞。比起从眼睛提取大组织样本来说，本技术少有侵入性，从而降低了对其中一眼的损伤。
'The key is whether you can find a good stem cell population and expand it,' she said.