Researchers have succeeded in producing corneal tissue from stem cells
by Tamara Traubman
In a first operation of its kind, researchers were able to restore the sight of three blind people by transplanting corneal tissue. The transplanted tissue was made from a small number of special cells called stem cells. These cells are used in the human body to create new body cells instead of old or damaged cells.
Similar to the creation of the cornea, various laboratories around the world are currently trying to create tissues and organs by taking a small number of stem cells and creating conditions for their reproduction. The reproduction is done on a "scaffold" that provides the cells with nutrition and directs their growth so that they develop into an organ. When the organ reaches its final form, it is transplanted into the patient's body. Many doctors and scientists hope that one day they will be able to use these methods to create a "storehouse of transplant-ready organs."
In the current study published today in the medical journal "Cornea", the researchers, Dr. Ivan Schaub and Dr. Rebecca Isroff from the University of California, Davis, were able to grow the outer layer of the cornea and implant it successfully in ten out of 14 patients.
Corneal stem cells - from which new corneal cells are produced - were taken from the patients themselves or from their relatives and placed on a grid made of the membrane that surrounds the fetus. The membrane provided the cells with a base as well as the nutritional supplements they needed to reproduce. The cells proliferated into tissue with characteristics close to those of natural tissue.
All patients suffered from defects in the outer layer of the cornea before the transplant as a result of illness, burn or work accident; Their vision was impaired in varying degrees of severity. Even after the transplant, their vision is not completely normal, but with the help of glasses they can read a book, drive and perform daily tasks. Some of the patients have been living with the implant for more than a year. Isroff said in a telephone interview that they implanted the engineered cornea in two more patients. "So far they are doing well," she said, but not enough time has yet passed since the transplant to determine how successful the surgery was.
"This is a wonderful advance," said Dr. David Versano, director of the cornea service at the Ichilov Medical Center. "It gives cornea patients and cornea doctors new hope." He said that one of the important achievements of the current research lies in the fact that the researchers were able to create a graft from a very small amount of cells A race that was taken from a healthy eye and thus did not damage its function.
"It's still not the complete and ideal product, but it's definitely the beginning of the road," said Prof. Zvi Nebo, a tissue engineering expert from Tel Aviv University, referring to the researchers' ultimate goal of producing a complete cornea.
A more difficult task is to restore organs made up of a larger number of cells, such as liver and kidneys - "a task that is not impossible", Nebo believes. He noted that engineered cartilage and skin grafts have already come into use in the past two years in several countries. Isroff said that they must "solve a few more problems that are certainly not simple, including the network on which we grow the tissues, which is probably not the most suitable for the cells, but the transplantation of genetically engineered biological tissues and organs is moving quickly from the realm of science fiction to the world of reality."
{Appeared in Haaretz newspaper, 13/7/2000}
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