Research aiming to prevent blindness and to restore vision.
From Press Release: Neuroscience Meeting, Chicago, October 21, 2009
Transplanted Tissue Improves Vision
“A clinical study is the first to show that advanced stages of incurable retinal diseases can be stopped and improved by a cell replacement technique. The researchers transplanted intact "sheets" of fetal retinal cells that develop into light-sensitive nerve cells, along with a supporting layer of tissue, into damaged human eyes. The findings were presented at Neuroscience 2009, the annual meeting of the Society for Neuroscience and the world's largest source of emerging news about brain science and health.
To date, most clinical studies have targeted the early stages of retinal disease in attempts to rescue photoreceptors, the light-sensitive nerve cells. But once photoreceptors have died, they cannot be regenerated. Animal studies have shown that transplanted donor cells and nearby sustaining tissue grow into healthy cells and integrate with the recipient's own damaged retina. The researchers created a special instrument to transplant these extremely fragile sheets of young retinal cells.
Of the 10 patients who received the transplants (four with age-related macular degeneration and six with retinitis pigmentosa), seven improved, one remained the same, and two continued to deteriorate. The individuals were assessed using different methods. The main test was to read letters on a chart to check visual acuity, and follow-up time was between one and six years. Although most tissue donors and recipients were tested for compatibility, no immunological match was seen. "Despite this limitation, it was encouraging that no rejection was seen clinically and the surgery had no negative side effects," said Robert Aramant, PhD, visiting scientist at the University of California, Irvine, and lead author. The authors suggest that these results -- along with previous positive results in animal retinal degeneration studies -- are evidence of the safety and benefits of retinal transplantation in humans...”
After 24 years of research, this team has shown in a phase II clinical study that transplants can prevent further blindness and even improve vision in macular degeneration and retinitis pigmentosa patients. The clinical study has been preceded and accompanied by basic research showing successful restoration of visual responses in several animal models that otherwise develop total blindness. This success has been possible by development of a unique patented instrument and method that can gently place the fragile transplant in the back of the eye in the place of the damaged retina.
The team’s basic research has been recognized and supported by grants from the National Institutes of Health and by different foundations.
The transplant consists of an immature piece of tissue (not a suspension of single cells) but a piece of undisturbed retina that has already developed its primordial three dimensional network between the cells and will develop organized retinal layers. The transplanted cells are already committed to become different retinal cells and develop in the host to replace the lost cells. They integrate with the host and send out a lot of processes into the still functional part of the host retina. In this way, the transplant can repair an area of a damaged retina. The transplant replaces not only retinal pigment epithelium and the photosensitive cells but also other retinal cells which many/most patients also need. See publications.