Years of research and studies have gone into tests using human embryonic stem cells to treat various  degenerative eye diseases. They have subsequently went on and proved safe and effective in animal studies. If all goes well then scientists may initiate early human trials in the next few months if it receives approval from the Food and Drug Administration.

If granted approval, the stem cell therapy will provide a test case for further applications of stem cells. Scientists have made huge advances by using stem cell therapy to treat diseases in animal models. Testing these experimental therapies in humans poses some unique challenges. This is something that the scientists wish to try out soon and effectively. There are several challenges which lay in front of scientists when regarding stem cell therapy in humans.

One is proving that the use of stem cells is safe to use in humans. Another challenge that the body faces is the threat of immune rejection of the transplanted cells. In such cases care is taken. When introducing foreign cells in the body it requires that the patient should take powerful drugs to suppress the immune system, as is the case with organ transplants. For that reason, the first stem-cell therapies have focused on the eye and nervous system, so-called immune-privileged sites. This is because they do not experience this response to foreign cells.

Stem Cells for Blinds

This latest treatment for eye disease uses human embryonic stem cells to re-create a type of cell in the retina that supports the photoreceptors needed for vision. These cells, called retinal pigment epithelium (RPE), are often the first to die off in age-related macular degeneration and other eye diseases. This leads to loss of vision. To test the efficacy of the stem cell therapy to cure the eye disease the researchers injected RPE cells derived from embryonic-stem-cell lines into the eyes of rats. These rats had a genetic defect in their RPE that causes their vision to gradually deteriorate.

After three months, the retinas of treated rats had many more photoreceptors than those of untreated diseased rats. The treated animals performed better in vision tests. This however decreased with time. The transplants were also able to improve vision in a mouse model of Stargardt’s disease. This is a rare but untreatable illness that has been associated with causing early blindness.