RETINAL CELL TRANSPLANTATION

Experimental transplantation of cells into the human retina is taking two directions. One of these is the transplantation of photoreceptor cells. The RPE cells are 'nurse' cells, which lie behind the photoreceptors and provide them with essential nutrients. A practical form of treatment will depend on surgical advances and on whether tissue rejection and other problems can be overcome to ensure that transplanted cells can be made to survive over extended periods of time.

In contrast, photoreceptor transplantation is not encountering unmanageable rejection difficulties as it causes less stimulation of the immune system. However, there is an even bigger challenge. It is not only necessary that transplanted photoreceptors survive but also that they connect to nerve cells in order to be able to transmit signals to the brain. If only this very great challenge can be surmounted, photoreceptor transplantation may in time open the way to saving sight, either by inhibiting further degeneration or even by restoring some sight by having transplanted photoreceptor cells communicate with surviving retinal nerve cells.