Multi-Graft Surgery to Combat Dry Macular Degeneration

Researchers at the National Institutes of Health (NIH) have introduced an innovative surgical method for implanting multiple tissue grafts into the retina. This breakthrough, tested in animal models, could pave the way for improved treatments for dry age-related macular degeneration (AMD)—a major contributor to vision loss in older adults.

The study detailing this technique appears in the latest edition of JCI Insight.

Restoring Sight: Stem Cell Grafts for AMD

In diseases such as AMD, the light-sensitive retina tissue at the back of the eye degenerates. Scientists are testing therapies for restoring damaged retinas with grafts of tissue grown in the lab from patient-derived stem cells.

Until now, surgeons have only been able to place one graft in the retina, limiting the area that can be treated in patients, and as well as the ability to conduct side-by-side comparisons in animal models. Such comparisons are crucial for confirming that the tissue grafts are integrating with the retina and the underlying blood supply from a network of tiny blood vessels known as the choriocapillaris.

For the technique, investigators designed a new surgical clamp that maintains eye pressure during the insertion of two tissue patches in immediate succession while minimizing damage to the surrounding tissue.

One graft consisted of retinal pigment epithelial (RPE) cells grown on a biodegradable scaffold. RPE cells support and nourish the retina’s light-sensing photoreceptors. In AMD, vision loss occurs alongside the loss of RPE cells and photoreceptors. In the lab, RPE cells are grown from human blood cells after they’ve been converted into stem cells. The second graft consisted of just the biodegradable scaffold to serve as a control.

Post surgery, scientists used artificial intelligence to analyze retinal images and compare the effects of each graft. They observed that the RPE grafts promoted the survival of photoreceptors, while photoreceptors near scaffold-only grafts died at a much higher rate. Additionally, they were able to confirm for the first time that the RPE graft also regenerated the choriocapillaris, which supplies the retina with oxygen and nutrients.

Source-Eurekalert