Could 3-D Retina Transplants Put a Stop to Degenerative Blindness?

More than two million Americans suffer from age-related macular degeneration (AMD). While AMD does not result in total blindness, it is the leading cause of vision loss among Americans age 50 and above, and it causes sufferers to slowly lose central vision and interferes with an individual’s ability to drive, read, write, recognize faces, and more. There is no cure for AMD, although doctors can prescribe treatments in an effort to slow its progression.

AMD is only one of several degenerative eye conditions that lead to vision loss for which there has been no cure since it is caused by the actual decay of structures within the eye. However, this may soon change thanks to a groundbreaking advance in medicine: the development of transplantable 3-D retinas.

A team of researchers at California-based AIVITA Biomedical led by CEO Hans Keirstead, PhD have successfully used human embryonic stem cells (hESCs) to develop a 3-D “retinal organoid” made of laminated retinal progenitor cells and retinal pigment epithelium (RPE). In preclinical studies, the researchers showed that, when injected into the eye, the organoid was able to form synaptic connections with existing tissue and thus restore vision.

“The cause for hope for transplanting a 3-D retina has never been greater,” Keirstead told Modern Retina. “We have been on a relatively long journey, but are now at a point where we will be walking along a well-articulated path that will lead us to the beginning of our first in-human study.”

Keirstead, who suspects that a clinical research phase for the 3-D retinas may be as soon as two years away, explained that AIVITA’s target population is patients with degenerative disease of the outer retina, like AMD or retinitis pigmentosa. The 3-D retinas can be transplanted in the patient’s eye to replace the diseased or non-functional photoreceptors and RPE and establish new, functional connections with the inner retina and restore lost vision.

Of course, there are still a number of challenges ahead of the researchers, and the retinas are still years away from becoming commercially available for patients. But the possibility that 3-D retinas could be viable for use in patients opens the door for millions of patients, potentially, to get their sight back.

Are Eye Transplants on the Horizon?

The human body is incredibly resilient, and even after parts of it have been destroyed, it can accept foreign tissue via transplants–in certain circumstances–and continue to function as if nothing ever happened. Doctors today can transplant organs such as hearts, lungs, kidneys, and others from one person to another; there’s even a doctor who wants to perform a head transplant by next year. One organ that still cannot be transplanted is the eye, but thanks to a team of doctors and researchers in Pittsburgh, Pennsylvania, that may not be the case for very long.

Dr. Kia Washington, a plastic surgeon at the University of Pittsburgh Medical Center, is leading a research team with the goal of performing the first successful human eye transplant. She hopes that the procedure will be ready within the next 10 years.

In the United States, over one million people have vision impairments as a result of injuries. In fact, traumatic eye injuries are the fourth most common cause of combat injuries for American soldiers, which is why the Department of Defense is sponsoring Washington’s research: If she discovers a procedure for eye transplants, then it will go a long way toward treating soldiers, as well as the thousands of civilians who have impaired vision or no vision at all due to injuries.

Of course, this is all much easier said than done. A successful eye transplant would require, for one, a way of keeping the optic nerve alive during the procedure and reattaching it to the new host’s brain. Normally, upon removal, the cells in the optic nerve die immediately, thus rendering the eye useless; even if they didn’t, the new optic nerve would need to grow from the eye all the way back to the brain, which is no small feat.

However, one of Washington’s colleagues recently published a paper indicating that a cocktail of drugs, including the multiple sclerosis drug 4-AP, could help blind mice regrow their optic nerves and regain their sight after injury. This procedure, if replicable in humans, could lead to successful eye transplants. Although it is a “moonshot,” transplanting eyes in the next 10 years would be an incredible achievement that would help to treat cases of injury-related vision loss.