• Posted August 18, 2023

Blinded by Chemical Burns, Patients Regained Sight With New Stem Cell Therapy

Phillip Durst was working near an industrial dishwasher when something went awry, and the machinery spewed caustic chemicals into his eyes.

"If I had been standing a foot left or right, it wouldn't have hit me right where it did. I was just standing in the wrong place,"said Durst, 51, of Birmingham, Ala.

The chemicals caused severe burns to his eyes, blinding him.

"I can't describe the pain -- more pain than I've ever been in,"Durst recalled of the April 2017 incident. "I've had broken bones, stitches in my head, crashed on skateboard ramps, you name it. I've hit and hurt myself so many times, the sins of my youth, and I've never felt anything so intense or so unreal in my life.

"I was clawing at my face, just trying to get my left eye open to get some sort of water flush solution in it,"he continued. "At one point I asked somebody to pick me up and turn me upside down in a 25-gallon sink that we had been filling with water. I was squeezing lemons into my eyes (in an attempt to neutralize the chemicals). That was preferable to the pain I was feeling."

At first, it appeared Durst might be permanently blinded. The injury had clouded over his corneas and blocked his eyes' natural ability to regenerate healthy tissue.

But an experimental procedure using stem cells to grow new tissue for implantation has restored some of his sight.

In the procedure, outlined Aug. 18 in the journal Science Advances, researchers used stem cells collected from one healthier eye to culture tissue that can then be implanted in the damaged eye.

"Corneas normally are transparent structures,"said lead researcher Dr. Ula Jurkunas, associate director of the Cornea Service at Mass Eye and Ear in Boston. "Every adult cornea has stem cells that are residing in the very periphery of the cornea. And when these stem cells are depleted or destroyed by a chemical injury, they do not provide the function of keeping cornea clear."

Blood vessels and conjunctiva -- the thin mucous membrane that keeps your eye lubricated -- start growing into the cornea, causing blindness.

Few options for this eye injury

There aren't a lot of options for patients with this type of eye injury, said Dr. Anat Galor, an ophthalmologist specializing in cornea diseases at the University of Miami Miller School of Medicine.

"Our techniques for replacing the injured epithelial stem cells aren't as good as for other corneal problems because if you take epithelial stem cells from a donor and you try to transplant them, the risk of rejection is much higher than with a corneal transplant,"said Galor, who wasn't involved in the study.

"Where it's the epithelial stem cells that are injured or lost, our regular corneal transplant techniques don't work, and we're looking for something else,"she added.

Surgeons took a biopsy from Durst's right eye -- which had been damaged, but had enough healthy stem cells left to partially recover -- and sent the tissue off to a stem cell laboratory at Dana-Farber Cancer Institute in Boston.

After two to three weeks, the lab sent back the cultured tissue. Eye surgeons cleared out the damaged tissue and replaced it with the lab-grown transplant, which is about three-fourths of an inch, Jurkunas said.

"These new cells engraft, meaning they kind of stick to the eye and provide the source of new stem cells for that cornea,"she said.

Durst underwent his surgery almost exactly a year after the accident, in April 2018. Doctors implanted the tissue into his left eye.

Durst now describes his vision as like swimming in a bay, compared to swimming in a pool.

Phillip Durst with son Ben

"Right now, it's just cloudy. It accepts light. I can see images. If I hold my hand up, I can see it,"he said. "It's just everything just looks like I'm swimming in the bay."

Durst is one of four patients successfully provided transplants in this method, according to the new report. Others include:

• A 31-year-old man who experienced a complete resolution of symptoms, with vision improving from 20/40 to 20/30.
• A 36-year-old man whose corneal defect was resolved and his vision improved from only being able to see broad hand movements like waving to 20/30.
• A 52-year-old man who initially did not have a successful biopsy but three years later had a successful transplant.

Two of the four patients experienced significant improvement through treatment alone, while two others needed a follow-up cornea transplant, researchers reported.

Because doctors are implanting tissue grown from the patient's own stem cells, the risk of rejection is much lower than receiving donor tissue, Jurkunas said.

"These are patients' own cells, so there is very low risk of the body rejecting them,"she said. "That is basically one of the advantages. Every person also has a very unique footprint of how their cells grow. So there's quite a bit of variability between patient to patient."

'A very boutique type of treatment'

If the process receives FDA approval, the transplant surgery could be performed across the nation if one or more biotech firms step forward to do the stem cell culturing, Galor said.

She said various academic centers -- not just one or two -- could do the procedure and use an intermediary company, if available, as the site where the cells are expanded.

"If there's a company that can do this at mass scale, I would think that there would be several centers around the country that would be able to take the specimens and then receive them back and do the procedure, because these are procedures that many of us are already doing,"Galor added.

"What we're missing is the ex vivo expansion, where the cells are expanded outside the eye. So I definitely think that if this would get off the ground that there would be many academic centers that could partner with whatever business takes it on to provide the service for patients," Galor explained.

However, Jurkunas said it's likely to be an expensive procedure, given that each patient's cells must be cultured individually.

"This is a very boutique type of treatment. It is fairly costly,"Jurkunas said. "So we'll have to see how the economics of this therapy will turn out, with approvals and so forth."

Researchers have already finished with the next wave of 15 patients, Jurkunas said. A third trial involving a larger group of patients and multiple surgeons in different centers might be required for approval, she added.

The techniques developed here also might help with other eye injuries and problems, Jurkunas said.

"This particular technology is limited to corneal issues, but here are no proven or FDA approved cell therapies in the eye,"she said. "So having at least corneal cell therapy would be a great stepping stone for other therapies as well, retinal and so forth, although this specific technique would not necessarily be used the same way in retinal cells. Retinal cells are very different than the cornea."

In the meantime, patients are flocking to her Boston center for treatment.

"We had a lot of patients from all over the country,"Jurkunas said. "We had a patient who actually rented an RV and came from Florida and lived in one in our own Boston area for six months."

More information

The U.S. National Eye Institute has more about corneal diseases and injuries.

SOURCES: Phillip Durst, 51, Birmingham, Ala.; Ula Jurkunas, MD, associate director, Cornea Service, Mass Eye and Ear, Boston; Anat Galor, MD, MSPH, ophthalmologist specializing in cornea diseases, University of Miami Miller School of Medicine; Science Advances, Aug. 18, 2023