Nick Calfe's life changed on Independence Day 2020. Only 23 at the time, he was attending his family's party when an accidentally set off firework hit him in the left eye.
There was no pain, but I couldn't see what was going to happen. It was so dark outside that his father couldn't see how bad the damage was. So Calfe, of Rancho Cucamonga, California, went inside to ask his mother to take a look. she passed out.
After Calfe, now 26, was rushed to hospital, it was discovered that he had not completely lost his eye as everyone had feared. But her doctors said there wasn't much they could do, as her eye might have to be removed. His eyelids were also damaged and his eyes remained completely white and non-functional for several months afterwards.
“I was really depressed. I had no intention of leaving the house,” he said. “I didn't even tell my friends what happened because I didn't want them to question me. I didn't want them to see my disheveled face.”
His dream of becoming a pilot seemed to be doomed.
The accident caused an eye disease called limbal stem cell deficiency, which can lead to painful ulcers, corneal clouding, and blindness. These stem cells originate from the limbus, an area of tissue around the cornea that produces transparent cells that protect and heal the eye's surface. Chemical burns and accidents can cause severe cases like his, but excessive contact lens wear, multiple eye surgeries, and inflammatory conditions can also be contributing factors. Limbal stem cell deficiency is one of the leading causes of corneal blindness, affecting six million people worldwide.
However, a new type of stem cell therapy appears to be a safe option for people with this condition.
In a study published Friday in Science Advances, Dr. Ulla Jarknath and colleagues demonstrated that the technique, known as cultured autologous limbal epithelial cell transplantation (CALEC), is safe. In a phase 1 or “proof of concept” trial, four of her patients with chemical burns in one eye received her CALEC implants.
During surgery, it is important that only one eye is injured. This involves taking stem cells from a patient's healthy eye, culturing them in a lab for two to three weeks, and then growing them in the damaged eye, said Jurkunas, associate director of member Mass Eye & Ear Cornea Services. He said that this includes porting to. of General Brigham Mass. of Boston. Because it takes time for the cells to grow after transplantation, the researchers followed the patients for a year.
“When you lose stem cells, your eyes become really opaque, so I distinctly remember my first patient who was pain-free. Her vision wasn't very good, but she was also in a lot of pain,” she said. “And one of our first patients…was pain-free and her vision started to noticeably improve.”
In order for a person to see clearly, the stem cells surrounding the cornea, the clear outermost layer of the eye, must be constantly renewed.
“Sometimes if you see a patient whose eyes are completely white, it could be due to a stem cell defect,” Jarknath says.
stem cell growth
Although new in the United States, similar stem cell transplants are also used in Europe, and much of the first groundbreaking research was done decades ago in Italy and Japan. But the procedure is not available in the United States because the Food and Drug Administration considers it unsafe to use animal-derived products, such as serum, to grow cells for human transplants.
Jharknath and her team were able to grow the cells in a liquid free of animal serum, which was an important step toward gaining FDA approval.
“It took a lot of effort to get to the manufacturing process that they did,” says Dr. Sophie Deng, a professor in the cornea division at the UCLA Stein Eye Institute. “We must congratulate them on their accomplishments.”
Although Deng was not involved in Jarknath's research, he is also conducting clinical trials of CALEC transplants. Her research compares how well patients fare with a control group of patients treated with scleral contact lenses. These large-diameter rigid contact lenses are filled with fluid and are used to stabilize the surface of the eye, she said.
“This is one of the treatments offered to patients with limbal stem cell deficiency, in addition to direct transplantation of the limbus itself,” she said, using another term for corneal stem cells. “So, in our clinical trial, we included scleral lenses as a treatment group.”“I'll see you again.”
Djurkunas said her team treated about 15 patients. One such patient is Calfe.
A few months after the accident, Kalfe's mother came across an article about Jharknath's experimental stem cell transplant.
“I thought, oh my God, I'll see you again,” Calfe said. “Actually, I didn't know much about it. I just knew there was hope.”
Calfe moved to Boston and underwent multiple surgeries, including eyelid reconstruction, two CALEC implants, and a corneal transplant.
“It wasn't long after the first surgery that I could see again,” he said. “And I remember I FaceTimed one of my friends and I was crying.”
Several of Jharknath's patients have also undergone corneal transplants in addition to CALEC transplants, she said.
Dr. Sezen Karakus, assistant professor of ophthalmology at the Wilmer Eye Institute at Johns Hopkins University School of Medicine, pointed out that corneal transplants alone cannot help people with limbal stem cell deficiency. It quickly fails and becomes cloudy.
Limbal stem cell defects can be overlooked or misdiagnosed, and some people have multiple failed corneal transplant surgeries. They may not be able to do anything and be told to “just accept their fate,” Karakus said.
“A very difficult condition to treat”
There are other treatments for limbal stem cell deficiency. Doctors sometimes harvest stem cells from a healthy eye and transplant them directly into the damaged eye without culturing them in a lab. However, too much stem cell intake risks causing limbal stem cell deficiency in healthy eyes.
“Limbal stem cell deficiency can occur in both eyes, but that's even worse,” says Dr. Karakus. If both eyes have this condition, there is no suitable source of stem cells for transplantation. Doctors can also transplant stem cells from cadaver eyes, but patients will need to take immunosuppressants for the rest of their lives to prevent rejection.
Karakus said the new technology is “very promising and will hopefully be a good option for complex cases involving people who are told there is nothing they can do.”
Dr. Julie Schalhoun, associate professor of ophthalmology at the University of California, San Francisco, called the new study a “really exciting” proof of concept.
“This is a very difficult condition to treat,” she says. “There is no good solution to this at this time.”
UCLA's Deng emphasized the importance of growing cells in the lab in a way that could lead to FDA approval in the future.
“This is a cell-based therapy, [for FDA approval] It’s very expensive,” Deng Xiaoping said. “I'm so excited to see this published. And I think they've really put in a huge amount of effort to get here.”
This technique may not work for everyone. A fifth patient in the study was unable to receive a transplant because stem cells taken from a healthy eye did not grow in the lab.
Calfe said he and his identical twin brother, who are commercial pilots, are returning to flying “just for fun.”
“It's really crazy to be able to see just the blue sky to the left, because I never thought I'd ever see something like this again,” he said. “It's really calming. You just leave all your problems out there.”
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