Helping the Eye Repair Itself
The clear surface at the front of the eye, called the cornea, plays a major role in healthy vision. To stay clear and smooth, it depends on special regenerative cells found around the outer edge of the cornea.
When these cells become badly damaged, the eye can have trouble repairing its surface. This condition, known as limbal stem cell deficiency, may lead to irritation, inflammation, scarring, abnormal blood vessel growth, and vision problems.
A 2025 clinical trial explored an interesting solution: using a small sample of a patient’s own healthy eye cells to help repair the damaged eye.
The treatment is called cultivated autologous limbal epithelial cell transplantation, or CALEC. While the name sounds complicated, the basic idea is fairly simple—take healthy cells, grow more of them in a laboratory, and then use those cells to help rebuild the injured surface of the eye.
Turning a Small Sample into a New Graft
The study included 15 people who had severe damage in one eye while their other eye remained healthy enough to provide a small tissue sample.
Researchers carefully collected cells from the healthy eye and expanded them in the laboratory. The cells were then placed onto a thin human amniotic membrane, creating a sheet of tissue that could be transplanted onto the damaged eye.
The process worked well from a manufacturing standpoint. Researchers successfully created usable grafts for 14 of the 15 participants, giving the process a 93% success rate. Fourteen patients ultimately received the treatment and were followed for as long as 18 months.
The Results Became More Encouraging With Time
One of the most interesting parts of the study was that improvement continued as time went on. Researchers looked at how well the corneal surface healed, whether abnormal blood vessel growth improved, and whether patients experienced changes in symptoms and vision.
The percentage of patients reaching complete or partial treatment success was:
- 86% after 3 months
- 93% after 12 months
- 92% after 18 months
Complete success also increased over time. Half of the treated eyes reached complete success after three months, rising to 79% at 12 months and remaining at 77% after 18 months.
Every participant achieved complete treatment success at least once during the study. Researchers also reported overall improvements in areas such as corneal surface damage, eye symptoms, visual clarity, abnormal blood vessel growth, and cloudiness of the cornea.
What About the Healthy Eye?
Because the treatment requires taking a small sample from the patient’s healthier eye, researchers closely monitored that eye as well.
The biopsy was generally well tolerated. Temporary surface irritation healed within about a week, and vision in the donor eyes remained close to where it had been before the procedure. It was reported that no serious treatment-related safety problems involving either eye.
One participant developed an eye infection several months after treatment, but investigators linked it to long-term contact lens use rather than the CALEC therapy.
Why This Approach Is So Interesting
What makes CALEC especially appealing from a regenerative medicine perspective is that it uses the patient’s own cells.
Instead of relying on a large amount of donor tissue, researchers can take a very small sample, grow the cells outside the body, and create a much larger graft. In a sense, the treatment gives the eye more of the building blocks it normally uses to maintain and repair its surface.
The study also showed that these personalized cell grafts could be produced successfully for nearly every participant, an important step when considering how a therapy might eventually be used more broadly.
A Bright Step Forward for Regenerative Eye Care
This was an early Phase I/II trial with a relatively small number of participants, so larger studies will be needed to confirm how effective the treatment may be for a wider group of patients. But still, the results are encouraging.
Most treated eyes showed complete or partial success through 18 months, the healthy donor eyes remained stable, and researchers found no serious treatment-related safety concerns.
The study offers a fascinating example of what regenerative medicine may make possible: taking a small number of a patient’s own healthy cells, expanding them in the lab, and using them to help restore damaged tissue elsewhere in the body.
Source
Jurkunas UV, Kaufman AR, Yin J, et al. Cultivated autologous limbal epithelial cell (CALEC) transplantation for limbal stem cell deficiency: a phase I/II clinical trial of the first xenobiotic-free, serum-free, antibiotic-free manufacturing protocol developed in the US. Nature Communications. 2025;16:1607. Available from: https://www.nature.com/articles/s41467-025-56461-1
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