In a significant breakthrough, US researchers restored vision in patients with eye injuries using their own stem cells.

The revolutionary stem cell treatment called cultivated autologous limbal epithelial cell transplantation (CALEC) was found to be safe and well-tolerated over the short term in four patients with significant chemical burns in one eye.

The team from Mass Eye and Ear, a member of Mass General Brigham, followed the patients for 12 months who experienced restored cornea surfaces — two were able to undergo a corneal transplant and two reported significant improvements in vision without additional treatment.

“Our early results suggest that CALEC might offer hope to patients who had been left with untreatable vision loss and pain associated with major cornea injuries,” said principal investigator and lead study author Ula Jurkunas, Associate director of the Cornea Service at Mass Eye and Ear.

“Cornea specialists have been hindered by a lack of treatment options with a high safety profile to help our patients with chemical burns and injuries that render them unable to get an artificial cornea transplant. We are hopeful with further study, CALEC can one day fill this crucially needed treatment gap,” added Jurkunas, Associate Professor of ophthalmology at Harvard Medical School.

In CALEC, stem cells from a patient’s healthy eye are removed via a small biopsy and then expanded and grown on a graft via an innovative manufacturing process.

After two to three weeks, the CALEC graft is sent back to the doctors and transplanted into the eye with corneal damage.

People who experience chemical burns and other eye injuries may develop limbal stem cell deficiency, an irreversible loss of cells on the tissue surrounding the cornea. These patients experience permanent vision loss, pain and discomfort in the affected eye.

Without limbal cells and a healthy eye surface, patients are unable to undergo artificial cornea transplants, the current standard of vision rehabilitation.

In the phase I trial of CALEC, described in the journal Science Advances, the first patient was a 46-year-old male who experienced a resolution of his eye surface defect. It primed him to undergo an artificial cornea transplant for vision rehabilitation.

The second, a 31-year-old male, experienced a complete resolution of symptoms with vision improving from 20/40 to 20/30.

The third was a 36-year-old male who had his corneal defect resolved and his vision improved from hand motion — only being able to see broad movements like waving — to 20/30 vision.

The fourth was a 52-year-old male who initially did not have a successful biopsy that resulted in a viable stem cell graft.

After re-attempting CALEC three years later, he underwent a successful transplant and his vision improved from hand motion to being able to count fingers.

He then received an artificial cornea.

The phase I trial shows promise, said the researchers, who now aim to advance to a second phase of the trial.