Autologous Mitochondrial Injection Therapy to Restore Vision

Scientists have extracted mitochondria from a woman’s leg muscles and injected them into the vitreous humor of her eye in an experimental attempt to treat severe blindness. The procedure caused no inflammation or other reported side effects, but it produced only a limited and temporary improvement in the eye’s response to light. The treatment did not restore the woman’s vision.

Mitochondria are the energy-producing organelles inside cells. Transplanting healthy mitochondria is being investigated as a potential treatment for diseases that damage these organelles in specific tissues. In some studies, damaged cells have absorbed transplanted mitochondria, improving cell survival and partially restoring tissue function. Previous human trials have tested mitochondrial transplantation in the heart and brain; this report describes the first implantation of mitochondria into the eye.

A brain hemorrhage in February damaged the woman’s optic nerve and retina, leaving her almost completely blind. Her pupils did not react to flashing lights before treatment. After the mitochondrial injection, her pupils responded to light, but the response diminished after approximately four weeks. The findings were described in a preprint posted on August 10 and have not yet been peer-reviewed.¹.

Temurkhan Ayupov, a mitochondrial biologist at the Basel Institute of Molecular and Clinical Ophthalmology in Switzerland, said the study suggests that injecting a person’s own mitochondria into the eye is “relatively safe”. However, he cautioned that the results do not demonstrate that mitochondrial transplantation is an effective treatment.

The researchers’ primary aim was to assess the safety of the procedure, says David Putrino, a neuroscientist at the Icahn School of Medicine at Mount Sinai in New York City and a co-author of the preprint. “We can’t prove efficacy at all, and we’re not trying to prove it,” he said. However, the team did observe “a significant effect on physiological changes in the eye”.

Mitochondrial transplantation shows limited success

Putrino and his colleagues investigated whether injecting mitochondria directly into the eye could improve the function of retinal ganglion cells. These neurons are located in the retina and transmit visual signals to the brain.

Studies in mice have suggested that delivering mitochondria into the vitreous humor can improve the survival of neurons that remain after optic-nerve injury. These findings provided the rationale for testing the approach in a human patient.

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In May, researchers received emergency approval from the U.S. Food and Drug Administration (FDA) to test mitochondrial transplantation in the eyes of women.

“The most concerning thing was the triggering of an immune response, where the immune system starts attacking the foreign substance that was injected into the body,” Putrino said. However, examinations after the procedure found no evidence of inflammation or damage in either eye.

Although the pupil’s response to light was temporary, it “remained at a higher level than before the transplant,” Putrino said. The researchers also conducted a post-transplant assessment for visual function and reported that the woman could perceive shapes and shadows with her left eye. These observations are preliminary and require confirmation in peer-reviewed studies and larger clinical trials.