Mitochondrial transplant offers hope for vision loss

Although the patient has not regained her sight, preliminary findings suggest that the procedure was safe and produced some encouraging changes that could pave the way for future research.

Mitochondria are microscopic structures that convert food and oxygen into energy that cells need to function. Retinal ganglion cells, the neurons responsible for transmitting visual information from the retina to the brain, depend heavily on mitochondria and are among the most energy-intensive cells in the central nervous system.

When the supply of blood and oxygen is interrupted, mitochondria can become damaged, triggering a cascade of processes that ultimately lead to cell death.

A Patient Offers a Glimpse of Hope

The patient was a 26-year-old woman who suffered a severe brain hemorrhage and did not reach the hospital until 18 hours after the event. Although emergency surgery saved her life, prolonged deprivation of blood and oxygen to her optic nerves left her almost completely blind in both eyes.

Eight weeks later, her optic nerves showed clear signs of atrophy, and an examination three months after the incident found no significant improvement.

However, imaging showed that the retinal nerve fiber layers and ganglion cells had not completely disappeared, and some visual information was still reaching the visual cortex. This raised the possibility that mitochondrial transplantation could reactivate the surviving cells.

To reduce the risk of an immune reaction, doctors used the patient’s own cells. They took a sample from her thigh muscle, extracted tens of millions of mitochondria, and injected them fresh into the vitreous gel of both eyes.

Changes began to appear in the days following the injections. Before treatment, doctors recorded 45 measurements of the pupils’ responses to light, none of which showed a normal response. Within days of the injections, however, both pupils began showing normal responses.

Three brain-imaging sessions also detected organized activity in the visual cortex.

The changes were not sustained. The left eye showed its last normal response on day 11, while the right eye continued to show intermittent normal responses through day 39. Visual acuity did not improve significantly and remained limited to light perception.

Experts caution that this is a single case without a control group, and there is no direct evidence that the transplanted mitochondria entered the retinal ganglion cells. The findings therefore cannot establish a causal relationship.

Nevertheless, the procedure caused no serious adverse effects, and the patient did not experience a severe immune reaction.

Researchers suggest that the temporary nature of the changes could mean that damaged cells may require repeated doses of healthy mitochondria to maintain any potential benefits.

David Putrino, a neuroscientist at the Icahn School of Medicine at Mount Sinai and lead author of the study, which was published on the Research Square platform, said researchers are now working with the U.S. Food and Drug Administration to develop a protocol for repeated mitochondrial injections after demonstrating that the procedure can be performed safely.

The findings open a new avenue for treating optic nerve damage and could eventually offer a way to rescue damaged cells in the eye using cellular “batteries” taken from another part of the patient’s own body.