Doctors injected a patient with severe vision loss with her own mitochondria, the structures that produce energy inside cells

Doctors injected a patient with severe vision loss with her own mitochondria, the structures that produce energy inside cells

A preprint published on August 10 describes two procedures. Fresh mitochondria isolated from the muscle of a 26-year-old woman were injected into the vitreous humor of both eyes 24 hours apart. Her pupils began responding to light within several days after each injection, while her visual acuity remained limited to light perception.

The patient had lost almost all vision after a cerebral hemorrhage, prolonged disruption of blood flow, and injury to the optic nerves. Her condition then remained unchanged for three months. Imaging showed severe thinning of the retinal ganglion cell layer, which contains neurons that transmit signals from the eye to the brain. The authors proposed that some of these damaged cells remained alive and attempted to support them with mitochondria.

The mitochondria were injected into the vitreous humor, the transparent gel-like substance inside the eye. From there, the suspension can reach the inner surface of the retina, where the retinal ganglion cell bodies are located. In rodent experiments, mitochondria administered by this route entered mainly the inner retinal layers.

Before each procedure, the team isolated mitochondria from a biopsy of the patient’s muscle, tested the suspension for particles, endotoxin, and microorganisms, and then injected 50 microliters into the eye. They treated the right eye first. After 24 hours and a predefined tolerability assessment, they treated the left eye. This sequence allowed them to determine whether it was safe to proceed with the second injection.

During four weeks of follow-up, the patient showed no intraocular inflammation, increased intraocular pressure, retinal detachment, or systemic immune changes. Over the preceding 71 days, the device had taken 45 measurements without detecting a normal pupillary light response. After the injections, 13 of 52 measurements reached the normal threshold. In the left eye, the response first appeared on the second day and persisted through day 11. In the right eye, it was present from day 4 through day 39.

The pupillary light response measures an automatic reaction to light, while visual acuity measures whether a person can distinguish objects. The first measure improved in this patient, while the second remained unchanged. The authors propose a controlled study to assess the dose, intervals between injections, and selection of patients who retain functioning retinal cells after injury.