Experimental Therapy Shows Promise in Rejuvenating Eye Cells for Vision Restoration

Scientists are exploring an experimental therapy that rejuvenates aging eye cells, potentially restoring vision lost due to conditions like glaucoma. In an ongoing Phase 1 clinical trial, researchers are using a modified reprogramming technique on diseased retinal ganglion cells in people. This method does not return the cells to their embryonic state but rather to a point before they lost proper function.

Retinal ganglion cells are crucial for transmitting visual signals from the retina to the brain via the optic nerve. Glaucoma can damage these cells through increased pressure within the eye, impairing their ability to send signals and leading to vision loss. While the cells may not die, their function is significantly compromised.

The experimental therapy involves injecting specially designed proteins, known as transcription factors, into the vitreous, the gel-like fluid at the back of the eye. This location is advantageous as it is shielded from the body's immune system, which could otherwise attack the introduced proteins. The injected proteins then work to reprogram the damaged and aging cells, aiming to restore their functionality.

This approach is based on the work of David Sinclair, a professor of genetics at Harvard Medical School. His theory suggests that aging cells lose functionality due to accumulated epigenetic noise, which disrupts the cells' original genetic instructions. Sinclair believes that restoring correct epigenetic information by reprogramming cells to a younger, more functional state could help treat age-related diseases like glaucoma.

"We are scientifically reversing epigenetic age to restore youthful function," Sinclair stated. Sharon Rosenzweig-Lipson, chief scientific officer at Life Biosciences, described the process as "restoration," aiming to return the cells' genetic code to a healthy, functional state.

Previous attempts at full cellular reprogramming using four Yamanaka factors carried a risk of uncontrolled cell growth and tumor formation. Sinclair's research focused on using only three of these factors, omitting the one most associated with cancer. This modification was crucial for developing a delivery method. Early studies with mice faced challenges, as the three factors were initially too large to fit into the viral vectors used for delivery. However, a breakthrough allowed the three factors to be small enough for effective delivery into animals.

In 2018, the first successful reprogramming of retinal ganglion cells in a mouse model with glaucoma was achieved, regenerating lost connections between the cells and the optic nerve. This breakthrough paved the way for the therapy now being tested in people.

In the current trial, two out of the three participants have shown early signs of improved vision. Participants underwent a visual field test before the therapy and were reassessed eight weeks after receiving the reprogramming factors. Two individuals demonstrated improvements in areas where they previously had reduced vision, now showing better detection of lights.

These encouraging results are prompting researchers to begin testing a higher dose of the therapy to assess its safety and determine the optimal dosage for vision improvement. The therapy's potential may extend to other eye conditions, such as Non-arteritic anterior ischemic optic neuropathy (NAION), which causes sudden vision loss. Researchers are hopeful that reprogramming could help restore vision in NAION patients.

To date, the therapy has shown no adverse effects beyond those related to the injection itself. The reprogramming factors are temporarily activated by the antibiotic doxycycline, acting as an on-off switch. Participants took doxycycline for eight weeks, after which the factors stopped producing proteins. This controlled activation allows for potential future treatments if additional reprogramming is needed.

The success in eye cells could pave the way for similar rejuvenation techniques in other parts of the body. Sinclair's lab has reported positive preclinical findings in animal models for brain, knee, back, and liver cells. If the approach continues to prove safe and effective, it could offer new avenues for treating a wide range of age-related diseases beyond vision impairment.