How age-reversal gene therapy could help restore sight

Yuancheng (Ryan) Lu is investigating whether cellular reprogramming—a technique designed to restore more youthful patterns of gene activity—can help repair damaged eyes. His early work restored optic-nerve growth and visual responses in mice, and a closely related therapy has now entered a human clinical trial involving glaucoma.

The research offers a potential new approach to age-related vision loss. It also illustrates the limits of current rejuvenation science: Lu views his original treatment as a proof of concept, not a universal answer to aging.

A personal interest in aging and vision

Lu, a 34-year-old geneticist at the Whitehead Institute in Cambridge, Massachusetts, studies gene therapies intended to prevent age-related vision loss. His interest is partly personal.

Age-related blindness runs in his family, and a 23andMe test indicated that he carries a mutation associated with macular degeneration, a major cause of vision loss in older people. He also takes precautions against bright sunlight, another risk factor, by wearing glasses that darken outdoors.

For Lu, the eye is particularly useful for studying both aging and rejuvenation. It is accessible enough for researchers to deliver experimental treatments and directly examine whether damaged structures respond.

Restoring optic nerves in mice

Lu produced his best-known result in 2018 while completing his PhD at Harvard Medical School in the laboratory of longevity researcher David Sinclair.

In the experiment, Lu crushed the optic nerves of mice, leaving the animals unable to see. He then delivered a gene therapy intended to return affected cells to a younger state. After 16 days, the nerves had begun to regenerate. Under a microscope, newly growing axons appeared as thin orange filaments.

The researchers also assessed whether the physical repair translated into restored function. In later tests, the mice were placed in a box with rotating bars of light. Their ability to track the changing patterns indicated that they could see again.

The work was published in Nature in 2020. It became an influential result in rejuvenation research and helped draw investment toward companies exploring cellular reprogramming and anti-aging medicine.

How cellular reprogramming works

Reprogramming is based on a resetting process that occurs in embryos. Although embryos inherit DNA from their parents, that genetic material undergoes changes that allow a baby to begin life young rather than carrying the biological age of the parents.

In 2006, Japanese researchers showed that they could reproduce aspects of this process in the laboratory by adding four genes collectively known as OSKM. When introduced into a cell from a 100-year-old person, those genes can transform it into a stem cell that behaves as though it came from an embryo.

That full transformation is not suitable as a therapy because cells could lose their established identities. Lu therefore used a reduced combination known as OSK:

O, S and K provide the reprogramming activity.
M, representing Myc, is omitted.
Myc is the factor considered most likely to cause dangerous changes, including cancer.

By using only three factors, Lu sought to produce rejuvenating effects without completely turning mature cells into stem cells. Testing the approach in the optic nerve allowed the team to examine whether injured nerve cells could recover youthful regenerative abilities.

The therapy reaches a human trial

A treatment closely based on Lu’s work is now called ER-100. Life Biosciences, a startup cofounded by Sinclair, announced on June 9 that the therapy had been injected into the eye of a person with glaucoma. Lu owns a small stake in the company.

According to Sinclair, the treatment has changed very little since Lu developed it as a graduate student. The move into a human clinical trial represents an important transition, but the available information does not establish whether ER-100 will restore vision in people or prove safe and effective more broadly.

The trial has nevertheless attracted substantial attention, including claims that reprogramming could transform humanity or amount to a fountain of youth. Lu has taken a more restrained position while continuing to study what the therapy does inside different kinds of cells.

Why one rejuvenation treatment may not fit every cell

Over the past six years, Lu has worked to understand the biological effects of OSK and to search for what he calls the next generation of rejuvenation therapies. That research has exposed significant complications.

OSK remains toxic to many types of cells. Lu also says it is becoming clear that the causes of aging differ among cell types, making it unlikely that a single combination of genes will correct every age-related problem.

His more recent work has included identifying a gene that protects the retina from free-radical damage, described as the main cause of age-related macular degeneration. Such findings could support treatments that target specific mechanisms rather than trying to reverse aging throughout the body with one intervention.

Lu also disagrees with Sinclair’s belief that humans could live to 200. In his view, aging involves too many separate failures for OSK to serve as a silver bullet. Its larger contribution may be demonstrating that molecular age is not necessarily fixed.

A promising concept with unresolved questions

Lu’s mouse experiments showed that cellular reprogramming can promote optic-nerve regeneration and restore visual responses under experimental conditions. The related human trial will test whether that promise can begin to translate into treatment for people with glaucoma.

For now, the work is best understood as evidence that some features of cellular aging may be reversible—not proof that aging itself can be comprehensively undone. Safety, cell-specific toxicity and the different mechanisms involved in age-related decline remain central challenges.

Attribution: revew

Originally reported by revew.