Scientists at Harvard Medical School have successfully recaptured youthful biological function and restored vision by using gene therapy on the eyes of mice. Previous studies had restored youthful gene function, but only in laboratory-grown cells. The new study has achieved the first demonstration that gene therapy might be safely employed to reverse the aging of cells in living organisms.*

What they did

The team delivered three youth-restoring genes, Oct4, Sox2, and Klf4, into the retinal ganglion cells of mice. These genes are usually activated during embryonic development. Cells in the central nervous system (CNS) were targeted because it is the first area of the body affected by the aging process. The ability of the CNS to regenerate declines rapidly after birth.

Two sets of mice were involved in the study:

• Adult mice with optic nerve injury, similar to that seen in glaucoma 
• Adult (12-month-old) mice without injury, but with reduced vision from normal aging

What they found

The new, specially-targeted gene therapy demonstrated several beneficial effects: 

• Promoted nerve regeneration following an injury to the optic nerve, including:
  • A two-fold increase in the number of surviving retinal ganglion cells after injury
  • A five-fold increase in nerve regrowth
• Reversed vision loss in animals with a condition mimicking human glaucoma
• Restored visual acuity in aging animals without glaucoma

What it means

This study is the first to reverse glaucoma-related vision loss instead of simply slowing or halting its progression. “Our study demonstrates that it’s possible to safely reverse the age of complex tissues such as the retina and restore its youthful biological function,” said David Sinclair, professor of genetics in the Blavatnik Institute at Harvard Medical School and a senior author of the study.

According to the researchers, if their results are confirmed in further animal studies, they could start clinical trials within two years to test the efficacy of the approach in people with glaucoma. 

Yuancheng Lu, a research fellow at Harvard Medical School and lead author of the study, added that the new therapy could also pave the way for tissue repair across various human body systems.

“At the beginning of this project,” said Lu, “many of our colleagues said our approach would fail or would be too dangerous to ever be used. Our results suggest this method is safe and could potentially revolutionize the treatment of the eye and many other organs affected by aging.”

*Jaslow, R. (2020, Dec. 2). Harvard Medical School Scientists Reverse Age-Related Vision Loss, Eye Damage from Glaucoma in Mice. The Harvard Gazette. https://news.harvard.edu/gazette/story/2020/12/reversing-glaucoma-damage-and-vision-loss/

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