CNN is not my favorite news source, but this is where the better article is published:
http://www.cnn.com/2022/06/02/health/reverse-aging-life-itself-scn-wellness/index.html
Excerpt:
A reset button
In Sinclair’s lab, two mice sit side by side. One is the picture of youth, the other gray and feeble. Yet they are brother and sister, born from the same litter – only one has been genetically altered to age faster.
If that could be done, Sinclair asked his team, could the reverse be accomplished as well? Japanese biomedical researcher Dr. Shinya Yamanaka had already reprogrammed human adult skin cells to behave like embryonic or pluripotent stem cells, capable of developing into any cell in the body. The 2007 discovery won the scientist a Nobel Prize, and his “induced pluripotent stem cells,” soon became known as “Yamanaka factors.”
However, adult cells fully switched back to stem cells via Yamanaka factors lose their identity. They forget they are blood, heart and skin cells, making them perfect for rebirth as “cell du jour,” but lousy at rejuvenation. You don’t want Brad Pitt in “The Curious Case of Benjamin Button” to become a baby all at once; you want him to age backward while still remembering who he is.
Labs around the world jumped on the problem. A study published in 2016 by researchers at the Salk Institute for Biological Studies in La Jolla, California, showed signs of aging could be expunged in genetically aged mice, exposed for a short time to four main Yamanaka factors, without erasing the cells’ identity.
But there was a downside in all this research: In certain situations, the altered mice developed cancerous tumors.
02 ghost heart
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Looking for a safer alternative, Sinclair lab geneticist Yuancheng Lu chose three of the four factors and genetically added them to a harmless virus. The virus was designed to deliver the rejuvenating Yamanaka factors to damaged retinal ganglion cells at the back of an aged mouse’s eye. After injecting the virus into the eye, the pluripotent genes were then switched on by feeding the mouse an antibiotic.
“The antibiotic is just a tool. It could be any chemical really, just a way to be sure the three genes are switched on,” Sinclair said. “Normally they are only on in very young developing embryos and then turn off as we age.”
Amazingly, damaged neurons in the eyes of mice injected with the three cells rejuvenated, even growing new axons, or projections from the eye into the brain. Since that original study, Sinclair said his lab has reversed aging in the muscles and brains of mice and is now working on rejuvenating a mouse’s entire body.
“Somehow the cells know the body can reset itself, and they still know which genes should be on when they were young,” Sinclair said. “We think we’re tapping into an ancient regeneration system that some animals use – when you cut the limb off a salamander, it regrows the limb. The tail of a fish will grow back; a finger of a mouse will grow back.”
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