Skin is the first to take the hits of time: sun, wind, age. Scientists have long sought ways to slow its aging, but most approaches target fibroblasts, the cells that produce collagen. Yet skin is more complex: its basal layer harbors stem cells that constantly renew the epidermis. Nearby in the archive are studies on brain age maps, cellular methylation, and light-based diagnostics of bone fragility, all of which build tissue atlases to find points of intervention. This work stands apart: it doesn't just describe aging but immediately offers a therapy tested at multiple levels.
First, they collected 16 skin samples from donors aged 23, 53, and 85, taking paired biopsies from the arm (chronological aging plus photoaging) and the back (chronological aging only). The cells were separated into single cells and their RNA was read on the 10x Genomics platform, yielding 109,086 cells. Using clustering algorithms, they identified 31 cell subtypes and found genes that change with age. Among them stood out ATF3, which fell in all donors. Then they tested its role: they knocked out the gene in cells and observed how this affected aging. After that, they created mRNA that makes cells produce ATF3 again and delivered it to cells, skin samples, and mice.
ATF3 levels in basal stem cells declined with age across all datasets. When the gene was knocked out, cells aged faster: the activity of the aging enzyme rose by 20-30%, and the proportion of dividing cells fell by 25%. When mRNA for ATF3 was added to old cells, aging decreased by 22-25%, and division accelerated by 20-25%. In skin samples from a 62-year-old donor, after treatment the thickness of the basal layer increased 1.8-fold, and collagen and elastin increased noticeably. In mice with wounds, ATF3 treatment reduced scarring. Interestingly, the effect on fibroblasts was indirect: the mRNA acted on keratinocytes, which then sent signals that made fibroblasts produce collagen.
The work shifts the focus from fibroblasts to basal stem cells. Neighboring studies described aging as a passive process, but here it is shown that it can be reversed by restoring a single protein. This changes the understanding of which cells are the main target for rejuvenation. Furthermore, the importance of communication between skin layers is proven: keratinocytes control fibroblasts through signaling molecules. This approach may work not only for skin but also for other organs that have stem cell niches.
The next step is human trials. We need to understand how long the effect of a single injection lasts and whether repeating the procedure is safe. It's also possible to combine ATF3 with other factors to enhance rejuvenation. mRNA technology has already been proven in vaccines, so adaptation for skin could be rapid. In the future, such methods could treat not only aging but also chronic wounds, alopecia, and inflammatory skin diseases.
The results will influence regenerative medicine, cosmetology, and gerontology. A new class of drugs will emerge that precisely switch on youth genes without altering DNA.
Conduct clinical trials on volunteers. Work out the dosage and method of delivering mRNA into human skin.
In the biology of aging, the question of why stem cells lose their ability to renew remains open. This work shows that a single transcription factor may be the key to this process in skin. This links aging to epigenetic regulation and intercellular communication, two major unsolved problems.
To deliver the mRNA, they used a microneedle patch with needles 600 micrometers tall, thinner than a human hair. It painlessly pierces the stratum corneum and delivers the drug directly to living cells.
The idea of rejuvenation through stem cell activation brings to mind the film 'Paragraph 78' or the series 'Altered Carbon,' where bodies can be renewed. But here, instead of futuristic capsules, it's a simple mRNA injection that works on the principle of a vaccine.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.