“Younging” is my stab at a term that’s shorter and more descriptive than “rejuvenation” and more positive than “de-aging.”
Once it becomes possible to shed years, people will be asking: “You look good, are you younging?” (Whatever word they use, I hope they ask it of me.)
Contemptuous dismissal of younging, especially in the mainstream media, is all that you see. But now The Wall Street Journal has published an opinion piece that gives a . . . wait for it . . . non-contemptuous dismissal! How’s that for gaining acceptance!
The headline is,
Nobody Ever Got Younger, but it May Be Worth a Try
The physician who wrote the piece thinks the anti-aging movement makes older people more health-conscious, and that’s a good thing—even though he claims that the idea of defeating aging is “absurd.”
But the full sentence walks it back ever so slightly:
As a physician-scientist, I could dismiss the antiaging trend as absurd.
Not as a scientist he couldn’t. And the headline tells the story:
Nobody Ever Got Younger . . .
A scientist would recognize that as a half-truth and a smear. Mice have gotten younger, monkeys have gotten younger. In the below, the bolding is mine.
In a recent study published in Cell, researchers from the Chinese Academy of Sciences and Capital Medical University introduced a new type of human stem cell called senescence-resistant mesenchymal progenitor cells (SRCs) by reprogramming the genetic pathways associated with longevity. These cells, which resist aging and stress without developing tumors, were tested on elderly crab-eating macaques [monkeys], which share physiological similarities with humans in their 60s and 70s.
The research team conducted a 44-week experiment on these macaques. The macaques received biweekly intravenous injections of SRCs, with a dosage of 2×106 cells per kilogram of body weight. The researchers found no adverse effects among the macaques. Detailed assessments confirmed that the transplanted cells did not cause tissue damage or tumors.
The researchers discovered that SRCs triggered a multi-system rejuvenation, reversing key markers of aging across 10 major physiological systems and 61 different tissue types. The treated macaques exhibited improved cognitive function, and tissue analyses indicated a reduction in age-related degenerative conditions such as brain atrophy, osteoporosis, fibrosis, and lipid buildup.
At the cellular level, SRCs decreased the number of senescent cells, reduced inflammation, and increased progenitor cell populations in neural and reproductive tissues. They even stimulated sperm production. At the molecular level, SRCs enhanced genomic stability, improved responses to oxidative stress, and restored protein balance. More than 50% of the examined tissues showed a reversal of aging-related gene expression profiles to a younger state. Single-cell analyses revealed significant reversals in gene expression among peripheral blood cells (33%), the hippocampus (42%), and ovarian tissue (45%). Machine learning-based aging clocks estimated that the biological age of immature neurons was reversed by six-seven years, and that of oocytes by five years.
[Is that monkey years or human equivalent?–HB]
Furthermore, the researchers found that tiny particles called exosomes, released by the SRCs, were the key agents of rejuvenation. These exosomes suppressed chronic inflammation while preserving genomic and epigenomic integrity. When isolated SRC exosomes were administered to aged mice, they significantly reduced organ degeneration. In vitro studies demonstrated that these exosomes could rejuvenate various human cell types, including neurons, ovarian, and liver cells. This discovery suggests that exosome signaling could be a fundamental pathway for reversing aging. [June 23, 2025, link]
But I’ll rest my case with the much older and more replicated mouse studies. Having learned just recently that sliding away from topics is the chief means of resisting persuasion, I’d ask the WSJ guest author (and skeptics among HBLers) to face squarely one question:
Is it conceivable that mice can be made young again but human beings can’t be?
Hint: the answer is no. Aging is not some species-specific condition. Aging crosses all animal boundaries. Not every animal species ages, but every class, order, phylum, and sub-phylum of animals do. That’s the very thing that makes people skeptical about stopping it, let alone reversing it.
Now, maybe the mice experiments aren’t valid. But it is just “absurd” to think that fellow mammals, mice, can be rejuvenated but human beings can’t be. That position would be on a par with holding in the early 50s, sure the heredity of mice is governed by a DNA double helix, but how do we know human heredity operates that way?
The best argument against the mice studies is that some (all?) of them work with artificially aged mice and then restore them to, approximately, where they would have been had they not been artificially aged. That could be likened to giving the mice a disease and then curing it.
I don’t know if this is a fair characterization of many or all mouse rejuvenation studies. It seems unlikely because these studies were carried out at top-level universities, like Harvard (and no, not just David Sinclair’s lab—also George Church’s lab).
Here’s my exchange with AI agent “Claude”:
HB: How many studies on mice have shown rejuvenation?
I don’t have a precise count of all rejuvenation studies in mice, as this is an active and rapidly growing field of research. However, I can tell you that there have been dozens of significant studies demonstrating various forms of rejuvenation in mice, particularly in recent years.
Partial cellular reprogramming – Studies using Yamanaka factors (Oct4, Sox2, Klf4, c-Myc) to reverse aging markers in tissues like the retina, muscle, and brain
Senescent cell removal (senolytics) – Multiple studies showing that clearing senescent cells extends healthspan and lifespan in mice
Heterochronic parabiosis – Research where young and old mice share circulation, showing rejuvenation of various tissues in old mice
NAD+ precursors, Blood plasma factors – Research identifying rejuvenating factors in young blood and inhibitory factors in old blood
Epigenetic reprogramming – Studies reversing the epigenetic clock and restoring youthful function
The number continues to grow as the field advances. Would you like me to search for more current statistics on the total number of such studies, or information about specific types of rejuvenation research?