If only humans could master regeneration. It seems like that would open the door to far better health. Maybe to longer life too. We can see how many other creatures innately can regenerate organs.
I can see it in the lizards that run around in my garden. Every now and then I see one with a stubby tail with a bit of new tail growing out the end. Maybe a raccoon got it by the tail and nearly made a meal of it, the tail popped off, and a new tail started growing there. If a bird eats a lizard’s entire foot, it can regrow a version of a new one. Some species can regrow most of their body from just a fragment that remains.
We humans can’t do that at all. The best regenerative organ we have may be the liver but not much else if you’re talking about replacing a large part of a lost organ. Our ability to maintain (and in a sense regenerate) tissues that turn over rapidly like gut, blood, and skin suggests the programming is still there and maybe could be directed in a new way.
Part of the reason for our highly limited regeneration may be that we have evolved a trade-off in a lower risk of cancer. Even so, it makes sense to keep trying to get better at regeneration including through research and everyday things. As to the latter, some folks will try almost anything on this front from supplements to fasting. However, that link between regeneration and cancer keeps popping up.
We’ll start there.
Regeneration is tricky for people, animals have many strategies
- The surprising cause of fasting’s regenerative powers, Nature. Fasting can potentially boost regeneration but also promote cancer. Here’s the article subtitle: “Post-fast feasting helps to activate stem cells in the gut but can also prompt development of precancerous growths, mouse research shows.” Does this happen in people too? There has been some evidence that fasting alone might boost levels of some types of stem cells too.
- Hallmarks of regeneration, Cell Stem Cell. The abstract is notable for using the word “heroic” to describe regeneration: “Regeneration is a heroic biological process that restores tissue architecture and function in the face of day-to-day cell loss or the aftershock of injury. Capacities and mechanisms for regeneration can vary widely among species, organs, and injury contexts. Here, we describe “hallmarks” of regeneration found in diverse settings of the animal kingdom, including activation of a cell source, initiation of regenerative programs in the source, interplay with supporting cell types, and control of tissue size and function. We discuss these hallmarks with an eye toward major challenges and applications of regenerative biology.” One of the more interesting aspects of this view is the point that different species sometimes use quite distinct mechanisms for regeneration. I always thought it was said that we humans cannot form blastema, the structures that appear necessary for limb regeneration.
Leonard Hayflick dies
Dr. Leonard Hayflick just recently passed away from cancer. Here’s an obituary: Leonard Hayflick, Who Discovered Why No One Lives Forever, Dies at 96, NYT. The Hayflick Limit on cells defined cellular mortality concretely. I hope to have more on Dr. Hayflick from one or more of those who knew him best.
More reads
- Genetically engineered hypoimmunogenic cell therapy, Nat Rev BioEng.
- The formation and maintenance of peri-implant fibrosis requires skeletal cells expressing the leptin receptor, Nat Bio Engin.
- What to Know about Project 2025’s Dangers to Science, SciAm.
- Heman Bekele Is TIME’s 2024 Kid of the Year, Time.
- Whistleblowing in science: this physician faced ostracization after standing up to pharma, Nature. This piece about physician-scientist Nancy Olivieri is an important read but discouraging about “the system.”
Dear Paul:
Thanks for your notice of the death of Len Hayflick. I sent this message to the NYT correction desk after reading the news report you referenced:
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Dear Editor:
I wish to provide a correction for the August 19, NYT report “Leonard Hayflick, Who Discovered Why No One Lives Forever, Dies at 96.” However, being a scientific refinement of Hayflick’s important discovery, this correction may seem of little significance or consequence to editors.
I have investigated the basis for the world-renown “Hayflick limit” for most of my scientific career. In 2018, when my company, Asymmetrex® LLC, was developing its first report of the first-ever method for routinely quantifying therapeutic tissue stem cells (attached), I contacted Hayflick to ask if any of his original datasets were available for inclusion in our seminal analyses. Since our new method for determining the first differential stem cell counts is based on his discovery of the Hayflick limit, I thought it would be very cool to include him in our first report in this manner. Unfortunately, he no longer had the original datasets of interest that were required for our method. So, we ended up citing and repeating his essential work with WI-38 cells for our report.
Hayflick was quite engaging and encouraging in that conversation. He completely understood the basis for our method; and he said we were among the very few who did not misunderstand his discovery. The Hayflick limit may provide imagined insights into human aging. However, what most scientists still do not understand at all is that it simply represents the continuation in culture of the normal cell kinetics of tissue cells in the body, with little to do with aging at all..
Sincerely,
James L. Sherley, M.D., Ph.D.
President and CEO
Asymmetrex® LLC
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Kind regards,
James @ Asymmetrex®