FOUNDATONAL IDEAS: Hayflick and the Immortal Cells

This series covers the development of aging research and examines the ideas of the leading voices in the aging research community around the world. Research into aging with an eye to slow or stop it was not considered to be reputable science until recently, and so the people involved in this endeavor are real pioneers in the grand human project. 

At this writing, Leonard Hayflick is still alive and employed by the University of California at San Francisco. His expertise in aging has been enhanced by his very long life; Hayflick was born in Pennsylvania in 1928. He received a Ph.D. in 1956 and over the decades, taught at Stanford, the University of Florida, the University of Texas, the Wistar Institute, and the University of California. His carrier has been storied and prolonged, and his discoveries and inventions profoundly affected the world of cellular biology.

In 1996, Hayflick published a book called How and Why We Age which is a classic of the aging research world, and in his book, he recounts how he and a fellow researcher, Paul Morehead, discovered groundbreaking pathways in the area of cell replication. The ‘Hayflick Limit’ is named after him.

But also in his book, he recounts an early experience in discovering facts about cellular aging that were thought to have been established and proven, and yet were wrong. The experience is enlightening because it demonstrates the relentless nature of real scientific research, and also demonstrates the constant possibility that humans will stumble upon great concepts and processes that can be bent to the human will.

The sciences have just as much pomp and ceremony as other academies and one need only observe the deference and celebrity bestowed upon the grandees of science to confirm this. Academic and research institutions have all manner of ‘endowments’ and ‘chairs’ and ‘fellowships’ and grand titles for the leadership. This hierarchy is made even steeper if someone wins a prestigious award, such as a Nobel Prize. The (mostly) men at the top lord their power and prestige over the other scientists, and though everyone knows this practice is not good for discovery, it proliferates because scientists are human.

Young Leonard Hayflick knew that older scientists had power over his career and opportunities and so he and young Paul Morehead tread lightly, but they were bothered by a famous experiment carried out by a French Nobel Prize winner named Alexis Carrel. Carrel was a pioneering doctor who was awarded the Nobel Prize for this work in vascular suturing, and his later work open the doorway to organ transplantation. He was a real innovator, but he was also a bit of a showman. 

 In 1912, Carrel put some cells from a chicken heart in a solution, housed them in a Pyrex bottle, and ‘fed’ the cells for the next 30+ years. The cells, it was said, had long outlived the normal lifespan of a chicken and therefore were not only theoretically immortal, but they also proved where aging occurred, which was in the body, not in the cells. In other words, if cells could live indefinitely outside the body, aging didn’t occur at the cellular level. These cells became famous and were reported year after year in newspaper accounts. 

Hayflick and Morehead were skeptical of Carrel and his chicken cells since no one had been able to replicate this famous experiment. They delicately set out to disprove the immortal nature of these cells.

Over time, they did, in fact, prove that normal cells were not immortal and had real divisional limits because the caps of the cells, called telomeres, become shorter with each cell replication, and then eventually, the cells can’t successfully renew themselves. Successful cell division is typically limited to around 50 cycles before they become dysfunctional and should be recycled by the body. The exception to this rule is cancer cells that really are functionally immortal and replicate without limits or purpose. Tumors are, in a sense, cells that have passed the Hayflick Limit. Hayflick and Morehead went a long way to establishing which cells were mortal and which weren’t, and they pioneered many kinds of cancer therapies. 

Regarding Carrels’ chicken cells, they were destroyed in 1946 and it is now widely thought that the nutrients fed to those cells in the Pyrex bottle were simply refreshing the cells with fresh cells. Carrel died in wartime Paris, in 1944, never having explained much about his cells. 

It should be noted that while Hayflick is considered to be a pioneer and founder of modern research into anti-aging medicine, he does not believe that aging can or even should be stopped. The entire idea of stopping the aging process is philosophical and in Hayflick’s philosophy, it should not be stopped, even if Hayflick’s scientific contributions have made it more likely.

Here is an interesting summary on Hayflick’s long term effects on science: Leonard Hayflick and the limits of ageing

About The Hayflick Limit

Leonard Hayflick

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