Leonard Hayflick

Leonard Hayflick (May 20, 1928 – August 1, 2024) was an American anatomist who was Professor of Anatomy at the UCSF School of Medicine, and was Professor of Medical Microbiology at Stanford University School of Medicine. He was also past president of the Gerontological Society of America and was a founding member of the council of the National Institute on Aging (NIA). The recipient of a number of research prizes and awards, including the 1991 Sandoz Prize for Gerontological Research, he studied the ageing process for more than fifty years. He is known for discovering that normal human cells divide for a limited number of times in vitro (refuting the contention by Alexis Carrel that normal body cells are immortal). This is known as the Hayflick limit. His discoveries overturned a 60-year old dogma that all cultured cells are immortal. Hayflick demonstrated that normal cells have a memory and can remember what doubling level they have reached. He demonstrated that his normal human cell strains were free from contaminating viruses. His cell strain WI-38 soon replaced primary monkey kidney cells and became the substrate for the production of most of the world's human virus vaccines. Hayflick discovered that the etiological agent of primary atypical pneumonia (also called "walking pneumonia") was not a virus as previously believed. He was the first to cultivate the causative organism called a mycoplasma, the smallest free-living organism, which Hayflick isolated on a unique culture medium that bears his name. He named the organism Mycoplasma pneumoniae.

In 1959, Hayflick developed the first inverted microscope for use in cell culture research. To this day, all inverted microscopes used in cell culture laboratories worldwide are descended from this prototype. His microscope was accessioned by the Smithsonian Institution in 2009.

Hayflick developed the first practical method for producing powdered cell culture media in 1965. This method is now used worldwide for the production of many tons of powdered media annually for use in research laboratories and commercial production facilities. The technique is not patented and Hayflick received no remuneration from this invention.

Hayflick was the author of the book, How and Why We Age, published in August 1994 by Ballantine Books, New York City and available since 1996 as a paperback. This book has been translated into nine languages and is published in Brazil, the Czech Republic, Germany, Hungary, Israel, Japan, Poland, Russia, and Spain. It was a selection of the Book of the Month Club and has sold over 50,000 copies worldwide.

Hayflick and his associates have vehemently condemned "anti-aging medicine" and criticized organizations such as the American Academy of Anti-Aging Medicine. Hayflick has written numerous articles criticizing both the feasibility and desirability of human life extension, which have provoked responses critical of his views.

Hayflick was born May 20, 1928, in Philadelphia, Pennsylvania. His parents were Nathan Hayflick and Edna (née Silver) Hayflick.

He received his Ph.D. at the University of Pennsylvania in 1956. After receiving a post-doctoral fellowship for study at the University of Texas Medical Branch in Galveston under the tutelage of the renowned cell culturist Charles M. Pomerat (1905–1964), he returned to Philadelphia, where he spent ten years as an Associate Member of the Wistar Institute and two years as an Assistant Professor of Research Medicine at the University of Pennsylvania.^{[citation needed]}

In 1968, Hayflick was appointed Professor of Medical Microbiology at the Stanford University School of Medicine, Stanford, California. Hayflick resigned from Stanford in 1976 in protest to the behavior of a few of its administrators who were later shown to have wrongly accepted the beliefs of an NIH accountant who was unable to understand the unique concept of title to a self-duplicating biological system. Hayflick sued the NIH, who later agreed that the issue was in dispute. The behavior of Stanford and the NIH was later condemned by 85 prominent biologists who viewed him as having been "exonerated" by subsequent events. In 1982 he moved to the University of Florida, Gainesville, where he became Director of the Center for Gerontological Studies and Professor of Zoology in the College of Liberal Arts and Sciences and Professor of Microbiology and Immunology in the College of Medicine.^{[citation needed]}