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'When I go down in flames, I'm going to have a very important company'


The cells have a memory!
Leonard Hayflick Scientist
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Also during this period of time, as I mentioned earlier in my description of how you preserve cells in liquid nitrogen or in super cold conditions... during the period that we were writing our paper, I had described and derived 25 cell populations. 25 different so-called diploid, which means the normal number of chromosomes... the term diploid means, in the case of humans, 46 chromosomes. And I may use that term frequently. That the cells can be preserved in liquid nitrogen.

In the early days during the time the paper was written, we had... liquid nitrogen storage was not known in cell culture and we stored our cultures in a deepfreeze, in a... well, later... later in a CO2 freezer. But when the paper was being written, our cell strains were stored in an electrically-driven deep freeze with a temperature near that of dry ice, -7 degrees Celsius. So, during the writing of the paper, that freezer failed and all of the cultures described in my original paper published in 1961 were dead by the time the paper was published.

During that... when I was informed of the failure, of course, it was very disturbing and I simply started to make another cell strain which, by that time, was an easy proposition. I knew very well how to do it, access to human embryonic tissue was still easy and I'll return to that issue in a moment. But the reason I mention this is that during the time these cells were frozen before we lost them in the freezer failure, we had withdrawn ampoules of cells at various population doublings.

Just to make it simple, if you took an ampoule of cells at the twentieth population doubling that was frozen, reconstituted them in a culture vessel and then continued to subculture them as usual as they divided, you learned that the cells had a memory. They remembered at what population doubling, in this case let's say 20, and they would go on to undergo 30 more doublings. If you reconstituted one at the tenth doubling, it would have 40 left. If you reconstituted one at the fortieth, it would have ten left. Well, that was an amazing observation and the only way I could account for that is to argue that the cells had a memory, they had a mechanism for counting the number of population doublings. That seemed really bizarre but, nonetheless, you had to consider it and I did and this is a substantial part of one of my original papers.

Leonard Hayflick (b. 1928), the recipient of several research prizes and awards, including the 1991 Sandoz Prize for Gerontological Research, is known for his research in cell biology, virus vaccine development, and mycoplasmology. He also has studied the ageing process for more than thirty years. Hayflick is known for discovering that human cells divide for a limited number of times in vitro (refuting the contention by Alexis Carrel that normal body cells are immortal), which is known as the Hayflick limit, as well as developing the first normal human diploid cell strains for studies on human ageing and for research use throughout the world. He also made the first oral polio vaccine produced in a continuously propogated cell strain - work which contributed to significant virus vaccine development.

Listeners: Christopher Sykes

Christopher Sykes is a London-based television producer and director who has made a number of documentary films for BBC TV, Channel 4 and PBS.

Tags: liquid nitrogen, diploid cell population, freezer, subculture, memory, counting

Duration: 3 minutes, 37 seconds

Date story recorded: July 2011

Date story went live: 08 August 2012