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Determining cell karyology


A surprising observation: older cell cultures stop growing
Leonard Hayflick Scientist
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So records were kept, as I indicated, of this particular event and a few weeks later, the same event occurred in another culture. I don't recall the precise number of cultures in which this event of... this event occurred. And the event was that the cells looked bigger. There were many fewer mitotic figures, that is fewer cells were dividing. And as the weeks went by in those particular cultures, there was no division occurring at all. But the cells didn't die, they continued to metabolise. That's an important observation. And we knew that because the media in which cells are generally grown contained a pH indicator. And neutral pH, which is their favourite pH condition, produces a colour that's rosy red and when they're metabolising, that neutral media becomes acidic and the culture turns orange and then yellow. And although the cells in these cultures that weren't dividing seemed to be metabolising because the media turned yellow, we had to change the media every week or two now, although we couldn't subculture them because they weren't dividing any longer, the... it was apparent to us that they were not dead, just sitting there metabolising.

I can't recall with accuracy the number of times we saw that... those events in... in cultures from individual embryos, but the number got increasingly greater and looking at my records, I then realised an important point and that was that the cultures that had stopped dividing – let's say from three or four of the 20 that were in the incubator – were the oldest ones. That is they were ones that were derived from embryos received about ten months or so roughly prior to this event. The other ones, received a week ago, a month ago, three months ago, were happy and it's important to say that the same technician was culturing these weekly, or semi-weekly and the same pool of glassware obtained from our storage area was used, so... and the same pool of culture media. So it became obvious that there was something about a cell culture that was older producing this effect.

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: cell culture, mitotic figure, cell metabolism, pH indicator

Duration: 3 minutes, 16 seconds

Date story recorded/uploaded: 15 May 2012

Date story went live: 08 August 2012