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Studying the transformation of normal cells into cancerous cells


Leonard Hayflick Scientist
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In the following week, if it takes a week for these daughter culture vessels to become what we call 'confluent', which means they've covered the whole floor and have stopped dividing. In the second week, you can now make four vessels and then the next week eight vessels and then 16, 32, 64, in each subsequent week. Well, if you do the math, you can easily see that within a few weeks, you're going to be overrun with bottles for which you have no real use, since most experiments don't involve thousands of bottles. What you can do with the surplus cells each week is freeze them and that's very important. You can now... there are techniques for freezing cells in a viable or living state, so that you can recover them or resurrect them months, years, decades later and that's an essential point. That's called 'cryobiology', or 'cryogenics'.

So that technology of freezing cells crept into the field actually from veterinary medicine, where the exact technique used in cell culture was lifted over from veterinary practice in circumstances of artificial insemination of cattle in the field. In fact, the preservation under cryogenic conditions is usually best done in liquid nitrogen, which is extremely cold, about -196 degrees Celsius, which is equivalent to putting your finger, if you were foolish enough to do that, into a fire. It's that cold. You get the same disastrous results. And so that technology was just beginning to enter the field about this time and it exists even to this day with very little change. You can also preserve the cells at a temperature of dry ice, which is much warmer, it's about -70 degrees Celsius. And you can also, of course, preserve them at that temperature in an electrically driven freezer. So you have those three options. Liquid nitrogen is best because there are no moving parts. You top up the liquid nitrogen every three or four weeks and you don't have to worry too much about failure, although it does happen occasionally.

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: cryogenics, cryobiology, cell culture, surplus cells, veterinary medicine, dry ice, liquid nitrogen, freezer

Duration: 2 minutes, 53 seconds

Date story recorded: July 2011

Date story went live: 08 August 2012