I have searched the net and I have not been able to come up with an clear answer.

Edit: Here is the para quoted from Nature http://www.nature.com/news/medical-research-cell-division-1.13273 "So began WI-38, a strain of cells that has arguably helped to save more lives than any other created by researchers. Many of the experimental cell lines available at that time, such as the famous HeLa line, had been grown from cancers or were otherwise genetically abnormal. *WI-38 cells became the first 'normal' human cells available in virtually unlimited quantities to scientists and to industry and, as a result, have become the most extensively described and studied normal human cells available to this day".*

  • $\begingroup$ I essentially answered this here, pointing out that telomerase negates the supposed "limit," which stem cells and cancers usually express. $\endgroup$ – Amory Sep 19 '13 at 16:43
  • $\begingroup$ @ Amory - I doubt if your comment is relevant here. WI-38 is considered to be a 'normal human cell' line. I could not find it described as a stem cell. So where does the telomerase come from? The question is a genuine one and I am looking for a serious answer or comment. $\endgroup$ – Ram Manohar M Sep 19 '13 at 17:16
  • $\begingroup$ Did some digging, are you sure they actually do? ATCC seems to disagree $\endgroup$ – Amory Sep 19 '13 at 17:35
  • $\begingroup$ From your own article: "...they so reliably stop replicating after about 50 divisions..." $\endgroup$ – Amory Sep 19 '13 at 17:42
  • $\begingroup$ Yes but the original cell line is still there and is commercially available. I just want to know how they keep it going. $\endgroup$ – Ram Manohar M Sep 19 '13 at 17:48

The answer is that the majority of the cells were frozen from very early in their Hayflick lifetimes e.g. after 9 population doublings. They have been thawed out judiciously and only as needed thus preserving a lot of frozen stocks. When an ampule of cells frozen at, for instance 9 population doubling, is thawed, the cells pick up where they left off and still have 41 doubling a to go. So the magic of exponential growth combined with the fact that they keep dividing after being thawed has made for a decades- long supply . Does this answer the question to your satisfaction?

  • $\begingroup$ Is this Meredith Wadman of Nature? $\endgroup$ – Ram Manohar M Sep 21 '13 at 11:23

WI-38 are the cell lines which led to the proposal of the Hayflick limit and are the classic example of cells which will only divide ~40 times. they are not exempt - they are the example that proved the rule.

Lots of cell lines are commonly available, but have to recultivated regularly from animal/tissue source. If they can be frozen, then the extraction of new cells doesn't happen so often without exceeding the limit of divisions. This allows the cell lines to be used widely for experiments despite the limitations on their division in culture.

Other cell lines like HeLa and other tumor cells or Stem Cells can, under the proper conditions, divide without limit and are easier to culture in large volumes, but are often inappropriate for a given research project.


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