Okay, I’ve been searching the web for a while trying to figure out why cells from the the HeLa cell line are immortal.
Some sources say it is because they do not undergo programmed cell death. But many types of cancer cells suppress programmed cell death as far as I’m aware, and they are not all immortal.
Another reason sometimes given online is that they produce the enzyme telomerase which prevents the telomeres from shortening so much that the cells can’t divide any longer. OK cool, but many types of cancer cells produce telomerase. As far as I understand, tumors are not all immortal. Human sex cells also produce this enzyme and again, as far as I know, they are not immortal.
So what gives? Is there no answer to this, or have I just missed it?
Also, as a bonus, why aren’t the HeLa cells considered to be a different species? I read about this possibility on the Wikipedia page and it seems to make sense to me. They don’t contain the same number of chromosomes as humans, reproduce independently from a human body, et cetera.
Its because cancer cells divide indefinitely… because its cancer ?
Its out of control , its not doing the things of regular stem cells.
Normally a stem cell would
have a controlled rate production of child stem cells
have a controlled rate of production of the specialised cells
Normally stem cells produce specialised cells, which do not reproduce, and a limited number of stem cells (under some control).
Pretty much HeLA are not even like stem cells, they are like cancer… they reproduce themselves uncontrollably.
This is just like all life forms, they can reproduce themselves - Outside of Henrietta Lacks’ body, HeLa Cells are effectively a new life form, a single cell organism just like a bacteria.
Pretty much the chromosomes are abnormal …
In concept, HGF and other Hormone therapies induce cancer by making the cells reproduce too fast, and then they become defective, or otherwise the cells that respond the hormone are too often defective , and otherwise the endocrine systems go haywire
But if the reason it can divide infinitely is just due to being a cancer cell, then couldn’t any cancer cell be used for the same purpose? Why would this line be so common?
I thought it had something “special” about it.
Or are you saying the chromosomal abnormalities are what make it able to reproduce indefinitely outside of her body?
HeLa are not the only immortalized cell lines. There is also Jurkat cells from a young teen who suffered from leukemia, as another example. There are others.
Ah, yeah, I did read that they are not the only immortalized ones. Thanks for that.
Again though I do have to wonder, what makes these cells special? Can you take any old cancer cell which produces telomerase and grow it in the lab but these lines just happen to be the ones most scientists use?
Or is there something rare and different about the cells that gave rise to these immortal cell lines?
Human tissue culture/cell lines/cancer is sort of outside my area of expertise - I study flies - but I do know a few things that may be of use. First, it’s a very common technique to “immortalize” interesting cells by fusing them with a cancer cell line. The immortality phenotype isn’t all that unusual. These fused cell lines are called hybridomas, and are often used to grow specific antibodies, for instance.
As I understand it, though I could be wrong here, HeLa cells don’t have anything in particular that isn’t found in other cancer cells, it’s just that they’re on the extreme end - they’re incredibly tough, virulent, and fecund. Any lab that has HeLa cells growing alongside other cell types has to be very vigilant to make sure that HeLa cells don’t contaminate and take over the other cultures.
Changes in chromosome number and makeup are also very, very common in cancer cells. Not only are they usually aneuploid (meaning they don’t have the normal makeup of 46 chromosomes), but they have chromosome instability, meaning that the number of chromosomes varies widely from cell to cell and over time.
There are hundreds, if not thousands of immortalized cell lines, from humans and a wide variety of other organisms.
That HeLa cells are one of the most commonly used is mostly an artifact of history - they were the first human cell line ever developed and at the beginning of the cell culture era were passed around to many many laboratories. They are also very easy to culture and work with (too easy by half!). They are persistant little fuckers and have a nasty tendency to contaminate other cell lines. There are many documented cases where experimental results were found to be wrong because the researchers thought they were working with one cell line, but in reality were working with HeLa (for example: Curbing rampant cross-contamination and misidentification of cell lines.).
Personally, I HATE HeLa cells and don’t allow them in my lab (we do a lot of cell culture).