Some people think that these cells are a new specie, a specie that lives in laboratories. These cells go from culture plates to culture plates at the minimal distraction. If someday the scientific want to erase all of them, it will be very difficult because a lot of other "cell cultures" are really HeLa. There are some examples of "transmissible cancer" that does something similar in the wild, in animals instead of culture plates. The cells in these tumors are more related to the cells in other tumors of the some kind, that to the cell in the actual animal host. Examples:
* Tasmanian Devil: http://en.wikipedia.org/wiki/Devil_facial_tumour_disease
* Dogs: http://en.wikipedia.org/wiki/Canine_transmissible_venereal_t...
So these cells are different, but most of their molecules are exactly like the molecules of a normal person. So they are useful to study most of the properties of humans cells.
Owing to the increased rate of cell division of immortalized cells grown in laboratory culture dishes versus those found within a living organism, the additional stresses that these cells face in an in vitro environment, and the many thousands of cell generations these cells have undergone since their derivation (in the many hundreds of laboratories that are growing some strain of these cells), the number of mutations introduced into HeLa cellular DNA makes it such that these cells are now very, very different than the original ones isolated from Henrietta Lacks.
Most organ donors would, then, still be alive. That would raise some interesting questions regarding inherited fortunes.
I would say yeah - a couple more :)
But according to wikipedia and [1] there are "only" 20 tons. (I think that the exact number is difficult to calculate, so 50 tons is perhaps a razonable number too.)
Still 20 tons (~ 40000 pounds) is much bigger than 50 or 100 Kg (~100 or200 pound) that is the weight of a person.
[1] http://hamptonroads.com/2010/05/cancer-cells-killed-her-then...