Archive for the 'leukemia' Category

The Difference Between Adult Stem Cells and Embryonic Stem Cells

Thursday, April 16th, 2009

This is Ken Aldrich.  I am Chairman of International Stem Cell Corporation and thought I’d talk for just a minute, or maybe a couple of minutes, about the different kinds of stem cells.  People are always asking, “What’s the difference between an adult stem cell and an embryonic stem cell?”   Let me try to make this as simple as possible.  Adult stem cells are those that are derived from the human body any time after the first, probably, week or two of development of the fetus in the womb. So, cells that come from cord blood, or cells that come from embryonic tissue as well as cells that come from an adult human being are all categorized as adult cells and as a result they can become certain types of cells in the body and can be changed into certain other kinds, but not all kinds.  That limits the range of diseases that you can possibly treat with adult cells; leukemia, for example, in some cases very well, you can’t treat diabetes and so on. 

The second broad category is what’s called pluripotent stem cells.  These are cells that can be converted into any cell in the body.  The best known example of pluripotent stem cells are embryonic stem cells which we have all heard about in the news.  These are created from a fertilized human egg and have all of the ethical issues that people debate about, but also have the ability to become any cell in the human body. 

The next category, that you haven’t heard as much about are what are called Induced Pluripotent Cells of IPS cells.  These are derived from adult tissue, but then that tissue is reprogrammed back to its primal state and you get a true pluripotent stem cell as if it were an embryonic cell.  The problem with these is that in order to get back to that state, you have to introduce what are called vectors which often are cancer causing agents and you are also involving genetic manipulation, so there is a big question as to whether the FDA will ever approve those kinds of cells for therapy.  What they are wonderful for, however, is research.  Scientists, for example, can reprogram cells from a patient who has Alzheimer’s or Parkinson’s and perhaps be able to study the development of that disease and find out exactly what goes wrong and when.  So they are very useful.

The third category is parthenogenetic stem cells.  These happen to be the ones created by our company, International Stem Cell Corporation.  We think they are the best so I will acknowledge a little bit of bias right here.  These are cells that have all the characteristics of embryonic stem cells, but they are created without using a fertilized human egg.  That has two huge advantages; one, obviously, is we take the ethical issue off of the table, the second advantage is however the genetic makeup is much simpler.  There is no sperm from the father to add to the genetic complexity.  As a result of this, we can take a single cell line, match it to the immune response system of literally hundreds of millions of people.  That leads to what we hope will be the final solution for creating a true human cell bank that anyone can tap into and get cells that match their own needs, on demand, when they need them.  Think of it like a blood bank, if you will, except that these are human cells and they are more complicated. 

That’s a quick overview.  If you are curious about more please go to our website at and if you browse around there a bit you’ll find quite a bit more to learn about stem cells and in particular about our parthenogenic stem cells. 


Thanks for listening.