Editor's Note: This article is a modified version of one originally posted on the Knoepfler Lab Stem Cell Blog.
The year's #1 most important science story occurred in a field which happens to be my area of expertise: Stem cells.
For the first time ever, the world witnessed successful human therapeutic cloning, or to be more precise “somatic cell nuclear transfer (SCNT)-based human therapeutic cloning.” This cloning approach generated apparently genetically normal human embryonic stem cells (hESC) without using a frozen in vitro fertilization (IVF) produced embryo.
To be clear, there are two kinds of human cloning: therapeutic and reproductive. The latter is making an actual new person with an identical genome to an existing person. The latter has never been achieved, but some of us are worried it is coming sooner than most imagine. The former is the kind of cloning that was the big event this year in the stem cell field. Confused between the two types of cloning? See the image below that clearly explains the two different, but related, kinds of cloning, adapted from my new book on stem cells: Stem Cells: An Insider’s Guide.
Shoukhrat Mitalipov at Oregon Health Sciences Universities (OHSU) published a paper in the journal Cell reporting the first ever human therapeutic cloning that made hESC. The paper got a lot of scientists very excited, but it also generated a great deal of controversy because of several instances of data duplication and the incredibly short review period of just a few days. Dr. Mitalipov, whom I had the chance to meet and talk with at the recent World Stem Cell Summit, calls the hESCs made by therapeutic cloning NT-hESC.
For me, human therapeutic cloning is the science event of the year because it has such powerful implications at a global level.
On the one hand, NT-hESC present an alternative to induced pluripotent stem (iPS) cells as a basis for personalized medicine. In principle, any sick patient could have NT-hESC made from them and then used as a basis to produce specific differentiated cells that when given back should be accepted by the body as “self.” There is huge positive potential there and reason for hope. Sure, iPS cells are incredibly powerful (more on those here), but having more stem cell “weapons” against disease is definitely a good thing.
On the other hand, I believe that therapeutic cloning opens the door to eventual human reproductive cloning, which I strongly oppose. It’s an unintentional consequence, as Mitalipov told me earlier this year, because he is also opposed to human reproductive cloning. However, that doesn’t mean that some rogue group will not try to clone a person. In fact, I think it will happen in the next 5-10 years. Some people also believe that therapeutic cloning itself is unethical because it creates a human embryo in the lab for the purpose of using it to make hESC or because it creates an unnatural embryo since it combines the egg from a woman with the nucleus from some other person’s cell.
All of these implications, both positive and negative, easily make therapeutic cloning the science story of the year.