I thought I would start out with a topic that falls within my wheelhouse. I study stem cells, and everyday I work on developing a strategy to make stem cell therapies work better in the elderly (more on that in a future post). Research on stem cells has been a hot topic and a source of much controversy ever since the first human embryonic stem cells were isolated and grown in a laboratory at University of Wisconsin nearly 20 years ago. Recently, two things got me concerned about how much the public understands about stem cells and stem cell research. First, during an informal poll of people in the San Antonio community, where I live an work, two-thirds of respondents stated that fetal tissue is necessary for stem cell research. Second, a number of groups have been using the recent Planned Parenthood controversy to rally opposition to embryonic stem cell research. These groups have been making this connection by saying that aborted fetal tissue being sold for research purposes could be used for embryonic stem cell research. The first reason why these statements trouble me, is that embryonic stem cells do not come from fetuses. They come from the blastocyst stage of development (4-5 days post-fertilization). The controversy over embryonic stem cell research is understandable, as anyone that believes that life begins at fertilization would view the blastocyst (a little ball of about 100 cells roughly .1mm in diameter) as a human life that we are ending. However, these statements about stem cell research reflect a fundamental misunderstanding of what the controversy is all about and what stem cells really are.
I like to think about stem cells like my favorite game on the price is right. That is, of course, Plinko. While the washer is still in the contestants hand, it is like an embryonic stem cell. It can go anywhere. It can become anything. As time goes on, the washer commits to a path. When the washer is halfway down the board it is like an adult stem cell, and its location on the board (left to right) is like its location in the body. If the washer is all the way on the right side of the board, it is unlikely that it will end on the left side. Similarly, if we get a stem cell from the bone marrow, it would be very difficult to make it turn into a brain cell. The opposite is also true. Now you understand the fundamental differences between embryonic stem cells and adult stem cells. The first difference is where they come from. Embryonic stem cells come from the blastocyst stage of the embryo. Adult stem cells come from a developed tissue (they can be found in children and adults). Where we get the cells is important, because adult stem cells have nothing to do with the debate over whether embryonic stem cell research morally acceptable. It is important that we all understand this distinction and know that adult stem cells can be found in virtually every tissue in our body and that no life is being ended by isolating or studying adult stem cells. The second difference is what they can do. In stem cell research we call this their potential. Think back to the plinko game. When the washer is in the contestants hand it could land in any slot at the bottom of the board. This tells us that an embryonic stem cell can turn into any type of cell in the body. As the washer falls down the board, we have a better idea of where it will end up. This means that when we isolate adult stem cells they can only turn into certain types of cells.
Armed with that information, we can think logically about the advantages and disadvantages of each type of cell. The major advantage of adult stem cells is availability. We all have lots of them. The major disadvantage is that they cannot turn into every type of cell, and it is much easier to get stem cells from your fat, than it would be from your brain, for instance. Therefore, we only have ease of availability of certain types of adult stem cells. The major advantages of embryonic stem cells are their potential to form any type of cell, and the idea that we can learn about developmental disorders from them. If we can understand how to manipulate an embryonic stem cell, we may be able to learn how to prevent some developmental disorders. The major disadvantage of embryonic stem cells is that we have to produce an embryo in order to isolate them.
Whether, or not, you support embryonic stem cell research is your own decision, but I hope that you can make that decision armed with facts, and a basic understanding of where stem cells come from, and what we can do with them. Leave any questions that you have in the comment section, and I will address them with a future post.