As midterm election season draws near and talk of stem cells continues to heat up at the local and national level, you may find your head spinning. Stem cells, hailed a mere eight years ago as the most profound discovery of their time, have become the common circumlocution of politicians.
As a result, it's no surprise if your understanding of stem cell science has grown fuzzy. While politicians and voters argue over stem cell research, the science of stem cells is moving forward.
Here at UW-Madison, you are in the heart of stem cell country â_ the home of the very first stem cell lines. UW-Madison has played and continues to play a major role in stem cell research.
Clive Svendsen, UW-Madison professor of anatomy and neurology, along with researchers from the Medical College of Wisconsin explained the history and current direction of stem cell research, as well as their future aspirations of their work.
Unlike a regular cell that is capable of only replicating to produce more of its own kind, stem cells are capable of generating multiple cell types. Stem cells come in two forms—adult stem cells and embryonic stem cells. While adult stem cells are capable of only developing a few, very specific cell types when taken out of the human body, embryonic stem cells have the power to develop into any of more than 200 human cell types in the proper laboratory environment.
Embryonic stem cells are the descendents of a group of cells that play an important role in the early development known as the inner cell mass. Before an embryo becomes implanted in the uterus, the ICM emerges within the embryo. Like superheroes, these cells possess the ability to morph into their choice of future cell types in the embryo.
The existence of the superhero cells in human development is ephemeral; once the embryo is implanted in the uterus, the ICM cells are forced to turn in their capes and become assigned to specific cell tasks, which will eventually give rise to the human.
In the laboratory, scientists developed a way to hold ICM cells in their superhero stage forever. Using donated in-vitro fertilized eggs, James Thomson, UW-Madison professor of anatomy, became the first scientist to cut out the ICM from an embryo and successfully replicate these cells, forming what we now know as human embryonic stem cells.
With the proper chemical nudges from scientists, embryonic stem cells demonstrated their ability to regenerate a smorgasbord of cell types. The replicated ICM cells are known today as embryonic stem cell lines. These cell lines are unable to form an entire human being, but provide a wide array of cell types. Without the presence of the ICM in an embryo, the embryo is no longer able to undergo its normal development.
While stem cell research is not banned in the United States, Federal regulations in 2001 restricted government funding to only the study of the stem cells generated before the regulation was announced. However, as embryonic stem cells are immortal in the laboratory setting, scientists have had something to work with.
The government's control on embryonic stem cell research has also forced researchers to work more closely with adult stem cells, which can be extracted from bone marrow and umbilical cord blood. Because adult stem cells are difficult to grow in the lab and very limited in their ability to make different types of tissue, they currently do not offer the same level of interest as embryonic stem cells. Limitations have not deterred the stem cell scientists; rather, they have kept the ball rolling.
While researchers hope that the diverse new cell types created by stem cells will some day be used to modulate or support the damaged cells that are characteristically found in diseases such as Lou Gehrig's, Parkinson's, heart disease and osteoporosis, they anticipate that it will take a while to gain a solid understanding of how stem cells work. By making the most of the adult stem cells and government-approved embryonic stem cells available, researchers are currently working to unlock the mysteries of early human development and to study human disease and drug treatment.
The legacy of embryonic stem cells may also lie in the development of better drug treatments.
""Embryonic stem cells provide well-defined human cells, which we can then use to screen for toxic effects of drugs,"" Svendsen said. ""We can also use stem cells to create specific cells similar to humans with disease.""
Dysfunctional cells and tissues in the body cause many human diseases. In order to develop drug treatments for such diseases, researchers begin by generating faulty human cells from embryonic stem cells.
""To understand how things work, you need to break them,"" said Stephen Duncan, Medical College of Wisconsin professor of cell biology, neurobiology and anatomy.
Using newly generated human cell types derived from embryonic stem cells, Duncan's research team intentionally disrupts normal function within cells. In turn, these dysfunctional cells form bad tissues, like those present in human diseases. Once scientists match a dysfunctional tissue with that present in a human disease, they then test various drug treatments in an attempt to reverse the damage.
""Drug discovery is a huge, complicated jigsaw puzzle,"" Duncan said.
In order to better understand the complex actions of stem cells, more research is needed. Of the 60 stem cell lines that existed in the United States at the time of the federal regulation, researchers estimate that currently only 21 remain.
One way that scientists are facing this shortage is by attempting to remove the ICM from embryos without causing the embryo to halt its development.
While scientists work to maintain the embryo following ICM removal, fertility clinics around the country are discarding excess frozen embryos. Because in-vitro fertilization is a complicated technique, clinicians often overestimate the number of embryos that will be needed by a woman.
At an in-vitro fertiliztion recipient's request, embryos may be discarded. Stem cell research does not wish to generate new IVF embryos, but rather to utilize the thousands thrown out with the trash.
""Stem cell research is a long slog,"" Duncan said. ""It is like trying to play a game of chess blindfolded with your hands tied behind your back and there are cymbals crashing around you. But, if we don't do it, we'll never have cures. If we do this research, I am convinced that stem cells will play an important part in the next decades.""
