By William Kang
Stem cells are unspecialized cells that can develop to become many different types of cells in the body. These cells are very important because they can either renew themselves through cell division or form specialized cells such as brain cells. In many organs, stem cells regularly divide to repair/replace damaged tissue. Because of their regenerative abilities, stem cells can help find cures for many illnesses, help develop regenerative medicines, and test drugs for safety.
There are three types of stem cells: embryonic stem cells, somatic (or adult) stem cells, and perinatal stem cells. Somatic stem cells can be altered to behave like embryonic stem cells. These altered cells are called induced pluripotent stem cells. Embryonic stem cells are cells that come from embryos during the blastocyst stage, when the embryo has only about 150 cells. Because these cells are taken from embryos, there are many moral complications associated with using embryonic stem cells for research. Somatic stem cells are found in various parts of the body, but are much less versatile than embryonic stem cells. They are able to form some different types of cells, but much less so than embryonic stem cells. Perinatal stem cells are found in amniotic fluids and umbilical cord blood. Like embryonic stem cells, perinatal stems are able to become specialized cells. By altering the genes in somatic stem cells, scientists have been able to create induced pluripotent stem cells, which have similar properties to embryonic stem cells. However, it is unknown whether these cells will have negative effects on the human body.
In addition, human stem cells have incredible potential in drug testing. Induced pluripotent cells have been used to model many diseases (such as Parkinson’s and diabetes) and even entire organs. Using stem cells allows scientists to avoid using live animals, with better results and reproducibility. In several experiments, the human stem cell models have displayed more accurate responses to drugs than mice experiments. Another advantage to stem cell models is that they can be created to be more personalized. Drug testing on animals may not be necessarily accurate to humans and more generic models may not apply to many patients. By reprogramming cells from the patients into induced pluripotent cells, scientists can test various drugs on these cells and determine the best treatment.
Stem cells can also be used in regenerative medicine. In many organs in the body, stem cells already develop and repair damaged cells. Regenerative medicine is essentially artificially implementing this concept. To accomplish this, stem cells are grown and manipulated in a lab. These cells become specific cells such as blood cells and brain cells. Then, these cells are implanted into the person and help promote the repair of damaged cells in the body. However, while this research has great potential, there are many risks associated with it, specifically tumor formation, immune system rejection, or cells multiplying or changing inappropriately.
One of the most promising aspects of stem cell research is cancer treatment. In current cancer treatments (chemotherapy or radiation therapy), many healthy cells are killed along with cancer cells and the immune system is drastically weakened. Using stem cell transplants, the healthy cells can be replaced after chemotherapy or radiation therapy. This also allows for much higher doses of chemo/radiation therapy to ensure that more cancer cells are destroyed. These transplanted stem cells can either come from your own body or from a donor. Stem cells from your own body will not be rejected by the immune system and will not have a risk of infection. However, these transplants can still fail. Stem cells from a donor have a chance of rejection, but have some benefits as well. If these cells are not rejected by the immune system, they can attack the cancer cells (known as the graft vs cancer effect). While further research is still required before widespread implementation of stem cells, they have amazing potential in the field of cancer treatment.
What Did You Learn?
1. Why are embryonic stem cells more useful in stem cell research than somatic stem cells?
Embryonic stem cells can become a lot of different kinds of specialized cells, such as brain cells and blood cells. Somatic stem cells can also become certain cells, but it has a much more limited capability than embryonic stem cells. This also allows embryonic stem cells to have a much broader application in drug testing and stem cell transplants. Embryonic stem cells can become many more types of cells so they can test many types of drugs that somatic stem cells cannot. They can also be manipulated and transplanted to repair cells from all over the body, including the brain and the heart.
2. How are stem cells used in regenerative medicine?
Stem cells have the natural ability to develop and repair other cells in the body. Scientists implement this concept by using artificially grown stem cells to promote the same repairs in other parts of the body. This is mostly done with perinatal stem cells because they have the same ability to become specialized cells as embryonic stem cells without the moral implications of using the embryonic stem cells.