Currently, in the scientific community, there is a relatively new area of study that has caught the attention of the world. These scientists are researching a type of cell that was first discovered just over 50 years ago, stem cells. James Till and Ernest McCulloch, the "fathers of stem cell research”, discovered stem cells during an experiment with mice. They gave mice lethal amounts of radiation, and then injected them with bone marrow cells and what they found was astonishing. The more a mouse was injected with the bone marrow cells, the more likely they were to survive the radiation. Till and McCulloch were curious about why this was happening, during an autopsy of the mice lumps were found in their spleens. Under further investigation, they realized that these tumors were once the bone marrow cells, leading to discovery of stem cells. By 1961, they published a research paper proving the existence of stem cells and by 1963 they defined the two major characteristics that distinguishes stem cells from other types of cells. (3)
What are Stem Cells?
The two distinguishing characteristics of stem cells:
1. "have the capacity of self-renewal"
2. "can differentiate into more specialized cells" (3)
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What do they do naturally in our body?
Stem cells are found naturally everywhere inside of our bodies. Being unspecialized cells surrounded by specific cell types, their responsibility is to assist maintaining our body's health.
There are two different types of stem cells, embryonic and adult stem cells. Embryonic stem cells are deprived from embyros while adult stem cells can be taken after birth. Many different contributing factors help determine which type of stem cell to use.
Embryonic stem cells have a very high pluripotency, meaning they can differentiate into any cell type desired. They are also capable of continuously self-renewing in cell cultures. (6) Contreversy and immune rejection are major contributors when deciding to not use these cells. Depending on personal opinions about when life begins, some find it worthwhile, while other's believe we are stealing an innocent child's life. Immune rejection is a high probability to consider, with a probability between 60-80% reducing quality of life for the patient. (16)
Adult stem cells are starting to become more commonly used for many reasons. For instance, if a patient has cancer and is planning to undergo chemo therapy and/or radiation therapy, they have the oppertunity to collect stem cells from their bone marrow. When the time comes to be injected with stem cells, using their own will not cause immune rejection making treatment much easier. Even with avoiding immune rejection, the capabilities of the stem cells fighting the cancer is not certain. This is due to the fact that the cells were not able to control the cancer originally. (12) Adult stem cells are also believed to have limitations on differentiating, it is not verified due to lack of sufficent research. (6)