Imagine if scientists found a way to cure diseases such as diabetes, cancer, and Alzheimer’s. As it turns out, scientists have found a way that may be able to solve many of our medical problems. This method is known as stem cell therapy. Stem cells are cells that have not yet been specialized into a certain cell type. This means that scientists can stimulate them so they differentiate into any type of cell. By doing this, doctors can use stem cells to replace defective cell tissue. Embryonic stem cells are very popular and are obtained by destroying embryos human embryos. Because of this, many people believe that embryonic stem cell research should be discontinued. They suggest that alternate sources of stem cells should be utilized and pursued. Embryonic stem cell research should not be eliminated because embryonic stem cells are more viable than stem cells from other sources. This paper will compare the viability of embryonic stem cells to other types of stem cells by comparing their accessibility, pluripotency, and stability. Unlike most types of stem cells, embryonic stem cells are very accessible. These types of stem cells can be retrieved from “the inner cell mass (ICM) of mammalian blastocysts” (Ma). This inner cell mass is what eventually becomes the embryo. Because these stem cells are retrieved from embryos and the inner cell mass, and the large number of abortions per year, it is very easy for researchers get more of them. Also, unlike other types of stem cells, embryonic stem cells can be replicated indefinitely. This means that existing embryonic stem cells can be utilized to grow more of these stem cells for research. The most popular alternative sources of stem cells are from cord blood and bone marrow (Thompson). Stem cells from these two sources are known as tissue stem cells. Unlike embryonic stem cells, tissue stem cells are very difficult to isolate (Stem Cell Basics). This means it is difficult for researchers to remove these stem cells for research. Also, unlike embryonic stem cells, tissue stem cells are not able to be replicated easily. The high accessibility of embryonic stem cells and the fact that they can self-replicate indefinitely are very important for stem cell research. This quality makes it easy for researchers to form large masses, such as organs for transplantation. Another reason the high accessibility of embryonic stem cells is because they give researchers the opportunity to pursue drug testing more easily. These researchers have an unlimited source to different types of cells to allow for controlled, safe drug testing (Stem Cell Research). Embryonic stem cell research should also be continued because embryonic stem cells are pluripotent. Potency is the ability for a stem cell to be stimulated into various types of cells. “Embryonic stem cells can become all cell types of the body because they are pluripotent” (Stem Cell Basics). They can be stimulated to become cells such as liver cells, neurons, and heart cells. Because embryonic stem cells are pluripotent, they are more useful than tissue stem cells. Unlike embryonic stem cells, tissue stem cells are multipotent; they can only be used for a select few things. The pluripotency of embryonic stem cells is very significant. Because they can be differentiated into any type of human body cell, they can be used for almost any type of transplant or therapy necessary. Embryonic stem cells can be differentiated into liver cells to replace a person’s failing liver, if necessary. These stem cells can even be differentiated into cells with defects (Stem Cell Research). This aspect is most significant and useful for researchers doing studies and experiments on drugs. This quality of embryonic stem cells “will help us understand inherited diseases by allowing us to study human cells bearing the exact genetic defects that cause disease in patients” (Stem Cell Research). With this, researchers have a safe way of testing the effects of certain drugs on cells that cause diseases such as cancer without harming any humans. This can be done for other types of diseases, such as HIV, diabetes, or Parkinson’s disease. Embryonic stem cells are also more viable than other types of stem cells because they are more stable. The genetic modification of human embryonic stem cells is very stable and less likely to fail than the genetic modification of other types of stem cells. Since the genetic modification of embryonic stem cells is less likely to fail, these stem cells are a better option for research. These stem cells are able to prevent DNA errors in a variety of ways. This is possible because embryonic stem cells “are hypersensitive to DNA damage and readily undergo either apoptosis or differentiation, thus removing damaged cells from the pluripotent pool” (Giachino). Another way embryonic stem cells are stable is that the differences among them are insignificant. Embryonic stem cells retrieved from different embryos are generally identical. This makes it even easier for researchers to collect these stem cells since they do not have to worry about where they came from exactly. This is not the case for bone marrow stem cells, also known as mesenchymal stem cells (Bentivegna). In mesenchymal stem cells “transient clonal aneuploidies have been detected” (Bentivegna). An aneuploidy is very dangerous because this is the case when a cell has too few or too many chromosomes. One reason embryonic stem cells have these qualities is due to chromatin modifications within these cells. It has been found that a histone, known as H2A.Z “is highly enriched at promoters and enhancers and is required for both efficient self-renewal and differentiation of murine ESCs” (Hu). In this study, they found that H2A.Z played a role in both activating and repressing certain genes during the self-renewal and differentiation processes. These researchers believe that H2A.Z acts “as a general facilitator that generates access for a variety of complexes, both activating and repressive” (Hu).