Ever since human stem cells were first isolated, research on stem cells has received much public attention, both because of its extraordinary promise and because of relevant legal and ethical issues. Stem cells are self-renewing, unspecialized cells that can give rise to multiple types all of specialized cells of the body. These cells are incredibly valuable when it comes to answering some of the most fundamental questions about life with the goal of improving health. However, many more questions have been asked, as a result of the research, on how these cells can be obtained and on the ethics of stem cell research. Two of the most common places from which hematopoietic, or blood, stem cells are taken for transplantation are bone marrow and the placenta and umbilical cord of a newly born child. There have been several successful and unsuccessful transplantations in each instance. Bone marrow transplantations have been used more frequently in the past, but recently, umbilical cord blood stem cells have proven to be easier to match and they also have a lower risk of failure (Stem Cells).
             Typically researchers place stem cells into two separate groups-embryonic stem cells and adult stem cells. The embryonic stem cell is from one of the earliest stages of the development of the embryo, called the blastocyst. Embryonic stem cells are derived from the inner cell mass of the blastocyst at a stage before it would implant in the uterine wall. The embryonic stem cell can self-replicate and is pluripotent, meaning that it can give rise to cells derived from all three germ layers. However, the use of embryonic stem cells has been considered highly unethical since the first one was isolated in 1998. The adult stem cell is an unspecialized cell that is found in a specialized tissue. These cells are capable of self-renewal for the lifetime of the organism. Sources of adult stem cells have been found in the bone marrow, blood stream,...