Stem Cells Essay

Stem cells are found in multicellular organisms that divide using mitosis. Stem cells differentiate into specialized cell types and can produce more stem cells. Two types of stem cells exist in mammals, embryonic and adult stem cells. Embryonic stem cells are isolated in the inner cell mass of a blastocyst, the early stage of an embryo. Not all stem cells are equal. Some stem cells are called totipotent, which means they have the ability to replicate into more stem cells. Other stem cells are called pluripotent, meaning they have the ability to develop into many different cell types.

Embryonic stem cells, or ES cells, undergo mitosis and form specialized cells from these newly formed cells. ES cells can be found in either the inner cell mass of a blastocyst or in umbilical cord blood. Embryonic stem cells can develop into each of the 220 different cell types found in the adult body. ES cells do not require long hours of studying and research to harvest. A simple pipet inserted inside the blastocyst, can retrieve most of the embryonic stem cells. These stem cells can then be grown in a cell culture with a proper laboratory setting. If kept in the proper settings, the ES cells can continue to multiply and develop. Because ES cells can continue to divide into more ES cells, scientist can seed plates with a few starting ES cells and harvest an unlimited number of undifferentiated, pluripotent stem cells. These cells are then frozen and distributed to researchers to study them. These lab-grown stem cells can also be separated once more into separate plates and in time they each plate will contain a specialized group of cells. For example, four plates are made each from the same embryonic stem cell group. Over a period of time, each plate will have a specialized group of cells, such as bone cells, muscle cells, nerve cells, and pancreatic cells.

Transplanting ES cells into a patient can be difficult. The genetic background of the ES cells grown in the lab is different from the patient. Therefore, the organs and tissues that will be grown by them will also be genetically different from the patient, and this can lead to the rejection of the transplanted tissues. But a new technique, somatic cell nuclear transfusion, may solve this problem. Somatic cell nuclear transfer (SCNT) may be the solution. In this process, the nucleus of a donated egg is removed and the nucleus of a skin cell from the patient is transplanted into the enucleated egg. This causes the genetic material of the patient to be transferred to a host cell. The egg goes into activation and turns into an embryo. The egg now undergoes the same process that a fertile egg would. Once the egg reaches the blastocyst stage, the inner mass of embryonic stem cells can be removed. These ES cells now have the same genetic makeup as the patient who requires therapy. They can be grown on cell cultures and then transplanted to the patient. One potential research benefit from ES cells

...