Wet Lab. Cellular Replacement Therapy And Stem Cell Research Essay

Wet Lab. Cellular Replacement Therapy And Stem Cell Research - Essay Example When embryonic mouse stem cells were isolated more than 25 years ago, the significance of the discovery was soon realized. (Keller, 2005) there are many researchers and hold out hope for cellular replacement therapy arising from stem cell research. Specifically, embryonic stem cells, also known as ES - pluripotent cells are of great concern. They exhibit the potential to differentiate into a variety of final tissue types when they reach their ultimate, fully matured state. Embryonic stem cell lines are usually derived from a blastocyst, or in some cases an earlier stage of embryonic development. The 150 cells which at most comprise the blastocyst are able to differentiate into all types of body tissues. (Stem Cell Information, 2009) Most immediately, a pluripotent stem cell will give rise to the primary germ layers: ectoderm, mesoderm, and endoderm. From these layers, other cells and tissues differentiate but ultimately give rise to all internal organs of the future organism. (Schole r, 2007) Other types of stem cells, further in development also have uses in research and therapy; multipotent stem cells have some flexibility, but usually only within a closely related family of cells, such as cardiac tissue, blood cells. Furthermore, the cells can become Unipotent cells - which are not themselves per se, because they can only produce new cells of the exact same type. On the other end of the spectrum, are totipotent stem cells, these are fertilized zygotes which have the potential to grow into an entire individual, an embryonic stem cell from a blastocyst does not qualify.(Scholer, 2007) Cells can also be classified in terms of progenitor or precursor. Precursors exhibit recognizable traits of the function type they will become, while Progenitors are not outwardly committed to a cell type. (Rabbany et al. 2003) An extensive variety of proteins are responsible for differentiation of which much more research is needed. We are only now discovering the functions of re gulatory operators such as Shp2, or transforming growth factor-?, that aids in the expression of chorionic gonadotropin.(Burnham Institute, 2009), (Keller, 2005) A well-studied pathway is the process of hematopoiesis, by which stem cells give rise to various types of blood cells. (Mackey, 2001) There are essentially two branches to the hematopoietic differentiation process: the lineage beginning with a myeloid progenitor, and the lineage stemming from the common lymphoid progenitor. (Parslow et al. 1997) The lymphoid progenitor arises from the multi-potential Hemocytoblast. The lymphoid progenitor differentiates into what are described as T cells. Differentiation is possible into the natural killer cells, CD4 and CD8 types, known as large granular lymphocytes, from which no further cell lines arise. But the lymphoid progenitor can also become the small lymphocyte. This stem cell has the potential to become a T-lymphocyte helper cell, or a B lymphocyte, which can further differentiat e into plasma cells from which antibodies are produced. (Leishman et al. 2001), (Obeyesekere et al. 2004) But the hemocytoblast from which these types arise produces more cell types along the myeloid lineage. The myeloid progenitor can differentiate into four other cell lines; erythrocytes – otherwise known as oxygen-carrying red blood cells. Immature erythrocytes can be identified by the presence of a nucleus, since they are similar in size and shape to mature erythrocytes – but a nucleus is ejected from the cell upon reaching full differentiation. (Ownby, 2002) Another differentiation event results in mast cells, whose release of histamine and heparin is responsible for many allergic reactions including anaphylaxis. Myeloid progenitors can also