Overview of Stem Cell Research

Background and Significant

Medical research has brought the world many great improvements: cures for numerous types of illnesses, pain medication, and an infinite number of things that have changed the way people look at the scientific side of medical research. Along with remarkable breakthroughs of medical research come the cons that have derived from the practice. This includes the various usages of animals to further our scientific understanding. Medical research has the potential to be one of the greatest things that has ever happened to mankind or the worst. With every good product comes a controversial side, one such product is stem cell research. Stem cell research could be one of the biggest breakthroughs in medical history. Although proponents of this new science have boasted the potential to cure a vast number of diseases, there are moral and ethical issues that come into play.

So what exactly is Stem cell research and what does it involve? Stem cell research is the embodiment of over 20 years of continuous medical study. The inner mass of a blastocyte at about 4 days after post-coitum normally destined to form all the cells and tissues of the embryo and extraembryonic yolk sac. The first successfully stem cell lines were reported in 1981 (Evans 1981). These individuals isolated cells from a embryonic mouse blastocyte cell. A population of 20-40 mouse embryonic stem cells was obtained from a blastocyte by either invitro culture or surgical removed inner cell mass on a feeder layer of mitotically inactivated mouse embryonic fibroblasts (Evans 1981, Martin 1981).

What can we do with stem cells? The stem cells obtained are pluripotent; which means that they have the ability to differentiate into all types of cells. There are three primary cell populations from which pluripotent stem cell differentiate into: endoderm, ectoderm, and mesoderm. The endoderm is the innermost of the three primary germ layers of an animal embryo, developing into the gastrointestinal tract, the lungs, and associated structures. The ectoderm the outermost of the three primary germ layers of an embryo, from which the epidermis, nervous tissue, and, in vertebrates, sense organs develop. The mesoderm is the middle embryonic germ layer, lying between the ectoderm and the endoderm, from which connective tissue, muscle, bone, and the urogenital and circulatory systems develop. Various experiments have proven the differentiation pathway for each cell population. Another key feature of stem cells that make them interesting is their ability of self-renewal. Normally when a cell divides it loses a part of its DNA, but with stem cells that contain a high amount of telomerase allowing it to divide indefinitely without any chromosomal loss (Morrison 1996).

What is the significance of stem cells? Stem cells have many potential applications that researchers have only begun to imagine. One such application is using stem cells to repair of damaged tissue; which would allow medical science to treat a range of conditions including heart failure, spinal injuries, diabetes and Parkinson Disease (Biotechology 2005). Other applications can be a greater understanding of human development, new methods for testing new drugs, or a new technique to screen toxins within the environment.

Technical Applications

In the last 20 years, stem cell research has made great strides in medical applications. Such new techniques require an adequate source of the viable puripotent stem cells. These stem cells are derived from adult and embryonic stem cells. From each source come its advantages and disadvantages.

Adult stems cells are derived from, as the name suggests, adult cells of target species. In humans these cells are described as undifferentiated cells that occur in differentiated tissue. Adult stem cells have been identified in many organs and tissues (Mezey 2000). One disadvantage is that there are a very small number of stem cells in each tissue and stem cells are thought to reside in a specific area of each tissue where they may remain dormant for many years until they are activated by disease or tissue injury. The adult tissues reported to contain stem cells include brain, bone marrow, peripheral blood, blood vessels, skeletal muscle, skin and liver (Mezey 2000, Bjornson 1999).

Embryonic stem cells are derived extracting cells of a fertilized egg. The fertilized egg is allowed to develop for 3-4 days until a hollowed ball called the blastocyte is formed. The embryonic stem cells are extracted from the blastocyte. The first successful extraction and stable culture made from human embryonic stem cells occurred in 1998 (Thompson 1998). The advantage of using embryonic stem cells is that growth from a single cell line will develop in to a population of 300-400 cells within a short amount of time(Wobus 1999). The disadvantage