Scientists through their research, have discovered several ways to deal with diseases. One of the major break through is the discovery of stem cells. Stem cells are those cells that can generate all different cell types required in the body.
They can therefore be used to replace the abnormal cells or in treatment of injuries. Certain serious illnesses are targeted to be treated using this stem cell approach.They are diseases such as Parkinson's disease, cancers, immunodeficiency diseases, diabetes, arthritis and several others (Shi, Y. nd Clegg, 2008).
Stem cells can divide to produce more stem cells or to form cells that differentiate into different types of cells (Siemionow, 2006). This is the reason why it is considered a potential to the treatment of several serious illnesses. Cell division is by mitosis which produces two daughter cell of stem cells or a daughter stem cell and a daughter differentiating cell (Siemionow, 2006). Stem cells as indicated earlier, have the developmental potential, but this depends on the type of stem cell. There are three types of stem cells.
These are Totipotent stem cells, pluripotent stem cells and multipotent stem cells (Fong, 2007; Biology Pages, 2008). Tutipotent stem cells are able to differentiate to any extraembryonic cell types and any adult body cell type, that is in mammals. An example is the fertilised egg and the cells produced by its first four cleavage. These cells cannot divide to produce more Totipotent cells (Fong, 2007; Biology Pages, 2008). The other type is the Multipotent stem cell. These can only differentiate to specific types of cells.
They are always in areas where they can replace damaged or dead cells.Example of such cells are those found in the liver, brain and other adult animal organs. They are therefore adult stem cells. In some cases, these adult stem cells produce a clone of cancer cells when so many mutations occur in someone over a long period of time (Fong, 2007; Biology Pages, 2008). Pluripotent stem cells are the true stem cells. They are able to differentiate into all cell types except for the placental cells derived from the trophoblast.
There are three types of pluripotent stem cells. These are, Embryonic Germ cells, Embryonic Stem cells and Embryonic Carcinoma cells.Embryonic Stem cells can be obtained from the inner cell mass of the blastocysts. Human embryonic stem cells are obtained from the embryos produced by in vitro fertilisation (Greer, 2007; Fong, 2007; Biology Pages, 2008).
Obtaining the Embryonic stem cells from human embryos is very controversial as the embryos are destroyed. Embryonic Germ cells are obtained from aborted foetuses gonads' precursor while Embryonic Carcinoma cells are isolated from teratocarcinomas in the gonads of the foetus. EGs are aneuploid (Biology Pages, 2008).All these stem cells are used in several areas of research. In this paper, the main type of stem cell of concern is the pluripotent stem cell.
Challenges and promises of its used will be described. As had been noted earlier, these cells ability to differentiate acts as a great potential to discoveries of important treatments (Biology Pages, 2008). Promises of Pluripotent Stem Cell Research Pluripotent stem cells are seen as a great potential to treatment of so may diseases. These diseases are caused by cell damage or cell differentiation in different organs of the body.Type I diabetes mellitus is as a result of damage to the pancreatic beta cells by the autoimmune system (Lester, 2005), skeletal paralysis are due to injuries of the spinal cord, multiple sclerosis results from loss of myelin sheaths, Parkinson's disease is that disease caused due to the destruction of the brain's dopamine secreting cells, blindness is caused by cornea damage and ischemic stroke is due to the death of neurons (Biology Pages, 2008).
All these diseases can be treated if cells that can replace them can be found and ways of replacement found too.Pluripotent stem cells are used to generate tissues and cells for transplantation therapies (Fong, 2007). Apart from disease treatment, there are major contribution in many areas of science. The growth of human, how diseases develop and so many other issues are areas of potential that stem cell research and especially pluripotent stem cell can reveal (Fong, 2007). Pluripotent stem cells do differentiate into different cell types. Scientists hope to find out the process of decision making in the cell which makes one cell become of the heart and the other of the brain and so on.
Understanding the process of decision making can be a break through since it can make the scientist establish which cells will differentiate to specific cells (Fong, 2007). By understanding the process of differentiation, the process of disease causing aberration can be determined (Fong, 2007). The other is, understanding of the normal process of differentiation, will enable scientists determine the cause of abnormal differentiations which lead to cancers and several other disorders, and the reason why such abnormal differentiation occurs (Fong, 2007).Pluripotent stem cell research could also provide better ways of developing drugs. In the current field of research, there are few cell lines that provide invaluable tools for development and testing of drugs.
Pluripotent cell differentiate to more cell types therefore would provide expansion or testing along so many cell lines (Bellomo, 2006). This will eliminate harm as a specific cell line will be tested therefore risk of toxicity eliminated. Challenges of Pluripotent Stem Cell Research.The main challenge in its predicted use to produce human therapy, is immunological problems.
The kind of therapy that is still appropriate by use of stem cells is transplantation of cells. The cells to be transplanted do not belong to the immune system of the person who is to receive the transplant or the replacement, this therapy therefore faces the threat of rejection by one's immune system (Biology Pages, 2008). This happens if the allografts used belong to a genetically different individual. Scientists have done research and ways to deal with this problem have been found out.It may not a major problem as it only requires identification of similar (stem cell) allograft to the individual's genetic make up (Biology Pages, 2008).
Another solution to the immunological problem is by use of somatic cell nuclear transfer in cases where the stem cell and the host's organ are not genetically identical. In this kind of technique, the nucleus obtained from a somatic cell of the host is placed in a human egg that has its nucleus removed. This is allowed to develop to a blastocyst that provides embryonic stem cell for harvesting.The stem cells are allowed to differentiate to the desired properties then implanted. By this, no rejection can occur (Biology Pages, 2008). Immunological rejection could also occur with the graft which might identify the hosts tissues as foreign antigens and launch an attack against them.
There are several other problems that arise due to rejection. As scientists had found out that the replacements could be rejected by the immune system, solutions to this was provided, which is suppression of the immune system or use of the somatic cell nuclear transfer. Suppression of immune system has its problems too.It increases chances of getting cancer, reduces the ability of the patient to fight other infections such as from bacteria, viruses and fungi and the donated graft may also be infected, if the organ donor had infections (Biology Pages, 2008). There are some other unsolved issues in stem cell research which include imprinted genes that exist in the sperms and the eggs, somatic mutations that can be a problem when used for replacements and aneuploidy due to a new nucleus placed in the embryo which causes loss of some centromeric molecules hence disruption of spindle formation (Biology Pages, 2008).
Imprinted genes are those that are expressed depending on the parent that contributed them. It is only one gene that should be expressed while the other is repressed. An example is the IGF2 (Insulin like growth factor), if the genes encoding for this growth factor obtained from both the parents are both expressed, it causes cancer. It is for this reason that it poses a challenge to the stem cell research.
Determination of if the imprinted genes will all be expressed is not easy.Embryos developed for stem cell research may have such kind of a problem and both the genes may be expressed causing a problem to the recipient, to which implantation should be done. The major problem is determination of whether imprinted genes will both be expressed (Biology Pages, 2008). Stem cell research has problems still that have no solutions in somatic mutations. The process increases the spectra of amplifying somatic mutation effects. Ethical implications have also been a problem in stem cell research.
This is in the use of embryos for scientific research. People who believe that human beings have morals and that one becomes a complete human being immediately after conception, consider the use of embryos for research as immoral. Further more, harvesting of the stem cells which needs destruction of the embryo is considered killing. Some scientists use stem cell research for reproduction, that is, human cloning which is again considered unethical by so many people in the public (Ruse, M. and Pynes, 2003; Monroe et al.
, 2008).
