These are cell common in all multi cellular organisms and play a critical role in natural growth and development through replacement and repair of used and damaged cells. Through mitotic divisions, the stem cells are capable of renewing themselves and differentiating into specializing cells types. The origin of Researches into stem cells dates back to the 1960s studies of the subject by Ernest A. McCulloch and James E. Till, and since then the subject have stirred great excitement in the human medical researches (Marshak et al. 2).
In human, during fertilization, the newly formed embryo, divides a million times to form the various body cells through differentiation process which specializes them to the various functions. Stems cells plays a crucial roles in this process. Stem cells differ from other cells in the various ways (Baharvand, 4).
Stem cells have specific properties, which make them different from other cells in the body. Unlike the other body tissue cells, stem cells are not specialized since they are not differentiated. The cells are able to renew or replace themselves through mitotic process. The ordinary body cells do not have this capacity since once they are differentiated, they cannot produce new cells. One other unique element of stem cells is that they are capable of differentiating to produce more specialized tissue cells. Through this process of differentiating, the stem cells are able to repair or replace worn out, damaged or diseased cells in the body. Stem cells in various tissues and at different stages of development have potential to generate millions and varied types of specialized cells (Baharvand, 7)
Stem cells have been classified in to three main types. The differences between the various types of stem cells emanate from the extent of differentiation and the capability of self -renewal. In humans the various types so stems cells include embryonic stems cells, embryonic germ cells, adult stem cells, and umbilical cord stem cells.
Embryonic stems cells are common in five to six days old embryo. At this stage, the stem cells are capable of forming virtually any type of cell found in the human body. The embryonic germ cells, which ultimately produce the eggs or sperms, are derived from the foetus or the embryo.Adult stem cells are which have not yet differentiated but found in tissues or organs with specialized cells most commonly after birth. The recent researches have suggested that adult stem cells though still capable of differentiating, are however restricted to under the mitotic process to produce different cell types and to self-renew than embryonic stem cells. Finally, umbilical cord blood stem cells help the body to develop a natural immunity system (Marshak et al. 6-12).
Stem cells can also be pluripotents, multipotent or totipotent depending on their growing in culture. Embryonic stem cells are said to be pluripotents capable of developing into any type of cells in an adult organism. Adult stem cells are multipotent, be course of its potential to make limited cell types in the body while fertilized eggs is said to be totipotent. Totipotent cells are capable of forming new embryo, which eventually develops to a new organism.
Moral and ethical issues have been raised over the embryonic stem cells studies. According to Sandel (208, 2001), the embryonic stem cell controversy is an ethical debate that surrounding research involving the creation, usage, and destruction of human embryos. A lot of arguments for and against embryonic stem cell researches which various groups raiding ethical and moral concerns on usage of human embryos for researches. Most positions on these researches are or two side of a balance with relative moral and ethical weights between embryo lives and the possibility of saving or prolong other people of lives. The intricacies of this controversy have caused the US federal government to suspend research funds to medical researcher pursuing studies of embryonic stem cells (The President’s Council on Bioethics, 58-59).
This controversy has been complicates since consensus has never been arrived. For instance, US Conferences of Catholic also agrees with the bishop that Life begins at conception/fertilization and is immoral to use defenseless lives for the possible of others (Office of Communications, 2001). American Life League, another lobby group argued that life begins at conception/fertilization and for this reason it is illegal and unacceptable to take away human life.
There are several potential uses of stems cells suggested by various studies, which proposed, have confirmed a lot of relevance of stem cells in medicine and it related researches. Researchers are pursuing earlier findings that stem cells could be used to replace damage tissues. According to Marshak and others, earlier studies had proposed that Human stem cells can be used to generate cells and tissues to be used in cell based therapies and transplants. In this possible use of stem cells, laboratory-grown stem cells are to be used in treatment of patients who have been diagnosed for need of organ or tissue transplant (11-12).
The ability for stem cells to replace damage cells in the body could make them useful in treatment of spinal injuries, diabetes and even heart failure. Scientists anticipate that through transplantation, and development of appropriate stem cells in damaged organs or tissues would grow various types of the cells required to make that tissue or organ functional. One of the best examples that has been used is the possibility to use hematopoietic (bone marrow) stem cells to be transplanted into leukemia patients to enable them generate new own blood (Baharvand 10).
One other potential use of stem cells is the study of human development. Studying early event in each stage of human growth would help researchers in finding out how some of the cells in the human body turn cancerous and the cause of other genetic diseases. This knowledge will be critical in preventing such diseases.
There is also another possibility of trying new drugs using laboratory-grown stem cells before trying them on patients. Likewise, stem cells can be used to screen toxins on substances before there used in the environments e.g. pesticides. Gene therapy used to help individuals suffering from genetic illnesses may benefits from further studies and development on stem cells.