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Despite all the protests against embryonic stem cells for human testing, several studies have previously received a permit for the first human embryonic cells to be injected into the spinal cord. For some, this is the first step to cure common diseases, for others it is a moral crime. Feelings are running high, and the factual arguments come quickly out of sight. Pros and cons are summarized here (Strauer 249–67).
Pros and Cons of Stem Cell Research
In higher animals, stem cells have been classified into two groups. On the one hand, embryonic stem cells (stem or EScells Embrionic). These cells are derived from the inner cell mass of blastocyst stage embryo (7-14 days), and are able to generate all the different cell types of the body, so they are called pluripotent cells (Strauer 249–67). After many cell divisions, the other cell type, the organ-specific stem cells derived from them. These cells are multipotent, meaning that they are capable of creating cells of a particular organ in the embryo, and also in the adult.
The clearest example of organ-specific stem cells is that of bone marrow cells, which are able to generate all blood cell types and immune system. But these stem cells exist in many other parts of the body, and can be found in the literature as we have isolated stem cells from adult skin, subcutaneous fat, skeletal and cardiac muscle, brain, retina, pancreas. Today, they have managed to grow (multiply) these cells both in vitro (laboratory) and in-vivo (animal model), using them for repairing damaged tissues (Yen p.359–72). Nevertheless, the application of these techniques transfer of adult stem cells for replacement and repair of diseased tissue is still in its infancy.
So far there has been a widespread belief that organ specific stem cells are limited to only generate specialized cells and differentiated tissue where they reside, i.e., have lost the ability to give rise to other cell lines body, are multipotent cells. However, the recent publication of multiple studies has changed this view of organ-specific stem cells, making clear that adult stem cells from any tissue can differentiate into other cells and tissues of different locations and strains (Yen 359–72). These experiments have shown that adult stem cells, cultured and subjected to environments other than the usual humoral, can be reprogrammed (transdifferentiated), and give rise to other cell types that until now were believed to be incapable of generating cells. It would no longer be multipotent, if not pluripotent. If so, you could say that there is no essential difference between embryonic stem cells and adult stem cells. These "cells of Hope" can produce any type of cells and can be used to cure hitherto incurable diseases. Alzheimer's, Parkinson's, diabetes - the possibilities seem endless. But from surplus embryos or therapeutic cloning, these "cells medicines" are at the heart of bioethical upheavals. We called stem cells, or stem cells, a special type of undifferentiated cells that have the ability to divide indefinitely without losing their properties and able to produce specialized cells (Yen 359–72).
Most of the cells of an adult (we are referring to the man and the higher mammals) usually do not multiply, except for maintenance of some tissues such as blood and skin. Muscle cells and fat do not normally divide. If you gain weight, not that we have more cells, we actually have the same amount of cells, but these have increased in size.
If a lizard loses its tail, it grows back. But mammals cannot do it. If an individual loses a limb, it will never develope. Regeneration capacity is limited to healing. However, in virtually all tissues there are cells which, although typically not divided, in particular conditions can proliferate and regenerate tissue. Artificially has been that these cells have the capacity to reproduce and generate various other tissues, and are called stem cells. Recently the British government has allowed research with human embryos to obtain stem cells. They usually use a similar process to that used in animal cloning. You take an egg cell and extract the nucleus material. It is extracted from an adult cell nucleus of the individual to be cloned (Gurtner 299–312).
From here on we have an artificial zygote that may, after embryonic development, grow into a cloned individual, genetically identical to the person, who drew the adult cell. If we earlier specialized in development of the embryo cells extract the cells from the blastocyst inner cell mass, we could obtain any tissue for transplantation. Stem cells have the ability to multiply indefinitely and generate specialized cells. In an adult there are tissues in which some cells are actively dividing, but not in others. Among them are bone marrow and skin, including bone marrow and skin stem cells (Gurtner 299–312). These cells reproduce and generate specialized cells in blood and skin respectively. Specialized stem cells are also found in other tissues. They are able to reproduce and generate specialized tissues and only those tissues. These specialized stem cells are rare and difficult to isolate.
Primally, it was believed that only specific stem cells could specialize cells of the same type. Nevertheles,, it was monitored that they can generate various cells, which differ from the oroginal ones. Thus, neural stem cells of the spinal cord can produced different types of blood cells. Rat liver cells study obtained starting demédula cord stem cells. With every new day new examples of specialized stem cells, which produce specialized cells different from the expected, are discovered (Gurtner 299–312). This fact stresses the idea of the adult stem cells flexibility, as never before. It arose great prospect of innovative therapies. It shows that adult stem cells have bigger potential and, therefore, have more facilities than embryonic stem cells, because it can from person's own cells with the same genetics. In addition, this solves,serious ethical problems of handling and destroying embryos (Chambers 643–55).
Firstly, embryonic stem cells proliferate rapidly.If you want to cure common diseases, we need large quantities of stem cells. Unlike adult cells, embryonic stem cells can be almost indefinitely multiplied and raised to any desired cell numbers. So far, the culture in the laboratory is extremely expensive, and automated techniques for a quasi-industrial production are not yet developed. It has other advantages, i.e. it can be easily obtained from fertility clinics, it can provide an infinite number of cells with definite qualities with only one cell lineage and they can create any cell in the body.
Secondly, embryonic stem cells are highly viable, since each cell in the body is created from embryonic stem cells. Theoretically, every human body can be treated with these cells. Slow-growing organs, like the brain, contain no adult stem cells. In such a case a therapy is only possible with embryonic stem cells. However, most still lack the necessary knowledge to understand the proper development of tissue cells in vitro (Chambers 643–55).
Thirdly, genetic defects are kept to a minimum. Over time the genoms may mutate, which in the long term can cause cancer. This is also in stem cells that, and therefore applies: the younger the better - and are younger than embryonic stem cells is not there. However, there is also a problem here: If embryonic stem cells are multiplied for along time in the laboratory, then they are also changing. Therefore, scientists need regular replenishment of fresh stem cell lines (Chambers 643–55).
Firstly, embryonic stem cells are shed from the body: Each exogenous cell, which includes the embryonic stem cell,is recognized by the immune system and attacked. With appropriate medication, this problem is manageable, but the side effects are sometimes considerable. Unlike a heart or a kidney transplantation, it is mainly associated with a significant loss of quality of life (Ron 102-133).
Secondly, embryonic stem cells are hard to control in the body: The viability of embryonic stem cells poses a risk to form in the body a certain form of cancer called teratoma. Prior to the treatment, a patient must, therefore, be ensured that each stem cell has developed in the direction of a fabric - otherwise it may be a cancer-risk venture.
Thirdly, ethical concerns reduce the acceptance: Human embryos must be destroyed for those cells, which is synonymous for many with the destruction of human life . And the number of embryos needed could easily soar: Presumably you need a variety of stem cell lines that must be additionally regularly renewed. The mass consumption of embryos in the pharmaceutical industry would bring significant gains (Ron 102-133). Difficult to control, therefore, the cell type to treat a disease must be optimized and properly defined. They can generate conflicts in the person's immune system because they differ in this respect with the container in which they are contained. Those, who think that life begins at the moment of conception, research on human embryos is unethical, regardless of whether or not there was consent for donation.
Stem cells will have applications in cell therapy, regenerative medicine or tissue engineering. Many diseases result from malfunctions of cell or tissue destruction.One of the remedies, in severe cases, is the transplantation. Pluripotent stem cells stimulate to develop into specialized cells, which often provides the ability to replace damaged cells and tissues. This may be used for cases of Parkinson's and Alzheimer's diseases, spinal injuries, burns, heart or brain injuries, diabetes, osteoporosis and rheumatoid arthritis.