Very few other ongoing areas of research have been the focus of numerous articles, Presidential and Congressional scrutiny, and numerous ethical debates played out in the national media. The key question that is being dealt with is the issue of Federal funding for research with embryonic stem cells; the underlying issues of this simple question cause strong opinions and necessitate serious ethical considerations.
This study is intended to shape a personal position on the subject of Federal funding for embryonic stem cell research and a critique of the current status of such funding. However, outlining a position on this subject requires a background on all types of stem cells.
In particular, some idea of the nature of various types of stem cells and the potential and realized uses of stem cells is necessary. Before outlining a personal position, an overview of the spectrum of positions and the evolution of the stem cell debate will also be required. Thus, the majority of this paper will outline the nature of stem cells, a history of the ongoing embryonic stem cell debate, and current policy regarding stem cell research.
My personal position will then be juxtaposed alongside supporting and opposing opinions on the matter of Federal funding of embryonic stem cells. Stem cells are a pluripotent cell type, able to differentiate into multiple cell types. There are many kinds of stem cells in the human body, though some are more differentiated to a particular function than others.trogindecenes.cf
Embryonic stem cell research: the relevance of ethics in the progress of science.
Thus the term stem cell "commonly is used to refer to the cells within the adult organism that renew tissue. Embryonic stem cells are unlike any adult stem cell. Another type of stem cell which has properties similar to the embryonic stem cell is the embryonic germ cell, derived from the primordial reproductive cells of the developing fetus.
Too often stem cells are lumped together into one category. However, all stem cells do not share common characteristics or sources and it is important to distinguish between various types of stem cells. Embryonic stem cells can be derived by a number of methods. Of the above sources, only types A and B have been utilized. Type C represents a real option based on the knowledge that embryonic stem cells can be extracted from embryos and Type D would involve a similar process utilized in the well-known "Dolly" sheep example.
As all the methods of obtaining stem cells are somewhat controversial, why is such extraction of cells and research being done?
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There are a great many possibilities for the use of stem cells. Perhaps the most exciting is in the area of treatment of diseases and disorders. The key here is that stem cell stock of various immunotypes could be stocked, allowing replacement of dysfunctional cell types in the body without need for cross matching immunotypes to a donor or suppressing the immune system. Such treatments have been proposed in particular for juvenile-onset diabetes, Parkinson's disease, and other disorders involving problems or defects in one or a few isolated cell types.
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Such approaches could also be used in regenerating tissue. For example it might be possible to repair damaged heart muscle by injecting new cardiomyocytes. Another possible use for embryonic stem cells include using the cells to study early embryonic development after implantation of the embryo into the uterus. The body can use these stem cells whenever it needs them. Also called tissue-specific or somatic stem cells, adult stem cells exist throughout the body from the time an embryo develops.
The cells are in a non-specific state, but they are more specialized than embryonic stem cells. They remain in this state until the body needs them for a specific purpose, say, as skin or muscle cells. Day-to-day living means the body is constantly renewing its tissues. In some parts of the body, such as the gut and bone marrow , stem cells regularly divide to produce new body tissues for maintenance and repair. Stem cells are present inside different types of tissue. Scientists have found stem cells in tissues, including:. However, stem cells can be difficult to find.
They can stay non-dividing and non-specific for years until the body summons them to repair or grow new tissue. Adult stem cells can divide or self-renew indefinitely. This means they can generate various cell types from the originating organ or even regenerate the original organ, entirely. This division and regeneration are how a skin wound heals, or how an organ such as the liver, for example, can repair itself after damage.
In the past, scientists believed adult stem cells could only differentiate based on their tissue of origin.
The Case Against Embryonic Stem Cell Research: An Interview with Yuval Levin
However, some evidence now suggests that they can differentiate to become other cell types, as well. Around 3—5 days after a sperm fertilizes an egg, the embryo takes the form of a blastocyst or ball of cells. The blastocyst contains stem cells and will later implant in the womb. Embryonic stem cells come from a blastocyst that is 4—5 days old.
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When scientists take stem cells from embryos, these are usually extra embryos that result from in vitro fertilization IVF. In IVF clinics, the doctors fertilize several eggs in a test tube, to ensure that at least one survives. They will then implant a limited number of eggs to start a pregnancy. This single-celled zygote then starts to divide, forming 2, 4, 8, 16 cells, and so on. Now it is an embryo. Soon, and before the embryo implants in the uterus, this mass of around — cells is the blastocyst.
The blastocyst consists of two parts:. The inner cell mass is where embryonic stem cells are found.
Scientists call these totipotent cells. The term totipotent refer to the fact that they have total potential to develop into any cell in the body.
Stem cells in therapy
With the right stimulation, the cells can become blood cells, skin cells, and all the other cell types that a body needs. In early pregnancy, the blastocyst stage continues for about 5 days before the embryo implants in the uterus, or womb.
At this stage, stem cells begin to differentiate. MSCs come from the connective tissue or stroma that surrounds the body's organs and other tissues. Scientists have used MSCs to create new body tissues, such as bone, cartilage, and fat cells. They may one day play a role in solving a wide range of health problems.
Scientists create these in a lab, using skin cells and other tissue-specific cells. These cells behave in a similar way to embryonic stem cells, so they could be useful for developing a range of therapies. To grow stem cells, scientists first extract samples from adult tissue or an embryo. They then place these cells in a controlled culture where they will divide and reproduce but not specialize further.
Stem cells that are dividing and reproducing in a controlled culture are called a stem-cell line. Researchers manage and share stem-cell lines for different purposes. They can stimulate the stem cells to specialize in a particular way. This process is known as directed differentiation. Until now, it has been easier to grow large numbers of embryonic stem cells than adult stem cells.
However, scientists are making progress with both cell types. Researchers categorize stem cells, according to their potential to differentiate into other types of cells. Embryonic stem cells are the most potent, as their job is to become every type of cell in the body.