Friday, October 10, 2008

Embryonic stem cells

Embryonic Stem Cells. (A) shows hESCs (Human embryonic stem cells).Embryonic stem cells (ES cells) are stem cells derived from the inner cell mass of an early stage embryo known as a blastocyst. Human embryos reach the blastocyst stage 4-5 days post fertilization, at which time they consist of 50-150 cells.

Embryonic Stem (ES) cells are pluripotent. This means they are able to differentiate into all derivatives of the three primary germ layers: ectoderm, endoderm, and mesoderm. These include each of the more than 220 cell types in the adult body. Pluripotency distinguishes ES cells from multipotent progenitor cells found in the adult; these only form a limited number of cell types. When given no stimuli for differentiation, (i.e. when grown in vitro), ES cells maintain pluripotency through multiple cell divisions.

The presence of pluripotent adult stem cells remains a subject of scientific debate, however, research has demonstrated that pluripotent stem cells can be directly generated from adult fibroblast cultures.

Because of their plasticity and potentially unlimited capacity for self-renewal, ES cell therapies have been proposed for regenerative medicine and tissue replacement after injury or disease. However, to date, no approved medical treatments have been derived from embryonic stem cell research (ESCR). Adult stem cells and cord blood stems cells have thus far been the only stem cells used to successfully treat any diseases. Diseases treated by these non-embryonic stem cells include a number of blood and immune-system related genetic diseases, cancers, and disorders; juvenile diabetes; Parkinson's; blindness and spinal cord injuries. Besides the ethical problems of stem cell therapy (see stem cell controversy), there is a technical problem of graft-versus-host disease associated with allogeneic stem cell transplantation. However, these problems associated with histocompatibility may be solved using autologous donor adult stem cells or via therapeutic cloning.

Stem cell controversy is the ethical debate centered around research involving the creation, usage and destruction of human embryonic stem cells. Some opponents of the research argue that this practice is a slippery slope to reproductive cloning and fundamentally devalues the worth of a human being. Contrarily, medical researchers in the field argue that it is necessary to pursue embryonic stem cell research because the resultant technologies could have significant medical potential, and that excess embryos created for in vitro fertilisation could be donated with consent and used for the research. This in turn, conflicts with opponents in the pro-life movement, who advocate for the protection of human embryos. The ensuing debate has prompted authorities around the world to seek regulatory frameworks and highlighted the fact that embryonic stem cell research represents a social and ethical challenge.

In his article Embryonic Stem Cell Research: Humane for Whom?, president and chairman of the board of the North Carolina-based Christian Research Institute Hank Hanegraaff says:

" Two years ago in this column I reiterated the truth that the only thing necessary for evil to triumph was for good men to do nothing. This was evident already in 1973 when Christians quietly passed by a major battle in the war against abortion. Two and a half decades later, the far-reaching impact of this silence is being felt in a raging debate over human cloning. Now my worst fears are beginning to be realized, for Great Britain has become the first nation to legalize human cloning. The House of Lords approved a law allowing embryos to be created for the harvesting of stem cells. Thankfully, there are some good men doing something. Chuck Colson, for instance, has spoken out eloquently against misguided citizens and celebrities who are pleading with Congress to endorse government-sponsored research involving the use of human embryos. His insights are so significant that I asked him to reiterate them in my Practical Apologetics column. Pandora’s box is already open, and Christians must do all that is permissible to prevent a human clone from emerging. "

—Hank Hanegraaff, STATEMENT DE444
Embryonic Stem Cell Research: Humane for Whom?,


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