Stem Cell

WHAT ARE STEM CELLS?

Stem cells are cells that have the ability to renew themselves through mitosis and can differentiate into many different specialized cells.

Embyronic stem cells are derived from blastocysts

In the embryo, embryonic stem cells are essential for development, acting as the precursor to all specialized embryonic tissue

adult stem cells are found in adult tissue,

and cord blood stem cells can be harvested from the umbilical cord following birth.

In adults, stem cells and progenitor cells aid in repair of tissue, replenishing specialized cell types.

Amniotic/placental stem cells:

In 2005, researchers at the University of Pittsburgh discovered that embryo-like stem cells could be obtained from the placenta. They are called "amniotic epithelial cells" after the amnion -- the outer membrane of the placenta's amniotic sac

They do not require the destruction of an embryo. They can apparently be coaxed into developing into a wide range of cell types. They are much easier to obtain than embryonic stem cells.

They can double in number every 36 hours. They can divide at least 250 times without mutating and without forming tumors. They have been converted into bone, heart muscle, blood vessels, fat, nerve and liver tissues in lab mice. Unlike embryonic stem cells, they cannot reproduce indefinitely.

Stem cells have varying differentiation potential, referred to as potency.

Totipotent stem cells arise from the fusion of egg and sperm cell and are remarkable because they can differentiate into any cell type.

Pluripotent stem cells are close descendents of totipotent stem cells. They have wide differentiation powers, but are limited to cell types of the 3 germ layers (ectoderm, endoderm, mesoderm).

Differentiation of multipotent stem cells is limited to a specific subtype of cell.

Embryonic stem cell lines (ES cell lines) are pluripotent and can give rise to any of the cell types present in adults when given the correct stimulation.Once stem cells are removed from an embryo, that embryo can no longer trigger a pregnancy, and be born

Adult stem cells are also known as somatic cells. Like embryonic stem cells, adult stem cells are also pluripotent. However, unlike embryonic stem cells, adult stem cells have been successfully used in the treatment of disease.

Adult stem cells:stem cells in the bone marrow of adults may be capable of becoming almost any of the 220 tissue types in the human body. These "multipotent adult progenitor cells" or (MAPCs) might match the flexibility and potential of stem cells derived from embryos.

"mesenchymal stem cells" (MSCs) has been shown capable of producing a few tissue types, such as bone, cartilage, fat and muscle.

The use of adult stem cells and tissues derived from the patient's own adult stem cells would mean that the cells are less likely to be rejected by the immune system.

To be useful for transplant purposes, stem cells must be reproducibly

made to:

Proliferate extensively and generate sufficient quantities of tissue. Differentiate into the desired cell type(s) Survive in the recipient after transplant. Integrate into the surrounding tissue after transplant. Function appropriately for the duration of the recipient's life. Avoid harming the recipient in any way.

One concern of treatment is the possible risk that transplanted stem cells could form tumors and have the possibility of becoming cancerous if cell division continues uncontrollably.

Transitional Page

The Key Points in Embryo Issues

human life (as in an ovum or spermatozoon) becomes a human person and is thus worthy of legal protection:

The pro-life movement generally believes that no potential health benefits to even hundreds of millions of people can justify the murder of other humans.

pro-choice movement generally believes that personhood is attained much later in pregnancy, perhaps when the fetal brain develops consciousness during the third trimester. Thus, extracting stem cells from an five or ten-day old pre-embryo is not murder.

The Efficiency Argument

Embryonic stem cells appear to have certain desirable characteristics and may be able to work better than adult stem cells

Ethics must always come before efficiency.Taking the lives of young humans (whether as little boys or little embryos) cannot be pronounced ethical simply because it might result in huge benefits to older, more powerful,or more wealthy humans.

Argument from Wastage

The total loss of conception from fertilization to birth is believed to be as high as 50-80%

The fact that most embryos don’t survive are then taken and used as a justification for destroying embryos to get stem cells

The human person has been endowed with a very exalted

dignity,which is rooted in the intimate bond that

unites him with his Creator: a reflection of God’s own reality shines out in the human person , in every

person ,whatever the stage or condition of his life.

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