Sunday, August 3, 2014

Disposition Of Unused Embryos After IVF

By Annabelle Holman


When couples have difficulty conceiving a child by any other means, including artificial insemination, they may decide to try in vitro fertilization. In this process, the woman's eggs may be fertilized in the laboratory; the resulting embryos are then implanted into her uterus. Unused embryos that do not get implanted remain the responsibility of the parents from whose cells they are derived.

Once the eggs are fertilized, spare embryos that are not implanted may be frozen and stored. With modern vitrification freezing techniques, these living embryos may remain viable for years. Parents may decide to store them for future use, donate them for pioneering stem cell research, donate them to other couples who are unable to create their own embryos, continue to store them year after year or they may choose to have them destroyed.

Stem cells are highly primitive cells that have the ability to differentiate into all other cell types in the body. This is what is meant by the term, "pluripotent." Stem cells are turning out to be incredibly useful for medical purposes, although they are very tightly regulated because of their potential for abuse.

Scientists at a Utah university first injected stem cells into the hearts of patients as a therapeutic strategy for heart failure. Cells were derived from the patient's bone marrow and then cultured for just short of two weeks. Those that survived in tissue culture became stronger than the patient's original bone marrow. These cells were then placed into the left side of the patients' hearts.

The very first stem cells to be isolated came from mice in 1981. They were consequently harvested from humans in 1998. There are other sources of this material other than human embryos. For one thing, they may come from the bone marrow. They may also be isolated from peripheral blood or from neonatal umbilical cords.

Bone marrow is the spongy tissue located deep in the center of some of the larger bones in the body, mostly from the pelvic bone. Harvesting stem cells from this location is extremely painful so the donors are placed under a general anesthetic. A large needle is then placed into the marrow via the hip bone and the cells are harvested.

Typically, peripheral blood is not endowed with a plethora of stem cells. In this case, patients are prepared by giving them hormones called growth factors. This takes place a few days prior to harvesting. The actual collection process may take hours. Newborn blood is also rich in these cells. Some remain in the umbilical cord, which is set aside for future transplantation. To date, human umbilical cord cells have only been transplanted into small adults and children.

When couples who have stored embryos no longer want to have children, they may donate the spare embryos to scientific research or they may give them to other couples who are having trouble conceiving by other means.




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