What To Do With Unused Embryos

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.

These spare embryos remain frozen and stored. With today's tissue-freezing methods, these spare embryos retain their viability for many, many years. The parents can decide to keep them in storage, pass them on to other childless couples who are unable to conceive or donate them for scientific research using stem cells.
This is becoming an extremely popular process with couples who find themselves unable to produce their own embryos via in vitro fertilization. The parents of the excess embryos may also ultimately decide to discard them.

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 the University of Utah were the first to inject stem cells into the left ventricles of patients to treat heart failure. Cardiac repair cells were drawn from the patients' own bone marrow and placed into culture for around 12 days. The cells that survived in culture turned out to be stronger than the patient's original cells and were injected into the left ventricles 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 comes from rich deposits deep inside the larger bones of the human body, most notably the pelvic bone. This process is very painful so it is performed under a general anesthetic. A wide-bore needle is injected into the hip and then into the bone marrow from which the tissue is collected.

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.

Once the couples who have been storing embryos are sure they no longer want any more children, their spare embryos may be donated to other couples, to scientific research or they may be ultimately destroyed.




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