After childbirth, some moms like to keep their baby's umbilical cord for sentimental reasons. For the last couple of decades however, umbilical cords are seen as a rich source of stem cells rather than as a 'keepsake' that linked mother and child during pregnancy.

Stem cells

According to Wikipedia, stem cells are cells that are usually found in multi-cellular organisms. Stem cells are characterized by their ability to renew themselves through mitotic cell division and differentiate and develop into various cell types in our body.

Stem cells are used to treat a number of diseases because of their distinct abilities. This treatment is called stem cell therapy. Scientists and physicians usually work with two kinds of stem cells: embryonic stem cells and adult stem cells.

Embryonic stem cells

Embryonic stem cells come specifically from embryos that develop from cells that were fertilized in vitro (not from a woman's body, and were donated for research with informed consent of the donors). Stem cells in developing tissue are necessary for living organisms.

For instance, the 3-5 day old embryo, the stem cells in developing tissues bring about the multiple specialized cell types that make up the heart lungs, and other tissues. Embryonic stem cells received a lot of controversy because of how they are obtained. The fact that they came from human embryos (which are then destroyed) became a huge ethical issue in the US.

Adult stem cells

Adult stem cells on the other hand, are undifferentiated cells that are found among specialized cells in a tissue or organ. They are also called somatic stem cells. Scientists are still unsure of the origin of somatic stem cells in mature tissues. In adult tissues such as bone marrow, distinct groups of stem cells produce replacements for cells that were lost through injuries, diseases or through normal wear and tear.

Cord blood stem cells

Cord blood is the blood that is left in the umbilical cord and placenta following delivery and after the cord is cut. The umbilical cord blood is a good source of stem cells. Stem cells from umbilical cord blood posses the same abilities as embryonic and adult stem cells.

A recent study revealed that cord blood stem cells are "not quite as primitive as embryonic stem cells, which can give rise to any tissue type of the body. But they appear to be much more versatile than "adult stem cells" such as those found in bone marrow which repair damaged tissue during life."

Colin McGuckin of Kingston University in Surrey, UK and co-leader of the research team who studied stem cells from cord blood adds that "We have found a unique group of cells that bring together the essential qualities of both types of stem cells for the first time."

Since the first successful cord blood stem transplant in 1988, cord blood has steadily gained popularity as a vital source of stem cells. Today, though stem cells from the bone marrow are still primarily used in stem cell therapy, cord blood is not far behind. In fact, experts revealed a number of reasons why stem cells from cord blood is preferred over bone marrow stem cells.

Cord blood vs. bone marrow

GVHD - Graft Vs. Host Disease is condition where the body of the recipient is attacked by the transplanted stem cells. GVHD can be fatal in about 40% of patients . Since cord blood is more primitive that bone marrow, the chances of the cells attacking the host's body is much lower.

HLA - Human Leukocyte Antigen is a marker that the immune system uses to recognizes foreign cells. HLA tissue types are inherited. This is why bone marrow donors should be a family member of the recipient. But since cord blood stem cells are purer, finding an HLA match is unnecessary.

Source - stem cells are found in greater proportions in umbilical cord blood than bone marrow.

Repair - cord blood stem cells are believed to have greater regenerative abilities than bone marrow stem cells because they are younger.

Availability - cord blood banks make stem cells readily available to transplant patients.

Pain - cord blood stem cells are gotten right after birth, meaning it is a non-invasive procedure. Bone marrow stem cells on the other hand, require the donor to be under general anesthesia so that marrow can be removed from the pelvic bone through injections.

Graft rejection - cord blood stem cell transplants are more likely to be attacked by the host's body than bone marrow transplants.