Overview

If you are planning to donate stem cells, you have agreed to allow doctors to draw bone marrow stem cells from either your blood or bone marrow for transplantation.

There are two broad types of stem cells: embryonic and bone marrow stem cells. Embryonic stem cells are studied in therapeutic cloning and other types of research. Bone marrow stem cells are formed and mature in the bone marrow and are then released into the bloodstream. This type of stem cell is used in the treatment of cancers.

In the past, surgery to draw bone marrow stem cells directly from the bone was the only way to collect stem cells. Today, however, it's more common to collect stem cells from the blood. This is called peripheral blood stem cell donation.

Stem cells can also be collected from umbilical cord blood at birth. However, only a small amount of blood can be retrieved from the umbilical cord, so this type of transplant is generally reserved for children and small adults.