When stem cells are used for the treatment of blood cancers, patients have (typically) been treated with chemotherapy and/or radiation to destroy the cancer cells invading the body. Stem cells are then given (or transplanted) to regenerate the patients' blood and immune systems. Whether the bone marrow has been damaged by medical treatment, such as chemotherapy or radiation, or by the disease itself, a stem cell transplant usually becomes necessary.

Blood cells grow in the same way as other human cells. They are developed in the bone marrow from a parent cell known as a “stem cell.” These stem cells begin to divide and mature until they are fully developed, forming all the different types of blood cells: white blood cells, platelets and red blood cells. Stem cells are usually found inside the bone marrow spaces of large bones, however, they can also travel from one bone to the other by way of the blood system.

Hematopoietic stem cells (HSCs), present in the bone marrow and precursors to all blood cells, are currently the only type of stem cells commonly used for therapy. Doctors have been transferring HSCs in bone marrow transplants for more than 40 years. Advanced techniques for collecting or "harvesting" HSCs are now used to treat leukemia, lymphoma and several inherited blood disorders.

The uses for stem cells in different treatment therapies are increasing every day. In addition to the already documented 80 to 90 present uses for stem cells, researchers are anticipating their use in treatments for diabetes, heart disease, stroke, and muscular dystrophy. Repair of spinal cord injuries, blood vessel growth, treatment of Alzheimer’s and Parkinson’s disease are other areas of anticipated use.

Yes, adult or somatic stem cells have been used for some time to treat disease. For example, blood stem cells created in the bone-marrow are used in “bone-marrow transplant" as a common therapy for various blood based diseases such as leukemia and aplastic anemia. Organ transplantation also uses stem cell technology.

Embryonic stem cells are undifferentiated, meaning that they don't belong to one specific organ. They have the potential to generate any type of tissue in the body. The potential that embryonic stem cells present to scientists is immeasurable. There have already been promising findings in the field of Parkinson's research using embryonic stem cells in mice and monkeys.

Embryonic stem cells are derived at a very early stage of development called a blastocyst. This is a simple ball of about 100 cells that is similar in all species of animals at this stage of development. Embryonic stem cells are derived from the cells in the center of this blastocyst. Blastocysts are obtained from in vitro fertilization clinics. These clinics have produced an estimated 500,000 healthy, much-loved children over the two decades of their existence.

Stem cells are cells that have the remarkable potential to develop into many different cell types in the body. Serving as a sort of repair system for the body, they can theoretically divide without limit to replenish other cells for as long as the person or animal is still alive. When a stem cell divides, each "daughter" cell has the potential to either remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell.

Pluripotent stem cells are isolated from human embryos that are a few days old. Cells from these embryos can be used to create pluripotent stem cell "lines" —cell cultures that can be grown indefinitely in the laboratory. Pluripotent stem cell lines have also been developed from fetal tissue obtained from fetal tissue (older than 8 weeks of development).

Bone marrow is the soft, sponge-like material found inside bones. It contains immature cells called stem cells that produce blood cells. There are three types of blood cells: white blood cells, which fight infection; red blood cells, which carry oxygen to and remove waste products from organs and tissues; and platelets, which enable the blood to clot. Most stem cells are found in the bone marrow, but some stem cells called peripheral blood stem cells (PBSCs) can be found in the bloodstream.