Healthy stem cells when injected into a person’s bone marrow or blood is called a stem cell transplant. These healthy stem cells can replenish the person’s stem cells when their bone marrow has been damaged by chemotherapy, radiation, or a disease. If the healthy cells are taken from bone marrow, then its called as a bone marrow transplant.  The purpose of stem cells is tissue regeneration, which is when old or damaged tissues are replaced with new, healthy ones.

However, stem cells can be damaged during illness or treatment for an illness such as patients with cancer who receive high doses of chemotherapy, radiation therapy, or both. Such treatments kill healthy stem cells along with cancer cells. This type of aggressive treatment is called myeloablation.

Once treatment is complete, doctors transplant new stem cells to replace the damaged ones. The goal of a transplant is that over time, the new cells will settle in the bone marrow and regenerate. 

Reasons to have a stem cell transplant

A person usually receives a stem cell transplant because their bone marrow has been damaged, leaving it unable to produce healthy cells. 

Doctors may also carry out a transplant on a person to replace blood cells that are damaged by intensive cancer treatment.

Doctors use stem cell transplants to treat following disorders: 

• Leukemia: This cancer affects the white blood cells.
• Severe aplastic anemia:  This disorder damages stem cells in the bone marrow.
• Myeloma: This is a cancer that affects plasma cells.
• Lymphoma: This is a type of cancer that affects white blood cells
• Certain immune system, blood, and metabolic disorders: egs. are thalassemia, Hurler syndrome, and sickle cell anemia

Types of stem cell transplants

Stem cell transplants can be divided into different types:

Autologous

The stem cells transplanted are their own cells. This kind of transplant is done before a person receives treatments such as chemotherapy or radiation, which will likely damage the body’s supply of stem cells. The cells are harvested from the bone marrow or blood before the treatment and stored.  After the completion of the treatment, the cells will be transplanted back into the bone marrow. 

Allogenic

Allogenic transplants are done with donor stem cells. The donors are usually matched before the transplant and they have a similar type of tissue to the recipient.

Typically, close family members make the best donors. If a person does not have an available match in their family, they can find a donor through a national registry.

There are two different types of allogenic stem cell transplant:

Syngenic

Syngenic stem cell transplants are used when a person has an identical sibling, such as a twin or triplet, who has the exact same tissue type.

Cord blood

Cord blood stem cell transplants are also a type of allogenic transplant. In this type of transplant, donor blood from the umbilical cord or placenta is used.  This type of blood is particularly good for transplants because of its high concentration of stem cells.

Donating or harvesting stem cells

People can donate stem cells to help a loved one, or possibly for their own use in the future.

Donations can be obtained from the following sources:

Bone marrow: Bone marrow is extracted under a general anesthetic, usually from the hip or pelvic bone. Technicians then isolate the stem cells from the bone marrow for storage or donation.

Peripheral stem cells: Prior to extraction, several injections are given that induces the bone marrow to release stem cells into the blood. Subsequently, blood is withdrawn from the body, and an apharesis instrument separates the stem cells from the blood and the balance blood is returned to the body.

Umbilical cord blood: Stem cells can be harvested from the umbilical cord after delivery, with no harm to the baby. Some people donate the cord blood, and others store it for future use if needed.

This harvesting of stem cells can be expensive, but the advantages for future needs include:

• the stem cells are easily accessible
• less chance of transplanted tissue being rejected if it comes from the recipient’s own body