Bone marrow transplant, also referred to as BMT, is a method through which damaged or destroyed bone marrow is replaced with healthy bone marrow stem cells. Within the bones, there is spongy tissue known as bone marrow, responsible for the production of blood. The transplant is usually done for people suffering from ailments that affect marrow, such as particular cancers, genetic disorders, or those who have undergone chemotherapy & radiation.

What Is Bone Marrow?

Bone marrow is located in the middle of bones like hip bones, thigh bones, etc. It contains stem cells, which are the body's "master cells," capable of developing into various types of blood cells. They make red blood cells, white blood cells, and platelets. These cells perform numerous important functions, such as respiration, immune response, and blood clotting.

In cases where the bone marrow is affected by diseases, it is unable to adequately generate proper red blood cells. This may result in anemia, infections, uncontrolled bleeding, or other blood-related complications. A bone marrow transplant is a surgical procedure that introduces healthy stem cells into the body, ensuring the formation of healthy blood cells.

There are different types of bone marrow transplants. The following are the three main types:

Autologous Transplant: This is when the patient’s stem cells are harvested and preserved before they undergo chemotherapy or radiation therapy. After this process, the preserved stem cells are reintroduced into the patient’s body. This type of transplant is mostly done for patients with certain types of cancer, such as Lymphomas and Multiple Myelomas. The advantage of this method is that since the patient’s own cells are grafted, the chances of the body rejecting the transplant are small, though there is a chance that cancerous cells may be transplanted.
Allogeneic Transplant: In this case, the stem cells used are from a different individual, referred to as a donor. This may be a sibling or an unrelated donor with a similar genetic type of stem cells. Allogeneic transplants are mostly employed for patients with leukemia, other cardiovascular diseases, or diseases of genetic nature. The benefits include the potential for the donor stem cells to attack any remaining cancer in the patient’s body (graft versus tumor). However, allogeneic transplants entail more complications, including graft versus host disease (GVHD).
Umbilical Cord Blood Transplant: This type of allogeneic transplant uses stem cells harvested from the umbilical cord of a newborn baby. Cord blood contains a large quantity of stem cells, and these cells do not need to be fully compatible with the patient. This type of transplant is most often employed with children or smaller adults due to the typically fewer stem cells available compared to an adult donation.

What conditions can be treated by performing Bone Marrow Transplants?

It is used to treat a variety of conditions, including:

Leukemia: A type of cancer that begins in the blood and bone marrow, involving white blood cells. A bone marrow transplant can replace defective bone marrow with healthy cells.
Lymphoma: A disease affecting the lymphatic system, the body’s immune system for identifying and fighting diseases. A transplant may be given after high doses of chemotherapy or radiation to replace the bone marrow.
Multiple Myeloma: A cancer of plasma cells in the bone marrow. Transplants are used to extend the time the patient remains in remission.
Aplastic Anemia: A condition in which the body fails to produce enough blood cells through the bone marrow. A transplant can help restore normal blood cell production.
Sickle Cell Disease: A condition where a person’s red blood cells have an abnormal shape. An allogeneic transplant, also known as BMT, can cure the disease by replacing defective bone marrow with donor stem cells.
Severe Combined Immunodeficiency (SCID): A genetic disorder that severely weakens the immune system. A transplant is crucial for rebuilding the immune system.

What is the Bone Marrow procedure?

Pre-transplant Evaluation: This assessment is done to determine if the patient is suitable for the transplant. It involves various investigations to evaluate organ function and the severity of the disease.
Conditioning: Before the transplant, the patient undergoes a conditioning regimen, often consisting of high doses of chemotherapy and sometimes radiation. This treatment eliminates any remaining cancerous cells and prepares the immune system for the new stem cells.
Infusion of Stem Cells: After conditioning, healthy stem cells are transferred into the patient’s body through an intravenous line. These stem cells travel to the bone marrow and divide to produce new blood cells.
Recovery: It takes time for the new bone marrow to produce healthy blood cells. This process may take weeks or even months. During this time, the patient is closely monitored for infections, bleeding, and other complications.

Risks and Complications of Bone Marrow Transplants

While bone marrow transplants can offer a cure or significant relief from serious diseases, they are not without risks. Some of the most common complications include:

Graft-Versus-Host Disease (GVHD): This occurs when the donated stem cells attack the recipient’s body. GVHD can cause a wide range of symptoms, from mild skin rashes to serious liver, lung, and gastrointestinal damage. Managing GVHD requires long-term immunosuppressive therapy.
Infections: These patients undergo an immune suppressive procedure through transplant and the conditioning process, hence they get easily infected by bacteria, viruses and fungi.
Graft Failure: Sometimes the stem cells may not re-establish themselves in the patient’s body and this may result to re-emergence of the disease or other disorders.
Organ Damage: Cytotoxic drugs or high levels of radiation treatment may selectively injure organs within the body inclusive of the heart, the lungs, liver and the kidneys.

What to expect after a Bone Marrow Transplant?

Recovery from a bone marrow transplant is often long and challenging. Full recovery of the immune system can take months or even years. Patients will need regular follow-ups with their healthcare team to monitor for complications and ensure the transplant's success. While some patients return to a relatively normal life, others may deal with long-term effects, including chronic GVHD, fatigue, or organ dysfunction.

Conclusion

A bone marrow transplant is a powerful treatment for many life-threatening diseases, but it is not without challenges. Recent advancements in medical research and a better understanding of the causes and strategies for reducing complications have significantly increased survival rates. Nonetheless, the process remains time-consuming and complex, requiring careful planning, expertise, and support systems for patients and their families. One hopes that as research progresses, bone marrow transplants will become a safer and more successful treatment for severe illnesses.