Bone marrow transplantation

What is a bone marrow transplantation?

Bone marrow transplantation (BMT) is a medical procedure used to treat patients with certain cancers and diseases that affect the bone marrow. It involves transferring healthy stem cells from bone marrow to a patient, either from their own body (autologous) or a donor (allogeneic), to replace unhealthy bone marrow.

What is bone marrow?

Bone marrow is a spongy tissue inside bones, like the hips, spine, and skull. It produces 95% of the body’s blood cells, including:

• Red blood cells (erythrocytes) - carry oxygen
• White blood cells (leukocytes) - fight infections 
• Platelets - helps with blood clotting

Each of these cells carries a life-maintaining function. The bone marrow is a vital part of the human body.

What are stem cells?

Stem cells are immature cells in bone marrow that can develop into various types of blood cells. These are crucial in BMT as they regenerate the body's blood cells once transplanted.

Why is a bone marrow transplant needed?

BMT helps treat various conditions, including cancer, blood diseases, and immune system disorders. It's commonly used for:

• Replacing diseased bone marrow (e.g., leukemia, sickle cell anemia)
• Restoring bone marrow after cancer treatments (e.g., lymphoma, neuroblastoma)
• Correcting genetic disorders (e.g., Hurler’s syndrome)

Conditions treated by BMTs include:

• Leukemia, lymphomas, and some cancers
• Aplastic anemia, immune deficiencies, bone marrow failure syndromes
• Sickle cell disease, thalassemia
• Metabolic diseases (e.g., Hurler’s syndrome)

What are the different types of bone marrow transplants?

There are different types of bone marrow transplants depending on who the donor is. The different types of bone marrow transplant include the following:

• Autologous Transplant: The patient’s own stem cells are collected, treated, and reinfused after chemotherapy.
• Allogeneic Transplant: Stem cells come from a genetically matched donor, such as a sibling, parent, or even an unrelated donor.
• Umbilical Cord Blood Transplant: Stem cells from a newborn’s umbilical cord are used, offering faster blood cell production and lower risk of graft-versus-host disease.

The bone marrow transplant team:

A multidisciplinary team supports the patient throughout the process:

• Physicians (oncology, hematology, immunology)
• Nurses (coordinate care and educate)
• Social Workers (family support, logistics)
• Dietitians, Therapists, Pastoral Care (nutrition, physical recovery, spiritual support)

Evaluation for BMT:

An extensive evaluation is required to determine if BMT is suitable, considering factors such as the child’s age, overall health, disease extent, donor availability, and personal preferences.

Bone marrow transplantation is a complex and life-saving procedure with associated risks, but when successful, it can offer hope for patients with serious, life-threatening conditions.

Bone Marrow Transplantation (BMT) Preparation

Recipient Preparation:

1. Evaluation & Testing: Before a transplant, the child undergoes a thorough evaluation, including medical history, physical exams, and tests to assess blood and organ functions (heart, kidney, liver, lungs).
2. Hydration & Central Line Placement: The child may arrive up to 10 days before the procedure for hydration, a central venous line placement, and chemotherapy or radiation. This line will be used for blood products and medication administration.
3. Donor Matching: A best matched donor is essential. The search may take time, involving national and international registries to find the best match.

Donor Preparation:

1. Donor Types: Donors can be family members (e.g., sibling, parent), a non-related individual, or umbilical cord blood. Donors are tested for health, virus exposure, and genetic compatibility.
2. Stem Cell Collection:
• Peripheral Blood Stem Cells (PBSCs): Collected through apheresis, where blood is drawn, processed to remove stem cells, and returned.
• Bone Marrow Harvest: Involves collecting stem cells directly from the bone marrow, typically from the hip bones.
• Umbilical Cord Blood: Collected at birth, tested, and stored for later use.

Matching Donor and Recipient:

• HLA Typing: The match is determined by comparing human leukocyte antigens (HLA), which are key to immune system compatibility. A higher number of matching antigens improves the chances of a successful transplant.

Bone Marrow Transplant Procedure:

1. Pre-transplant Treatment: High doses of chemotherapy or radiation are given to prepare the body, destroy unhealthy cells, and make room for the new marrow. This is called conditioning.
2. Stem Cell Infusion: The stem cells are infused into the bloodstream (like a blood transfusion), where they travel to the bone marrow and begin creating healthy blood cells.
3. Post-transplant Care: The child will need close monitoring for infections, bleeding, and side effects. Medications will be administered to prevent complications like graft-versus-host disease (GVHD) in allogeneic transplants.

Engraftment & Recovery:

• Engraftment is the process when the transplanted stem cells begin to produce new blood cells. It typically occurs between Day +10 to +30.
• Full recovery of the immune system can take months or even years. Regular blood tests will monitor progress.

Challenges Post-Transplant:

• The child may experience pain, chills, fever, and other symptoms during and after the stem cell infusion.
• The recovery process may involve a prolonged hospital stay, antibiotics, blood transfusions, and medications to prevent infection and GVHD.

Psychosocial Support:

• Mental and emotional health are key to recovery, and support from specialists is provided throughout the process.

Complications and Side Effects of Bone Marrow Transplantation (BMT)

Bone marrow transplantation (BMT) involves risks and complications, which can vary based on several factors, including the type of transplant, the disease being treated, and the recipient's overall health. Common complications include:

1. Infections

• Risk: Due to weakened immunity from bone marrow suppression, infections (bacterial, viral, fungal) are common and can be life-threatening.
• Prevention: Strict infection control measures, including isolation, hygiene regimens, filtered rooms, and antibiotics, are used to reduce the risk.

2. Low Platelets and Red Blood Cells

• Thrombocytopenia (low platelets) and anemia (low red blood cells) are frequent and may lead to bleeding, requiring blood transfusions.
• Management: Blood product transfusions and GI tract care to prevent complications.

3. Pain

• Cause: Pain from mouth sores (mucositis) and gastrointestinal irritation due to high-dose chemotherapy and radiation.
• Management: Pain medications and mouth care to prevent infection.

4. Fluid Overload

• Cause: Excess fluid administered during treatment can stress the kidneys, leading to complications like pneumonia and liver damage.
• Management: Close monitoring of fluid balance and kidney function.

5. Respiratory Distress

• Cause: Infection, inflammation, fluid overload, and complications like graft-versus-host disease (GVHD) can affect the lungs.
• Monitoring: Chest x-rays, pulse oximetry, and supplemental oxygen are used to manage respiratory issues.

6. Organ Damage

• Affected Organs: The liver and heart can be damaged by infections, GVHD, high doses of chemotherapy, and radiation.
• Management: Monitoring blood work and vital signs to detect and minimize damage.

7. Graft Failure

• Cause: If the stem cell count is too low, or due to infection or recurrent disease or rejection, the transplanted marrow may not engraft.
• Treatment: Additional transplants may be considered if available.

8. Graft-versus-Host Disease (GVHD)

• Cause: Occurs when the donor's immune cells attack the recipient’s tissue.
• Symptoms: Diarrhea, fever, rash, abdominal pain, and liver or lung issues.
• Management: Preventive medications are given before transplant, and treatment is based on severity.

Discharge and Long-term Outlook:

• Discharge Criteria: Depends on engraftment status, complications, and overall health. Frequent follow-ups are required to monitor progress and detect issues.
• Prognosis: The outcome depends on several factors, including the type of transplant, disease response, genetics, and overall health. Continuous follow-up care is essential, as long-term survival can vary. Advances in BMT have improved outcomes, and new methods are being developed to reduce complications.