Infectious Diseases

Introduction

Over the past four decades, there has been a remarkable emergence in the field of bone marrow transplant (BMT) as a therapeutic breakthrough for fatal diseases. It also stands as a beacon of hope for individuals born with inherited disorders, particularly impactful in primary immunodeficiency diseases. Let’s explore some common conditions where BMT is recommended.

Common Conditions

• Thalassemia Major: It is a type of genetic disorder caused by reduced hemoglobin production, leading to lifelong anemia. Thalassemia major patients have very low hemoglobin A levels and are known to suffer from major consequences, such as jaundice, hepatosplenomegaly, endocrine abnormalities, and severe anemia requiring life-long blood transfusion. 
• Multiple Myeloma: It is a plasma cell cancer marked by an increase in the levels of an abnormal antibody called M protein. This type of cancer emerges in bone marrow and disrupts immune function by overproducing abnormal antibodies.
• Aplastic Anemia: This type of condition is caused by bone marrow damage, reducing the complete blood cell count. This condition can be either acquired or inherited, and it often results in symptoms such as fatigue, weakness, frequent infections, and excessive bleeding or bruising.
• Chronic Myeloid Leukemia: It is a type of blood cancer where the BCR-ABL1 gene mutation causes uncontrolled growth of white blood cells. Eventually, these white blood cells take over the other types of healthy blood cells.

To improve the quality of life by providing a chance of remission for patients suffering from such conditions, BMT stands as a sign of hope. 

Significance of BMT

A BMT involves replacing unhealthy bone marrow cells with healthy stem cells. The primary purposes of BMT are as follows:

• Restoring Blood Cells Post-Cancer Treatment: After intensive chemotherapy or radiation therapy to eradicate cancer cells, the transplant replenishes the depleted cells with healthy ones, restoring the blood cell count in the body.
• Replacing Damaged Blood Cells During Another Treatment: Chemotherapy is known to cause harm to healthy blood cells while targeting cancer cells. In the BMT procedure, cell transplants are employed to swap the damaged cells with new, healthy ones, aiding recovery.
• Introducing Cells to Combat Cancer Directly: BMT introduces fresh cells capable of directly attacking and eradicating cancer cells, providing a targeted approach in the fight against the disease.

Types of Bone Marrow Transplantation

Depending on the type of transplant, the donor source and the facility of BMT might vary. 

• Autologous Transplantation: Autologous transplantation involves harvesting healthy stem cells from the patient’s body. After intensive chemotherapy or radiation treatment, these cells are collected, stored, and reintroduced into the patient. This type of BMT is often recommended when the patient’s bone marrow is not severely damaged, such as in certain lymphomas.
• Allogeneic Transplantation: Allogeneic transplantation involves using stem cells from a compatible donor, such as a sibling or an unrelated donor. These donor cells are carefully matched to the patient’s tissue type to reduce the risk of rejection. Allogeneic BMT is often preferred in severely damaged bone marrow cases, such as chronic myeloid leukemia and severe aplastic anemia.
• Umbilical Cord Blood Transplantation: Umbilical cord blood transplantation utilizes stem cells collected from the umbilical cord and placenta after childbirth, which are frozen and preserved in cord blood banks for future use. It is used to treat blood disorders, genetic conditions, and immune deficiencies. This type of BMT is usually favored owing to its reduced risk of graft-versus-host disease, a common complication in allogeneic BMT.

BMT Procedure

Unlike a major surgery, BMT is not complex and requires shorter hospital stays. However, evaluation by a consultant hematologist or physician is mandatory. In addition, as per the Indian National Guidelines for Hematopoietic Cell Transplantation, specific criteria must be met before proceeding with transplantation.

• Based on the type of recommended transplantation, the treating physician or a healthcare coordinator will ask the individual to read, understand, and sign the Informed consent form (ICF).
• During the informed consent process, the individual can educate themselves about the procedure by clarifying doubts about the transplant process.
• After signing the ICF, the treating physician may advise a complete health examination, which includes:
  • Echocardiogram to assess heart function
  • Pulmonary function test to evaluate lung performance
  • A 24-hour urinalysis to assess kidney function
  • Blood tests determine liver function
• Bone Marrow Biopsy: This clinic-based procedure involves numbing a small area on the lower back with lidocaine. A needle is then inserted into the pelvis to extract liquid and spongy bone marrow samples for disease assessment.
• Depending on the disease, tests like CT scans, PET scans, and skeletal surveys may be done to determine the disease’s extent and location.

Post-BMT Essentials

After the BMT, a specific follow-up period is crucial to check for any early side effects and prevent future complications. Follow-up might include:

• Weekly clinic visits to check vitals, blood counts, and kidney and liver functions 
• Monitoring drug levels like cyclosporine, tacrolimus, or sirolimus
• Screening for viral infections like CMV, EBV, and adenovirus depends on the type of transplant
• Checking donor chimerism on specific days after engraftment
• Infection prevention measures for at least 100 days, including hygiene and diet precautions
• Live vaccination 24 months after transplant in cases without chronic graft-versus-host-disease or immunosuppression

BMT in India stands as a remarkable medical advancement, providing hope for individuals with hematological or immunodeficiency disorders. With different types of BMT tailored to the needs of each patient, this treatment modality continues to pave the way for improved outcomes. Ongoing research expands its scope as a treatment option for broader conditions, reflecting continual progress in medical science.