Bone Marrow Transplantation
The most important feature of bone marrow is that it contains stem cells that can transform into blood cells, which help to maintain a strong immune system and eliminate infections. Stem cells can transform into other blood cells as needed and play an active role in ensuring the healthy functioning of body systems. Therefore, bone marrow is an important tissue where critical cells are produced.
• Table of Contents
• What is Bone Marrow?
• What are the Types of Bone Marrow?
• What Cells are Produced in Bone Marrow?
• What are the Diseases of Bone Marrow?
• What are the Symptoms of Bone Marrow Diseases?
• What is a Bone Marrow Transplant Unit?
• What Diseases are Treated by Bone Marrow Transplant Unit?
What is bone marrow?
Bone marrow (Medulla Ossea) is a spongy, soft, and fatty tissue located in the center of flat and long bones such as hip bones, thigh bones, and breastbones. It supports the growth of stem cells that are present inside the cells and have not yet differentiated. These stem cells can differentiate into white blood cells (leukocytes), red blood cells (erythrocytes), and platelets when required.
The lifespan of red blood cells, white blood cells, and platelets in the body is limited. Therefore, there is a continuous need to produce new blood cells. The production of these new blood cells by the bone marrow depends on the body's needs. In cases of infection, the number of white blood cells increases. In situations where the body requires oxygen, the number of red blood cells increases. In cases of bleeding, the number of platelets increases.
What are the types of Bone Marrow?
Bone marrow can be divided into two types: red bone marrow and yellow bone marrow. Both types contain blood vessels. Red bone marrow produces all types of blood cells. It is found in flat bones such as the skull, sternum, and ribs, as well as in the ends of long bones. Red bone marrow produces red and white blood cells and platelets. On the other hand, yellow bone marrow functions as a fat store. Stored fats can be converted into energy. Yellow bone marrow gets its name from the color of its stored fats and is mainly found in the central cavities of long bones in the arms and legs. It can also produce red blood cells in case of tissue damage. Therefore, a small amount of blood cells can also be produced in yellow bone marrow. Moreover, all bone marrows in newborns are red, but as they age, yellow bone marrow begins to form, and the number of red bone marrow cells decreases.
What Cells are Produced in Bone Marrow?
The cells produced in the bone marrow are white blood cells, red blood cells, and platelets.
What is a white blood cell, also known as leukocyte or lymphocyte?
White blood cells, also known as leukocytes, are crucial for a healthy immune system, despite only making up about 1% of the blood. These cells play a significant role in preventing and treating infections. There are different types of white blood cells, such as lymphocytes, monocytes, and granulocytes. White blood cells produced by the bone marrow produce antibodies to fight infections caused by cuts, injuries, or infections that enter the body through the mouth and nose. The number of lymphocytes can increase when the body fights foreign substances.
Monocytes mostly live inside cells but transform into macrophages when they move to tissues. Macrophages, which persist in tissues for a long time, kill harmful microorganisms, clean up dead cells, and activate other cells of the immune system.
Granulocytes, which are the general name for some white blood cell groups, live in the bone marrow for a few weeks and are used in cases of infection. The bone marrow contains a large number of granulocytes. When there is an infection in the body, these white blood cells (leukocytes) can effectively fight against the infection and reach all tissues. There are three different types of granulocytes: neutrophil granulocytes, eosinophil granulocytes, and basophil granulocytes.
What is a red blood cell, also known as erythrocyte?
Red blood cells, also known as erythrocytes, are the most abundant cells in the blood and are responsible for carrying oxygen from the lungs. Red blood cells are the blood cells that provide the oxygen-carbon dioxide cycle in the tissues. In a healthy adult, more than 200 billion red blood cells are produced daily.
Red blood cells can live up to 120 days in the body, so they need to be constantly replenished. Aging cells are destroyed by macrophages and released into the bloodstream.
What is Platelet / Blood Platelet?
Platelets, also known as thrombocytes, are produced in the bone marrow as a result of the thrombopoiesis process. They play a crucial role in blood clotting and stopping bleeding. Therefore, the number of these cells can increase in the area of a cut. On average, 150,000 to 500,000 platelets are produced per microliter of blood. Low levels of platelets in the body can prevent blood from clotting properly, which can cause internal bleeding.
What are Bone Marrow Diseases?
The bone marrow, which is crucial for the production of blood cells, can cause various diseases related to blood. Some of these diseases are:
• Multiple Myeloma
• Aplastic Anemia
• Sickle Cell Anemia
• Mediterranean Anemia (Thalassemia)
• Paroxysmal Nocturnal Hemoglobinuria
• Non-Hodgkin Lymphoma
• Hodgkin Lymphoma
• Chronic Myeloid Leukemia
• Chronic Lymphocytic Leukemia
• Acute Lymphoblastic Leukemia
• Myelodysplastic Syndrome
What are the Symptoms of Bone Marrow Diseases?
Anomalies in the number of blood cells produced in the bone marrow can cause some commonly observed symptoms, including:
• Fever: May be seen in those who do not have enough healthy white blood cells.
• Weakness, pale appearance, and fatigue: May be seen in the absence of hemoglobin carried by red blood cells.
• Increased infection: Associated with the decrease of healthy white blood cells that fight infection.
• Shortness of breath: The decrease in the number of red blood cells can lead to less oxygen going to the tissues and cause shortness of breath.
• Easy bleeding and bruising: The decrease in platelet count makes it difficult for blood to clot.
In addition to these symptoms, other symptoms such as sudden weight loss, night sweats, joint and bone pain, swollen lymph nodes, abdominal pain, vomiting, seizures, and confusion may also be observed.
What is a Bone Marrow Transplant Unit?
A bone marrow transplant is a procedure where the bone marrow, which produces the body's blood cells, is replaced with stem cells from either the patient's own body or from a compatible donor. This is necessary when the bone marrow is damaged or not functioning properly due to certain infections, blood cell disorders, or chemotherapy treatments. The stem cells, also known as hematopoietic stem cells, not only regenerate the bone marrow but also differentiate into various blood cells such as red blood cells, white blood cells, and platelets.
The process of a bone marrow transplant involves obtaining stem cells from the patient's own bone marrow or from a compatible donor, which are then stored under suitable conditions for a period of time. After the patient's bone marrow is eliminated with intense chemotherapy or radiation therapy, the stem cells are infused back into the patient. The stem cells settle in the bone marrow regions and begin to produce new bone marrow tissue, which in turn regenerates blood cell synthesis.
Since the bone marrow transplant process involves a long and intense treatment that includes the collection and storage of stem cells, patient preparation for the transplant, chemotherapy or radiation therapy, and the transplant itself, it is often carried out and monitored in specialized clinics called Bone Marrow Transplant Units. Patients require intense medication and blood product treatment before and after the transplant, so they must be assessed for various health conditions and treated accordingly before the transplant. The Bone Marrow Transplant Unit is responsible for the evaluation of the patient before the transplant, the management of the transplant process, and the follow-up and treatment after the transplant. The patient's blood values are monitored at regular intervals to ensure the success of the transplant. The patient is susceptible to infections, bleeding, and anemia during the bone marrow purging chemotherapy and radiation therapy, so close monitoring and necessary treatment is critical. The patient's close monitoring and treatment are also crucial during the stem cell collection and bone marrow regeneration processes after the transplant.
What Diseases Does Bone Marrow Transplantation Unit Treat?
Bone marrow transplantation is a method that comes to the forefront in the treatment of certain hematological health problems. Depending on the health problem and the patient's clinical condition, stem cells for bone marrow transplantation can be obtained from the patient's own body or from another person with tissue compatibility. Therefore, bone marrow transplantation can be applied in the treatment of the following conditions:
Hematologic cancers occur when any cell produced from the bone marrow multiplies uncontrollably. Leukemias, which are blood cancers, can occur especially when cells belonging to the white blood cell class multiply. In addition, diseases such as polycythemia vera can occur when cells belonging to the red blood cell group multiply, essential thrombocythemia when cells belonging to the platelet group multiply, and multiple myeloma when plasma cells multiply. Since stem cells in the bone marrow are prone to forming cancer cells in hematological cancers, bone marrow transplantations using stem cells obtained from donors can be performed. However, in some diseases, the patient's own stem cells can also be used in transplantation.
Lymphomas, also known as lymphatic cancers, occur when special white blood cells called lymphocytes collect in the lymph nodes of the body and show uncontrolled growth. Since some of the lymphocytes that cause lymphoma originate from the bone marrow tissue, bone marrow transplantation can be considered as a treatment option.
Bone Marrow Failure Due to Chemotherapy
Chemotherapy treatment can be used in the treatment of various diseases and different types of cancer. However, some drugs used in chemotherapy can damage the stem cells in the bone marrow, resulting in suppression and insufficiency of varying degrees in the bone marrow after treatment. If this insufficiency leads to a decrease in the number of red blood cells, white blood cells or platelets in patients, it can cause health problems such as anemia, susceptibility to infections or bleeding, and bone marrow transplantation may be necessary.
Aplastic anemia is a condition where the bone marrow fails to produce enough blood cells due to various reasons, either congenital or acquired. In this disorder, the bone marrow tissue in the bones is severely depleted or reduced. One of the most effective methods of treating aplastic anemia is through a bone marrow transplant.
Sickle Cell Anemia
In individuals with sickle cell anemia, the hemoglobin protein responsible for carrying oxygen in the red blood cells is genetically faulty. As a result, the affected red blood cells may assume a sickle shape and cause blockages in the blood vessels, leading to various complications. Since the production of red blood cells in the bone marrow is genetically defective in sickle cell anemia, one of the most effective treatments is through a bone marrow transplant using genetically healthy bone marrow stem cells.
In conditions where genes responsible for hemoglobin production in red blood cells are faulty or incomplete, hemoglobin molecules cannot be produced as required or are produced in a functionally weak form, similar to sickle cell anemia. Thalassemia, also known as Mediterranean anemia, results in a lifelong anemia problem due to the inadequate functioning of hemoglobin molecules. Therefore, bone marrow transplantation, which can produce healthy red blood cells, may be necessary for treatment.