What Is Hematopoietic Stem Cell Transplantation?
Hematopoietic stem cell transplantation or bone marrow transplantation refers to the placement of new and healthy stem cells with dysfunctional and defective bone marrow. It was first introduced in the 1950s based on observational studies. Stem cell transplantation is indicated as a treatment modality for several malignant or non-malignant blood and immunological disorders. Transplantation allows the body to produce completely healthy and mature stem cells and enhance its functional abilities. Hematopoietic stem cells refer to the blood cells and blood-forming cells involving red blood cells, white blood cells, and platelets. These stem cells are found in the spongy tissues, a part of long bones called bone marrow. Bone marrow is where all the stem cells proliferate and mature and are then transmitted into the bloodstream.
What Are the Types of Hematopoietic Stem Cell Transplantation?
Two types of hematopoietic stem cell transplantation are indicated as a required treatment for several disorders:
1. Autologous Hematopoietic Stem Cell Transplantation:
The word auto-suggests the same or self. An autologous transplant is a process in which the stem cells are removed from the patient's body before effective therapies such as high-dose chemotherapy and radiation therapy are administered and stored in a freezer because these therapies have several cycles in a given interval and can affect the normal cells of the body. As these therapies are over the removed stem cells are injected back into the body. In an autologous transplant, the chances of recurrences of the disorder are high.
2. Allogeneic Hematopoietic Stem Cell Transplantation:
The word allogenic suggests other. An allogeneic transplant refers to the process in which the stem cells are replaced by taking the stem cells from another person called the donor to the patient's body after the chemo and radiation therapy. The donor should have a completely similar match of a protein called human leukocyte antigens, which are present in the blood. This match will lead to graft versus cancer cell effect and tends to kill the abnormal cells. But, if the donor's blood protein does not match with the patient's, it may cause graft versus host disease, leading to a complicated condition in which the cells start to destroy the body's normal cells.
3. Umbilical Cord Blood Transplant:
It is an allogeneic stem cell transplant; in this transplant, mostly the stem cells are collected from the newborn's umbilical cord, which attaches the mother to the fetus for nourishment and growth. At the time of birth, the umbilical cord's blood is stored and can be used in transplantation, and the stem cells present in the blood are not completely mature, so there is less need to match the human leukocyte's antigens protein with the patient.
4. Parent-child Transplant and Haplotype Mismatched Transplant:
In this type of transplantation, the protein human leukocyte antigens may or may not match with the parents or siblings. There are only 50 % chance of a good match with the blood relation. But nowadays, this type of practice is increasing for treating cancer patients.
5. Synergetic Bone Marrow Transplantation:
Synergetic bone marrow transplantation is a process in which the stem cells are transplanted between identical twins; the chances of graft versus host disease are significantly less because, in identical twins, the blood protein human leukocytes antigen has a good match.
What Are the Indications of Hematopoietic Stem Cell Transplantation?
Hematopoietic stem cell transplantation is a non-surgical treatment modality for treating malignant or non-malignant disorders.
The following are some examples of disorders that require stem cell transplantation.
1. Malignant Conditions:
Hodgkin's Lymphomas:
Hodgkin's lymphoma is defined as lymphoid neoplasm that arises within the lymph nodes. The main significant cells present in Hodgkin's lymphomas are called Reed-Sternberg cells. In Hodgkin's lymphoma, autogenic stem cell transplantation indicates a better outcome.
Non-Hodgkin's Lymphomas:
Non-Hodgkin's lymphomas includes a large group of heterogeneous neoplasms of lymphoid tissues and blood. It is more common than Hodgkin's lymphoma; this malignancy does not contain Reed-Sternberg cells. Instead, it occurs from T cells, B cells, and natural killer cells. The lymph nodes present in the neck and the head are commonly involved as the extranodal tissues of this area. Non-Hodgkin's lymphoma can be treated with autogenic stem cell transplantation.
Acute Lymphocytic Leukemia:
Acute lymphocytic leukemia leads to the abnormal growth of the lymphocytes. Bone marrow produces an excessive amount of immature lymphocytes. The immature lymphocytes crowd out the normal cells and affect their functions and performance. It is most commonly seen in children and spreads to lymph nodes, liver, and other organs. Hematopoietic stem cell transplantation is needed when acute lymphocytic leukemia is a refractory type that reoccurs after the treatment and requires more medical attention for a better prognosis. Allogeneic stem cell transplantation can be used.
Acute Myeloid Leukemia:
Acute myeloid leukemia is defined as the excessive production of immature leukocytes, also called myeloblasts, that rapidly fill the bone marrow and crowd out the normal cells, leading to rapid progressive infections. Most commonly seen in adults involves lymph nodes, spleen, and bone marrow. Hematopoietic stem cell transplantation is needed when the inductive therapies do not show better results. Allogeneic type of stem cell transplantation can help in the treatment of acute myeloid leukemia
Chronic Myelogenous Leukemia And Chronic Lymphocytic Leukemia:
Chronic myelogenous leukemia is a very uncommon type of leukemia; it is a myeloproliferative disorder mainly characterized by the proliferation of myeloid cells in the bone marrow. Chronic lymphocytic leukemia leads to the accumulation of mature lymphocytes in the bone marrow. Allogeneic hematopoietic stem cell transplantation can be a treatment of choice in both types of leukemia.
Myelodysplastic Syndrome:
Myelodysplastic syndrome comprises a group of blood-related disorders involving abnormal hematopoiesis and dysplastic and hypercellular bone marrow. Allogenic stem cell transplantation can be the treatment of choice in high-risk patients.
Other malignant Conditions:
Myelofibrosis, essential thrombocytosis, polycythemia vera, and solid tumors can be treated with hematopoietic stem cell transplantation.
2. Non-Malignant Conditions:
Aplastic Anemia
Aplastic anemia is considered a disorder of red bone marrow. The reduction of red bone marrow causes the accumulation of fatty tissues. Bone marrow disorders occur because of exposure to X-rays, tuberculosis, and viral hepatitis. Allogeneic stem cell transplantation is indicated with conventional immunosuppressive therapy in aplastic anemia.
Sickle Cell Anemia:
Sickle cell anemia is defined as an inherited disease with sickle-shaped red blood cells. It occurs due to the abnormal hemoglobin called hemoglobin S. In this type of anemia, the red blood cells attain sickle shape and become more fragile, resulting in easy hemolysis. These sickle-shaped cells get clogged into the small and narrow capillaries, which can cause obstruction in the blood flow and decrease oxygen supply to the body's parts. Allogeneic stem cell transplantation is indicated for the treatment.
Thalassemia:
Thalassemia is defined as a genetic disorder that refers to abnormal hemoglobin. In general, normal hemoglobin has an equal number of polypeptide chains, whereas, in thalassemia, the chain production becomes imbalanced because of the defective synthesis of globin genes. In the cases of thalassemia, allogeneic stem transplantation is recommended multiple times with supportive treatment.
Some Other Non-Malignant Conditions:
Several combinations of deficiencies, sclerosis, and systemic lupus erythematosus are treated by hematopoietic stem cell transplantation.
What Is Human Leukocyte Antigen Typing?
In the procedure of hematopoietic stem cell transplantation, it is very important to match the protein called human leukocytes antigen present in the blood to the patient's blood to the donors to create a graft versus cancer cell effect that allows the stem to proliferate and fight against the cancer cells.
To get a proper match, a process of human leukocyte antigen typing is done before injecting the stem cells into the patient's body. There are different types of donors, like stem cells from non-related donors, cord blood, and haploidentical donors, to determine the best donor polymerase chain reaction, and next-generation sequencing is practiced in the process. There are different types of donors, like stem cells from non-related donors, cord blood, and haploidentical donors.
What Are the Complications of Hematopoietic Stem Cell Transplantation?
There can be certain complications and risks in the transplantation of stem cells.
1. Anemia.
2. Bleeding in the lungs, brain, and intestine.
3. Toxicity.
4. Graft versus host disease.
5. Chest pain.
6. Depressive in the blood pressure level.
7. Shortness of breath.
8. Clotting in the small vessels.
9. Fever and chills.
10. Headache.
Conclusion
Hematopoietic stem cell transplantation is a kind of advanced medical treatment modality used in several malignant and non-malignant conditions, and it involves the placement of new, healthy stem cells into patients. Stem cell transplantation is a very effective and non-surgical choice of treatment with a good prognosis.
