What is a Stem Cell?
Stem cells are the primary cells in the human body responsible for the formation, proliferation, or repair of all tissues. For example, the liver requires its stem cells, nerve tissue requires its stem cells, and blood requires its stem cells. Regarding blood formation, stem cells (hematopoietic stem cells) are most commonly found in the bone marrow. They can also be found in infants’ peripheral and umbilical cord blood.
What is Bone Marrow Transplantation?
Bone marrow transplantation is a procedure in which healthy bone marrow is collected from a donor and infused into the recipient (patient) through a vein.
BONE MARROW TRANSPLANTATION – PERIPHERAL STEM CELL TRANSPLANTATION
Both procedures are collectively called Hematopoietic Stem Cell Transplantation (HSCT).
Is There a Difference Between Bone Marrow Transplantation and Stem Cell Transplantation?
The fundamental goal is to collect hematopoietic stem cells and administer them to the patient. This can be done using bone marrow, which is rich in hematopoietic stem cells, or stem cells obtained from blood (peripheral blood or umbilical cord blood). The methods used for stem cell collection can vary, leading to differences in side effects and complications.
How Are Stem Cells Collected?
1- Special needles can collect stem cells from the donor’s bone marrow under anaesthesia.
2- Stem cells in circulating blood can be collected via a vein using a specialised device. The donor rests with an intravenous line inserted in the arm, similar to giving blood, which is a simple and painless process. Before the procedure, donors receive an injection to increase the number of stem cells in the bloodstream temporarily. The method does not require operating room conditions. The collected cells are stored in liquid nitrogen at -196°C and are thawed and infused into the recipient as needed.
What Are the Sources of Stem Cells?
Bone Marrow:
They are collected under general or spinal anaesthesia in a sterile operating room using bone marrow aspiration needles. The procedure takes about 1-2 hours to collect adequate bone marrow for the recipient.
Circulating Blood:
Stem cells are collected from the blood using an apheresis device. Needles are placed in the donor’s veins, or a catheter is used if the veins are unsuitable. The process takes about 3-4 hours, depending on the amount of stem cells needed, and may be repeated if necessary.
Umbilical Cord:
Stem cells can be collected from the umbilical cord at the time of birth.
How Many Types of Stem Cell Applications Are There?
Allogeneic Stem Cell Transplantation:
Transplant from another person. Stem cells are collected from the bone marrow or peripheral blood (from the veins) of a donor, a sibling, a relative, or an unrelated individual and then transferred to the patient.
Autologous Transplantation:
Transplant of the patient’s stem cells. The patient’s stem cells are collected, frozen after chemotherapy to eliminate the underlying blood disease, and re-infused after high-dose chemotherapy. This method generally has fewer complications since the stem cells are the patient’s own.
Syngeneic Transplantation:
A transplant from an identical twin.
Diseases Treated with Stem Cell Transplantation:
- Acute Myeloblastic and Acute Lymphoblastic Leukemias (AML, ALL)
- Chronic Myelogenous Leukemia (CML)
- Hodgkin and Non-Hodgkin Lymphomas
- Multiple Myeloma
- Bone Marrow Failure Syndromes (Myelodysplastic Syndromes, Aplastic Anemia)
- Paroxysmal Nocturnal Hemoglobinuria
- Inherited Diseases (Thalassemia, Immunodeficiency Disorders, etc.)
- Primary Amyloidosis
- Solid Tumors (Testicular Cancer, Ovarian Cancer)
Source: Turkish Bone Marrow Transplantation Foundation, Blood and Bone Marrow Association
