The highly cellular soft area in the hollow of the bones where all blood cells generate before circulating in the bloodstream is bone marrow. The immune system of the body relies heavily on bone marrow. As a result, the damaged bone marrow will be unable to produce essential cells, potentially compromising the patients’ overall immunity and resulting in life-threatening infections.
What is a bone marrow transplant?
When primary cells in the bone marrow (also known as stem cells since they can develop and mature into multiple cell types) become malignant, it results in a variety of blood cancers. Healthy stem cells replace these stem cells. They are from a genetically matching donor and produce healthy blood cells and heal the malignancy. Bone marrow transplantation (BMT) or stem cell transplantation describes this technique.
Reasons for bone marrow transplantation
There are several reasons for your doctor to suggest a bone marrow transplant. Leukemia, lymphoma, myelodysplasia, Hodgkin’s disease, multiple myeloma, and disorders that influence the generation of bone marrow cells, such as aplastic anemia, congenital neutropenia, sickle cell anemia, POEMS syndrome, and neuroblastoma, are examples of blood malignancies, that might lead to a person getting bone marrow transplant.
What are the eligibility criteria for donors in bone marrow transplant
If a person meets the following criteria, they could be a healthy donor for a bone marrow transplant:
Age: People between the ages of 18 and 60 who are in good health may be good candidates for a bone marrow transplant.
Weight: The maximum Body-Mass-Index (BMI) limit for registering as a potential blood stem cell donor is 40 kg/m2. Furthermore, if a person’s weight is less than 50 kg, they are not qualified to donate a blood stem.
Conditions of health: Donating stem cells is not possible for those who have the following conditions
- Conditions that affect the central nervous system or any mental illness
- Autoimmune diseases
- Chronic conditions, such as diabetes or rheumatism
- Chronic heart diseases
- Very Chronic lung diseases
- Infectious diseases, such as HIV, hepatitis B or hepatitis C, and syphilis
- Blood disorders
Pregnancy: Women who are pregnant can register as blood stem cell donors. However, they will not be able to give until they fully recover from the birth.
Types of donors:
Optimal donors: They have the same HLA tissue typing as the recipient and are frequently a sibling or, in rare situations, a parent or grandparent of the recipient.
Partially matched donors: Donors partially matched have a 50% HLA tissue match (always half-matched or half compatible) with the recipient. The recipient’s biological parents are always partially matching donors.
Alternative Donors: Donors who are not relatives to the recipient are alternative donors. They are healthy people who share the patient’s HLA tissue typing and are willing to give bone marrow stem cells.
Autologous donors: In this case, the recipients are the ones who give. We collect and preserve the stem cells in circulation here. Only after the recipient’s body creates enough healthy bone marrow cells may they give.
How to select the best donors for a patient
The doctors will select possible donors who look to be an essential match for the patient. Physical examination, blood testing, and a medical history review are all part of a basic level evaluation. A series of blood tests happen on the patient and the donor to determine the best suitable transplant option,
Human Leukocyte Antigen (HLA) test
It’s also known as histocompatibility typing or tissue typing. This blood test looks for specific proteins (HLAs) on the surface of white blood cells and other cells that act as markers, allowing the body to identify which cells belong. The patient’s blood stem cells must have genetic markers that are identical to the donor’s. As a result, an essential matching criterion is a close HLA match between the donor and the recipient.
High-Resolution DNA typing
This test determines how similar or distinct donor and recipient cells are to one another. The value difference indicates the likelihood of stem cell rejection or graft vs host illness. The transplanted tissue’s immune cells will identify the recipient’s cells as “foreign” and attack them. The healthcare staff will begin the donation procedure if the recipient sample matches the donor.
Collecting Stem cells
The healthcare staff will inform the donor about the operation, recovery process, dangers, and side effects once the donor has been chosen for bone marrow transplantation. The donor must sign a consent form if they decide to participate in the procedure. Harvesting is the process of collecting stem cells from a donor. There are two methods for collecting donor stem cells. The following are the methods:
Bone marrow harvest
This is a minor surgical operation that is usually performed in a hospital operating theatre under general anaesthetic. The collection site will be the posterior pelvic bone, which contains a substantial amount of bone marrow. The bone marrow is extracted with a syringe, and the amount depends on the weight of the recipient. After the procedure, the site will be covered with a sterile bandage.
Apheresis
It is a medical process in which stem cells are extracted from the bloodstream. It entails taking a donor’s whole blood and centrifuging it to extract particular components.
Before apheresis, the number of stem cells must be boosted, which is accomplished by using growth factor drugs such as filgrastim or plerixafor for four to five days.
Blood is extracted from a vein of the donor once the required count is obtained. A centrifuge is then used to separate the stem cells from the rest of the blood. Usually, the harvested stem cells are maintained in a freezer until they are transplanted.
Successful transplant
Following the steps and precautions mentioned above, the doctor will ensure you have the safest possible bone marrow transplant. Any person undergoing a bone marrow transplant does not have much to worry about, with recent studies showing that the success rate of bone marrow transplants has risen to 90% in India alone.
