Bone marrow is a liquid-gelatinous tissue that occupies the interior of bones. It plays a central role in the development of blood cells, as it contains the hematopoietic stem cells that produce the components of blood: leukocytes (white blood cells), erythrocytes (red blood cells) and platelets. Leukocytes are the most important agents of the immune system, as they protect against infections. In red blood cells, oxygen is transported from the lungs to cells throughout the body and carbon dioxide is carried from them to the lungs to be expired. And finally, platelets are part of the blood clotting system.
Your transplant is a type of treatment for some diseases that affect blood cells, such as leukemias and lymphomas. In addition, it is used in other conditions not related to cancer, such as severe aplastic anemia (which is characterized by a lack of production of blood cells in the bone marrow), Fanconi anemia and sickle cell anemia.
This process consists of replacing a diseased or deficient bone marrow with normal bone marrow cells. With this, it is expected that the bone marrow will reconstitute, becoming healthy and functional again.
Types of bone marrow transplants
Autologous or autogenic transplantation
Bone marrow precursor cells (bone marrow or peripheral blood cells) are from the transplanted individual (recipient). They are collected and frozen for later use.
This type of transplant is generally chosen for the treatment of diseases that do not affect the quality of the bone marrow (i.e., those that do not originate directly from the bone marrow) or when the disease has diminished to the point of no longer being detected (remission status).
Some examples include:
- Acute myeloid leukemia;
- Non-Hodgkin’s Lymphoma;
- Chemosensitive Hodgkin’s Disease;
- Multiple myeloma;
- Germ cell tumor; and
- Neuroblastoma.
Allogeneic transplant
The marrow precursor cells come from another individual (donor), according to the compatibility level of the blood material. The first option is always for the marrow of a brother. If the recipient (patient) does not have a sibling or is not compatible, compatibility with the mother and father is verified. If there is no matched related donor, a matched unrelated donor is sought in the bone marrow bank records.
The indications are:
Allogeneic bone marrow transplantation:
- Acute myeloid leukemia;
- Acute lymphoblastic leukemia / lymphoblastic lymphoma;
- Ph+ acute lymphoblastic leukemia;
- Chronic myeloid leukemia;
- Severe acquired or constitutional aplastic anemia;
- Myelodysplastic syndrome, including chronic myelomonocytic leukemia;
- Primary cellular immunodeficiency;
- thalassemia;
- Primary myelofibrosis in an evolving phase;
- Chronic lymphoid leukemia;
- Multiple myeloma;
- Indolent non-Hodgkin’s lymphoma; and
- Chemosensitive Hodgkin’s disease.
Allogeneic peripheral blood transplantation:
- Acute myeloid leukemia;
- Acute lymphoblastic leukemia / lymphoblastic lymphoma;
- Ph+ acute lymphocytic leukemia
- Chronic myeloid leukemia;
- Myelodysplastic syndrome, including chronic myelomonocytic leukemia;
- thalassemia;
- Primary myelofibrosis in an evolving phase;
- Chronic lymphoid leukemia;
- Multiple myeloma;
- Indolent non-Hodgkin’s lymphoma; and
- Chemosensitive Hodgkin’s disease.
Transplantation of bone marrow precursor cells obtained from umbilical cord blood
Umbilical cord stem cells are used. The main advantage is that the cells are immediately available, that is, there is no need to locate the donor and have him removed from the bone marrow. In addition, complete compatibility between cord blood and patient is not required.
However, there are also factors against it. The main thing is the dose used, since the donation occurs in a single collection (with no possibility of a new collection), right after delivery, and the volume is restricted – therefore, the number of stem cells can be limited. Thus, there is a weight limit for the patient depending on the amount of stem cells taken from the cord blood: he must weigh between 50kg and 60kg. The good news is that it is currently possible to use a technique of joining two cords for the same patient, which allows for use in adults with greater weight.
The main indications for this type of transplant are:
- Acute myeloid leukemia;
- Acute lymphoblastic leukemia / lymphoblastic lymphoma;
- Ph+ acute lymphoblastic leukemia;
- Severe acquired or constitutional aplastic anemia;
- Myelodysplastic syndrome, including chronic myelomonocytic leukemia;
- Primary cellular immunodeficiency;
- thalassemia;
- Primary myelofibrosis in an evolving phase;
- Indolent non-Hodgkin’s lymphoma; and
- Chemosensitive Hodgkin’s disease.
Bone marrow transplant applications
How is a bone marrow transplant performed?
Firstly, they are compatible with specific tests. Among the samples, it is the samples that make the recipient’s blood and make the control to verify that there are compatible parts, minimizing the risk of the marrow being fully reproduced by the recipient.
When there is compatibility, the worshiper is twice a procedure in a surgical center, lasting approximately anesthetized hours. It consists of performing several punctures with needles in the posterior bones of the pelvis and aspiration of the marrow. There is no harm or compromise to the donor’s health.
In attacking the transplant, the cells need first a treatment to the recipient and its own marrow. Once this is done, you will receive a healthy marrow in a relatively simple process, as if it were a blood transfusion. As new marrow cells circulate through the bloodstream, they lodge in the bone marrow, where they develop.
How do you know if the transplant was successful?
There are two ways to tell if your bone marrow transplant has worked:
1) The patient’s blood count is normal. This means that the red blood cell (red blood cell), leukocyte (white blood cell) and platelet count is within the range expected for a healthy individual. It is important to inform that, soon after the transplant (two weeks later), these values are expected to drop to very low levels, which affects the immune system and leaves the patient more prone to opportunistic infections, hemorrhage and fatigue. To avoid these complications, the medical team may opt for blood and platelet transfusions, in addition to the use of antibiotics. As the new stem cells begin to multiply, more red blood cells are formed. With this, the blood count normalizes, indicating that the transplant was successful; and
2) The cancer is under control. Curing cancer is often the main goal of a bone marrow transplant. And it may be possible in some cases, such as in certain types of leukemia or lymphoma. For other diseases, cancer remission may be the best achievable outcome. This means no more signs or symptoms of the neoplasm.
Possible adverse effects and complications
The main risks for the patient are related to infections and chemotherapy drugs used during treatment. As the marrow recovers, its new cells grow with a new “memory”. As they are the body’s defense cells, they can recognize some of the individual’s organs as foreign. This complication, called graft-versus-host disease, is relatively common, of variable intensity, and can be controlled with appropriate medications. In bone marrow transplantation, rejection is relatively rare, but it can happen. That is why the analysis and selection of the donor and the prior preparation of the patient are so important.
The risks for bone marrow donors are minimal. A few weeks after the aspiration procedure, the bone marrow will have fully recovered. Symptoms that may eventually occur after donation are local pain, asthenia (temporary weakness) and headache. In general, they are transient symptoms and are easily controlled with simple medications, such as painkillers.
