Starting with the basics helps you get a better understanding of the topic. So, let’s first see what bone marrow is and what role it plays in the body.
Bone marrow refers to the soft and fatty tissue located within the cavities of the bones. Hematopoietic stem cells, which are present in both the peripheral blood and bone marrow, have the ability to differentiate into different types of blood cells, including red blood cells, white blood cells, and platelets. Red blood cells are responsible for oxygen transportation. platelets aid in blood clotting; and white blood cells play a vital role in fighting infections. The bone marrow continuously generates these stem cells to ensure a sufficient supply of the required blood cells. Certain disease conditions, such as cancer, may necessitate individuals to undergo bone marrow or stem cell transplants.
This page discusses bone marrow or stem cell transplantation, the types of stem cell transplantation, preparation, what happens during and after the stem cell transplant surgery, and the potential risks associated with the bone marrow or stem cell transplant.
Bone Marrow Transplant Surgery
Bone marrow transplant (BMT), also called stem cell transplant surgery, is a specialised treatment utilised for individuals diagnosed with specific cancers or other medical conditions. It involves collecting and filtering stem cells that are naturally present in the bone marrow and transplanting them either to the same person (the donor) or to another individual. The primary objective of BMT is to infuse normal (healthy) bone marrow cells into an individual following treatment of their diseased bone marrow to eliminate abnormal cells.
Since its introduction, bone marrow transplantation has demonstrated successful outcomes in managing conditions including leukaemia, lymphomas, aplastic anaemia, immunodeficiency disorders, and select solid tumour cancers.
Bone Marrow Transplant Types
The bone marrow transplant type depends on who the donor is. These include:
Autologous transplant
As the term ‘auto’ in the word autologous implies ‘self’, this type of transplant involves taking the stem cells from your own blood prior to receiving radiation therapy or high doses of chemotherapies. These stem cells are then stored in the specialised freezers so that you can receive them after your treatment. After your chemotherapy and radiotherapy, these stem cells are re-introduced in your body to produce healthy (normal) blood cells. This type of transplant is often referred to as a ‘rescue transplant’.
Allogenic bone transplant
The term ‘allo’ refers to ‘other’, implying that taking stem cells from another person (donor). Genetically, the donor and recipient (patient) have the same makeup. In order to obtain stem cells, a genetically compatible donor—typically a sibling —must either extract bone marrow or undergo apheresis. The following donors might serve as additional allogeneic bone marrow donors:
- Matched unrelated bone marrow transplants, or MUDs: In this bone marrow transplant, the stem cells are taken from an unrelated donor who is genetically matched.
- Parent: when a parent serves as a donor and the genetic match is at least 50% that of the recipient, a haploid-identical match occurs.
Umbilical cord blood transplant
This is a form of allogenic transplant where the stem cells are obtained from the umbilical cord of the newborn soon after the baby is born. Till the time they are required for a transplant, these stem cells are frozen and kept in storage. Since the blood cells from the umbilical cord are immature, exact matching is not as important. Because there are fewer stem cells, the blood counts recover at a slower pace.
Why is Bone Marrow Transplant Surgery Needed?
Bone marrow transplantation is necessary to cure various diseases and types of cancer. It becomes a treatment option when the dose of radiation or chemotherapy required to eliminate cancer cells is so high that it permanently destroys or damages a person’s bone marrow (stem cells). Additionally, a bone marrow transplantation may be required if the bone marrow has been damaged by a disease condition.
The purposes of a bone marrow transplantation include:
- Replacing non-functioning or diseased bone marrow with normal bone marrow that functions properly. This is true for conditions such as sickle cell anaemia, leukaemia, and aplastic anaemia.
- Restoring the normal function of the bone marrow after administering significant radiation and/or chemotherapy doses to treat a cancer (malignancy). This process is commonly known as ‘rescue’.
- Regenerating a new immune system that can combat existing or residual leukaemia or other cancers that were not eliminated by previous radiation or chemotherapy treatments.
- Replacing the bone marrow with genetically normal and healthy bone marrow to prevent further damage caused by a genetic disease process, such as adrenoleukodystrophy and Hurler’s syndrome.
Before the procedure, one should have an in-depth discussion with the doctor and bone marrow transplant experts to consider the risks and benefits.
Preparation for the Bone Marrow Transplant
Recipient preparation
The patient who will receive the transplant will go through the following before the procedure:
- Comprehensive evaluation: The bone marrow transplant team performs a thorough examination prior to the transplant. The risks and benefits of all potential treatment options are discussed.
- Medical history and physical examination: The patient undergo a physical evaluation and thorough medical history, as well as a multitude of tests to assess their organs (heart, liver, kidney, and lungs) and blood function.
- Pre-transplant procedures: A few days prior to the transplant, the patient will be required to visit the transplant centre. During the visit, they undergo hydration, additional evaluations, and the insertion of a central line (also called a catheter, which is surgically positioned into a vein, typically in the chest area), allowing for the administration of medications and blood products during the transplant.
- Donor Selection: In the case of an allogeneic transplant, a suitable donor must be identified. The search for a matching donor can be challenging and time-consuming, particularly if a sibling match is not available.
Donor preparation
- There are several possible donor sources, including umbilical cord stem cells from an unrelated or related person, oneself, parents, siblings, or other family members. In some cases, other family members may be tested for compatibility if they express a willingness to help.
- If a potential donor has been identified as a suitable match for a patient who needs a bone marrow transplant, they will be put through additional testing in order to assess the extent of the compatibility and evaluate their general health, genetic analysis, and virus exposure. The procedure for donating bone marrow will be explained to the donor.
- Once a match is confirmed for a patient requiring a bone marrow transplant, stem cells will either be collected through a peripheral blood stem cell collection or a bone marrow harvest. A needle is used to extract stem cells from the soft interior of the bone marrow during a bone marrow harvest. Alternatively, stem cells can be extracted from circulating blood cells in a peripheral blood stem cell collection. Donations of peripheral blood stem cells have become more frequently performed than bone marrow harvests. Cord (umbilical) blood, collected at the time of birth and stored for future use, is another source of stem cells.
- When preparing for an autologous transplant (a transplant using your own stem cells), a procedure called apheresis is conducted.
- Prior to apheresis, the person receives daily injections of a growth factor to stimulate stem cell production and facilitate their movement into the bloodstream for collection.
- During the apheresis process, blood is extracted from a vein and passed through a machine that separates it into various components, including the targeted stem cells, which are then frozen for future use in the transplant, while the remaining blood components are returned to the person’s body.
Bone Marrow Transplant Procedure
- Once the pretransplant evaluations and procedures are complete, the conditioning phase will be initiated, which involves undergoing chemotherapy and, in some cases, radiation. The goal of conditioning is the elimination of cancer cells in cases where the individual is being treated for cancer that has the potential to metastasize (spread to other parts of the body), immune system suppression, and preparation of the bone marrow for the engrafted stem cells.
- The specific approach to conditioning is determined by various factors, including the individual’s overall health, the underlying disease, and the transplant type being conducted. The individual may receive a combination of radiation and chemotherapy or solely one of these treatments as part of their conditioning regimen.
- Following the administration of conditioning chemotherapy or/and radiation, the bone marrow transplant is infused into the bloodstream via a central venous catheter. This method resembles having a blood transfusion as opposed to surgery.
- The transplant infusion does not hurt. During the process, the patient will be awake.
After the Bone Marrow Transplant
When the body receives new stem cells, the transplanted stem cells naturally find their way to the bone marrow, where they initiate the production and development of fresh, healthy blood cells. This is known as engraftment. Typically, it takes a few weeks for the blood cell count in the body to gradually normalise and reach the standard range following a bone marrow transplant. However, it is possible for this process to take longer than usual for some people.
During the initial period following the bone marrow transplant, supportive care is provided to minimise and manage infections, treatment-related side effects, and complications. This encompasses vigilant watching of vital signs, regular blood tests, precise tracking of fluid intake and output, regular weight assessments, and the provision of a hygienic environment. Additionally, some people may require periodic platelet and red blood cell transfusions till the time the bone marrow starts making adequate amounts of cells.
In addition, certain steps must be taken with respect to medications and lifestyle factors. In the case of an allogeneic transplant using donor stem cells, immunosuppressive medications may be prescribed for preventing graft-versus-host disease and minimising immune system reactions. Furthermore, medications will be provided to prevent infections while the immune system recovers. It is also crucial to make dietary modifications to maintain a healthy weight and address the potential side effects of chemotherapy and radiation. Working closely with a nutrition specialist, a personalised eating plan will be developed to meet the specific needs and accommodate the lifestyle.
Potential Risks Associated with the Bone Marrow Transplant
The following signs and symptoms might occur after a bone marrow transplant:
- Pain in the chest
- Shortness of breath
- Blood pressure drops
- Flushing, chills, and fever
- Taste alterations
- Hives
- Headache
- Nausea
The following factors may contribute to bone marrow transplant complications:
- Whether an individual had an allogeneic, umbilical cord, or autologous blood transplant
- Differences in tissue compatibility between donors and recipients
- Age
- Overall well-being
Possible complications include:
- Anaemia
- Clotting in the liver’s small blood vessels
- Bleeding in the lungs, brain, intestines, and other areas
- Cataracts
- Damage to the liver, kidneys, and heart
- Premature menopause
- Children undergoing a bone marrow transplant experience delayed growth
- Graft failure, which occurs when newly transplanted cells fail to adapt to the host and stop producing stem cells
- Graft-versus-host disease (a condition when your own body is attacked by donor cells)
- Serious infections
- Mucositis (soreness and inflammation of the throat, mouth, oesophagus, and stomach)
- Stomach issues such as diarrhoea, nausea, and vomiting
Alternative names for Bone Marrow Transplant
- Stem cell transplant surgery
- Stem cell transplantation
- Bone marrow transplant surgery
- Bone marrow transplantation
