Definition & Overview
Bone marrow harvesting is the process of collecting bone marrow cells from a donor and transplanting it to the same person (autologous) or another person (allogeneic). If the donor is the identical twin of the recipient, the process is known as syngeneic. This procedure is performed as part of treatment for different types of diseases such as leukaemia, lymphomas, and solid tumour cancers.
The bone marrow is the soft tissue found in the inside of bones. There are two types of bone marrow; the yellow and the red marrow. The yellow marrow is mostly composed of fat cells and is found in the middle part of short bones. On the other hand, red marrow is found in flat bones and at the end of long bones like the femur and humerus. The red marrow functions as producer of red blood cells, most of the body’s white blood cells, and platelets. The red marrow is the one harvested for transplantation since it contains stem cells responsible for producing other blood cells.
Bone transplantation is done to replace a diseased bone marrow, so the body can continue producing healthy blood cells. It is also possible to develop a new immune system through the transplant of new bone marrow when the body is weakened after doses of chemotherapy or radiation therapy. In some cases, bone marrow is harvested and transplanted to help slow down certain inherited diseases.
A donor has to undergo several stringent tests to determine if he or she is a genetic match. One of these tests is HLA typing, in which human leukocyte antigens are checked for a match. These antigens are responsible for determining any foreign bodies entering the system. A match would indicate lesser chances of transplanted stem cells being rejected and attacked by the immune system.
Who Should Undergo and Expected Results
Patients who are candidates for autologous bone marrow transplant would need to undergo bone marrow harvesting. These patients are typically scheduled to undergo high-dose radiation or chemotherapy for cancer. The stem cells collected from this procedure are stored and injected back into the patient’s body after treatment. This process is meant to replace the blood cells destroyed by chemotherapy or radiation therapy. In some cases, the whole procedure is termed rescue transplant.
A close blood relative of a patient needing bone marrow transplant could also undergo bone marrow harvesting. In instances when the patient is unable to supply the needed bone marrow, close family members like a brother or a sister could become the donor. Any potential donor, even a close family member, still has to undergo several special tests to determine if they are a match to the recipient before commencing the harvest process. If a sibling is not a match, one of the parents or a close relative can be tested.
Bone marrow harvesting for transplantation is a safe procedure. The donor has to stay in the hospital recovery room for an hour or two to be closely monitored. The donor may feel weak and nauseated for several hours. They are usually allowed to go home after a day and should rest to help their body recover. Strenuous activities should be avoided while rest is advised for several days.
How is the Procedure Performed?
Bone marrow harvesting is done in a hospital operating room. Prior to the procedure, the patient is injected with a drug that prevents clotting to make it easier to collect the bone marrow. The patient is placed under spinal or general anaesthesia and is made to lie face down. The injection sites are then cleaned and made sterile. The surgeon will make several punctures in the skin over the pelvic bone or in the rear hipbone. A long hollow needle is inserted into the puncture site. Bone marrow is extracted into the attached syringes. The process is repeated until enough amount of bone marrow is collected. Concurrently, another needle is inserted into the other hipbone and bone marrow is collected from this site as well. Typically, two surgeons perform this procedure, which usually lasts for an hour or two. About a pint or two of bone marrow can be collected from a healthy adult donor, though this volume may vary according to the donor’s weight and other factors. Once done, the surgeon withdraws the needle and puts bandages on puncture sites. A pressure dressing may also be used.
In some cases, the collected red blood cells are returned to the donor through IV during the recovery period. The collected bone marrow is then filtered to remove any bone particles. Fat tissue is also removed through this process.
During an autologous bone marrow transplant, the collected bone marrow is frozen and injected back into the patient’s body after chemotherapy or radiation therapy. The marrow could be in storage for several days before being injected back or transplanted to another patient.
Possible Risks and Complications
Bone marrow harvesting for transplantation is a safe procedure. However, the patient or the donor can expect to feel tired and weak following the procedure. Soreness and pain at the puncture sites can also be expected. However, these typically resolve themselves after a day or two or the donor may be advised to take painkillers. In some cases, the donor may find it uncomfortable sitting down for long periods of time.
There is a tendency for bone marrow donors to become anaemic after the harvesting procedure. Physicians can prescribe iron supplements to address this issue.
Stem cell transplant (peripheral blood, bone marrow and cord blood transplants). American Cancer Society.
Resource guide for stem cell transplant. http://www.nbmtlink.org/documents/rg.pdf