Encyclopedia of Health and Medicine

one marrow transplantation 133
IV line in a different VEIN. Before PBSC the person
may receive injections of a medication to stimulate
the bone marrow to increase its production of
blood stem cells, to increase their numbers in the
blood. The blood yields a lower volume of blood
stem cells than does bone marrow.
See also BLOOD TRANSFUSION.
bone marrow transplantation A therapeutic
procedure to replace the BLOOD STEM CELLS, the
functional component of BONE MARROW, with
healthy donor BLOOD stem cells. Typically the
preparation process for the BONE marrow removes
T-cells and sometimes other leukocytes (white
blood cells) to lower the likelihood of ANTIGEN
response in the recipient. Common reasons for
bone marrow transplantation include
• some types of LEUKEMIA
• some types of lymphoma
• some other cancers that have not responded to
first line treatments
• severe aplastic ANEMIA
Bone marrow transplantation is a complex and
fairly high-risk procedure because the recipient’s
native bone marrow must first be destroyed,
which wipes out the body’s IMMUNE RESPONSE capability.
Doctors accomplish this through high-DOSE
CHEMOTHERAPY or RADIATION THERAPY. After this
preparation, the recipient must remain in protective
isolation in the hospital to limit exposure to
pathogens such as viruses and BACTERIA.
The transplant recipient receives the bone marrow
blood stem cells, tissue-matched for compatibility
between donor and recipient, via infusion
into an intravenous line, much like receiving a
BLOOD TRANSFUSION. The transplanted blood stem
cells migrate to the bone marrow where they
establish themselves (a process called engraftment).
The migration and engraftment takes
about three to four weeks, after which the transplanted
blood stem cells begin producing new
blood cells. The immune functions of the bone
marrow and blood cells begins to return in about
six months, though is not complete for as long as
two years. During this replenishment stage the
person remains especially vulnerable to INFECTION.
As well, some people take IMMUNOSUPPRESSIVE THER-
APY to reduce the risk for rejecting the transplanted
blood stem cells. Immunosuppression
further limits the immune response.
The primary risks of allogeneic (volunteer
donor) bone marrow transplantation are infection
and, with allogeneic donation, rejection of the
transplanted blood stem cells. There is no risk for
rejection with autologous donation. Infection,
however, can erupt at any time and has high risk
for serious or fatal consequences for as long as the
person’s immune response cannot provide protection.
Early intervention with ANTIBIOTIC MEDICA-
TIONS can head off or reduce the severity of many
bacterial infections. Frequent blood tests monitor
the return of healthy blood cells to the circulation.
The success of bone marrow transplantation is
highly variable and depends on numerous factors,
including the kind of cancer and the general
health of the person aside from the cancer. When
successful, bone marrow transplantation can put
the cancer into extended and sometimes permanent
REMISSION.
See also BONE MARROW DONATION; CANCER TREAT-
MENT OPTIONS AND DECISIONS; GRAFT VS. HOST DISEASE;
ORGAN TRANSPLANTATION.