Many patients with serious primary immune deficiencies such as SCID, WAS, or CGD require a Blood and Marrow Transplant (BMT) for cure of their disease. BMT
is also known as a Hematopoietic Stem Cell Transplant (HSCT) and the terms BMT and HSCT are often used interchangeably. BMT is a form of stem cell therapy
and is life-saving for many infants and children with serious primary immune deficiencies. Bone marrow stem cells used for transplant come from another
person (i.e. not the person with the primary immune deficiency). Stem cells will grow and form a new and normal immune system in the person affected by the
primary immune deficiency. Stem cells come from one of three sources: (1) Bone Marrow – this is what is most commonly known as a “Bone Marrow Transplant”;
(2) Peripheral Blood (bone marrow stem cells found in the blood); or (3) Umbilical cord from a newborn baby (contains a large number of bone marrow stem
In general, the best stem cell donor is a sibling to the patient who is both (1) a match (also called an HLA-match, or human leukocyte antigen match), and
(2) NOT affected by the same disease. For each sibling, these criteria only occur about 20% of the time. Your doctor will want to take blood from each
sibling to determine if they would be a suitable donor.
If a sibling is not available or is not a suitable match, other possible donors may include (1) a parent or sibling who is not a match (sometimes called a
“haploidentical” donor) (2) an unrelated person found on a stem cell registry, or (3) an unrelated umbilical cord blood donor. There are many factors that
go in to deciding who the best donor is when a matched sibling is not available. Speak to your doctor about these decisions.
Your doctor may recommend that certain medications be given to your child before the stem cells are infused. This is referred to as a conditioning
regimen and usually consists of various combinations of chemotherapy (drugs that open up space in the bone marrow to accept the new stem cells, and that
suppress the patient’s immune system so that it does not reject the new stem cells) and possibly other immune suppressing medications. These drugs will
usually be administered intravenously in the days or weeks before BMT. Many different conditioning regimens are available. Some forms of SCID may not
require a conditioning regimen. There are many factors that go in to deciding a conditioning regimen. As a result, it is impossible to make general
recommendations on this website about what is the best conditioning regimen, or whether a conditioning regimen is needed or not. Your doctor will be able
to discuss with you the recommendations regarding the conditioning regimen.
One common question asked by patients and parents is, “How do the new stem cells get into the body?” The answer is, the stem cells go right into the blood
stream! Stem cells do not need to be injected directly into the bone marrow with large needles. Patients do not need to be brought to an operating room for
a major surgery to receive the stem cells. In fact, the stem cell infusion is actually a minor procedure, usually done in the patient’s hospital room. The
procedure is in fact very similar to getting a blood transfusion. Patients will usually have a central line inserted before BMT. A surgeon or other doctor
will insert the central line in a minor surgery. A central line is a type of longer intravenous line (of which there are various types in use) that goes in
through the skin (often on the chest, but they can be other places) and ends in the large veins inside the chest. The stem cells are infused through the
central line and into the blood stream. The infusion takes anywhere between 15 minutes and 4 hours, depending upon the type of product and the volume. Once
in the blood stream, the stem cells eventually “home” to the bone marrow (which is continuous with the blood) – where they will make new blood and a new
immune system over time for the patient.
BMT can be a difficult process for patients and their families. Patients need to be treated at specialized hospitals that are used to treating young
infants and children with primary immune deficiencies (many of these hospitals are members of the PIDTC). Patients and their families may need to be away
from their home for months at a time. Patients may spend weeks or months in a hospital after the transplant. Patients can become very sick – both before
the transplant and after. Infections are a major problem for BMT patients, particularly those with primary immune deficiencies. Please see the section on
“What are the complications of Blood and Marrow Transplant?” for further information. Follow up occurs for years after BMT and probably will be life-long.