Bone marrow / stem cell transplantation
Transplantation is offered to a very select group of patients who are thought to be at high risk of relapse, or to patients who have relapsed and now have their disease back under control. High chemotherapy doses destroy the cancer cells as well as normal blood cells in the bone marrow. After chemotherapy, this select group of patients then receive an infusion of new, healthy stem cells to replace the destroyed cells.
The dedicated Adult Bone Marrow and Stem Cell Transplant Program at the Hematologic Oncology Center are the largest on Long Island and Queens, performing both autologous and allogeneic transplants. It is the only transplant program in Long Island, Queens and Brooklyn that is accredited by the Foundation for Accreditation in Cellular Therapy (FACT). Accreditation is awarded because of exceptional patient care.
The program, which has been collecting bone marrow for unrelated donors for over 20 years, has been designated a National Marrow Donor Program (NMDP) Apheresis Collection Center.
Bone marrow is the soft, spongy tissue found inside bones. It is the medium for development and storage of most of the body's blood cells.
The blood cells that produce other blood cells are called stem cells. The most primitive of the stem cells is called the pluripotent stem cell, which is different than other blood cells with regard to the following properties:
- Renewal. It is able to reproduce another cell identical to itself.
- Differentiation. It is able to generate one or more subsets of more mature cells.
It is the stem cells that are needed in bone marrow transplant.
Types of stem cell transplants include:
- Autologous bone marrow transplant. The donor is the patient himself or herself. Stem cells are taken from the patient either by bone marrow harvest or apheresis (a process of collecting peripheral blood stem cells), frozen, and then given back to the patient after intensive treatment. Often the term rescue is used instead of transplant.
- Allogeneic bone marrow transplant. The donor shares the same genetic type as the patient. Stem cells are taken either by bone marrow harvest or apheresis from a genetically matched donor, usually a brother or sister. Other donors for allogeneic bone marrow transplants may include the following:
- A parent. A haploid-identical match is when the donor is a parent and the genetic match is at least half identical to the recipient. These transplants are rare.
- Unrelated bone marrow transplants (UBMT or MUD for matched unrelated donor).The genetically matched marrow or stem cells are from an unrelated donor. Unrelated donors are found through national bone marrow registries.
- Umbilical cord blood transplant. Stem cells are taken from an umbilical cord immediately after delivery of an infant. These stem cells reproduce into mature, functioning blood cells quicker and more effectively than do stem cells taken from the bone marrow of another child or adult. The stem cells are tested, typed, counted, and frozen until they are needed for a transplant.
Matching involves typing human leukocyte antigen (HLA) tissue. The antigens on the surface of these special white blood cells determine the genetic makeup of a person's immune system. There are at least 100 HLA antigens; however, it is believed that there are a few major antigens that determine whether a donor and recipient match. The others are considered "minor" and their effect on a successful transplant is not as well-defined.
Medical research is still investigating the role all antigens play in the process of a bone marrow transplant. The more antigens that match, the better the engraftment of donated marrow. Engraftment of the stem cells occurs when the donated cells make their way to the marrow and begin producing new blood cells.
Most of the genes that "code" for the human immune system are on one chromosome. Since we only have two of each chromosome, one we received from each parent, a full sibling of a patient in need of a transplant has a one in four chance of having gotten the same set of chromosomes and being a "full match" for transplantation.