Transplant Candidates
A Transplant Physician must consider many factors when determining whether a patient is a candidate for a stem cell transplant. These include the type of disease, the stage of disease, how aggressive it is, the prognosis and the responsiveness of the disease to prior treatment, as well as a patient's age and general physical condition.
Types of Stem Cell Transplants: Overview
There are many types of stem cell transplants. This section defines each of the various types of transplants. First, stem cell transplants are defined by the source of the stem cells.
- Bone marrow stem cells are obtained directly from the marrow space within the donors bones, typically the pelvis. Obtaining stem cells from bone marrow requires that first a compatible donor be found and that then they be willing and available to undergo the bone marrow extraction procedure. While stem cells from a bone marrow often demonstrate quicker engraftment resulting in the recipients cell counts increasing more rapidly there is an increased risk of the complication known as Graft vs Host disease.
- Peripheral blood stem cells (PBSC) are obtained from the peripheral blood after the donor has received medication to cause the bone marrow to release stem cells into the circulation. The process requires that the donor attend an Apheresis clinic for a few hours over several days to be connected to a machine that removes the stem cells from the circulation. This procedure is often used to collect autologous stem cells from an adult who has a malignant disease and is about to start irradiation and/or chemotherapy treatment.
- Cord blood stem cells are obtained from the umbilical cord blood. Umbilical cord blood stem cells while taking longer to engraft, present fewer long term problems due to complications such as Graft vs Host disease, which in itself can be fatal. If collected and frozen at birth they are also readily available when needed. Cord blood stem cells are also available immediately in case of emergency and present an additional treatment option for some ethnicities that are not often represented in public banks.
Stem cell transplants are further categorized based on the donor who provides the stem cells.
- Allogeneic stem cell transplants (allografts) refer to stem cells that are taken from one person and given to another.
- Autologous stem cell transplants (autografts) refer to stem cells that are collected from an individual and given back to that same individual.
- Syngeneic stem cells refer to stem cells that are taken from an identical twin of the recipient. These types of transplants are quite rare.
