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 by the source of the stem cells.

• Bone marrow transplants are those that are obtained from the bone marrow. However, they are rarely performed today in myeloma because of the ability to collect stem cells from the peripheral blood (see below). Bone marrow transplants are sometimes used if insufficient numbers of stem cells can be obtained from the peripheral blood.
  
  
• Peripheral blood stem cell (PBSC) transplants are obtained from the peripheral blood. PBSC transplants are now performed much more often than bone marrow transplants because they are easier to collect, they provide a more reliable number of stem cells, the procedure puts less strain on the donor's system, and the patient recovers more quickly
  
  
• Cord blood transplants refer to transplants where the stem cells are obtained from umbilical cord blood. Historically they have not been used frequently due to limited numbers of stem cells that can be collected from each umbilical cord. Recently, however, exciting new data have been generated using multiple cord blood units from more than one donor.

Stem cell transplants are further categorized based on the donor who provides the stem cells.

• Autologous stem cell transplants (autografts) refer to stem cells that are collected from an individual and given back to that same individual. Most stem cell transplants in myeloma are autologous transplants.
  
  
• Allogeneic stem cell transplants (allografts) refer to stem cells that are taken from one person and given to another. Currently, these types of transplant are performed much less frequently in myeloma in the US and are usually performed in the context of clinical trials.
  
  
• Syngeneic stem cell transplants refer to stem cells that are taken from an identical twin of the recipient. These types of transplants are quite rare

Lastly, there are also several types of transplants under investigation in clinical trials.

• A tandem autologous transplant, also known as a double autologous transplant, requires the patient to undergo two autologous stem cell transplants within 6 months.
  
  
• A mini (nonmyeloablative) allogeneic transplant involves the use of moderately high-dose chemotherapy in combination with an allogeneic stem cell transplant.