Science in Action
Did You Know? Apheresis can play an important role in treating serious illness.
What is apheresis?
Apheresis, derived from the Greek word meaning “to separate,” is a medical technology used to separate a donor or patient’s blood into different components. The donor or patient is connected to an apheresis instrument via one or two intravenous lines and their blood is funneled into a centrifuge to be separated into these components. Once separated, the specified component is collected or replaced, and then the rest of the blood is returned to the donor or patient’s body.
A single apheresis instrument in a donor center or hospital can perform several different cell collection procedures. For example, in a donor center, plateletpheresis (see below box) can be performed on qualified donors to collect
platelets to be donated to patients who have low platelet counts. Using this same procedure, plasma and red blood cells can be collected from qualified donors to be used in transfusions to patients during surgeries or hospitalizations.
Collecting stem cells using apheresis
Volunteer donors or patients can also donate stem cells using the apheresis instrument that can then be then used for stem cell transplants. If the patient donates their own stem cells for their transplant, this is called an autologous transplant. If a patient receives stem cells from a matching donor (based on Human Leukocyte Antigens (HLA), the genetic markers of the immune system), this is called an allogeneic stem cell transplant.
Prior to the stem cell collection, the patient or donor is given a medication to increase the number of stem cells circulating in the blood stream. The collection of stem cells can take 4-6 hours and if a larger amount of stem cells are required for the specified treatment, may be repeated over 2-3 days.
There are other methods that can be used to collect stem cells, including bone marrow aspiration or removal from fat tissue, but apheresis is the least invasive option.
Stem cell collections by apheresis are most commonly used for cancers of the blood system, including lymphomas, leukemias and multiple myeloma. As cancer patients require intensive chemotherapy that can destroy their bone marrow and prevent them from creating enough blood cells, the collected stem cells can then be used to restore the normal cells of the bone marrow.
Similarly, some diseases are caused by excessive numbers of certain cells and by abnormalities of the proteins and other substances dissolved in the plasma. In these cases, plasmapheresis (see below box) might be used to temporarily separate the blood into its components and remove the plasma from the body.
The unwanted plasma can be collected and replaced with donated plasma or albumen while the other components are returned to the body. Although only a small volume of blood is removed from the body at any one time, large quantities of blood can be processed in this way, leading to a significant reduction in the level of cells or substances responsible for the disease.
The apheresis field
Apheresis specialists can be nurses or medical technologists and must be specially trained to perform apheresis procedures. These specialists work in hospitals, clinics and private offices. They may perform the apheresis procedures as part of the patient’s routine treatment or as part of the many clinical trials being performed all over the United States and other countries that are working to provide proof that apheresis procedures are viable treatments and/or cures for specified diseases.
The apheresis field is rapidly growing and is becoming one of the most evidence-based medical fields. Besides performing collections, many apheresis professionals are also collecting data on how to perform apheresis; the outcomes of all types of apheresis procedures to document the most efficient way to perform apheresis; and if apheresis works as the treatment, or as part of the treatment, for a specified disease. Many physicians and nurses are also working to promote apheresis-related education, research, and advocacy initiatives on behalf of donors and patients.