We are in the midst of an exciting time of medical breakthroughs: cellular and gene therapies are being developed to create cancer vaccines, immunotherapies to treat life-threatening diseases, and potential future treatments for conditions such as Parkinson’s disease or macular degeneration that can destroy a person’s quality of life and shorten their lifespan.
Today, the only cure for many types of blood cancer, sickle cell, and inherited immune disorders is still a transplant of hematopoietic stem cells (HSC) from a matching donor.
When you join Gift of Life Marrow Registry, you may be called as a matching donor for a specific patient, or possibly the development of a next generation therapy. Different types of cells may be collected for these different purposes.
Hematopoietic [hee-MAT-oh-poy-ET-ick] stem cells (HSC) are the immature cells found within both the bone marrow and the circulating blood that develop into all the types of blood cells: red blood cells, white blood cells, and platelets. There are multiple sub-types of white blood cells that fill different roles within the immune system.
HSC are a major component of the bone marrow and are also found in the circulating blood, where they are called peripheral blood stem cells (PBSC).
HSC are the cells that Gift of Life collects for transplant – whether a donor is requested for a PBSC transplant or a bone marrow transplant, the goal of both procedures is to replace a patient’s diseased bone marrow with new, healthy cells that create a blood and immune system free of disease.
PBSC transplants are requested more than 90% of the time for patients, with less than 10% of requests for bone marrow, usually for children who will benefit from getting the full range of cells found in the bone marrow.
To learn about how a PBSC donation is collected, read this article.
To learn how a bone marrow donation is collected, read this article.
When a transplant recipient is taking longer to recover than expected, the transplant physician may request the donor to provide a donor leukocyte infusion (DLI) – a transplant of only white blood cells (leukocytes). A DLI will help boost the recipient’s immune system and aid in their recovery. Leukocytes develop from hematopoietic stem cells and make up a significant part of the immune system, working to prevent infection and diseases. A DLI is easier to collect than PBSC because large amounts of leukocytes are always found in the blood and are easily collected.
There are multiple types of white blood cells performing different functions:
When a donor is invited to give cells for research to develop new therapies, they typically donate mononuclear cells. These cells are characterized by having a single, round nucleus and typically include lymphocytes and monocytes (see above). They are collected from the circulating blood, similar to donating PBSC.
MNC are used in clinical research because they provide researchers with excellent data about cell function and the response of the human immune system to pathogens, toxins, and cancer. MNC also have the potential to create cancer treatments without necessarily having a perfect donor match, which could bring treatments or cures to thousands of patients who do not have other options.