Guide to Stem Cell Transplants
A stem cell transplant is the process in which healthy stem cells are injected into the body to replace damaged or diseased cells. Stem cells are cells from which other cells in the body are created. Stem cells can divide to produce more stem cells (regeneration), and some stem cells have the ability to differentiate into specialized cells that perform specific functions in the body, i.e. they can become muscle cells, heart cells, blood cells, bone cells, et cetera. The stem cell transplant process can be likened to a liver or other organ transplant, only stem cells are transplanted instead of organs.
Where Are Transplanted Stem Cells Taken From?
There are a number of stem cell sources. Embryonic stem cells are found in very young embryos called blastocysts. These versatile stem cells not only divide into new cells but have the remarkable ability to develop into any of the 220 cell types found in the human body. Adult stem cells are largely found in the bone marrow or in the blood surrounding the bone marrow, as well as in umbilical cords. While the potential for adult stem cells to differentiate is more limited, recent findings indicate that adult stem cells may be more versatile than previously believed.
Stem Cell Collection and Transplantation
During a transplant procedure, if stem cells are taken from the bone marrow, a needle is inserted into the bone to extract a small amount of the liquid portion of the bone marrow in a process called bone marrow aspiration. This action is repeated until enough stem cells are collected for the stem cell transplant recipient. The bone marrow cells are then placed in a blood bag and frozen for storage and/or future use.
If stem cells are derived from blood, blood is removed from the body via a needle and then passed though a special machine that separates the stem cells from the blood. This method of stem cell collection is called apheresis. The remainder of the blood is then returned to the body via a needle or through a central venous catheter. In some cases the growth factor G-CSF, a protein found naturally in the body, is intentionally added to the blood in order to stimulate growth of new stem cells.
For the actual transplant, a central venous catheter is inserted into the chest. Stem cells hanging in a blood bag then flow via the catheter into the recipient's blood and to the bone marrow. Approximately one to three weeks after a stem cell transplant, new healthy cells should begin to be produced.
After a Stem Cell Transplant
Following a stem cell transplant antibiotics are administered to prevent or fight infection, and the blood will be tested repeatedly to check on blood levels - i.e. counts of red blood cells, white blood cells, and platelets in the body. Sometimes transfusions of blood cells and platelets are necessary until the body begins to produce them on its own.
Stem cell transplants are not always successful as the body can reject the stem cells or suffer a later relapse. This is more likely when stem cells are derived from a donor (allogeneic transplant) rather than from the recipient's own body (autologous transplant).
Sometimes severe infections can develop after a stem cell transplant and antibiotics may be necessary for even months after the procedure. Previous immunizations should also be updated, and the body's immune system may take up to one or two full years in order to completely recover after a stem cell transplant.