Stem cells are powerful, adaptable cells that can be used to promote healing and reverse damage. Stem cells are found in various places within the human body, but the purest stem cells are found in the umbilical cord.
Stem cells can be used in treatments for many different types of diseases. One of the main places young stem cells are found is in cord blood, which can be stored at birth and saved for future use if needed. Stem cells are also found in other places in the human body, including blood and bone marrow.
Sources of Stem Cells
Regenerative transplants use stem cells from three main sources:
- Bone marrow
- Umbilical cords
Bone marrow stem cells
Bone marrow is tissue located in the center of your bones, making healthy blood cells that strengthen your immune system and fight off outside infections. A large amount of cells are located in bone marrow, and doctors frequently use hip bone marrow for most transplants, since the stem cells in this area are the most plentiful.
When doctors remove bone marrow, the patient receives anesthesia. This puts them to sleep and numbs any pain from the surgery. Doctors then insert a large needle, and pull the liquid marrow out. Once enough bone marrow is harvested, the solution is filtered and cryogenically frozen.
When a patient needs bone marrow for a transplant, stem cells are thawed and injected into the bloodstream. The cells then make their way to the bone marrow, and start producing new blood cells – this process usually takes a few weeks.
Peripheral blood stem cells
While most people have a small amount of stem cells in their bloodstream, donors produce more stem cells after taking growth factor hormones. Doctors give these medications a few days before stem cell harvesting, which makes the bone marrow push more cells into the bloodstream.
During the harvesting procedure, doctors use a catheter to draw out blood. The blood moves through a machine, which separates stem cells and allows these cells to be put into storage. This process takes a few hours, and may be repeated over several days in order for doctors to get enough stem cells.
Stem cells are injected into the veins during a peripheral blood transplant, and naturally work their way to the bone marrow. Once there, the new cells start increasing healthy blood count. Compared to bone marrow transplants, cells from peripheral blood are usually faster, creating new blood cells within two weeks.
Umbilical cord blood stem cells
Umbilical cord blood contains a large amount of stem cells. If parents sign up for personalized storage or donation, medical staff will remove stem cells from the umbilical cord and placenta. The blood is then cryogenically frozen, and put into long-term storage.
While the stem cell count is smaller during a cord blood transplant, these cells multiply quickly, and researchers are studying new methods to increase cells naturally. Compared to bone marrow, cord blood cells multiply faster and don’t require an exact match type to complete a successful transplant. Some techniques medical experts are testing to increase the amount of stem cells include:
- Making greater numbers of cord blood cells in a lab before the transplant
- Using cord blood from multiple sources
- Adding new cord blood cells to the existing patient’s cells
Finding the best stem cell source for your family
While all three stem cell sources are used in similar procedures, they each have advantages and drawbacks. Bone marrow transplants are the traditional form of therapy, but peripheral blood cells are becoming more popular, since doctors often get more stem cells from the bloodstream.
The procedure for peripheral blood harvesting is easier on the patient than a bone marrow transplant, and stem cell transplants are faster. However, the chances for graft-versus-host disease, where donated cells attack the patient’s body, are much higher after a peripheral blood transplant.
Cord blood transplants are the least invasive, since they come from an external source – the umbilical cord.
The biggest advantage for cord blood is the “immaturity” of the cells, which means transplants do not require an exact match. For bone marrow and peripheral blood transplants, donors need to match the patient’s cellular structure. However, cord blood cells can adapt to a wide variety of patients, and don’t require donor matching. Chances for graft-versus-host disease are also much lower for cord blood transplants.
Patients and doctors can avoid graft-versus-host disease, and other dangerous side effects, by using HLA matching.
Types of Stem Cells
Multipotent stem cells
Multipotent stem cells develop into organ system cells, and are made from two different types of cells:
- Hematopoietic Stem Cells (HSCs)
- Mesenchymal Stem Cells (MSCs)
Hematopoietic stem cells (HSCs)
HSCs can become any type of blood cell or cellular blood component inside the body, including white blood cells and red blood cells. These cells are found in umbilical cord blood and are multipotent, which means they can develop into more than one cell type.
This cell type has been used in over 1 million patient transplants around the world.
Mesenchymal stem cells (MSCs)
MSCs can turn into bone, cartilage, fat tissue, and more. Although they are associated with bone marrow, these cells are also found in umbilical cord blood. These cells can function as connective tissue, which connects vital organs inside the body. Like HSCs, MSCs are multipotent.
Pluripotent stem cells
Pluripotent cells can replace any type of cellular system in the body. Cord blood contains a rich variety of pluripotent stem cells, which allows treatment for a large amount of patients.
Induced pluripotent stem cells (iPS)
iPS cells are artificially-made pluripotent stem cells. This technique allows medical staff to create additional pluripotent cells, which will increase treatment options for patients using stem cell therapy in the near future.
Embryonic stem cells (ES)
ES cells are pluripotent, and similar to iPS cells, but come from an embryo. However, this kills the fertilized baby inside the embryo. This type of cell also has a high chance for graft-versus-host disease, when transplanted cells attack the patient’s body.
Drawbacks to adult stem cells
Your adult cells have one disadvantage to cord blood cells – they cannot change their cell type. When stem cells from cord blood and tissue are transplanted, they adjust to fit the individual patient and replace damaged cells. Adult stem cells are also older, which means they have been exposed to disease, and may damage patients after the transplant. Compared to cord blood cells, adult cells have a higher chance for graft-versus-host disease.
Cord blood contains a wide variety of cell types, but there are different stem cell sources available to patients in need of a transplant.