All About Stem Cells
What are stem cells?
Most cells in the body have specific purposes. Stem cells are undifferentiated cells that do not yet have a defined role and can become almost any cell that is required. This ranges from muscle cells to brain cells. In some cases, they can also repair damaged tissues.
Stem cells are the body’s raw material. Under the right conditions in the body or a laboratory, stem cells divide to form more cells called daughter cells. These daughter cells become either new stem cells or specialized cells with a more defined function, such as blood cells, brain cells, heart-muscle cells or bone cells. No other cell in the body has the natural ability to generate new cell types.
Are there different types of stem cells?
Stem cells are divided into two main forms. They are embryonic stem cells and adult stem cells.
The embryonic stem cells used in research today come from unused embryos. These result from an in vitro fertilization procedure. They are donated to science. These embryonic stem cells are pluripotent, which means they can turn into more than one type of cell.
There are two types of adult stem cells. One type comes from fully developed tissues such as the brain, skin and bone marrow. There are only small numbers of stem cells in these tissues. They are more likely to generate only certain types of cells. For example, a stem cell that comes from the liver will only make more liver cells.
The second type of adult stem cells are induced pluripotent stem cells. These are adult stem cells that have been changed in a laboratory to be more like embryonic stem cells. Scientists first reported that human stem cells could be changed in this way in 2006. Induced pluripotent stem cells do not seem to be different from embryonic stem cells, but scientists have not yet found one that can develop every type of cell and tissue.
The only type of stem cell used to treat disease is hematopoietic stem cells. These are adult stem cells that form blood cells and are found in the bone marrow. Every type of blood cell in the bone marrow starts as a stem cell. These immature stem cells are able to make other blood cells that mature and function as needed, including red blood cells, platelets, and several types of white blood cells.
These cells are used in procedures such as bone-marrow transplants. They also help people with cancer make new blood cells after their own hematopoietic stem cells have been killed by radiation and chemotherapy.
Why are stem cells important?
Researchers hope stem-cell studies can increase understanding of how diseases occur. By watching stem cells mature into cells in bones, heart muscle, nerves and other organs and tissue, researchers may better understand how diseases and conditions develop.
Studies have shown that stem cells can be guided into becoming specific cells that can be used to regenerate and repair tissues that have been damaged or affected by disease. Some human conditions that may benefit from stem-cell therapies include spinal-cord injuries, type 1 diabetes, Parkinson’s disease, amyotrophic lateral sclerosis (ALS or Lou Gehrig’s disease), Alzheimer’s disease, heart disease, strokes, burns, cancer and osteoarthritis.
Stem cells have the potential to be grown to become new tissue for use in transplant and regenerative medicine. They can also be used to test the safety and effectiveness of new drugs, especially when testing to see if new drugs will be harmful or toxic to the heart.
New areas of study include developing stem cells that have been programmed into tissue-specific cells to test new drugs. For instance, nerve cells could be generated to test a new drug for nerve disease. The tests could show whether the new drug had any effect on the cells and whether the cells were harmed.
What conditions can be treated with stem-cell therapy for dogs?
The most common use of stem-cell therapy for dogs has been in the treatment of osteoarthritis. Other potential uses include repairing bone, ligament and spinal-cord injuries; treating kidney and liver disease, and certain inflammatory diseases of the skin and intestinal tract. I spoke this week with a client who is a veterinarian doing research on the treatment of heart diseases, including cardiomyopathy, using stem cells.
Certain types of cancer treatment with stem cells are not considered appropriate because of the risk of causing the cancer to worsen, grow or spread more rapidly if stem cells are introduced. However, some forms of cancer can be treated with stem cells taken from the dog’s own bone marrow. Research is pending to test the use of stem cells for diabetes treatment to regenerate the missing insulin-producing cells in the pancreas, as well as treatment for dogs that have lost control of their bladder function.
How is stem-cell therapy for dogs performed?
There are basically three steps in stem-cell therapy. The first involves collection of fat from your dog. This procedure is typically performed while the dog is sedated. Fat cells are most often taken from a small incision in the groin or shoulder.
The fat cells are then transferred to a specialized laboratory, where stem cells are obtained and concentrated. The final stage of treatment is the injection of stem cells into the affected area, such as the hip, elbow or knee joint. This step also requires some form of anesthesia for the dog.
Most cases are performed as an out-patient procedure. Other than rest and supportive measures, no special care is required after treatment.
Is stem-cell therapy safe?
Because stem cells are taken from your dog, there is little risk of reaction or rejection. Any injection into a joint or tendon involves some risk of inflammation, infection or injury. These procedures should be performed using strict, sterile conditions by veterinarians with special training.
Your veterinarian should discuss your dog’s risk factors before any treatment. Stem-cell therapy requires anesthesia, and although adverse reactions are rare, there is always some risk.
How successful is stem-cell therapy for dogs?
At this time, there is no definitive way to predict which dogs will benefit from stem-cell therapy. Some dogs respond favorably and show improvement within a few days. Others may take several weeks or months before any noticeable changes are seen.
It is important to have realistic expectations, as positive outcomes cannot be guaranteed. Stem-cell therapy can be repeated in cases where poor to no improvement is noted. As the research continues, hopefully progress can be made toward successful treatment of some of the more challenging diseases and conditions that affect our dogs.