Flipping the Right Switches – Stem Cell Therapy
by Ben J. Character, DVM
It’s the “latest and greatest” therapy that is being further researched to – optimistically – help with all kinds of diseases and ailments. Stem cells: Cells that have the potential to become another type of cell. These cells are already being used with success in treating human problems such as strokes and particular types of intestinal damage, and we are now finding application for them in horses, dogs, and cats.
When you think of cells that have the potential to become any and every cell in the body it is quite natural to think of the very first cell that is created with the union of the sperm and egg. This cell is called the embryo, from which we derive the term “embryonic stem cell”. Of course, ultimately from this cell comes every cell of the body – so that you might think of it as the “mother of all stem cells.” As it turns out, it is not quite as robust as first thought. In fact, research and clinical trials with embryonic stem cells have been quite disappointing while adult stem cells have produced much greater and more lasting results.
Even though the embryonic stem cell is very active in making all kinds of new cells, it is not the only cell type with this potential. Inside every cell of the more than one trillion cells found in your dog’s body is a set of blueprints – the same set that was in the embryonic stem cell. This set of blueprints is called DNA. To make it even better, every set of DNA blueprints found in every cell has all the information needed to make any other structure found in the body. [The one exception to this are the actual spermatozoa (male) and egg (female) cells, which only carry one-half the genetic material of the individual.]
What this means is, the information to reconstruct cells and materials needed for repair of damaged areas of the body, or orchestrate the whole process, is always available. The key is the ability to “turn on” the correct sections of DNA (genes) and/or “turn off” other sections that inhibit whatever process you desire to be initiated. The machines and the raw materials to heal the body are already in the body; it just takes getting them in the right location and flipping the right switches.
What are Stem Cells?
Stem cells are most famous for their ability to be “turned on” to change into another type of cell. Most cells in the body are fairly inactive, not really doing much replication. Nerve cells are, for all practical purposes, non-reproductive. Most other cells just sort of do their jobs and are then replaced by another of the same cell type once they reach the end of their lifespan, maybe replicating themselves only a few times.
Some cells in the body are in a constant state of replication, but the majority of these cells simply replicate themselves – their own type. They play the role as production cells. Examples of these cells are those that line the gastrointestinal tract and the cells that form the foundational layers of the skin.
Other cells are more robust in their abilities and these are our stars – the adult stem cells. For each of the major tissues types, there are cells that can differentiate into any number of the different types of cells found within that type of tissue. But even though these cells can replicate themselves into a variety of cells, it is not really this function that is what makes them so powerful. While related to this ability, it is actually the ability of the stem cells to orchestrate repairs that is most important, as we will see shortly.
As such, these cells form the foundation for the current therapeutic use of stem cells in veterinary medicine.
Where do these stem cells come from?
Your animal stores nutrients as fat in adipose tissue. Within this tissue are fat cells sitting in a matrix, or scaffolding, of connective tissue. As your dog builds more fat supply, there is need for more places to store the fat, along with more blood vessels and other components. Within these bands of tissue are multiple cells (in addition to the fat cells) called the adipose-derived stem cells. While this source of stem cells is not the only available source, it does provide an easy to harvest, concentrated, and non-essential supply source for the cells necessary for stem cell therapy.
It is important note here that when stem cells are taken from the patient that will eventually receive them back, this is called autologous stem-cell therapy. Unlike getting blood from another person, stem cell therapy (as described here) is more analogous to receiving a blood transfusion of your own blood. Therefore, there is no chance of the cells being rejected, it precludes the necessity for any “typing” or “matching”, and it means that as long as the processing of the fat to concentrate the cells is done in an appropriate way, there is very little risk of adverse reaction. In addition to this, typically most patients’ fat samples can result in many more stem cells being collected than are needed. These additional cells can be frozen and retrieved later for additional treatments when needed.
How Does Stem Cell Therapy Work?
Stem cell therapy, in a nut shell, is simply the placement of multipotent cells into damaged areas where these cells are induced (by chemicals produced by the body at the damaged site) to work to repair a damaged area. This is called regenerative medicine.
Even though stem cells are capable of dividing and becoming other types of cells, as noted above, this is not all that stem cells do. Stem cells are very involved in acting as a type of cellular administrator. In terms of importance this trumps even their ability to differentiate into various types of cells.
This important function of stem cells makes them like the air-traffic controllers of the body. They receive input from chemical, physical, and electrical signals in the area. Then based on these signals, the stem cells send out instructions (via their own chemical signals) that induce other cells to do their jobs in the repair process. Sometimes these cells are close by; other times, the cells are recruited from other areas of the body. But the main point is that it is not necessarily the stem cells that are doing all the grunt work.
So why does adding stem cells to a damaged area promote healing? The answer is related to timing. And without getting too involved in the details, putting stem cells in the body in high numbers, especially when they are put directly at the site of injury, gets them there faster and in greater numbers than would normally be the case. The result is that stem cells are there at a time in which they can start modulating the healing process sooner, directing healing that normally occurs later in the process to begin earlier (reducing less functional healing such as scaring). It also means that they can, at an earlier time, turn off the appropriate cells that are no longer needed.
Here are the basic steps for stem cell therapy:
- Adipose (fat) tissue is harvested from the patient in need of the stem cell therapy.
- Tissue is sent to a laboratory so that the multipotent cells can be separated from the tissue and prepared for injection back into the patient.
- Stem cells are shipped back to the veterinarian and injected into the patient at the damaged area.
Because of the variety of multipotent cells that are harvested from the adipose tissue, there is a wide range of applications for this source of stem cells. In many cases, the cells are injected directly into the damaged area (tendons, joints) while other times they are given intravenously so that the blood stream can take them to the areas of need (liver, kidney, etc.)
How are Stem Cells Being Used?
In veterinary medicine most stem cell therapy is being performed in dogs and horses. In dogs, the focus at this time is in using this therapy for treatment of osteoarthritis (OA), while in horses the application is also directed toward ligament and tendon injuries. Use in OA cases are typically aimed at animals in which the dog has stopped responding to conventional therapy (use of anti-inflammatories), conventional therapy is not an option (possibly due to other medical issues), and/or there is not a total joint replacement therapy, for whatever reason. However, it is becoming increasingly common for stem cells to be use at the first indication of OA instead of waiting.
I personally think we will begin seeing more owners start falling into this last category, especially if the results gained from the use of stem cells
continue to be proven and the price continues to fall. It is less expensive to have stem cell therapy performed on a dog’s hips than to have just one total hip replacement, and if further OA can be prevented in the performance horse there is high value.
While it is absolutely proper to use anti-inflammatory medications for early onset OA, stem cell therapy will begin to beg the question: For how long? How long should we use the drugs to reduce the inflammation (rarely do we eliminate it) in an attempt to allow them to run, swim, jump on the joints, when we could inject them and promote pain relief and healing? This question has not been answered, but I will bet that as the price of stem cell therapy continues to drop, it will not be long before it will become just as economical to go ahead and start using the cells versus buying the drugs long-term.
What’s the Future for Stem Cell Therapy?
The addition of another helpful therapy for OA and other acute and chronic diseases is a welcomed development. Areas in which stem cells are not predicted to be of use are for cancers and systemic infections. But stem cells can still do a lot of good. Other areas in which the therapy is currently being evaluated include the treatment of immune medicated diseases, such as inflammatory bowel disease, as well as heart and liver disease, and kidney disease in cats.
In terms of the use and cost of stem cell therapy, one is rising while the other is falling. As you can tell, stem cell therapy is a new modality that is full of potential. We are just beginning to see what all the use of these powerful self-healing cells might produce. Stay tuned for more!
If you are interested in stem cell therapy for your animal please contact us for more information.