There are many ways to classify different stem cells including yours versus someone else’s cells, or in a clinical sense what we call an allogeneic versus autologous stem cell transplant.
This post is focused on the difference between allogeneic (someone else’s cells) and autologous (your own) stem cell injections. As a stem cell biologist I have been following and using stem cells of various kinds for about 20 years. My lab at UC Davis School of Medicine has published many papers on stem cells.
If you want to learn more about the different core kinds of stem cell types, you can find facts about them by going to this educational page I wrote: multipotent, pluripotent, and totipotent stem cells.
Autologous versus allogeneic stem cells: definitions
What is the definition of autologous stem cells? Autologous comes from the root “auto” meaning self. Therefore, any time you see a reference to autologous stem cells, it is talking about the patient’s own cells. An example of an autologous stem cell transplant would be taking bone marrow cells from your hip and injecting them somewhere else in your body. Everything happens in the same person in this case.
What is the definition of allogeneic stem cells? The term “allogeneic stem cells” means that the cells are coming from someone else. That other person could be an adult or could come from placenta or umbilical cord. Note that birth-related tissues like placenta, amnion, and umbilical cord come from a baby, not from the mother. Most often these tissues are discarded, but more recently sometimes cells from them are isolated in a lab and studied or used in clinical trials. They are often sold these days as some kind of panacea as well at unproven stem cell clinics.
Autologous stem cell transplant versus allogeneic: clinical implications
In general, autologous stem cells have several advantages.
A match. First, since they are the patient’s own cells, they have little to no risk of being rejected by the immune system. This means that an autologous stem cell transplant is more likely to “take”, which we scientists call “engraft”. In other words, autologous cells are likely to stick around longer than allogeneic after a transplant. Of course, this depends on the context. For instance, autologous fat stem cells injected into the bloodstream by IV seem to be rapidly removed by the body. This happens even though the cells are the patient’s own material. As a result, this frequent offering sold by unproven stem cell clinics is unlikely to do anything helpful.
Safety. Also, autologous stem cell transplants are generally going to be safer than allogeneic because of the matching factor, but not always. Autologous does not equal safe. There have been people blinded or have other problems after getting injections of their own fat stem cell cells and possibly their own bone marrow cells into their eyes.
Allogeneic stem cell transplant advantages. There are ways that allogeneic transplants could be better, but they are somewhat less clear or more hypothetical.
One potential clear advantage is cost. As more stem cell transplants are approved in the coming decade by regulators like the FDA, allogeneic therapies may have lower price tags. This is because they can be expanded to a great scale ahead of time and frozen for use on demand. In contrast, many autologous therapies need to be made anew for each patient. This also means that another possible advantage of allogeneic cell therapies is the quick turnaround time for treating the patient.
There could be other advantages to allogeneic therapies depending on the disease and approach.
A disadvantage to allogeneic cells is that they are foreign to the patient’s body. This means that there is a high risk of the cells, once injected, simply being obliterated by the patient’s immune system. Some allogeneic stem cells may have the ability to fly under the radar of the immune system, but this is still being studied and debated. It’s important for patients to know that it is false to claim, as some unproven stem cell clinics do, that any kind of allogeneic therapy is universally going to be tolerated by patients’ immune systems.
Bone marrow transplant versus other offerings
Finally, it is crucial to know that bone marrow transplants, whether autologous or allogeneic, are fundamentally different than what is being offered at stem cell clinics.
Bone marrow transplants and the related therapy of hematopoietic stem cell transplants (including cord blood stem cells), are proven to work to help patients have a better chance to overcome blood cancers in combination with chemotherapy. These cells may have some utility in treating certain immune disorders as well, which is exciting. It is sobering, though, how severe these treatments can be overall because of the chemotherapy, but that is necessary to have the best chance to wipe out all the cancer cells.
With that context, keep in mind that using bone marrow or cord blood stem cells to do anything else is not really proven to be useful and safe. Not yet at least.
- Autologous stem cell transplant resource, Mayo Clinic.
- Stem cell transplant fact sheet, National Cancer Institute.
- Mesenchymal stem cells: immune evasive, not immune privileged, Nature Biotechnology
Disclaimer: this post is not meant as medical advice. Always consult your physician before making health-related decisions.