Introduction#
When people hear “ treatment,” many picture stem cells being placed into the body to replace damaged tissue with new cells.
So what is actually administered in real treatment? The short answer: what is administered differs by therapy. Sometimes the stem cells themselves are administered; sometimes cells made from stem cells are used; and sometimes they are given as a “processed cell product” made by culturing and processing cells.
The most basic form: treatment that administers living cells#
In stem-cell-based , a processed cell product containing living cells is basically administered into the patient's body. The cells used may be “autologous”—taken from the patient—or “allogeneic”—taken from another person.
In treatment using mesenchymal stem cells (MSCs), for example, the flow is: collect tissue (such as fat) → isolate and the needed cells → check quality → administer to the patient.
Japan's Ministry of Health, Labour and Welfare handles human cells that have undergone culture or other processing as “specified processed cell products” and similar categories, requiring certain controls for the manufacturing facilities and for safety.
It is not always “stem cells themselves” that go in#
In , what is administered is not necessarily the stem cells themselves. For example, there is research and medical care in which pluripotent stem cells such as iPS cells are differentiated into target cells—cardiomyocytes, nervous-system cells, retinal pigment epithelial cells, or other tissue-forming cells—which are then used in treatment.
In other words, the concept is: stem cells → produce the target cells → administer those cells.
In fact, the “regenerative medical products” handled by (the Pharmaceuticals and Medical Devices Agency) include products in which human cells are cultured or otherwise processed for rebuilding, repairing, or forming body structure and function, or for treating or preventing disease.
There are also treatments that administer “something other than cells”#
Even where the term regenerative medicine is used, what is administered is not always living stem cells. Research is also advancing on substances secreted by stem cells and components obtained from cells—for example, various factors secreted by stem cells and extracellular vesicles (EVs) are subjects of study.
One point to note here: “treatment that administers stem cells” and “treatment that uses components produced by stem cells” are not the same thing.
In particular, “stem-cell ” and “exosomes” are distinguished from treatments that administer the cells themselves, because under the Ministry of Health, Labour and Welfare's definition they do not constitute regenerative medicine and therefore do not require an application as regenerative medicine.
Your own cells—or someone else's cells#
Where the administered cells come from also matters.
Autologous cells: cells collected from the patient are used—for example, collect cells from your own tissue → culture/process → administer to yourself.
Allogeneic cells: cells collected from someone other than the patient, such as a healthy donor, are used. In this case too, the collected cells are not administered as-is; they are used after the necessary processing and quality control. Which is used depends on the treatment method and the type of cells.
At present in Japan, the use of allogeneic cells is not permitted for regenerative medicine; the use of allogeneic cells is limited to conventional and -marrow transplantation.
When given by drip, a “liquid containing cells” is being administered#
Some stem-cell treatments administer cells by intravenous drip. In that case, the drip liquid is not equal to stem cells alone. In practice, the cells to be administered are suspended in an appropriate solution and given as a “cell suspension.”
The image is: drip bag → liquid containing cells → administration into the blood vessel. Note, however, that the composition of the administered fluid, the cell count, and the method of administration differ by treatment.
Do stem cells that enter the body “become organs as they are”?#
This is another point that is easily misunderstood. It is tempting to think that “stem cells given by drip travel to the damaged organ and become new cells there,” but the actual action of cell therapy is not that simple.
Especially for mesenchymal stem cells and the like, research is investigating not only the administered cells themselves rebuilding large amounts of target tissue, but also actions mediated by the various factors the cells secrete.
Therefore, “putting in stem cells = those cells replace the new tissue” cannot be assumed uniformly. The expected action and mechanism differ depending on the type of cells used, the administration method, and the target disease.
The words “stem cell treatment” alone cannot tell you what is administered#
As we have seen, the words “stem cell treatment” alone cannot tell you what actually enters the body. At minimum, confirm the following points.
What is being administered? Whether it is the stem cells themselves, cells differentiated from stem cells, a processed cell product, or components produced by cells rather than cells.
Where were the cells collected from? Whether they are your own cells or cells derived from another person.
How have they been processed? What culture is performed, what processing is done, and what quality control is in place.
How are they administered? Drip infusion, intravenous injection, local injection, tissue transplantation, and so on differ by treatment.
Summary#
Even under the single label “stem cell treatment,” what actually enters the body varies: 1) stem cells themselves, 2) target cells made from stem cells, 3) cultured and processed cell products, 4) methods that use components produced by stem cells, and more.
Therefore, when considering regenerative medicine, it is important to confirm not just the explanation “this is stem cell treatment,” but “which cells are collected from where, how they are processed, what is administered, and by what method.”
For regenerative medical products, PMDA publishes information on approved products and package inserts. Checking such public information is also important for understanding what a treatment involves.
Going deeper#
Once the basics click, the next question is whether a given stem cell is already an approved treatment or still a research subject — the same word can mean very different things.
Reading the and Safety categories next, and checking unfamiliar terms in the glossary, will sharpen how you read future material.
Common questions#
Q. What actually goes into the body?
A. It may be living cells, cells expanded by culture, or only cell-derived products such as exosomes — check whether materials name the contents.
Q. How are the cells made?
A. Either collected from you and cultured, or taken from a donor. Ask about the source, culture period, and quality checks.
Q. Is dose or concentration disclosed?
A. Practices vary by facility — get in writing what is administered and in what amount.