Muse cells come up more and more in conversations about regenerative medicine, sometimes with promises that go beyond what has been shown. What are they, really? Are they the same as mesenchymal cells? Here is what published research says.
What are Muse cells?
Muse stands for multilineage-differentiating stress enduring: cells that differentiate into multiple lineages and withstand stress. They were described in 2010 by the group of researcher Mari Dezawa at Tohoku University in Japan, in the journal PNAS.
They occur naturally in the bone marrow, peripheral blood and connective tissue of several organs. They are identified by a surface marker called SSEA-3.
What makes them different?
The original study and later work describe these characteristics:
- They survive cellular stress. That is how they were isolated: they withstood prolonged exposure to an enzyme.
- They can give rise to cells of all three embryonic layers, according to laboratory experiments.
- They did not form teratomas in the testes of immunodeficient mice, unlike embryonic stem cells.
- They appear to home in on damaged tissue: in experimental models, they detect an injury signal called sphingosine-1-phosphate.
These are important findings, but most come from laboratory and animal work. They do not mean a product works in people.
How do they differ from mesenchymal cells?
Muse cells are found within mesenchymal cell cultures, but they are only a small fraction. In the original study, they made up about 1 to 1.3% of unenriched mesenchymal populations.
| Mesenchymal cells | Muse cells | |
|---|---|---|
| What they are | A broad, varied population of stromal cells | A small subpopulation, positive for SSEA-3 |
| How they are identified | Culture criteria and markers such as CD105, CD73 and CD90 | SSEA-3, often together with CD105 |
| Clinical research | Extensive, with at least one FDA-approved product for a specific indication | More recent, with small studies |
To learn more, read our guide to mesenchymal stem cells and the news on Ryoncil, the FDA-approved mesenchymal therapy.
What have human studies shown?
The most cited trial was published in 2023. It tested CL2020, a donor-derived Muse cell product, in people with subacute ischemic stroke, at a single hospital in Japan:
- 35 patients took part: 25 received CL2020 and 10 received placebo, 14 to 28 days after the stroke.
- At 12 weeks, 40% of the CL2020 group reached the level of recovery defined in the study, compared with 10% on placebo.
- Almost all patients in both groups had some adverse event. There was one serious adverse reaction in the CL2020 group: status epilepticus, from which the patient recovered.
The authors acknowledge the limitations: a single center, a small sample and a slight baseline difference between groups. They were planning a larger phase 3 study; however, according to a summary published in 2026, Mitsubishi Chemical Group reported in 2023 that it was discontinuing CL2020 development for business strategy reasons.
Early studies have also been reported in conditions such as myocardial infarction, epidermolysis bullosa, spinal cord injury and amyotrophic lateral sclerosis. They are generally small and focus mainly on safety.
Are they approved?
Based on the information we could verify, we did not find full approval of a Muse cell product by the U.S. FDA. Some websites mention approvals in other countries; before believing them, ask for the official document from the relevant authority. In Mexico, check the product’s scope with COFEPRIS.
What to ask about a Muse cell product
- Which laboratory makes it, and what is the lot?
- How was the presence of Muse cells confirmed? What percentage of SSEA-3 positive cells does the certificate report?
- What studies exist for that product and for my condition?
- What are the risks, and which alternatives have stronger evidence?
The bottom line
Muse cells are an interesting line of research, with one encouraging but small controlled trial. More evidence is needed to know who they may help and under what conditions. In our informational catalog, the laboratory NarCells includes MUSE cells. If you are a physician and would like more information, message us; if you are a patient, we can refer you to a physician on our list in your state.
- Kuroda Y, Kitada M, Wakao S, et al. Unique multipotent cells in adult human mesenchymal cell populations. Proceedings of the National Academy of Sciences. 2010;107(19):8639-8643.
- Niizuma K, et al. Randomized placebo-controlled trial of CL2020, an allogenic muse cell-based product, in subacute ischemic stroke. Journal of Cerebral Blood Flow & Metabolism. 2023;43(12):2029-2039.
- Heretic. Muse cell therapy: evidence, taxonomy and clinical translation. Updated November 1, 2026. Summarizes the Mitsubishi Chemical Group announcement (July 2023) on CL2020.
This content is for informational purposes only and does not replace evaluation by a health professional. It has not been evaluated by the FDA.
