What Is a Muse Cell? How Is It Different from Regular Stem Cells? Everything to Know Before Deciding to Have It Done

Muse Cell or Multilineage-differentiating Stress-Enduring Cell is a stem cell that exists naturally in the human body (Endogenous Stem Cell). It was discovered in 2010. The name Muse comes from the ability to develop into many types of cells (Multilineage-differentiating) and the ability to withstand severe cellular stress (Stress-Enduring), which are the properties the research team used to first isolate this group of cells (Kuroda et al., 2010)

Muse Cells can be identified by a cell-surface protein called SSEA-3 (Stage-Specific Embryonic Antigen-3), a marker found on pluripotent stem cells. Muse Cells in bone marrow and connective tissue are found to be SSEA-3 positive together with CD105, whereas Muse Cells in the bloodstream are found to be SSEA-3 positive together with CD45.

However, Muse Cell is still an approach under research. It is not an approved treatment for disease and cannot be used to replace standard medical care.

Based on research to date, Muse Cells have key properties that have attracted attention in regenerative medicine, as follows:

• Withstands conditions that damage cells

  This group of cells was discovered by selecting cells that survived severe stress in the laboratory (Kuroda et al., 2010), and research has found that they tolerate agents that damage genetic material (DNA) better than ordinary MSCs, involving the systems inside the cell that detect and repair damage (Alessio et al., 2018)

• Turns into the same type of cell as the damaged cells through engulfment (Phagocytosis-dependent Differentiation)

  When it reaches the damaged site, the Muse Cell engulfs damaged or dying cells (Phagocytosis) and uses the signals obtained from those cells, allowing it to turn into the same type of cell. This is information from laboratory studies (Dezawa, 2025)

• Detects and travels to damaged areas (Homing)

  When tissue is injured, the damaged cells release a substance called Sphingosine-1-Phosphate (S1P) as a warning signal. Muse Cells have the S1P Receptor 2 (S1PR2), so they can move to that area when given intravenously (Dezawa, 2025)

• No genetic modification or induction of differentiation is needed before use

  Because Muse Cells can turn into tissue cells on their own after reaching the damaged site, clinical studies to date have used cells that were not genetically modified or induced to change before administration (Dezawa, 2025)

• Smaller than ordinary MSCs, with a diameter of about 10–15 micrometers, or 0.010–0.015 millimeters; size may vary depending on the source and culture conditions (Gimeno et al., 2017)

Each type of stem cell differs in its source and in its ability to develop into different types of cells

Muse Cell

Normally, MSCs contain a small number of Muse Cells, which laboratories isolate. Muse Cells are smaller than ordinary MSCs, with a diameter of about 10–15 micrometers, or 0.010–0.015 millimeters, and can withstand conditions that damage cells, move into injured areas of the body, and turn into many types of cells in experiments (Kuroda et al., 2010). They stand out for restoring the nervous system, but their market price is higher than that of MSCs.

Mesenchymal Stem Cells, or MSCs

These are groups of cells whose properties can differ depending on their source and culture method. Studies have examined both their turning into certain types of cells and their release of substances that affect neighboring cells, which may be involved in inflammation and tissue repair (Uchida et al., 2017)

Muse Cells and MSCs are therefore related, because Muse Cells may be found as part of some sources of MSCs. However, receiving MSCs does not mean receiving isolated Muse Cells, or receiving Muse Cells in the desired proportion. The test results of that specific product must also be checked (Kuroda et al., 2013).

Embryonic Stem Cells, or stem cells from embryos

These are cells obtained from an early-stage embryo and can develop into many types of cells. This differs from Muse Cells, which can be isolated from certain sources of body tissue. Developing embryonic stem cells into a treatment requires controlling the process to obtain the desired cell type and testing for cells that have not yet developed, which may carry a risk of tumor formation, as well as considering ethical issues regarding the source (International Society for Stem Cell Research, 2025)

As explained in research, Muse Cells work like the body's natural repair system, with the following main steps:

• Detecting damage signals. When tissue is damaged, the damaged cells produce a substance called Sphingosine-1-Phosphate (S1P), a warning signal of damage found in many tissues. Muse Cells have the S1PR2 receptor, which is sensitive to this signal (Yamada et al., 2018)

• Traveling to the damaged area (Homing). When Muse Cells are given intravenously, the cells move and accumulate in the damaged area. For example, in a rabbit model of acute myocardial infarction, about 14.5% of the Muse Cells were found embedded in the damaged heart tissue, whereas most Non-Muse cells were stuck in the lungs and were hardly found in the heart (Yamada et al., 2018)

• Engulfing damaged cells and turning into the same cell type. After reaching the damaged area, Muse Cells engulf damaged or dying cells (Phagocytosis) and reuse signals necessary for cell development, such as transcription factors, allowing them to turn into the same cell type as the damaged cells within about 15 hours to several days, which is faster than cytokine induction in the laboratory that takes several weeks to several months (Dezawa, 2025)

• Helping reduce inflammation and fibrosis and protecting cells. In addition to replacing cells, Muse Cells also secrete substances that help reduce inflammation, reduce cell death, and reduce fibrosis. And because donor cells may remain in tissue for a long time, these effects may last longer than those of ordinary MSCs (Dezawa, 2025)

Safety depends on the product, the method of administering the cells, the dose, and each person's health. It should therefore not be concluded that Muse Cell is "100% safe" or has "no side effects" (International Society for Stem Cell Research, 2025)

That said, administration of Muse Cells has already been studied in humans

• A study in 3 patients with myocardial ischemia, who received CL2020 and were followed for 12 weeks, found no adverse events related to the product. The researchers monitored symptoms, blood tests, and the function of various organs (Noda et al., 2020)

• There is data on repeated administration in ALS patients. A study in 5 patients gave CL2020 once a month for a total of 6 doses and reported that participants tolerated the product well, with no pulmonary embolism or severe anaphylactic-shock-type allergic reaction (Yamashita et al., 2023)

Things to consider before undergoing treatment

• Infection from contamination during production, preparation, or administration of the cells. It is recommended to choose a clinic with high standards.

• Long-term outcomes, for which data remain limited, and side effects that may occur so infrequently that small studies cannot detect them (International Society for Stem Cell Research, 2025; International Society for Stem Cell Research, 2024)

Blood tests and a health check before treatment so that the doctor can assess suitability, as well as self-care after treatment and choosing a clinic that meets standards, are important

Highlights that interest researchers

• No embryo is needed as a source of cells. Muse Cells can be isolated from cells in body tissues such as bone marrow, connective tissue, the umbilical cord, and the membranes surrounding the fetus (amnion)

• Senses damaged sites and travels to them on its own

• Can turn into many types of cells without needing to be induced before use

• No reports of tumor formation have been found yet

However, cost should be considered together with the expected results and the treatment alternatives available.