Authentication standard
Muse cells aren't manufactured from scratch — they're separated out of an ordinary cell culture. So the number that matters most for any batch is simple: what percentage of the cells in it actually test positive for the Muse marker, SSEA-3? Everything else on this page follows from that one figure.
The scale
In plain terms
Picture an unsorted cell culture as a jar of mixed beans with only a few rare gold beans mixed in. “Enrichment” means running the jar through a process that sorts out the gold beans and concentrates them. Skip that step, and the jar still has the same small handful of gold beans it started with — but nothing stops a supplier from writing “gold beans” on the label anyway. Counting the beans is the only way to tell the difference.
Selling a Muse preparation means selling one in which the SSEA-3-positive fraction has been deliberately concentrated well above what tissue naturally contains. If that fraction sits at background level, the material is — functionally and scientifically — a mesenchymal preparation carrying a Muse label.
That distinction is not a matter of opinion or of sourcing. It is a measurement, taken on an instrument, on a specific batch, at a stated passage number. Everything else on this page follows from that one figure.
Published SSEA-3-positive percentages by preparation type. The distance between the left band and the right bands is the entire difference between an unsorted mesenchymal culture and an enriched Muse preparation.
Figures from the published literature: Leng et al., Cell Transplantation 2019;28(7):907–923; Foundational literature; Wakao et al., 2026 (canine 0.93%, feline 2.9%). Ranges vary with tissue source, sorting method and passage number.
Published benchmarks
| Material | SSEA-3 positive | Source |
|---|---|---|
| Bone marrow mononuclear cells, naive | 0.025–0.05% | Foundational literature |
| Canine adipose-derived stem cells | 0.93 ± 0.16% | Wakao et al., 2026 |
| Cultured mesenchymal cells, generally | ~1% to a few % | Consensus across literature |
| Feline adipose-derived stem cells | 2.9 ± 0.15% | Wakao et al., 2026 |
| Umbilical cord, earliest passage | 5.0–5.3% | Leng et al., 2019 |
| Sorted, expanded to passages 6–9 | 42.0–54.7% | Leng et al., 2019 |
| Sorted, expanded to passages 2–5 | 62.5–76.0% | Leng et al., 2019 |
| Immediately after magnetic sorting | 91.4 ± 3.2% | Leng et al., 2019 |
How to read this table
The top rows are measurements of what tissue naturally contains. The bottom rows are products. A figure in the low single digits has not been enriched — it has been measured. That distinction is the whole of the authentication question.
Manufacture
Muse cells cannot be obtained by centrifuging tissue or by using a generic isolation kit. The steps below are what distinguish the product from the source material — and steps two and three are the ones that create it.
Step three is the one that costs money and the one that is easiest to skip. A preparation whose marker percentage sits at background level is evidence that it was either not performed or did not work.
Starting material from adult bone marrow, fat tissue, umbilical cord, or a skin-derived cell culture.
Grow the culture under harsh conditions — no serum, low oxygen, or a long chemical soak — that ordinary cells don't survive but Muse cells do. This is the property the cells are named for, and it's the first filter.
Physically sort out the SSEA-3-marked cells with a lab instrument. This is the step that actually creates the product — skip it, and there's nothing to call "enriched."
Confirm the sorted cells behave like Muse cells: check for the right internal genes (OCT4, NANOG, TERT), show in a dish that they can turn into different cell types, and confirm they don't form tumours.
Grow the sorted cells under controlled conditions to reach a usable quantity. They often cluster into small ball-shaped groups during this stage.
A Certificate of Analysis for this specific batch — covering the SSEA-3 percentage, how many cells are alive, cell count, and sterility.
Certificate of analysis
Think of this as a checklist. If a supplier's paperwork is missing more than one or two of these fields, that's worth asking about before you order.
| Field | Why it matters |
|---|---|
| SSEA-3 positive % | The defining figure. Must be from this batch, not a reference lot or historical run. |
| Method and passage | SSEA-3 declines across post-sort expansion, so a percentage is only interpretable alongside the passage number at which it was measured. |
| Enrichment step | Whether MACS or FACS sorting was performed, and documented. |
| Viability | Typically assessed by dual staining. Distinguishes freeze-thaw injury from a culture that was already deteriorating. |
| Total and viable cell count | Should reconcile with the labelled content, and state which of the two the label refers to. |
| Mesenchymal panel | CD73, CD90, CD105 positive; haematopoietic markers low, against ISCT minimal criteria. |
| Pluripotency and differentiation | OCT4, NANOG, TERT expression and trilineage capacity. See the caveat below. |
| Lot, date, chain of custody | Lot number, date of manufacture and passage should be legible and should reconcile across vial, CoA and shipping documentation. |
A caveat on the marker itself
SSEA-3 is the standard Muse marker, but it has been documented on some non-stem cells. A high percentage is therefore necessary but not sufficient to establish identity. Rigorous characterisation also requires pluripotency gene expression, demonstrated trilineage differentiation, and documented absence of teratoma formation. A certificate reporting SSEA-3 alone is better than nothing, but it is not a complete identity test.
For buyers
01
Request the Certificate of Analysis for the specific lot being shipped.
02
A percentage without a passage number cannot be compared to a published benchmark.
03
MACS or FACS enrichment, documented. Without it, the vial holds source material.
04
Pluripotency gene expression and trilineage differentiation, beyond the marker alone.
05
Lot, date, passage and cell count should agree across every document.
06
Published human data exists for a specific short list. Applications outside it are extrapolations.
