How Is the Potency of Stem Cell Conditioned Media Actually Measured? Dr. Moriwaki Explains ELISA, Protein Arrays, and Bioassays2026.07.21

“Contains ◯◯ ng/mL of growth factors,” “◯ trillion exosomes per dose” — the marketing materials of stem cell conditioned media often line up numbers like these. Yet, in medical terms, simply listing numbers does not describe a product’s true “potency.” The stem cell supernatant potency is not merely the amount of substance contained; it is an indicator of how much that content can actually act on cells and tissues, and the methods used to measure it fall into several layers. Dr. Moriwaki, who treats hair regeneration cases with conditioned media at AVAN TOKYO Ginza, outlines what these measurements really tell us and what patients should watch for when reading potency figures.

Key Points

・The stem cell supernatant potency is a two-sided concept — content and activity — and ng/mL numbers alone cannot guarantee quality.

・ELISA reliably quantifies a single growth factor but does not represent the overall biological activity of the media.

・Protein arrays and multiplex assays offer broad coverage, but comparing absolute values across lots and instruments requires careful calibration.

・Bioassays evaluate whether cells actually move or grow in response, and therefore sit closest to real potency.

・When encountering potency claims, patients should always check the unit, the measurement method, and the comparator together.

What Does “Potency” Actually Refer to in Stem Cell Conditioned Media?

In medicine, “potency” has long been used for vaccines, antibodies, and hormone preparations to describe the biological effect per unit dose. The same concept applies to conditioned media: it covers both what is inside each milliliter (content) and what that content does to target cells (activity). Since conditioned media contain growth factors, cytokines, exosomes, miRNAs, extracellular matrix fragments, and many other ingredients, no single indicator can decisively answer “does it work?” That is why it is essential to distinguish which yardstick was used to measure the potency.

ELISA: A Reliable Way to Quantify a Single Component

ELISA (enzyme-linked immunosorbent assay) uses antibodies to capture and quantify one specific protein. Certificates of Analysis (CoA) for growth factors such as VEGF, HGF, IGF-1, and bFGF often list ELISA results, offering the strength of absolute values for individual molecules. However, ELISA only confirms that a molecule is present. It cannot tell whether the molecule is still folded correctly and functionally active. A growth factor whose 3D structure has been disrupted by freeze-thaw cycles or dilution can still be recognized by an antibody.

Protein Arrays and Multiplex Assays: Coverage With Caveats

To view dozens to hundreds of proteins at once, antibody arrays or bead-based multiplex platforms such as Luminex are used. They are useful for capturing lot-to-lot profiles, yet absolute concentration accuracy is often lower than ELISA alone. Comparing numbers across different instruments or kits requires caution. The intuitive idea that “more factors mean stronger media” is not necessarily true when discussing potency.

Bioassays Come Closest to “Does It Actually Work?”

No matter how impressive the content numbers look, whether they produce a real biological event in cells is a different question. That is where bioassays come in. By adding conditioned media to human fibroblasts or dermal papilla cells and observing changes in proliferation, migration, and gene expression, the stem cell supernatant potency can be evaluated from the perspective of action. In approved pharmaceutical products, bioassays are effectively mandatory when discussing potency. However, for unapproved products such as conditioned media, this rigor still varies significantly between manufacturers.

What Proliferation and Migration Assays Show

Proliferation assays using BrdU or colorimetric reagents, and scratch assays for migration ability, quantify whether conditioned media “activate” cells. These are often performed on hair follicle-derived cells or skin cells, and they can reveal differences that content numbers alone cannot explain. That said, cell behavior in a dish does not directly equal what happens in the hair follicles of a human scalp, and this limitation must be honestly acknowledged.

The Difficulty of Measuring “Potency for the Hair Follicle”

Hair follicles are miniature organs where epithelial, mesenchymal, vascular, and immune cells interact. Substituting a single bioassay for the question “do the media work on the hair follicle?” is therefore fundamentally difficult. Multiple cell systems and multiple endpoints need to be combined. When discussing potency in the hair regeneration context, Dr. Moriwaki considers it a clinician’s responsibility to explain these limitations honestly.

Three Perspectives Patients Should Bring to “Potency” Claims

When you encounter potency figures in clinic materials or advertising, three perspectives help you read them wisely. First, the unit and the measurement method: numbers in ng/mL mean very different things depending on whether they come from ELISA, an array, or a bioassay. Second, the comparator: a claim like “◯ times more than other brands” carries little meaning without transparency about the measurement conditions of the compared products. Third, lot-to-lot consistency: because biological products naturally vary between lots, it is reassuring when each lot’s CoA is disclosed and specifications are managed within a defined range. For further reading, see our hair regeneration column archive. For general dermatological guidance on AGA and related conditions, please also refer to the Japanese Dermatological Association as a primary source.

Summary: Read Stem Cell Supernatant Potency as a Yardstick of Action

Potency is not a one-dimensional number of content. It is a multilayered concept combining content, activity, and reproducibility. ELISA, protein arrays, and bioassays each have their strengths and limits, and no single method alone can guarantee quality. In a field where numbers can easily walk on their own, patients and physicians speaking the same language about potency provides both safety and confidence when choosing hair regeneration therapy. Effects vary between individuals and conditioned media are not a cure-all. Yet sharing a way to read potency deepens understanding of why a particular treatment is chosen.

Frequently Asked Questions

Q. Is a higher potency number always better for stem cell conditioned media?

Not necessarily. Content numbers vary with the measurement method and sample dilution, and a large quantity is meaningless if activity has been lost. The medically sound approach is to evaluate both content and biological activity in balance.

Q. Can I choose a product based only on growth factor concentrations measured by ELISA?

It can be a reference, but ELISA only shows the quantity of specific components. To speak of the overall potency of conditioned media, it is safer to also review bioassay data and profiles of multiple factors where available.

Q. Does lot-to-lot variation in potency mean the product is defective?

Not necessarily. Some batch-to-batch fluctuation is expected in biological products; what matters is whether values are managed within the defined specification range. The CoA (Certificate of Analysis) shows the relationship between the spec range and the measured value.

Q. Is it acceptable for patients to ask to see potency data?

Yes — it is even encouraged. If a clinic is providing treatment on solid grounds, honest explanations regarding the CoA and measurement methods should come naturally.

Q. Will choosing a higher-potency supernatant guarantee hair growth?

Unfortunately, we cannot guarantee that. Hair follicle status, AGA progression, lifestyle factors, and combinations with other treatments introduce large individual variation. Potency is one element in decision-making, not a guarantee of outcome — that is the honest answer.

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[Supervising Physician] Shin Moriwaki, MD

Member of the Japan Society of Aesthetic Surgery (JSAS)

Member of the American Academy of Aesthetic Medicine

ECFMG Certificate

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📍AVAN TOKYO Ginza Hair Regenerative Medicine

AVAN TOKYO Ginza Hair Regenerative Medicine

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