Technical notes
Technical Notes
Articles on manufacturing methods, quality control, and related research, written for physicians at medical institutions. For product specifications, see the product page.
How Are Class I, II, and III Regenerative Medicine Decided in Japan? Committees, the 90-Day Rule, and Penalties by Class
Class I, II, and III under Japan’s Act on the Safety of Regenerative Medicine are not chosen by the medical institution: they follow from fitting the technology to the categories set out in MHLW ordinance. This article follows the statutory text to explain how the same cells change class depending on whose they are and where they are put, the 90-day rule that applies only to Class I, the committee and penalty differences by class, and the grounds on which culture supernatant currently sits outside the Act.
Read moreWhat Is Stem Cell Conditioned Medium? How It Differs from Exosomes and How to Read Specifications
Stem cell conditioned medium and exosomes are not the same thing. This article covers the definition — the whole liquid that remains after the cells are removed — the regulatory fact that no approved pharmaceutical product exists in Japan or any other country, and how to read the specification items called for by the guidance of the Japanese Society for Regenerative Medicine. It also explains why origin alone (adipose, deciduous tooth pulp, umbilical cord) does not determine quality, together with the nine factors behind quality variability.
Read moreCan You Trust “X Trillion Particles”? How to Read an Exosome Count, and Three Traps
The international MISEV2023 guidelines state in their own words that particle counts are “often unreliable.” Change nothing but the method and the same sample can shift a millionfold; clumps of protein get counted as vesicles; and a bigger number has never been shown to mean a bigger effect. Three traps, and four things to check in any product document.
Read moreWhy can’t bovine serum RNA be “removed later”? How 70% survives a 24-hour ultracentrifugation
Measured data show that even 24 hours of ultracentrifugation of fetal bovine serum — longer than usual — removed only 19–33% of total RNA, leaving 67–81% behind. Why it stays, what it does to your data, and what the study does not show, with quotations from the original paper.
Read moreDoes “serum-free” mean xeno-free? How to read the four “-free” media labels
A medium labeled “serum-free” can still contain bovine-derived components. We sort out what each of the four categories — serum-free, xeno-free, animal component-free, chemically defined — excludes, why the label alone cannot settle safety, and how far back to trace the raw materials.
Read moreWhat Is Lost When Only the Exosomes Are Isolated? How to Read Two Peer-Reviewed Comparisons with the Whole
An exosome preparation is made by isolating only the membrane vesicles from conditioned medium (the secretome). In two peer-reviewed studies that compared the whole, the exosome fraction, and the exosome-depleted fraction under identical conditions, the vesicle-only fraction did not produce the same cellular changes as the whole. We walk through how to read the results — including the fact that both studies are in vitro.
Read moreHow far can you trust a “safety tested” claim? Why sterility testing alone isn’t enough
Even when a product says “safety tested,” the meaning depends on which layer was examined: the raw material (donor), the process (manufacturing environment), or the final product. We diagram what sterility, mycoplasma, and endotoxin testing each detect — and do not detect — and list the three questions to verify on a Certificate of Analysis (COA).
Read moreWhat Is a Secretome? 6 Conditions to Judge a Term With No Official Definition
The word “secretome” has no official definition and no industry standard. This article maps the nested relationship between stem cell conditioned medium, secretome, and exosomes in a single diagram, then sets out the six conditions we impose, how medium design decides the manufacturing process, and the quality standards you can verify in a lot-by-lot test report.
Read moreDo You Need a Freezer to Store Conditioned Medium? Testing the 40°C Limit Against Measured Temperatures
How much headroom does 'store at room temperature (up to 40°C)' really leave for freeze-dried products? We place the limit on the same axis as measured values — 34.5°C indoors on an extreme heat day, 57°C in a car in direct sun — and cover why shipping is refrigerated, how not needing a freezer changes inventory operations, and how shelf life is counted.
Read moreWhy “99% Purity” Is Not a Basis for Comparison Three Blind Spots: Measurement, Impurities, the α-Form
The same sample measured two ways differs by up to 5.2 points, near-identical purity hides 3 versus 7 impurity species, and the α-form never shows in the number.
Read moreCan You Get NMN from Food? 250 mg a Day = 640 Tomatoes
NMN is found in everyday vegetables such as edamame and broccoli, but only at around 1 mg per 100 g. To reach the 250 mg daily dose used in clinical studies from food alone would take 24 kg of mushrooms (about 2,400 pieces) — the most efficient source — or 96 kg of tomatoes (640 pieces) a day. The basis for the conversion is shown in figures and a table.
Read moreWhy Do Cultured Cells "Age"? Measured Diameters of 22.3 μm and 14.9 μm
Cells cultured for 30 days in a conventional medium measured 22.3 μm in diameter; 20 days in our proprietary medium, 14.9 μm. A 1.5-fold gap in diameter is about 3.4-fold in volume. With hemocytometer and phase-contrast images and surface marker data, we explain how days in culture change the condition of the source cells.
Read moreIs "Serum-Free" Conditioned Medium Really Serum-Free? 6 Questions to Ask Your Supplier
A product labeled "serum-free" may still use serum in the expansion step that grows the cells, switching to serum-free medium only at collection. Since the terms conditioned medium and secretome have no official definition, we have organized six points to confirm with the supplier into a question list, so you never have to choose on the name alone.
Read moreAre conditioned medium and secretome the same thing? The “never let it in” design and 6 conditions
The dividing line is whether unwanted components are removed afterward or never mixed in at all. A composition diagram, a three-approach comparison table, and the six conditions we require before using the word “secretome.”
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