Counts, viability, and dose.

What is being counted. and what isn't.

The first number on a vial label is a cell count. It sounds simple, but a count means nothing without specifying which cells are being counted and how. Three counts coexist in this field, and they are not interchangeable: TNC (every cell with a nucleus), MSC count (cells confirmed as MSCs by flow cytometry against the ISCT criteria. CD73⁺ CD90⁺ CD105⁺ and CD45⁻ CD34⁻ CD14⁻), and viable MSC count (MSCs that are also alive).

A "100 million cell" same-day bone-marrow concentrate might contain 100 million nucleated cells: of which perhaps 1,000 to 10,000 are actually MSCs. A "100 million cell" lab-expanded cGMP MSC product contains 100 million cells that are ≥95% identified as MSCs by flow. Same headline. ~10,000× difference in delivered MSCs.

This is why the very first question is not "how many cells?". it's "how many MSCs?" and "how is identity confirmed?"

Viability. how many are alive.

A cell count counts cells. A viability assay tells you how many of them are alive. Dead cells are still cells. They still scatter light, still get counted by an automated hemocytometer, still show up in the headline number. They do nothing biologically.

At Celva, viability is held to ≥95% post-thaw at infusion, measured on the same vial within sixty minutes of administration by 7-AAD flow cytometry. That is the number that matters: not the viability at freeze (which marketing pages quote), but the viability of the cells actually entering the patient. Post-thaw is the harder number to hold, because thawing is where viability slips, so a high post-thaw figure reflects the care taken at harvest, controlled-rate freezing, and storage, not just a healthy starting culture. A well-run cGMP product has both at-freeze and post-thaw viability on the Certificate of Analysis. If only one is quoted, ask for the other. More on the cGMP release panel.

Effective dose, count × identity × viability.

Put the three numbers together and you get an effective dose: the number of viable, identified MSCs actually delivered. The math is multiplicative, and small drops at each step compound quickly.

What the cells actually deliver.

An effective-dose number tells you how many viable, identified cells reached the patient. It does not tell you how much therapeutic signal those cells will produce once they're in. That second question is the secretome: the complex mix of cytokines, growth factors, and extracellular vesicles (exosomes) that cells release into the environment around them. The secretome is the delivery mechanism for all four primary mechanisms: anti-inflammatory, anti-fibrotic, immunomodulatory, pro-angiogenic. It is what the cells do, once they are alive and where they are supposed to be.

Two preparations with the same count, the same identity panel, and the same viability can still produce very different secretomes. Cell age (a newborn cord cell vs. a sixty-year-old marrow cell), passage number (low vs. high), the manufacturing media, the cryopreservation method, the thaw protocol: all of it influences what the cells secrete once they are dosed. The reason cGMP manufacturing matters is not that the count on the box is more accurate. It is that everything upstream of that count is consistent enough to produce a consistent secretome.

For most patients, the practical takeaway is short: a count without viability is misleading; a viable count without a characterized secretome is half the picture; and a "potency" line item on a certificate of analysis is the only thing that ties the upstream manufacturing to a number that maps to clinical response.

Weight-adjusted dosing, cells per kilogram.

Clinical research on MSC therapies doses by weight, not by flat-rate vials. Cells delivered systemically distribute through a body proportional to its size. A 60 kg patient and a 100 kg patient given the "same vial" receive meaningfully different per-kilogram doses.

The convention in MSC clinical research is cells per kilogram (cells/kg). Typical research doses sit in the 1–4 million cells/kg range for IV infusion, with some protocols going higher. A 70 kg patient at 2M/kg = 140M MSCs total. At 4M/kg = 280M total.

Local injections into a specific joint or disc are dosed differently, by volume and site geometry, not body weight, because the cells stay in that compartment. Systemic IV infusions are the ones that should scale with weight.

Ask any clinic quoting a flat number: "Is this dose adjusted for my weight? If not, what's the per-kilogram?" A serious operation answers immediately, often with a chart. An operation that quotes a flat dose for every patient regardless of size is not following clinical-research dosing convention.

What an honest dose statement looks like.

An honest clinic, given the question "how much am I getting?", can answer it in five numbers. A clinic that can't is selling a headline.

These five numbers should appear on the patient-facing summary, the Certificate of Analysis for the batch, or both. A clinic that cannot produce them on request is either disorganized or hiding the answer. Neither is acceptable for a treatment of this magnitude.