Cell Counts and Quality Metrics: A Reader's Glossary

The lab printout one is handed at a Gangnam clinic reads, on first impression, as a small piece of editorial restraint — three or four lines, a few numbers, no flourish. It is also the document the entire procedure sits on. 呢張紙, a Hong Kong colleague said to me once, 仲緊要過 menu — this paper matters more than the menu. Total nucleated cell count, viability percentage, surface-marker phenotype, dose volume — the numbers describe a preparation, set the boundary of what one is consenting to, and frame the published evidence the procedure leans on. The careful guest learns to read them.

Why a printout is given at all — and what it commits the clinic to

The cell-count printout is, in editorial terms, the contract between the lab and the consultation room — and a clinic that prints, signs, and hands it across is a clinic that has consented to be measured against it. The document is generated at the close of the processing window, after the cells have been harvested, washed, separated, counted, and resuspended; it captures the preparation as it stood at the moment immediately before reinjection, with the timestamp, the counting method, the operator's initials, and the lot identifier of the consumables used. The printout commits the clinic to several specific things at once. It commits to the total nucleated cell count it has reported, which is the number of nucleated particles per unit volume of the resuspended preparation. It commits to the viability percentage, which is the proportion of those particles whose membranes are intact at the moment of counting and therefore plausibly capable of post-injection function. It commits to the dose volume the operator has used, and by extension to the absolute number of viable nucleated cells the patient is to receive. And it commits, in the better-run rooms, to a phenotype panel — a small set of surface-marker positive and negative percentages — that places the preparation within the published cohorts the field draws its evidence from. The printout does not, importantly, commit to the clinical response. The numbers describe a preparation; the response is shaped by the preparation, the patient, the indication, the operator, and the months that follow. The honest editorial framing is that a good number is a necessary condition for a credible procedure and not, by itself, a sufficient one. The room that prints, signs, and hands across is the room one returns to. The room that elides this step is the room one declines.

Total nucleated cell count — what the headline number describes

Total nucleated cell count, abbreviated TNC and reported as cells per millilitre, is the headline number on most regenerative-medicine printouts and the figure one ought to read carefully. The count is generated by an automated counter — a Coulter-principle device, a fluorescence-based image analyser, or in some labs a flow cytometer — and the figure represents the number of particles in the preparation that carry a nucleus, irrespective of cell type, irrespective of viability, irrespective of regenerative phenotype. For an adipose-derived stromal vascular fraction preparation a typical TNC at the close of processing falls in the range of two to ten million cells per millilitre of resuspended preparation, with the variance shaped by the harvest volume, the lipoaspirate quality, and the processing protocol. For a bone-marrow concentrate the typical TNC is higher per millilitre, reflecting the marrow's denser nucleated-cell content. For a cultured adipose-derived stem cell product the TNC is reported per dose rather than per millilitre, with the dose typically standardised by the cell-therapy registration. The reader's first task is to read the units. A printout that reports a number without units is, in editorial terms, an incomplete printout. The reader's second task is to read the count against the published cohort range for the indication. A 2020 review in Cytotherapy summarising adipose-derived stromal vascular fraction yields across more than thirty published cohorts reported wide variability in absolute counts but a relatively consistent narrative: well-conducted protocols tend to produce yields in the millions-per-millilitre range, with the variance attributable more to processing technique than to patient demographics within the studied populations. The reader's third task is to read the count alongside, not above, the other figures on the page. The TNC sets the upper bound of what could be useful. The viability and the phenotype set the boundary of what is.

Viability — the percentage that decides what the count means

Viability is the proportion of nucleated cells in the preparation whose membranes are intact at the moment of counting, and it is the figure that converts a TNC into a clinically meaningful number. The standard counting method excludes a vital dye — typically trypan blue or, in fluorescence-based systems, propidium iodide — from the cytoplasm of cells whose membranes are intact, and includes the dye in cells whose membranes have been disrupted; the counter reports the percentage of cells in the former category as the viability figure. A well-conducted same-session autologous preparation typically reports viability in the eighty-five to ninety-five per cent range, with the figure shaped by the harvest gentleness, the wash protocol, the resuspension medium, and the time elapsed between processing and counting. A preparation reporting viability below seventy per cent is a preparation a careful operator would re-process, re-prepare, or in some cases decline to inject; the rooms one trusts have a written threshold below which they do not proceed, and the printout, in those rooms, names the threshold alongside the figure. The reader's task is to convert the TNC and the viability into the clinically meaningful number — the absolute count of viable nucleated cells per millilitre, calculated as TNC multiplied by viability percentage divided by one hundred — and to read that number against the published dose range for the indication. The patient who is offered a preparation with a high TNC and a low viability is being offered, in editorial terms, a preparation whose headline figure is misleading. The patient who is offered a preparation with a moderate TNC and a high viability is, often, being offered a more clinically useful product. The careful clinic explains this distinction without being asked. The careless one reports the TNC alone.

Phenotype panels — the surface-marker percentages and what they place

Phenotype panels are the figures on the printout that place a preparation within the published cohort literature, and they are the figures the consumer-facing brochures most often omit. The panel is generated by flow cytometry — the cells are passed in single file through a laser, the fluorescent signals from antibody-conjugated probes are captured, and the percentage of cells positive for a defined marker (CD73, CD90, CD105, the canonical positive markers for mesenchymal stromal cells per the International Society for Cellular Therapy minimum criteria) and negative for a counter-defined marker (CD45, CD34 in the cultured-cell framing, HLA-DR) is reported. For a stromal vascular fraction preparation, which is heterogeneous by design, the panel reads differently — a mixture of CD34-positive endothelial-progenitor and pre-adipocyte populations, CD45-positive haematopoietic populations, and the stromal subpopulation that overlaps with the cultured-cell phenotype. The reader's task is not to memorise the markers but to confirm the panel exists. A clinic that reports the TNC and the viability without the phenotype is reporting two-thirds of the relevant figure. A clinic that reports the phenotype, even briefly, is making the procedure traceable to the published evidence base. The honest editorial framing is that the phenotype panel is the figure that distinguishes a regenerative-medicine clinic from a rebranded liposuction clinic, and the patient who reads the printout for it is the patient who is reading carefully. A 2022 consensus paper from the International Society for Cellular Therapy reaffirmed the minimum surface-marker criteria for mesenchymal stromal cell identity and noted, with some emphasis, that preparations described as stem-cell therapies in clinical settings should be characterised against those criteria as a baseline of phenotypic transparency.

Dose volume and the clinical translation — what the patient receives

Dose volume is the figure that converts the laboratory numbers into the clinical number — the absolute count of viable nucleated cells the patient receives at the injection. The calculation is direct. Total nucleated cells per millilitre, multiplied by viability percentage divided by one hundred, multiplied by the dose volume in millilitres, equals the absolute viable nucleated cell dose. For a stromal vascular fraction injection of three to five millilitres for a facial aesthetic indication the absolute dose typically falls in the tens of millions of viable nucleated cells; for an intra-articular injection of five to ten millilitres for a knee indication the absolute dose typically falls in the tens to low hundreds of millions; for a multi-site protocol distributed across more than one indication the doses are reported per site and summed per session. The careful clinic prints the per-site doses, the per-session sum, and the published cohort range for each indication on the discharge document the patient signs at the close of the consultation. The reader's task is to compare the absolute dose to the published range. A dose at the lower end of the published range is not, by itself, an inadequate dose; the response curve is multifactorial and the published ranges are wide. A dose meaningfully below the published range is a conversation worth having with the operator before the procedure begins. The brief Korean Ministry of Food and Drug Safety [classification framework](https://www.mfds.go.kr/eng/) for cell preparations distinguishes minimally manipulated, same-session autologous preparations from culture-expanded products and from allogeneic preparations, and the dose-reporting expectations differ by category; the reader who confirms the category alongside the dose is the reader who is reading completely.

What the printout cannot tell you — the careful boundaries of the document

The printout is a document of impressive specific honesty about a small set of measurable properties, and it is silent on a larger set of properties that shape the clinical response. The silences are worth reading as carefully as the figures. The printout does not, in most cases, speak to functional potency — the capacity of the cells in the preparation to differentiate down a particular lineage in a standardised assay, the secretome profile under a standardised stimulus, the trophic-factor concentration in the preparation's supernatant. It does not speak to the donor's clinical phenotype as a modulator of preparation quality; the same TNC and viability figures, drawn from a forty-year-old patient and a sixty-year-old patient, may not deliver the same clinical response, though the literature on this is still evolving and a careful editorial reading would not currently treat patient age as a hard threshold. It does not speak to the immunomodulatory profile of the preparation, which is the property the field increasingly believes is doing much of the clinical work. It does not speak to the indication's responsiveness, the operator's injection technique, the patient's adherence to the post-procedure protocol, or the months of biological response that unfold between the injection and the assessable result. Patients sometimes read the printout as a guarantee. The honest editorial framing is that it is a baseline rather than a guarantee, a description of a preparation rather than a prediction of a response, and a piece of clinical-laboratory transparency that distinguishes the rooms that print from the rooms that do not. The patient who learns to read both the figures and the silences is the patient best served by the document.

How quality metrics compare across preparations and processing tracks

Different preparation types and processing tracks produce different quality-metric profiles, and the differences are larger than the consumer-facing brochures suggest. Below — categorically, not as a ranking — is how the quality registers read across the preparations a Seoul-bound patient is likely to compare. The table is descriptive; the choice between preparations is shaped by indication, regulatory category, and the patient's own preferences for processing transparency, not by marketing positioning.

How to read the printout in the room — five questions and the cadence of the answers

The printout is most usefully read in the consultation room itself, with the operator present and the cadence of the answers as informative as the answers themselves. Five questions, asked in sequence, frame the document well. What units are these figures in, and could you walk me through the calculation from TNC and viability to the absolute viable nucleated cell dose I will be receiving today? What is your in-house viability threshold below which you do not proceed, and how often does that threshold trigger a re-processing? What does the phenotype panel show, and how does this preparation compare to the published cohort literature for my indication? How does today's dose compare to the published dose range for the indication, and what is the rationale for the dose I am receiving? And what does the printout not tell us about today's preparation that we should discuss before the injection? The cadence of the answers is the second instrument. The careful operator does not rush; the careful operator names the unit, walks the calculation, volunteers the threshold, places the panel against the literature, frames the dose against the published range, and is candid about the silences. The careless operator quotes the TNC and moves on. Patients report — and the rooms one returns to confirm — that the printout reading is the moment the consultation either elevates or contracts. The room that elevates is the room one trusts. The room that contracts is the room one declines, with thanks, and proceeds to the next consultation on the list.

“The printout is a document of impressive specific honesty about a small set of measurable properties, and it is silent on a larger set of properties that shape the clinical response — a description of a preparation rather than a prediction of a response, a baseline of transparency rather than a guarantee, a piece of clinical-laboratory cadence that distinguishes the rooms that print from the rooms that do not.”

Liu Mei-Hua, on the editorial weight of a single page of figures

Frequently asked questions

What is total nucleated cell count and why is it the headline figure?

Total nucleated cell count, reported as cells per millilitre, is the number of nucleated particles in the preparation as measured by an automated counter. It is the headline figure because it sets the upper bound of what could be clinically useful — a preparation with a high TNC has more material to work with — but it is not, by itself, the clinically meaningful figure. The TNC is converted into the clinically meaningful figure by combining it with the viability percentage and the dose volume. Reading the TNC alone is reading one-third of the relevant data.

What viability percentage should I expect to see on a well-conducted preparation?

A well-conducted same-session autologous preparation typically reports viability in the eighty-five to ninety-five per cent range, with the figure shaped by harvest gentleness, wash protocol, resuspension medium, and the time elapsed between processing and counting. Cultured products commonly report figures above ninety per cent. A preparation reporting viability below seventy per cent is a preparation the careful clinic re-processes or declines; the rooms one trusts have a written threshold and name it alongside the figure on the printout.

What is a phenotype panel and why does it matter?

A phenotype panel is a flow-cytometry-derived set of surface-marker percentages that places the preparation within the published cohort literature. The International Society for Cellular Therapy minimum criteria include positivity for CD73, CD90, and CD105 and negativity for CD45 and HLA-DR for cultured mesenchymal stromal cells; stromal vascular fraction preparations are heterogeneous and read differently. The panel matters because it makes the procedure traceable to the evidence base — a clinic that omits the panel is omitting the figure that distinguishes a regenerative clinic from a rebranded one.

How do I calculate the actual cell dose I am receiving from the printout?

Total nucleated cells per millilitre, multiplied by viability percentage divided by one hundred, multiplied by the dose volume in millilitres, equals the absolute viable nucleated cell dose at the injection. For a stromal vascular fraction injection of three to five millilitres the absolute dose typically falls in the tens of millions; for an intra-articular injection of five to ten millilitres the dose typically falls in the tens to low hundreds of millions. The careful clinic prints the calculation on the discharge paperwork; the patient who reads it is reading completely.

What does the printout not tell me about my preparation?

The printout is silent on functional potency, donor-driven biological variability, the immunomodulatory profile of the preparation, the indication's responsiveness, the operator's injection technique, the patient's post-procedure adherence, and the months of biological response that unfold between the injection and the assessable result. It is a description of a preparation rather than a prediction of a response. The patient who learns to read both the figures and the silences is the patient best served by the document; the printout is a baseline of transparency, not a guarantee.

Should the dose I am receiving fall within a published range?

It should, broadly. The published cohort literature for each indication describes a wide dose range, and a dose at the lower end of that range is not, by itself, an inadequate dose; the response curve is multifactorial. A dose meaningfully below the published range is a conversation worth having with the operator before the procedure begins, with the rationale named and the alternative — a re-processing, a higher-volume harvest, a deferred procedure — discussed. The careful operator volunteers this conversation. The careless operator does not.

Is the printout the same for stromal vascular fraction and cultured stem cell products?

Categorically, no. Stromal vascular fraction printouts emphasise TNC per millilitre, viability, a heterogeneous phenotype panel reflecting the preparation's mixed-population nature, and the per-site dose calculation. Cultured stem cell product printouts emphasise cells per dose, viability typically above ninety per cent, an International Society for Cellular Therapy panel reflecting the cultured mesenchymal stromal cell phenotype, and a standardised dose tied to the product's regulatory registration. The preparations are different paradigms; the printouts read accordingly.