On this page
Two treatments described identically can deliver cell numbers that differ by a factor of fifty. MSC dosage research is the least discussed and most practically important variable in this field — it determines what you actually receive, it explains most of the price variation, and it is the question clinics answer least precisely.
How dose is expressed
Two conventions appear in the literature, and they are not interchangeable.
Per joint — a total cell count injected into a knee or hip, typically written in millions. This is standard in orthopaedic trials.
Per kilogram — cells per kilogram of body weight, used for intravenous infusion, where the relevant quantity scales with the person.
A quote citing “millions of cells” without saying which convention, or which joint, has told you very little. Nor is the distinction cosmetic: a hundred million cells into one knee and a hundred million spread through a bloodstream are not comparable exposures for the tissue you care about.
The range in published trials
Intra-articular doses in the knee literature span roughly from a few million cells to over a hundred million. Intravenous doses in systemic trials commonly sit around one to two million per kilogram, with escalation studies going higher.
That range is wide enough that pooling trials becomes genuinely difficult, and it is one of the limitations every meta-analysis in this area has to declare — Efficacy and safety of mesenchymal stem cells in knee osteoarthritis: a systematic review and meta-analysis.
Dose has also been studied directly rather than incidentally, in a randomised phase 2b escalation design — Randomized phase 2b dose-escalation trial of stem cell therapy.
Whether more is better
Not reliably, and this is the part that surprises people. A dose-response relationship has not been cleanly demonstrated across this field.
Some trials find higher doses no better than lower ones. There is a plausible reason: if the mechanism is signalling rather than tissue replacement, then saturating the available receptors may be achievable well below the maximum deliverable dose.
There is also a ceiling imposed by the joint itself. A knee holds a limited volume of fluid, and beyond a point additional cells are simply additional suspension rather than additional treatment.
Which means a clinic charging more for a larger dose is selling something whose additional benefit is not established — see MSC immunomodulation.
Repeat dosing, where there is better evidence
This is the clearest finding in the dosing literature. A randomised trial in knee osteoarthritis compared a single dose against repeated dosing and found the repeated schedule superior — Umbilical Cord-Derived Mesenchymal Stromal Cells for Knee Osteoarthritis: Repeated MSC Dosing Is Superior to a Single MSC Dose.
That fits the signalling model. A transient instruction delivered twice may do more than a larger instruction delivered once — which is a different shape of treatment from the one most patients imagine when they picture a single curative injection.
It also has a commercial implication worth noticing: a single-injection offer may be under-dosing relative to the trial that produced the result being quoted at you.
What viability does to the number
A dose is only as real as the proportion of cells still alive when they arrive. Cryopreserved cells lose viability on thawing, and handling between laboratory and patient matters.
A preparation described as fifty million cells may deliver considerably fewer living ones, and viability testing is what distinguishes a stated dose from a delivered one.
This is why release testing is a dosing question and not merely a safety question — see MSC therapy.
Passage number, which nobody mentions
Cells expanded in culture are passaged — repeatedly split and regrown. With each passage they change: proliferation slows and their characteristics drift.
The practical consequence is that a laboratory can reach any headline cell count it likes by expanding for longer, and the cells at the end of that process are not the cells it started with. Count alone therefore says nothing about quality.
Trials generally specify and limit passage number. Commercial preparations often do not disclose it, and a high-passage preparation is not the same product as a low-passage one even at an identical cell count.
It is a fair thing to ask, and the answer tells you how carefully a laboratory documents its own process. A laboratory that tracks passage number will say so immediately; one that does not will usually change the subject to how advanced its equipment is.
Why this is the question to ask about price
Dose, expansion and testing are where the actual cost of a cell product sits. A price difference between clinics usually reflects a difference in one of those three, not a difference in margin.
So the productive conversation is not about the total but about what the total buys — see the cost page.
And where a clinic cannot state its dose precisely, that is information in itself. Precision here is not pedantry — it is the difference between a product specification and a description of a hope.
What to ask
Short list, and every item has a defensible answer if the laboratory is documenting properly.
- How many cells per treatment, and per joint or per kilogram?
- How was that number chosen, and from which trial?
- How many treatments, at what interval?
- What viability is measured at release, and what is the minimum accepted?
- What passage number are the cells at?
See the research library and autologous versus allogeneic for how source interacts with all of this.
Frequently asked questions
How many cells should I get?
Published trial doses run from a few million to over a hundred million per joint, so the number alone settles nothing. The useful question is which trial a clinic’s figure came from, and whether that trial studied your joint.
Is a bigger dose better?
Not reliably. A clean dose-response relationship has not been demonstrated, and some trials find higher doses no better.
One treatment or several?
A randomised trial found repeated dosing beat a single dose. A single-injection offer may be under-dosing relative to the evidence quoted for it.
Does viability matter?
Substantially. A stated dose and a delivered dose differ by however many cells are no longer alive, which is what release testing measures.
What is passage number?
How many times cells have been split and regrown in culture. Characteristics drift with each passage, and trials limit it while commercial preparations often do not disclose it.
Why does dose explain the price?
Because dose, expansion and testing are where the real cost of producing cells sits. Price differences usually reflect those rather than margin.
Requesting a medical evaluation
Nothing on this page establishes whether any treatment is appropriate for you. That needs your history, your imaging and your current medications read by a clinician. If you would like that review, send your records and we will tell you honestly whether there is anything worth discussing — including when the answer is no.
This page is general information, not medical advice, and does not create a doctor–patient relationship. Regenerative treatments discussed here are in most cases investigational. Discuss any treatment with a clinician who knows your history.