Most of what is sold as a stem cell treatment contains very few stem cells.

PRP OR STEM CELLS

“Stem cell therapy” is the most oversold phrase in this field. Before comparing it to anything, it is worth establishing what is actually in the syringe, because the answer is rarely what the marketing implies.

What is actually being offered

Four quite different things get sold under the same phrase.

• PRP. Concentrated platelets from your blood. Contains no stem cells at all, and nobody serious claims otherwise.
• BMAC. Concentrated bone marrow, containing a mixed cell population of which mesenchymal stromal cells are a small fraction — well under one percent of nucleated cells. This is what most American clinics mean by stem cells.
• Adipose-derived preparations. Processed fat tissue. Whether a given preparation is legally permissible depends heavily on how much it was manipulated.
• Culture-expanded stem cells. Cells grown in a laboratory to increase their number. This is what most patients picture, and it is not legally available as a routine treatment in the United States outside an approved trial.

The regulatory line, in plain terms

The framework permits same-day autologous procedures that are minimally manipulated and used for a homologous purpose. Draw it, concentrate it, put it back in one visit and you are inside that line. Culture cells over days or weeks to expand them and you have created a drug, which requires approval that these products do not have.

This matters to you practically. Clinics offering “expanded” cells domestically, or arranging treatment abroad to get around the rule, are operating outside a framework that exists because unregulated cell products have caused real harm — including blindness, from intraocular injections at an unapproved clinic. The rule is not bureaucratic obstruction.

Umbilical, amniotic and “young” cell products

Be especially careful here. Products sold as umbilical cord or amniotic stem cell injections are widely marketed, frequently at seminars aimed at older patients, and independent analyses have repeatedly found that commercially available samples contain few or no living cells by the time they are injected. Cryopreservation and processing kill them.

These are allogeneic — from a donor — which removes the main safety argument for autologous treatment, and they are frequently the most expensive option on the menu. If a clinic offers you a product from someone else’s tissue as a stem cell treatment, ask for the viability data. There usually is not any.

What the cells are probably doing anyway

Even where living mesenchymal cells are genuinely delivered, the mechanism is most likely not what the name suggests. They do not appear to engraft and become new cartilage in any meaningful quantity. The current understanding is paracrine: the cells release signaling molecules and extracellular vesicles that modulate inflammation and influence resident cells, then largely disappear within days.

If that is the mechanism, then the gap between a cell preparation and a growth-factor preparation like PRP narrows considerably — both are ultimately delivering signal. That is consistent with the head-to-head trials, which mostly fail to find the large advantage the pricing implies.

Cost against evidence

Cell-based treatments typically cost several times what PRP costs. We do not publish prices here, but the ratio is the relevant point: the price gap is much larger than the evidence gap. In knee osteoarthritis, direct comparisons between BMAC and PRP have generally found no significant outcome difference at a year.

Paying substantially more for an equivalent result, via a more invasive procedure, is a poor trade in an earlier-stage joint. Where the joint is further along the calculation changes, and the reasons are set out on bone marrow aspirate concentrate. It is not a poor trade in all of them, which is what the next section is about.

When a cell-based treatment does make sense

• Osteonecrosis, particularly of the femoral head, where marrow-derived treatment has the strongest case of any indication discussed here
• More advanced joint degeneration where PRP has been tried and gave a partial answer
• Subchondral bone involvement, where the pathology sits in bone rather than only in cartilage
• As a considered escalation, on evidence, rather than as a first move

How to read a clinic that offers this

• Does it name the specific product, or only say “stem cells”?
• Can it tell you the cell content of what you are receiving, or is it assumed?
• Does it claim to regrow cartilage? Nothing available today reliably does.
• Does it use before-and-after imaging as proof? Radiographic change is not what these treatments produce.
• Is it an autologous, same-day procedure, or something shipped in frozen?
• Does it recommend PRP first for the indications where PRP performs well — or is everyone steered to the most expensive option?

What we do here

PRP first for most indications, because it performs well, costs less and carries the lower risk. BMAC where the tissue is further gone or the specific pathology argues for it. No allogeneic products, no expanded cells, and no use of the phrase “stem cell therapy” to describe something that is mostly platelets and signaling molecules.

The reason for the caution is not conservatism for its own sake. It is that this corner of medicine has an unusually high ratio of confident marketing to published evidence, and the people most exposed to it are those who have already been failed by several other treatments and are running out of options.

Why the marketing is so much louder than the evidence

The economics explain most of it. These are cash-pay treatments, which means the money comes directly from patients rather than from an insurer with a review process. That removes the usual brake. There is no prior authorization asking whether the indication fits, no medical director comparing your case to a policy, and no claims data accumulating somewhere that anyone reviews.

It also selects for a particular audience. The people most willing to pay out of pocket for a regenerative treatment are, by definition, the people for whom covered treatments have already failed — which is a population in some distress and with reduced bargaining power. A seminar aimed at that group, promising cartilage regeneration, is not selling into a skeptical market.

None of this means the underlying science is empty. It means the volume of a claim is uncorrelated with its support, and that the burden should sit on the clinic to show you what it is delivering rather than on you to disprove it.

What would change our position

Stating this openly seems fair, since the page is critical. We revise when adequately powered randomized trials showed a consistent, clinically meaningful advantage for a cell-based preparation over PRP in a named indication, with the preparation characterized well enough to reproduce. For osteonecrosis that case is already reasonable. For knee osteoarthritis and for tendinopathy it is not yet there, and we will say so until it is.

What people ask about stem cell offers

Is PRP a stem cell treatment?

No, and any clinic saying so is misdescribing it. PRP contains platelets, not stem cells. How PRP works.

Can I get real expanded stem cells somewhere?

Not routinely in the United States outside an approved trial. Treatment abroad carries genuine risk. What BMAC actually is.

Are umbilical cord injections worth it?

Independent testing has repeatedly found few or no living cells in commercial samples. Risks and side effects.

Will any of this regrow my cartilage?

No available treatment reliably does. Anyone claiming otherwise is overselling. PRP for knee osteoarthritis.

Related reading

• Bone marrow aspirate concentrate
• PRP compared with BMAC
• How PRP works
• Am I a candidate?