Patients walk into consultations with two beliefs about this comparison, and both are usually backwards.

The first: that stem cell therapy is simply the stronger, more advanced version of PRP — the upgrade you buy if you can afford it. The second: that because the cells come from your own body, the FDA has nothing to say about it.

Neither holds up. The two treatments differ in what's in the syringe, in how US law treats them, and in how much clinical evidence exists — and the direction of those differences isn't the one marketing implies.

What is actually in a PRP tube

PRP starts as a blood draw, usually 15–60 mL. The tube is spun in a centrifuge, and the layer richest in platelets is drawn off and injected back into the patient, typically in the same visit.

Platelets are cell fragments. They have no nucleus and cannot divide. What they carry is a payload of growth factors and signaling proteins released when they activate. Depending on the system, a PRP preparation may concentrate platelets somewhere in the range of two to eight times the patient's baseline whole-blood level, with widely varying red and white cell content — which is one reason study results are so hard to compare across trials.

What PRP does not meaningfully contain is stem cells. There are vanishingly small numbers of circulating progenitor cells in peripheral blood, but a standard PRP prep is not a cell therapy in any practical sense. If a clinic markets PRP as a "stem cell" treatment, or as "activating your stem cells," that second phrase is doing a lot of unearned work. The American Academy of Orthopaedic Surgeons' patient overview of PRP describes it as a concentration of platelets and growth factors, not cells.

What "stem cell therapy" means in a US clinic

The phrase covers at least four commercially distinct things, and patients are rarely told which one they're buying:

Bone marrow aspirate concentrate (BMAC). Marrow is drawn from the pelvis, usually under local anesthetic, and concentrated. It does contain mesenchymal stromal cells — but they are rare. In marrow, cells capable of forming fibroblastic colonies are typically a tiny fraction of one percent of nucleated cells, and yields vary a great deal by patient age, site, and aspiration technique. BMAC is best understood as a mixed biologic containing platelets, plasma, nucleated cells, and a small stromal cell population.

Adipose-derived preparations. Fat is harvested by mini-liposuction and either mechanically fragmented or, in some clinics, enzymatically digested to yield "stromal vascular fraction." The enzymatic route is the regulatory flashpoint, for reasons below.

Birth-tissue products. Amniotic fluid, amniotic membrane, umbilical cord blood, and Wharton's jelly, sold to clinics as vials from a supplier. These are marketed as "stem cell" products more aggressively than anything else in the category. Independent laboratory analyses of commercially available amniotic and cord-derived injectables have repeatedly found few or no viable cells after processing, shipping, and freeze-thaw — you may be paying for growth factors and extracellular matrix proteins in a vial, not for living cells. If a product arrives frozen, off the shelf, and is not from your own body, treat any claim about live stem cell counts as something to see documented.

Exosomes. Cell-derived vesicles, often from cultured donor cells. The FDA has stated plainly that it has approved no exosome products for any indication, and has warned consumers after adverse events tied to unapproved ones.

The FDA question, directly

Here is the part most often glossed over.

Human cell and tissue products fall into two buckets. Some qualify as "361 HCT/Ps" and can be used without premarket approval — but only if they are minimally manipulated, intended for homologous use, not combined with a drug or device, and don't have a systemic effect. Everything else is a biological drug requiring an approved license, which means clinical trials.

PRP made from your own blood at the point of care and returned to you in the same procedure has generally not been treated as requiring premarket approval. That does not mean PRP is FDA-approved. The centrifuges and kits are cleared devices — often cleared for narrow purposes such as preparing platelet concentrate to be mixed with bone graft — while the actual injection into a knee, a scalp, or a tendon is an off-label use of a cleared device. There is no FDA approval for PRP as a treatment for osteoarthritis, tendinopathy, or hair loss.

Most cell-based products are in a harder position. Enzymatic digestion of fat to isolate stromal cells is generally more than minimal manipulation; injecting fat-derived cells into a joint is not homologous use of fat. The FDA laid out this framework in 2017, allowed a period of enforcement discretion that ended in 2021, and has since pursued warning letters, injunctions, and litigation against clinics selling these products without an approved application. The agency's consumer-facing position is unambiguous: it warns patients about stem cell treatments marketed for conditions where they have not been proven safe or effective.

What is approved is narrow. The FDA maintains a public list of licensed cellular and gene therapy products: cord-blood-derived hematopoietic products for blood and immune disorders, engineered T-cell therapies for certain cancers, and a small number of others. Nothing on that list is an injection for knee arthritis, back pain, or anti-aging.

What "not FDA-approved" does and does not mean

It does not mean the treatment is fake, and it does not mean it is illegal for a physician to offer. Doctors practice medicine using off-label and unapproved approaches routinely.

It does mean nobody has submitted evidence to a regulator that the product works and that its risks are acceptable for a stated use. It means no agency has inspected the manufacturing of what's being injected into you. It means your insurer will almost certainly not cover it. And it means marketing claims have not been vetted by anyone with the power to require proof.

The evidence gap runs the other way

PRP has been studied in hundreds of randomized trials across knee osteoarthritis, lateral elbow tendinopathy, plantar fasciitis, rotator cuff disease, and androgenetic alopecia. The body of evidence is genuinely mixed — some well-conducted, placebo-controlled trials in knee osteoarthritis have found no benefit over saline on pain or cartilage volume, while other trials and meta-analyses report modest pain improvements, and preparation protocols differ so much that pooling results is arguably questionable. Specialty guidelines, including the AAOS guidance on knee osteoarthritis, treat the evidence as limited and inconsistent rather than settled.

That is still a much larger and better-controlled literature than exists for autologous cell injections in the same conditions, where trials tend to be small, frequently unblinded, and often lack a placebo arm. For commercial birth-tissue injectables, high-quality randomized evidence in orthopedic use is thinner still.

So the framing that stem cells are the premium tier and PRP the budget option inverts the evidence. The more expensive option is generally the less studied one.

Risk is not symmetrical either

PRP's adverse events are mostly local and self-limited: injection pain, swelling, a post-injection flare of a few days, bruising, and the ordinary small risk of infection or nerve irritation from any needle.

Cell products add procedural risk — marrow aspiration or liposuction under sedation — plus the risk that comes with an unregulated manufacturing chain. Clusters of serious bacterial infections have been traced to contaminated umbilical cord blood injectables, and a case series in the New England Journal of Medicine documented severe permanent vision loss after intravitreal injection of adipose-derived "stem cells" at commercial clinics. Those harms are rare relative to the number of procedures done, but they are real and they have no PRP equivalent.

Cost, and what the gap buys

Broadly, single-site PRP injections in the US run from a few hundred dollars to roughly $2,500, with multi-session protocols for hair loss or joints priced as packages. Cell-based injections commonly run from about $3,000 to $10,000 per site, and whole-body or intravenous protocols are advertised well above that.

The price difference reflects harvest complexity, product sourcing, and marketing — not a demonstrated difference in outcomes.

Questions worth asking before you pay

  • What exactly is being injected, and is it from my body or a purchased vial?
  • If it's a purchased product, what is the supplier's regulatory status, and is there a certificate of analysis showing viable cell count?
  • Is this a 361 HCT/P, or a product that would require an FDA-approved application?
  • Are you enrolling me in a registered clinical trial? If not, why is this being offered outside one?
  • What published randomized evidence exists for this specific product in my specific condition?
  • What is the total cost, including repeat sessions, and what is the refund policy if there's no response?

A clinic that answers these crisply is telling you something useful. So is one that changes the subject to testimonials.

This guide is information, not medical advice. Decisions about your own care belong with a clinician who has examined you and knows your history.