Why this is available in Mexico — and how medical approval works
The short version
The FDA regulates products. It does not prohibit you from traveling, and it does not decide what care you may seek in another country.
“Not FDA-approved” and “doesn’t work” are two different statements, and the difference matters. In December 2024 the FDA approved the first mesenchymal stromal cell therapy in the United States — a category that had been available in Japan since 2015. Some therapies reach approval in one country years before another. Some never do.
But sometimes “not approved” does mean the evidence didn’t hold. In 2024 a stem cell therapy that had been approved in Europe since 2018 was withdrawn, because a larger confirmatory trial found it worked no better than placebo.
The question that protects you is not which side of the border a treatment is on. It is how the product is made, and what evidence exists for that specific product. This page explains how to tell the difference.
What FDA approval actually is
FDA approval is a decision about a product, made for a specific use, based on evidence submitted by whoever manufactures it.
Three things follow from that, and most sites explain none of them:
Approval is applied for, not assigned. A therapy is not reviewed because it exists. Someone has to run the trials, assemble the file and pay for the process. Products with no company behind them, or no patent to recover the investment, may never be submitted — regardless of whether they work.
Approval is per indication, not per therapy. The same product can be approved for one condition and unapproved for another. “Approved” without naming the condition is an incomplete sentence.
Approval is national. Japan, the European Union, Mexico and the United States each run their own review. They frequently reach the same conclusion at different times, and occasionally reach different conclusions.
What “not approved in the U.S.” can mean
It can mean four different things, and they are not equivalent.
1. Nobody has submitted it yet. The most common case for cell-based therapies. The evidence may be early, or promising, or substantial — but the regulatory file does not exist.
2. It is approved somewhere else. Real, verifiable examples:
- Mesenchymal stromal cells. Japan approved a product for graft-versus-host disease in 2015. Canada approved one. The FDA approved its first in December 2024 — nine years later. The therapy did not change in December 2024. The paperwork did.
- Human placental extract. Approved as a pharmaceutical by Japan’s Ministry of Health, Labour and Welfare, with an approved indication in liver function. Not approved in the United States.
- Thymalfasin, a synthetic thymic peptide, is approved as a prescription medicine in more than 30 countries for hepatitis B and C. Not in the U.S. Thymalfasin is a defined, synthetic 28-amino-acid molecule. A product described as a “thymic peptide” or a thymic extract is not the same thing, and this approval says nothing about it.
These are examples of how regulatory systems differ. None of them is an endorsement of any therapy discussed elsewhere on this site. An approval belongs to one specific product, for one named indication, in one jurisdiction — that is the point of the section, and it applies to us as much as to anyone.
3. It is under investigation and genuinely uncertain. Most NK cell therapy sits here. There are trials in progress worldwide, the safety profile in those trials has been favorable, and no NK cell product is approved as a medicine by any major agency. That is the honest description, and it is the one we use.
4. It was tested and did not hold up. This is the case nobody in this industry mentions, so we will.
A stem cell therapy for a complication of Crohn’s disease was approved in the European Union in 2018 on the strength of a trial where it beat placebo. A larger confirmatory trial was then run. In it, the placebo group did just as well. The company voluntarily withdrew the product in December 2024 and the European regulator concluded the clinical benefit was no longer demonstrated.
That is what an honest evidence system looks like from the inside. A therapy can look real, get approved, and then turn out not to be. If a clinic never tells you this happens, ask yourself why.
Why approval takes so long
Bringing a therapy through full regulatory review takes years and costs an amount most laboratories and hospitals cannot raise. That is not a scandal — the process exists because it catches products that don’t work. It is also the reason the pace of approval reflects who could afford the process, not only what the science shows.
Both of those things are true at once. Holding both is the whole skill.
The question that actually protects you
Here is the part that matters more than the border.
What the FDA has documented is stated below as what it is — findings about specific products and specific facilities.
The FDA’s 2019 public safety notification on exosome products followed serious adverse events in patients in Nebraska, including bacterial infections traced to products made without validated sterility procedures. Warning letters issued since have repeatedly cited failure to validate sterility.
Those are findings about the products and manufacturers named in them. They do not describe every product of that type, or every manufacturer — and reading them as if they did would be the same mistake this page argues against, pointed the other way.
What the record does show is that manufacturing is where the documented harm has come from, more often than the underlying idea.
Verify the clinic, by name and by address
A published audit of 76 stem cell clinics in one Mexican border city found that 13 claimed to be licensed. Six matched the official registry by name or by address. One matched on both.
That audit describes the clinics it examined. It is not a statement about every clinic operating in Mexico — and reading it as one would be the same mistake this page argues against, pointed the other way.
What it is good for is the method: verify by name AND address, against the registry itself, not against what a website says.
A cell product made in a licensed facility, in a certified clean room, with documented quality control and release testing, is a different object from a vial produced in a back room — even if the label says the same word.
So the useful questions are not about geography. They are:
- Where was this made, and under what license?
- What testing is done on each batch before it is released?
- What exactly is in the vial — cell type, count, viability?
- Is there a potency assay, and what does it measure?
- What has been published on this preparation, not on the category?
A provider who can answer those five questions is telling you something. A provider who answers them with the word “advanced” is telling you something else.
What we do with this
We are a coordination platform, not a clinic and not a laboratory. We do not manufacture, prescribe, or decide what is appropriate for you — an independently licensed physician does that, and may conclude that nothing here is appropriate for you.
What we can do is show you the evidence as it actually stands, including the parts that argue against exploring, and help you arrive at that physician conversation with organized records and better questions.
The first step is not a commitment. It is a conversation, and then a review. You can stop at any point, and you can ask us to delete your information at any time.
Request a Medical ReviewOpens a conversation in your browser.
Next: How to decide whether to explore at all → (It is genuinely a page about deciding not to, as often as deciding to.)
The record
Regulatory actions cited on this page
| Item | Detail | Source |
|---|---|---|
| First FDA-approved MSC therapy | Remestemcel-L-rknd (Ryoncil), approved 18 Dec 2024 for steroid-refractory acute GvHD in pediatric patients ≥2 months. Pivotal trial: single-arm phase 3, day-28 overall response 70% | FDA approval notice, 18 Dec 2024 |
| Japan MSC approval | Temcell, approved Sept 2015 for acute GvHD — first MSC therapeutic product approved anywhere | Peer-reviewed review literature |
| EU approval and withdrawal | Darvadstrocel (Alofisel): EU authorization 2018; Japan 2021. ADMIRE-CD (n=212) showed 51.5% vs 35.6% combined remission at week 24. Confirmatory ADMIRE-CD II did not meet its primary endpoint. Marketing authorization voluntarily withdrawn 13 Dec 2024 | EMA / manufacturer statement, 13 Dec 2024 |
| Human placental extract | Laennec and Melsmon approved as pharmaceuticals by Japan’s MHLW; Laennec with an approved indication in liver function. Note: approved scope is narrower than the uses commonly marketed | Japanese regulatory listing; review, PMID 41451368 |
| Thymic peptide | Thymalfasin (thymosin alfa-1) approved in 30+ countries for hepatitis B/C and as an immune adjuvant. This is a defined synthetic 28-amino-acid peptide — not equivalent to a crude thymic extract | Review of >11,000 subjects across >30 trials, Dinetz 2024 |
| Exosome safety notification | FDA Public Safety Notification, 6 Dec 2019, following serious adverse events in Nebraska; no FDA-approved exosome products exist; multiple warning letters since, citing failure to validate sterility | FDA, 6 Dec 2019 |
| NK cell therapy status | No NK cell product approved as a medicine by FDA, EMA, PMDA or MFDS as of 2026. 125+ registered solid-tumor trials since 2011, predominantly phase I and I/II | ClinicalTrials.gov landscape analysis |
The four levels of evidence
Every claim on this site declares which level it sits at:
- Mechanism — biologically plausible
- Class — trials exist for this family of therapies
- Preparation — trials exist for this specific product
- Authorization — an agency approved it for a named indication
Evidence at one level does not transfer to another. An approval for one manufacturer’s product is not evidence for a different manufacturer’s vial.
Still open
- Cost and duration figures for regulatory approval — stated qualitatively on purpose. No numeric claim here until a primary source is cited for it.
This page describes regulatory systems and documented agency findings. It makes no claim about what any therapy does for a patient, so it carries no medical signature — the therapy pages do. Reviewed and approved for publication by legal counsel, 10 August 2026.