MSC Therapy: The Body's Repair Signals

What is MSC therapy?

Mesenchymal stem cells, or MSCs, are adult cells found in bone marrow, fat, and umbilical cord tissue. They were named in the 1990s, and a landmark 1999 study in Science showed they could give rise to bone, cartilage, and fat cells in the laboratory. For a while, that made them look like universal spare parts.

Decades of research later, the picture is more interesting than that. MSCs turn out to be less like spare parts and more like site managers: cells whose job is to sense damage and direct the repair effort. Because that is a job many tissues need done, MSC therapy has been studied in an unusually wide range of conditions, from arthritic knees to immune disease.

One definition worth knowing before anything else: the term MSC describes a cell population that meets a set of laboratory criteria, defined in 2006 by the International Society for Cellular Therapy. It is not one standardized drug. Two clinics can both say "MSCs" and hand you meaningfully different products. More on why that matters below.

How does it work?

The early theory was that MSCs would engraft in damaged tissue and rebuild it directly. The evidence pushed the field to a better model. In 2011, an influential review in Cell Stem Cell described the MSC as an "injury drugstore": a cell that shows up and dispenses the right signals. By 2017, Arnold Caplan, the researcher who gave the cells their name, was arguing they should be renamed Medicinal Signaling Cells.

Here is the current understanding, in plain terms. When MSCs arrive in injured or inflamed tissue, the inflammation itself switches them on. Inflammatory molecules such as interferon gamma act like a work order: in laboratory studies, exposure to those signals turned even weakly suppressive MSC lines into strong ones. Once activated, MSCs release a mix of factors that dial down excessive immune activity, encourage new blood vessel growth, and recruit the tissue's own repair cells.

The most surprising part is that the cells do not need to stick around. In animal studies, infused MSCs die off within days, and the recipient's own immune cells, in the act of clearing them, are pushed toward a repair state. The cells deliver a message, and the message outlives the messenger.

So the point of MSC therapy is not to install new tissue. It is to change the local environment, interrupt inflammation that has become self-sustaining, and let the body finish the job.

Why it matters in regenerative medicine

Once you see MSCs as immune-modulating signal cells, their range makes sense. A huge share of chronic problems, from an arthritic joint to an autoimmune flare to a wound that will not close, involve inflammation stuck in a loop: damage feeds inflammation, and inflammation feeds damage. A treatment that can interrupt that loop, even temporarily, gives the tissue a window to heal.

That is why the same therapy shows up in such different settings. It also explains something people often find confusing: MSC therapy is not really a treatment for one disease. It is a repair-and-calm signal, and the results in any given condition depend on whether that signal is what the condition needed, and whether enough of it was delivered to the right place. That framing carries through everything below.

What MSC therapy is used for

Start with what regulators have signed off on. In the United States, one MSC product is approved: remestemcel-L, sold as RYONCIL, for children with graft-versus-host disease that has not responded to steroids, a serious immune complication of bone marrow transplantation. Abroad, India has approved an MSC product for knee osteoarthritis, South Korea for cartilage defects, and Japan for graft-versus-host disease.

Beyond the approvals, MSCs have been given in registered clinical trials for knee osteoarthritis, Crohn's fistulas, lupus, multiple sclerosis, Parkinson's disease, and COVID-19 lung injury, among others. And beyond the trials, MSC treatment is offered by clinics around the world for orthopedic, autoimmune, recovery, and longevity purposes, mostly in jurisdictions that permit physician-directed use.

One clarification we think matters: autism is often listed alongside MSC therapy in clinic marketing, but the published trials in autism used umbilical cord blood cells, a different product. The largest randomized trial gave a single infusion and found no advantage over placebo on its main measure at six months. Repeat dosing and other protocols were not tested.

Strong Craft Regen operates in this space as a coordination service. Treatments are physician-led, through Dr. Adas Darinskas and the team at Innovita Clinic in Vilnius along with partner facilities, and protocols are adjusted to the individual client rather than run identically for everyone.

What clients notice in practice

Not all MSC products are equal

The biggest quality divide in this field is culture expansion. Culture-expanded cells are isolated from the donated tissue and grown in the laboratory for weeks, until a small starting sample becomes a full treatment dose of verified MSCs. That time in the lab is what makes quality control possible: the cells can be identity-checked, counted, tested for potency, and cryopreserved properly. Every MSC product used in a registered clinical trial was made this way.

Culture expansion is about preparation, not tissue type: bone marrow, fat, and cord cells can all be expanded into tested products, and all three have been in clinical trials. The same-day route, common in local clinics in the United States, skips the lab entirely: bone marrow aspirate concentrate is drawn and spun during the visit, and stromal vascular fraction is prepared from fat the same way. These are legitimate treatments, and the concentrate does carry regenerative cells. They are also mixtures in which actual MSCs are a small minority, with no growing, selection, or release-testing step before the mixture goes back into the patient. When two people report wildly different results from "stem cells," this divide is often the reason.

For umbilical cord products the question answers itself: cord tissue is processed and cryopreserved after collection, and the cells must be culture-expanded to become a dose at all. There, quality lives in the manufacturing details. A properly made product is frozen under controlled conditions and comes with post-thaw viability testing, which verifies how many cells are alive and functional once the dose is thawed for treatment. Serious manufacturers can show you potency and viability numbers, and it is fair to ask any provider for them.

The pros and the cons

Why the evidence lags the practice

A fair question: if MSCs are promising, why is the trial record so thin and so mixed after all these years?

Part of the answer is money. Late-stage trials cost enormous sums, and they get funded when a company owns a patentable product that can earn the investment back. Cells prepared from donated tissue are difficult to patent. So rigorous trials cluster around the few proprietary products, like remestemcel-L and darvadstrocel, while common clinical uses of ordinary MSC preparations may never get a definitive trial, whatever the truth about them is.

Part of the answer is the product problem again. Trials of MSC therapy have tested different tissues, different doses, different schedules, and mostly single administrations. Pooling those into one verdict blurs real differences.

Neither point means the evidence would be positive if someone paid for the trials. Untested means untested, in both directions. It does mean that the absence of a large trial for a given use is often an economic fact rather than a scientific verdict, and we think readers deserve to know the difference.

What the key trials tested

Our framing rule for evidence: a trial tests one product, at one dose, by one route, on one schedule, in one population, against one comparator. The design is the fact. First, where the evidence sits today:

And the trials that matter most:

• In knee osteoarthritis, the MILES trial compared one injection each of three different cell preparations against a corticosteroid shot in 440 analyzed patients, and none did better at twelve months. Only one arm used culture-expanded cells, and repeat dosing was not tested.
• The two small randomized trials that did test repeat dosing, 56 patients between them, both found the repeat arm outperformed a single dose.
• In children's graft-versus-host disease, a single-arm phase 3 trial supported the US approval, while a separate adult trial missed its primary endpoint.
• In Crohn's perianal fistulas, the first phase 3 trial was positive and led to an EU authorisation. A second trial then found nearly identical healing rates in both arms, with surgical closure given to everyone, and the authorisation was withdrawn in late 2024.
• A 2025 meta-analysis across autoimmune conditions found benefit signals in lupus and inflammatory bowel disease, and not in multiple sclerosis.

Every study behind this article, plus the rest of our research library, is filterable on our Science page.

Questions people ask

This article is for educational purposes only and is not medical advice, a diagnosis, or a treatment recommendation. MSC Therapy is discussed in the context of the published research; inclusion of a study does not imply a guaranteed outcome. Many of these compounds are investigational and not approved for the uses described in all jurisdictions. Any treatment decision should be made with a qualified physician. Individual results vary.