Are all stem cell treatments the same? This review covers how MSC subpopulations defined by specific markers may explain inconsistent results seen across cell therapy trials.
Most people asking whether all stem cell treatments are the same already suspect the answer is no. They are right, but probably not for the reasons they have been given.
The question matters because patients considering mesenchymal stem cell therapy are often handed a category, not a product. “MSC therapy” covers an enormous range of preparations, cell sources, and manufacturing choices, and the clinical results across trials have been inconsistent enough to leave both patients and physicians uncertain about what to expect. A review paper co-authored by TAM’s Francesco Marincola, published in the Journal of Translational Medicine, examines why that inconsistency exists and what the research on MSC subpopulations suggests about how to address it. By the end of this post, you will have a clearer model for why the identity of the cells being used may matter as much as the therapy itself.
The gap that created this problem is understandable. For years, MSC therapy was developed using mixed, unselected cell populations harvested from bone marrow, fat, or umbilical cord tissue. The assumption was that MSCs were a reasonably uniform group, that the therapy was the cells. Inconsistent trial results were chalked up to differences in disease stage, patient population, or dosing. What the field is now recognizing is that the cellular preparation itself was a major variable that researchers had not fully accounted for.
What MSCs Actually Do
Before the subpopulation question can mean anything, the basic mechanism has to be clear. MSCs do their work less like construction crews physically rebuilding damaged structures and more like a radio tower sending instructions to the cells already there. A mixed MSC preparation broadcasts across many frequencies at once: some signals useful for calming inflammation, some for stimulating repair, many overlapping or redundant.
A purified subpopulation, identified by markers like SSEA-3 or CD146, is more like a high-powered directional antenna locked onto the specific frequency an injured tissue needs to receive. Stronger signal, less noise, more of the message actually getting through. The signal here refers to paracrine molecules like PGE2 and IDO, which act as molecular peacekeepers by suppressing overactive immune responses rather than replacing damaged cells. In laboratory and animal model studies, these marker-defined subpopulations produce measurably higher concentrations of those molecules and appear better equipped to maintain that output when the surrounding environment is under stress.
What the Research Shows
The review pulls together preclinical studies, clinical trials, and regulatory milestones to build a case that MSC populations are heterogeneous in ways that matter therapeutically. Surface markers including STRO-1, CD146, CD271, ALDH, and SSEA-3 have been used to identify subgroups with measurably stronger healing, immune-regulating, and tissue-repair properties compared to standard mixed preparations. The evidence suggests that selecting for these subpopulations could produce more consistent and potent effects, though it must be stated clearly: this is a review of preclinical and clinical data, and definitive clinical proof that any one subpopulation outperforms others in human trials has not yet been established.
What has been established is that the broader field of MSC therapy reached a clinical milestone with the FDA approval of Ryoncil, the first approved MSC product, indicated for pediatric steroid-refractory acute graft-versus-host disease. The approval was based on the Phase III MSB-GVHD001 trial, which demonstrated an overall response rate of 70% (95% CI: 56.4-82.0%) at day 28 and a complete response rate of 30% (95% CI: 18.0-43.6%). That result, in a population with very limited options, gives the field a regulatory and clinical reference point it did not previously have.
TAM’s Role in This Work
Francesco Marincola, affiliated with TAM Center, is listed as a co-author on this review. His involvement situates TAM within the ongoing effort to understand the mechanistic basis for MSC therapeutic variability and to identify the conditions under which these therapies are most likely to succeed.
Where the Research Points Next
A defined, approved MSC product creates a framework that did not exist before. The next questions are translational ones: whether subpopulation selection can be standardized at manufacturing scale, whether specific marker profiles predict therapeutic performance across different disease indications, and whether the potency advantages observed preclinically survive the transition to regulated clinical products. Those are hard questions. The answers will require prospective trials designed specifically around cell identity rather than treating it as background noise. The direction is clear even where the destination is not yet.
What You Can Do Now
If you are evaluating MSC-based options, ask what is known about the specific cell population being used: how it was sourced, how it was characterized, and what evidence exists for the preparation being considered. The review is available open access at the link below. Patients who want to discuss what this research means for their specific situation can request a consultation with TAM’s clinical team. The most important question you can bring to that conversation is not whether MSC therapy works in general, but whether the preparation under consideration has been characterized precisely enough to give you a reasonable basis for a decision.
Source
Pearl JR; Marleau A; Pacheco DO; Mahant V; Mizer JC; Juarez P; Asadi A; Marincola FM; Guerena D; Clay E. “Hierarchical therapeutic potential in the mesenchymal stem cell landscape.” Journal of Translational Medicine 2025;23(1):1394. doi:10.1186/s12967-025-07391-5. https://doi.org/10.1186/s12967-025-07391-5
Source
Pearl JR; Marleau A; Pacheco DO; Mahant V; Mizer JC; Juarez P; Asadi A; Marincola FM; Guerena D; Clay E. “Hierarchical therapeutic potential in the mesenchymal stem cell landscape.” Journal of Translational Medicine 2025;23(1):1394. doi:10.1186/s12967-025-07391-5. https://doi.org/10.1186/s12967-025-07391-5
Frequently Asked Questions
Standard MSC therapies typically use a mixed population of cells harvested together, which means potency and behavior can vary from batch to batch. Specific subpopulations, identified by surface markers like STRO-1, CD146, or CD271, appear to concentrate the most therapeutically active cells into a more consistent group. The hypothesis is that a purified subpopulation would deliver more reliable results, though clinical proof that any one subpopulation definitively outperforms mixed populations has not yet been established.
MSCs work primarily by releasing signaling molecules, called paracrine factors, that calm inflammation and support tissue repair rather than by directly replacing damaged cells. When surrounding tissue is inflamed, MSCs detect those distress signals and increase production of immune-dampening molecules like IDO and PGE2. Specific subpopulations appear to produce higher concentrations of these signals and survive longer under stressful biological conditions.
This was a review paper, not a new clinical trial, so it pulled together findings from existing preclinical studies, clinical trials, and regulatory milestones in MSC research. The central conclusion is that certain MSC subpopulations defined by specific surface markers show stronger healing and immune-regulating properties compared to unsorted mixed populations. The authors note this as a promising direction, not a clinically confirmed advantage.
That figure comes from the Phase III trial that supported FDA approval of Ryoncil, the first MSC therapy to receive FDA approval, indicated specifically for pediatric steroid-refractory acute graft-versus-host disease. In that trial, 70% of patients showed an overall response by day 28. This statistic belongs to that specific trial and approved indication and should not be generalized to other MSC applications or subpopulation-based approaches.
Using a poorly characterized or inconsistent cell population introduces variability in how strongly and in which direction the therapy acts, which can affect both efficacy and safety. A well-defined subpopulation is more predictable in the signals it releases and how it interacts with the immune system. More consistent cell behavior is one reason researchers believe subpopulation selection could eventually lead to better-controlled therapeutic profiles, though this remains under investigation.
Francesco Marincola, a researcher affiliated with TAM Center, is listed as a co-author on this review paper. His involvement reflects TAM’s broader interest in translating findings from immunology and cell biology research into clinical understanding. The paper itself is a scientific review, not a TAM-conducted clinical trial.
The only FDA-approved MSC therapy currently available is Ryoncil, and its approval is limited to pediatric patients with steroid-refractory acute graft-versus-host disease. Subpopulation-selected MSC therapies, which are the focus of this review, are not approved or clinically available as a distinct treatment approach. Patients interested in MSC-based therapies should consult their physician and review clinicaltrials.gov for ongoing studies.
Interested in what targeted diagnostics could reveal about your own biology? Start with a conversation with the TAM Center team.
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