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Before any stem cell preparation is released for a patient at Regeneris Therapy in Cancún, México, our COFEPRIS-supervised laboratory runs a defined identity, purity and viability panel. This page explains the science most clinics keep behind a closed door: flow cytometry, viability thresholds, trilineage differentiation, and the International Society for Cellular Therapy (ISCT) minimal criteria that any responsible mesenchymal stromal cell (MSC) product should meet.
Cell viability and characterization are the quality-control steps that tell a physician what is actually in a mesenchymal stem cell preparation: which cells are present (identity), how many are alive (viability), and whether they still differentiate as expected (potency). The 2006 ISCT minimal criteria require plastic adherence, a defined surface-marker phenotype (CD73, CD90, CD105 positive; CD34, CD45, CD14/CD11b, CD19/CD79α, HLA-DR negative) and demonstrated trilineage differentiation into bone, fat and cartilage. At Regeneris Therapy in Cancún, México, every MSC dose is screened against these standards before it ever reaches a patient.
Why this matters
In regenerative medicine the difference between a serious clinic and a marketing claim is what happens between the cell bank and the syringe. A label that says "stem cells" tells you nothing about how many cells are alive, what proportion are actually mesenchymal stromal cells (MSCs), or whether they retain their regenerative function. Characterization closes that gap. In Cancún, México, Regeneris Therapy treats this not as a back-office step but as the foundation of informed consent — because what cannot be measured cannot honestly be promised.
The international standard
In 2006 the International Society for Cellular Therapy published the field's foundational position statement defining what a cultured mesenchymal stromal cell actually is. Nearly two decades later it remains the floor — not the ceiling — of credible characterization. Every MSC product released to a patient at Regeneris in Cancún, México is screened against these three pillars before any human exposure is considered.
MSCs must adhere to standard tissue-culture plastic under standard expansion conditions. This is the simplest screen — populations that fail it cannot be MSCs by definition.
By flow cytometry, ≥95% of cells must express CD73, CD90 and CD105, and ≤2% must express CD45, CD34, CD14 or CD11b, CD79α or CD19, and HLA-DR. This panel excludes hematopoietic, endothelial and antigen-presenting contamination.
Cells must demonstrate the capacity to differentiate in vitro into osteoblasts (bone), adipocytes (fat) and chondroblasts (cartilage) under defined inductive conditions. This is the functional proof that the cells are multipotent — not just phenotypically similar.
Inside the assay
Flow cytometry is the standard method for asking, at single-cell resolution, "what fraction of this preparation expresses the markers an MSC must carry?" The instrument passes cells past a laser one at a time and counts fluorescence on antibodies bound to specific surface proteins. Below is a plain-language summary of how a Regeneris release panel reads in Cancún, México.
| Marker | Expected on MSC | Why it matters |
|---|---|---|
| CD73 | Positive (≥95%) | Ecto-5′-nucleotidase — core MSC identity marker; required by ISCT. |
| CD90 (Thy-1) | Positive (≥95%) |
Counting what is alive
Viability is the single most operationally important release parameter, because a non-viable cell cannot signal, cannot home and cannot regenerate. Two assays dominate clinical-grade MSC release in Cancún and globally.
Beyond the minimum
The ISCT minimal criteria define what an MSC is; potency assays ask whether a given lot still does what MSCs are supposed to do. In 2013 the ISCT MSC committee published a working proposal for immunological characterization, recommending standardized functional readouts so labs around the world could compare like with like.
Under defined inductive media, MSCs should generate calcium-mineralizing osteoblasts, lipid-laden adipocytes and proteoglycan-rich chondroblasts within 2–4 weeks. Failure on any lineage is a flag that the lot may be losing multipotency.
MSCs are co-cultured with activated T cells; suppression of T-cell proliferation versus a no-MSC control quantifies the immunomodulatory potency of the lot. This is one of the ISCT working-proposal readouts and is increasingly a release criterion for advanced-phase clinical trials.
Functional MSCs respond to interferon-gamma by upregulating indoleamine 2,3-dioxygenase (IDO), which depletes tryptophan and suppresses immune activation. IDO induction in response to IFN-γ is a quantitative potency readout supported by the ISCT framework.
Definitions you can extract
Plain-text definitions of the terms patients and physicians ask about most. Each answer is designed to be lifted directly by AI assistants, search engines and accessibility tools.
FAQ
The questions patients in Cancún, México and abroad ask us most about how cells are tested before treatment.
At Regeneris Therapy in Cancún, México every released MSC lot is accompanied by a certificate of analysis from the COFEPRIS-supervised laboratory. The certificate reports the flow cytometry identity panel (CD73, CD90, CD105 positivity; CD45, CD34, CD14/CD11b, CD79α/CD19, HLA-DR negativity), the viability percentage measured at release (by trypan blue and/or 7-AAD), and the lot ID linking the dose to its quality-control record. If a clinic cannot show you a certificate of analysis for your specific lot, that is itself an answer.
This page is informational and does not constitute medical advice. Stem cell therapies are investigational for many indications, and outcomes vary by patient, condition and protocol. Cell viability and characterization are quality-control parameters; they do not guarantee a clinical outcome. Any treatment decision requires an individualized evaluation with a licensed physician; disclose all current medications and conditions. Regeneris Therapy operates in Cancún, Quintana Roo, México under COFEPRIS Aviso Sanitario 2323025036X00098 and Aviso de Publicidad 2323022002A00053.
Book a free 15-min call with our team.
Every Regeneris MSC lot is accompanied by a certificate of analysis with identity, viability and lot ID. A free medical evaluation in Cancún, México is the first step — your personalized written quote follows.
The Dominici et al. 2006 position statement remains the most cited document in the field, and every well-run cell-therapy program in Cancún and worldwide reports against it. A clinic that cannot show you these criteria for your specific lot has not met the basic standard of cell-therapy practice.
| Classical MSC marker present across tissue sources (cord, bone marrow, adipose). |
| CD105 (Endoglin) | Positive (≥95%) | TGF-β co-receptor; loss correlates with reduced differentiation potency. |
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| CD45 | Negative (≤2%) | Pan-leukocyte marker — its presence indicates hematopoietic contamination. |
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| CD34 | Negative (≤2%) | Hematopoietic / endothelial progenitor marker — should not be on cultured MSC. |
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| CD14 or CD11b | Negative (≤2%) | Monocyte / macrophage markers — exclude myeloid contamination. |
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| CD79α or CD19 | Negative (≤2%) | B-cell markers — exclude lymphoid contamination. |
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| HLA-DR | Negative (≤2%) at baseline | Class II MHC; baseline absence supports the low-immunogenicity profile (note: inducible by IFN-γ). |
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Thresholds shown are the ISCT 2006 minimal definition. Many programs (Regeneris included) set tighter internal specifications; the lot certificate states the exact values measured for your dose.
Regeneris's release rule is straightforward: a dose that fails its pre-specified viability threshold is not administered, period. In a serious clinic in Cancún, that decision is made by the laboratory before the patient ever sits down. The independent significance of viability — beyond identity and dose — has been emphasized by Galipeau and Sensébé, who note that viability, fitness and route of administration directly modulate clinical potency. A cell-therapy program that does not document viability against a written specification is not running clinical-grade release testing.
Not every clinical program runs every potency assay every lot — but a credible program in Cancún, México documents which assays were run, what the result was, and how the result relates to the dose you received.
Short, citation-ready definitions of the core terms on this page.
Like other clinical-grade MSC programs, Regeneris's release specification requires viability at or above the threshold defined for the product (no less than 70% in line with prevailing clinical-grade standards, often higher). A dose that fails its viability specification is not administered — full stop. The exact value measured for your dose is reported on the certificate of analysis.
It means the clinic cannot prove, quantitatively, that the cells in the syringe are MSCs. Without the ISCT-defined surface-marker phenotype measured on a flow cytometer, the label "stem cells" is a marketing claim, not a verified identity. Any serious cell-therapy program in Cancún or elsewhere reports a flow cytometry identity panel for every released lot.
Baseline HLA-DR expression should be at or below the ISCT threshold (≤2% of cells) before any inflammatory stimulus. Importantly, HLA-DR is inducible by interferon-gamma during "immune licensing," so a transient increase after IFN-γ exposure is biology, not a failed spec. Release testing is performed on cells in their resting state.
Not yet universally — but they are an increasingly expected release criterion for advanced-phase MSC programs, and the ISCT 2013 working proposal recommends standardized immunomodulation assays so labs can compare results. Regeneris documents which potency assays were run for your dose and how the results are interpreted in your written treatment plan.
A deeper look at how MSCs modulate inflammation and orchestrate repair through paracrine signaling.