How to Compare Stem Cell Products: Why Not All Stem Cells Are the Same

If you are researching stem cell therapy, you may hear clinics talk about cell counts, generations, passages, viability, potency, tissue source, growth factors, or certificates of analysis.

It can get confusing quickly.

Two products may both be described as “umbilical cord stem cells” while differing considerably in how they were sourced, processed, expanded, stored, tested, and prepared before treatment.

That matters because the words “stem cells” alone tell you very little about the final biologic product.

So how can a patient tell the difference?

The most useful questions involve cell identity, viability, potency, processing, safety testing, sourcing, and regulatory status.

Here is what to look for.

Quick Answer: Are All Stem Cell Products the Same?

No.

Cell-based products can differ in:

• Tissue source
• Donor characteristics
• Cell identity
• Number of viable cells
• Passage number
• Culture conditions
• Cryopreservation
• Storage and thawing
• Sterility
• Functional potency
• Final formulation

Researchers have repeatedly identified manufacturing variability as a major challenge in mesenchymal stromal cell research. Even MSC populations that look similar and express similar surface markers may have different biological and functional properties.

That means choosing a stem cell product should involve more than asking:

“How many cells are in the vial?”

A better question is:

“What exactly is in the final product, how was it tested, and what do we know about its quality?”

Watch: Dr. John Dame and Chuck Meeker Discuss Stem Cell Quality

Video Transcript

Chuck Meeker, Founder of Hyagen Medical:

Stem cells are 100% effective at doing what they’re designed to do. They will never fail.

Dr. John Dame:

I’ve yet to have a patient that said, “I didn’t get any benefit from this treatment.”

Chuck Meeker:

You just have to understand what the stem cell’s function is, and that is the delivery of bioactive molecules. It will not fail to do that.

Let me put a caveat in there.

If you’re getting a stem cell product that doesn’t actually include stem cells and bioactive protein molecules, I can’t make that promise.

Transcript lightly edited for punctuation and readability without changing the speakers’ meaning.

Important Context About the Video

The video raises an important point:

What is actually inside a stem cell product matters.

However, the statement that stem cells are “100% effective” should not be interpreted as a guarantee that every patient will experience a specific clinical result.

Cellular activity and clinical outcome are different questions.

A cell may release signaling molecules without producing a meaningful improvement in a patient’s symptoms.

Likewise, researchers have shown that mesenchymal stromal cell products with similar appearances and cell-surface markers can still differ substantially in biological function. That is why modern cell-therapy development places significant emphasis on potency testing, not simply cell identification.

No stem cell procedure should be presented as guaranteed to relieve pain, regenerate tissue, reverse disease, or produce a particular clinical outcome.

1. What Do Stem Cells Actually Do?

The popular image of stem cells is that they are injected into the body, travel directly to damaged tissue, turn into new tissue, and rebuild whatever is injured.

The biology is considerably more complicated.

Mesenchymal stromal cells, or MSCs, are being studied in part because of the substances they release into their surrounding environment.

These substances are collectively sometimes described as the secretome.

The secretome can contain biologically active molecules involved in cell communication.

Research has shown that the composition of MSC secretions can vary based on cell source, donor, culture conditions, passage, and other manufacturing variables.

This is one reason the final product matters so much.

Two products carrying the same broad label may not necessarily behave identically.

2. What Are “Bioactive Molecules”?

Chuck refers in the video to stem cells delivering bioactive molecules.

That is an important part of contemporary MSC research.

Cells communicate with surrounding cells by releasing signaling substances.

Researchers study molecules and components including:

• Cytokines
• Chemokines
• Growth factors
• Extracellular vesicles
• Other signaling proteins

These secreted factors may influence neighboring cells and biological pathways.

However, the exact profile can vary.

For example, experimental research has shown that changes in the environment surrounding MSCs can alter the cytokines and signaling molecules they release. Even factors such as the delivery vehicle and exposure to certain additives have changed secretion profiles in laboratory studies.

So simply saying that a product contains “growth factors” or “bioactive molecules” is not enough to establish its potency or clinical effectiveness.

3. Why “100% Effective” Needs Context

It helps to separate three ideas:

Cell Identity

Are these actually the type of cells the manufacturer claims they are?

Biological Activity

Are the cells alive and capable of performing measurable biological functions?

Clinical Effectiveness

Does treatment actually improve the patient’s condition?

Those are not interchangeable.

A laboratory can establish that cells are viable and biologically active without proving that a particular treatment will improve a particular disease or injury.

That is why regulatory development of cellular therapies involves tests for characteristics such as identity, purity, safety, viability, and potency, followed separately by clinical trials evaluating whether patients actually benefit.

4. Question 1: Where Does the Product Come From?

Start with the source.

Mesenchymal stromal cells can be studied or obtained from several tissues, including:

• Umbilical cord tissue
• Bone marrow
• Adipose tissue
• Other connective tissues

Even within an umbilical cord, MSCs may be isolated from different regions, including Wharton’s jelly and other cord structures. Research has demonstrated that different cell sources can have different growth and biological characteristics.

At The Re/ Clinic, our regenerative medicine program includes umbilical cord-derived products.

Patients should ask:

Where exactly did this product come from?

That question should have a clear answer.

5. Question 2: Does the Final Product Actually Contain Viable Cells?

This is one of the most important questions when a product is being described as a live-cell therapy.

Viability refers to the percentage of cells that are alive.

The key phrase is:

final product.

It is not enough to know that cells were alive before freezing.

Cells may experience:

• Cryopreservation
• Thawing
• Dilution
• Transportation
• Storage
• Preparation
• Administration

Each step can potentially affect the final preparation.

Research examining clinical MSC processing has shown that thawing conditions and post-thaw handling can materially affect viable cell recovery. One study found substantial cell loss under certain reconstitution and storage conditions, while optimized conditions maintained greater viability.

A large multicenter cryopreservation study also demonstrated measurable differences in post-thaw viability and viable cell recovery depending on the cryopreservation method.

So if a clinic advertises a specific number of cells, patients should consider asking:

Is that number measured before freezing, after thawing, or in the final preparation administered to the patient?

6. Question 3: How Are the Cells Identified?

Calling something an MSC requires more than simply looking at it under a microscope.

The International Society for Cell & Gene Therapy established widely used minimum criteria for characterizing human mesenchymal stromal cells.

Those criteria include adherence under standard culture conditions, the presence of certain surface markers, absence of others, and the ability to differentiate into specific cell lineages under laboratory conditions.

Commonly referenced positive markers include:

• CD73
• CD90
• CD105

Research-grade characterization often involves flow cytometry and other laboratory testing.

Why does this matter?

Because a product labeled “stem cells” should have evidence establishing what those cells actually are.

7. Question 4: What Does Potency Mean?

Viability tells you whether cells are alive.

Potency asks what they can actually do.

Those are very different questions.

A vial could theoretically contain a large number of living cells while still having limited biological activity relevant to its intended use.

Researchers working with clinical-grade MSC products therefore develop assays designed to evaluate characteristics such as:

• Immunomodulatory activity
• Colony-forming ability
• Cellular signaling
• Other product-specific biological functions

Researchers have emphasized that potency testing is one of the major challenges in developing standardized MSC therapies because superficially similar MSC populations can still behave differently.

This is why:

cell count + viability does not automatically equal potency.

8. Question 5: How Was the Product Processed and Stored?

Cell products do not go directly from donated tissue into a patient’s syringe.

Depending on the product, those steps can involve:

• Tissue processing
• Cell isolation
• Culture
• Expansion
• Passage
• Washing
• Cryopreservation
• Storage
• Shipping
• Thawing
• Final preparation

Each step potentially matters.

Research comparing MSC manufacturing across multiple laboratories has shown that even when laboratories attempt to harmonize their culture procedures, biological variability remains.

Likewise, donor variability remains an important issue with umbilical cord-derived MSCs. A 2025 study demonstrated meaningful differences in immunomodulatory function between UC-MSCs obtained from different donors.

This means:

the tissue source is only the beginning of the story.

The manufacturing process matters too.

9. Question 6: What Safety Testing Was Performed?

Clinical-grade cell manufacturing requires attention to more than cell count.

Common quality-control tests used in clinical MSC manufacturing can include:

• Sterility testing
• Endotoxin testing
• Mycoplasma testing
• Cell count
• Viability
• Immunophenotype
• Functional or potency-related testing

Published clinical-grade manufacturing protocols specifically describe these types of assays as part of release and quality-control strategies.

This is where patients should become comfortable asking direct questions.

For example:

Was this batch tested for contamination?

Was viability measured?

Was cell identity characterized?

A reputable provider should be willing to discuss what testing is available for the product being offered.

10. Question 7: Can You Review Product Documentation?

One of the simplest questions a patient can ask is:

Can I see the documentation for the product?

Depending on the product and manufacturer, documentation may include information about:

• Product source
• Donor screening
• Lot or batch number
• Cell count
• Viability
• Sterility testing
• Identity testing
• Processing
• Storage
• Other release criteria

Sometimes this information is summarized in a Certificate of Analysis, commonly called a COA.

A COA should not simply be viewed as a marketing document.

Patients and providers should understand:

What exactly was tested?

and

At what point in the manufacturing process was it tested?

A laboratory value may describe the product at one stage without necessarily describing its condition at another.

11. Does a Bigger Cell Count Mean a Better Product?

Not necessarily.

Cell count is useful information, but it does not tell you everything.

Imagine comparing two products.

One advertises a very high total cell number but gives little information about:

• Viability
• Cell identity
• Potency
• Sterility
• Processing

Another provides a lower advertised count but extensive characterization of the final product.

Cell count alone does not tell you which is the better product.

Modern cell-therapy quality control evaluates multiple attributes rather than relying on one number.

This is also why you should be cautious when comparing clinics solely by asking:

“How many millions of cells do I get?”

The better conversation is about quality, characterization, and clinical appropriateness.

12. Why Passage Number Matters

If MSCs are expanded in culture, researchers may refer to a passage number.

A passage occurs when cells growing in culture are transferred into a new culture environment so they can continue expanding.

For example:

• P1 means passage one
• P2 means passage two
• P3 means passage three

and so on.

Passaging allows researchers and manufacturers to generate more cells from an original population.

But cells are biological systems, not photocopies.

Their characteristics can change during culture.

Research has found that cell source, donor characteristics, culture conditions, and passage can influence MSC behavior and function.

That does not mean a simple rule such as:

“lower passage is always better”

can be applied to every product.

It means passage number is one quality variable that should be understood alongside viability, identity, potency, and the overall manufacturing process.

13. FDA Registration vs FDA Approval

This distinction is extremely important.

Patients may hear statements such as:

• “The lab is FDA registered.”
• “The product is FDA listed.”
• “The clinic follows FDA standards.”

Those phrases do not automatically mean the product is FDA-approved.

The FDA specifically warns consumers that registration with the FDA or appearance on ClinicalTrials.gov does not mean a regenerative medicine product is legally marketed or FDA-approved.

The FDA currently states that the stem-cell products it has approved are blood-forming stem cells derived from umbilical cord blood for specific disorders involving the blood-forming system. Those approvals do not extend to orthopedic, neurological, chronic pain, fatigue, autism, or other commonly marketed regenerative uses.

FDA regulation of human cell and tissue products also depends on factors including minimal manipulation and homologous use.

Patients deserve clear explanations of the regulatory status of the specific product being discussed.

14. What Should Patients Ask Before Stem Cell Treatment?

Before choosing a regenerative medicine clinic or product, consider asking:

1. Where does the product come from?
2. What cells or biologic components are actually present?
3. How was cell identity confirmed?
4. What is the viable cell count in the final product?
5. Has potency or biological activity been evaluated?
6. What passage number is used, if the cells are culture-expanded?
7. How are the cells frozen, transported, and thawed?
8. What sterility and safety testing was performed?
9. Can I review the Certificate of Analysis or other batch documentation?
10. What is the FDA regulatory status of this specific product and intended use?
11. What research applies to this specific product and my condition?
12. What results can and cannot realistically be promised?

A clinic should be willing to answer these questions without relying on vague claims such as:

“These are the best stem cells.”

Ask what makes them different.

Frequently Asked Questions

Are all umbilical cord stem cell products the same?

No.

Umbilical cord-derived cell products can differ based on donor, tissue region, processing, culture conditions, passage number, freezing, storage, final formulation, and quality-control testing. Research has documented both donor-dependent and manufacturing-dependent variability among MSC preparations.

What makes a stem cell product high quality?

There is no single number that defines quality.

Important characteristics can include appropriate cell identity, viable cell recovery, sterility, purity, functional potency, controlled manufacturing, and appropriate documentation.

What is stem cell viability?

Viability refers to the proportion of cells that are alive.

When discussing cryopreserved products, the most relevant measurement is often viability after thawing and preparation rather than only before freezing. Research demonstrates that post-thaw handling can affect cell recovery and viability.

Is viability the same as potency?

No.

Viability asks whether the cell is alive.

Potency evaluates whether the product demonstrates the relevant biological activity expected from it.

Researchers have emphasized that two MSC products with similar surface markers can still have different functional properties.

What is a stem cell passage?

Passage refers to the process of transferring cultured cells into a new culture vessel so they can continue expanding.

Passage number is one of several manufacturing variables that can influence cell characteristics.

Are first-generation stem cells always better?

The term “first generation” is not itself a standardized regulatory measure of cell potency.

If a clinic uses that term, ask exactly what it means in that product’s manufacturing process.

Passage number can matter, but potency, viability, identity, donor characteristics, processing, and final product testing matter too.

What is a Certificate of Analysis?

A Certificate of Analysis, or COA, is documentation that may summarize testing performed on a particular product or batch.

Depending on the manufacturer, it may contain information such as cell count, viability, sterility, identity, or other quality-control results.

The most useful question is not simply whether a COA exists.

Ask what was tested and when.

Does FDA registered mean FDA-approved?

No.

The FDA explicitly cautions that establishment registration or product listing does not mean a regenerative medicine product is FDA-approved or legally marketed for a particular treatment use.

Are umbilical cord stem cells FDA-approved for joint or orthopedic treatment?

No.

The FDA states that regenerative medicine products have not been approved for orthopedic conditions including osteoarthritis, tendonitis, back pain, knee pain, hip pain, neck pain, and shoulder pain.

Do stem cells work by releasing growth factors?

The release of signaling molecules is one important area of MSC research.

MSC secretions can include cytokines, growth factors, extracellular vesicles, and other biologically active substances.

However, the composition of that secretome can vary based on the cells and how they are cultured and handled.

Can any clinic guarantee stem cell treatment will work?

A clinical outcome should not be guaranteed.

Even if a product contains viable, biologically active cells, that does not prove a particular patient will experience pain relief, tissue regeneration, improved function, or another specific result.

Clinical response depends on the condition, patient, product, treatment protocol, and many other variables.

When It Comes to Stem Cells, Ask Better Questions

It is easy to compare regenerative medicine clinics based on one impressive-looking number.

Cell count.

Passage.

Dose.

But cell therapy is more complicated than that.

At The Re/ Clinic in Sandy, Utah, we believe patients should understand what is being used in their treatment and have the opportunity to ask detailed questions about sourcing, processing, testing, and quality.

Before choosing any regenerative procedure, ask what is actually inside the product.

Ask how it was tested.

Ask what the research supports.

And ask what the treatment can realistically be expected to do.

Schedule a consultation with The Re/ Clinic to discuss our regenerative medicine products, treatment protocols, and whether stem cell therapy may be appropriate for you.

Call: 385-240-1000
Location: 9035 S 700 E, Sandy, UT 84070

References

1. Dominici M, Le Blanc K, Mueller I, et al. Minimal criteria for defining multipotent mesenchymal stromal cells. The International Society for Cellular Therapy position statement. Cytotherapy. 2006. This paper established widely used criteria for MSC characterization, including surface markers and differentiation characteristics.

2. Radrizzani M, et al. Quality Control Assays for Clinical-Grade Human Mesenchymal Stromal Cells. Clinical-grade MSC release strategies include testing for sterility, endotoxin, mycoplasma, cell count, viability, immunophenotype, and functional characteristics.

3. Chinnadurai R, et al. Characterization of mesenchymal stromal cells: potency assay development. Research discussing why MSC products that appear phenotypically similar may still differ substantially in biological function and why potency testing matters.

4. Calcat-I-Cervera S, et al. Harmonised culture procedures minimise but do not eliminate mesenchymal stromal cell donor and tissue variability in a decentralised multicentre manufacturing approach. Stem Cell Research & Therapy. 2023. The study demonstrates continued biological variability even under harmonized manufacturing conditions.

5. Mesenchymal stromal cell secretomes are modulated by suspension time, delivery vehicle, passage through catheter, and exposure to adjuvants. Cytotherapy. Research showing that handling and administration conditions can alter MSC cytokine secretion profiles.

6. Pooling umbilical cord-derived MSCs derived from selected multiple donors reduces donor-dependent variability and improves their immunomodulatory properties. 2025. Research demonstrating measurable donor-to-donor functional differences among UC-MSC populations.

7. Cryopreservation of mesenchymal stem/stromal cells using a DMSO-free solution is comparable to DMSO-containing cryoprotectants: results of an international multicenter PACT/BEST collaborative study. Research evaluating changes in viability and recovery following different cryopreservation approaches.

8. U.S. Food and Drug Administration. Important Patient and Consumer Information About Regenerative Medicine Therapies. Current federal information regarding regenerative medicine products, FDA approval, risks, and consumer considerations.

9. U.S. Food and Drug Administration. Regulatory Considerations for Human Cells, Tissues, and Cellular and Tissue-Based Products: Minimal Manipulation and Homologous Use. FDA guidance regarding regulation of human cell and tissue products.

10. Utah Code § 58-1-512. Stem Cell Disclosure. Current Utah disclosure requirements applicable to certain stem cell therapies and related advertising.