Can Exosomes Help With Knee Pain? What the Research Says

Knee pain—particularly pain associated with osteoarthritis—is one of the areas where exosome and extracellular-vesicle research has become especially interesting.

Researchers are investigating whether extracellular vesicles may influence inflammation, cartilage biology and the cellular environment inside an osteoarthritic joint.

And the research is beginning to move beyond laboratory experiments.

A 2025 human clinical study evaluated umbilical-cord mesenchymal stem cell-derived exosomes in people with knee osteoarthritis and reported improvements in pain, stiffness and daily function within treatment groups, with the strongest changes seen in the highest-dose group.

So what exactly are researchers finding?

Why Are Exosomes Being Studied for Osteoarthritis?

Osteoarthritis is more complicated than cartilage simply “wearing out.”

The joint is a biological environment involving cartilage cells, inflammatory signaling, immune cells, synovium, subchondral bone and the extracellular matrix.

Extracellular vesicles are microscopic membrane-bound particles involved in communication between cells. Their cargo can include proteins, lipids and nucleic acids. For background on the particles themselves, see where exosomes come from.

Researchers have therefore investigated whether EVs could influence biological processes involved in osteoarthritis, including:

• inflammatory signaling
• cartilage-cell behavior
• extracellular-matrix metabolism
• macrophage activity
• cartilage degradation and repair pathways

Recent reviews describe anti-inflammatory, immunomodulatory and cartilage-related effects across preclinical EV research.

That biological rationale has helped push the field toward human investigation.

Research Highlight: Human Knee Osteoarthritis Study

Wang et al., 2025 — Journal of Translational Medicine

This study is particularly interesting because researchers moved from laboratory and animal experiments into a randomized, double-blind, ascending-dose human clinical study.

Researchers enrolled 41 patients representing 45 affected knees with mild-to-moderate knee osteoarthritis.

The participants had been experiencing knee osteoarthritis for more than five years on average despite conservative treatment. The study population had Kellgren-Lawrence grade 2 or 3 osteoarthritis.

What did they use?

The researchers produced exosomes from human umbilical-cord mesenchymal stem cells (hUC-MSCs). For context on how preparations are made, see how exosomes are produced.

Their characterization included:

• Nanoparticle Tracking Analysis (NTA) for particle size and concentration
• transmission electron microscopy
• CD9
• CD63
• TSG101
• calnexin as a negative marker

The researchers reported particles approximately 100 nm in diameter.

This is important because a particle number on its own provides limited information. Knowing how the preparation was characterized helps readers understand what the investigators actually studied — see extracellular vesicle characterization and testing.

How much did participants receive?

Participants were assigned to three dose groups:

• Low dose: 3 × 10¹¹ particles
• Medium dose: 4 × 10¹¹ particles
• High dose: 5 × 10¹¹ particles

Each administration consisted of 2.5 mL injected into the joint, with administrations performed on Day 0 → Day 21 → Day 42.

So this study investigated repeated administration rather than a single exposure.

What did researchers report?

Within the high-dose group, researchers reported statistically significant changes in:

• total WOMAC score
• pain
• stiffness
• difficulty with daily living

Earlier changes in total score and pain were observed beginning around day 21, while statistically significant changes in stiffness and difficulty with daily activities appeared later.

Researchers also performed MRI examinations in some participants.

They reported reductions in knee edema and joint effusion along with improvement in the appearance of joint inflammation following treatment.

No significant differences in efficacy were found between the three dose groups at the same follow-up points, so the study does not establish that simply using more particles produces better results.

What is the important limitation?

This was an early clinical study without a saline/placebo control group.

That means improvements over time cannot by themselves establish how much of the change was caused specifically by the exosome preparation.

The study nevertheless provides useful early human evidence because it moves exosome research beyond cell cultures and animal models and evaluates symptoms, function, dose and imaging in people with knee osteoarthritis.

What Has Preclinical Research Found?

The experimental literature surrounding osteoarthritis is considerably larger than the human literature.

A 2025 systematic review and meta-analysis examined 28 preclinical studies involving MSC-derived exosomes in rat knee-osteoarthritis models.

Across the studies, the researchers reported improvements in validated cartilage histology measures including OARSI, Mankin and ICRS scoring.

Their analysis also identified changes involving cartilage-associated factors such as collagen type II and aggrecan as well as inflammatory and matrix-degradation pathways.

The authors concluded that MSC-derived exosomes significantly improved histopathological outcomes in these animal models, while calling for high-quality clinical trials to determine appropriate EV sources, doses and administration schedules.

That last part matters.

Animal findings are evidence for continued investigation—not proof of what will happen in a human knee.

Research Highlight: From Preclinical Cartilage Findings to First-in-Human Use

Figueroa-Valdés et al., 2025 — Journal of Nanobiotechnology

Another 2025 study took a particularly comprehensive approach.

Researchers developed small extracellular vesicles derived from human umbilical-cord mesenchymal stromal cells and investigated them through laboratory experiments, an osteoarthritis mouse model, manufacturing development and an initial human application.

In the osteoarthritis mouse model, intra-articular sEV administration was associated with hyaline cartilage regeneration, assessed using histology and micro-CT.

The researchers also investigated inflammatory mechanisms and reported effects involving macrophage polarization.

They then developed a standardized manufacturing process and moved the preparation into an initial first-in-human application.

The human participant received approximately 2 × 10¹⁰ particles by intra-articular administration.

The researchers reported that VAS pain decreased from 60 mm at baseline to 0 mm at six months and remained 0 mm at 12 months. WOMAC decreased from 79.6 at baseline to 2 at six months and 23 at 12 months. No serious adverse effects were reported during the 12-month follow-up.

That's an intriguing observation.

But it involved one patient, so it should be viewed as an early proof-of-principle observation rather than evidence of efficacy across people with knee osteoarthritis.

The investigators subsequently designed an early-phase dose-escalation clinical trial to continue studying the preparation.

What About Cartilage Regeneration?

This is one of the most exciting—and easiest to overstate—parts of the research.

Numerous preclinical studies have investigated whether extracellular vesicles can influence cartilage repair.

The 2025 meta-analysis of 28 rat studies found improvements across cartilage histopathology measures and reported changes involving both cartilage-building and cartilage-degrading pathways.

Figueroa-Valdés and colleagues likewise reported hyaline cartilage regeneration in their mouse osteoarthritis model following intra-articular UC-MSC-sEV administration.

These findings help explain why researchers continue pursuing EV-based approaches for osteoarthritis.

But there's an important distinction:

What About Knee Pain and Function?

The Wang clinical study gives us an early look at this question in people.

Researchers measured WOMAC outcomes encompassing pain, stiffness and difficulty performing daily activities.

The highest-dose group showed statistically significant within-group improvements across all of those measures, while the low- and medium-dose groups showed improvements in narrower components of the WOMAC assessment.

The Figueroa-Valdés first-in-human case also reported substantial changes in VAS pain and WOMAC scores over 12 months.

Together, these studies are part of an emerging human research base.

They are not yet the large, independently replicated clinical-trial evidence needed to establish effectiveness, but they show that EV research in osteoarthritis has progressed beyond laboratory models.

Does the Number of Exosomes Matter?

The human studies make this question particularly interesting.

Wang and colleagues investigated doses ranging from 300 billion to 500 billion particles per administration.

Despite the strongest within-group changes appearing in the high-dose group, researchers found no statistically significant efficacy differences between dose groups at the same follow-up periods.

Meanwhile, the Figueroa-Valdés first-in-human case used approximately 20 billion particles.

That's an enormous difference in reported particle number.

It reinforces an important principle:

The Source of the EVs Matters

Both major human investigations discussed above used extracellular vesicles produced from cultured human umbilical-cord mesenchymal stromal cells.

That matters when interpreting the findings.

EV preparations derived from different biological sources should not automatically be treated as interchangeable simply because they're all described using terms such as “exosomes” or “extracellular vesicles.”

Differences can include:

• source material
• cell type
• cell-culture conditions
• isolation and purification
• particle populations
• characterization
• formulation
• concentration

Understanding what was actually studied is therefore essential when reading exosome research.

Why Results May Vary

As with many biologically active interventions, people may not respond identically. Individual genetics, age, underlying biology, disease severity and other person-specific factors may influence biological responses. The extracellular-vesicle preparation itself—including its source, manufacturing, characterization and formulation—may also matter. Researchers are still working to understand which factors may help predict how individuals respond.

The Bottom Line

Research into extracellular vesicles and knee osteoarthritis has progressed substantially.

Laboratory and animal studies have reported findings involving inflammatory signaling, cartilage biology and tissue repair. Systematic analyses of preclinical research have reported encouraging cartilage-related outcomes across numerous experimental studies.

More importantly, researchers have now begun investigating exosome preparations in people with knee osteoarthritis.

A 2025 human study involving 41 patients reported improvements in pain, stiffness and daily function within treatment groups, with particularly broad statistically significant changes in the highest-dose group. Another research program reported substantial improvements in pain and WOMAC scores in an initial first-in-human case after extensive preclinical development.

The evidence remains early.

But the progression from laboratory research → animal models → early human investigation is exactly why extracellular vesicles have become such an active area of osteoarthritis research.