This page is reference material for patients who are reviewing research information. We list only publicly available literature on knee osteoarthritis (knee OA) and extracellular vesicles (EVs), and we separate what the studies confirmed, what they did not confirm, and why the findings cannot be applied directly to an individual or to the care provided at our clinic.
Publisher: Medical Corporation Yamamoto Clinic | Last updated:
A published paper reports results obtained under specific research conditions. If the participants, the product, the cell source, the preparation method, the dose, the comparator, or the assessment time point differ, the same result does not necessarily follow.
Symptoms and imaging are separate measures. Changes in pain or function alone cannot determine structural change in cartilage, meniscus, or other tissue.
This page does not present clinical results from our clinic. The literature listed here is not evidence of our clinical outcomes, risks, superiority over other options, regulatory status, or suitability for any individual.
Weight management and exercise are not a separate "background" to injection treatments. They are interventions that have been evaluated in their own right in knee OA research. At the same time, results differ depending on how an exercise program is designed and how it is supported.
The IDEA trial followed adults with overweight or obesity and knee OA for 18 months, and reported improvements in pain, function, and other measures in the group that combined diet and exercise.
Limitation: The participants had overweight or obesity, so the results cannot be applied uniformly to every body size or disease stage.
PubMed · PMID 24065013At one year, WOMAC scores were better in the physical therapy group than in the intra-articular glucocorticoid injection group. This study placed exercise and movement instruction at the center of a treatment comparison.
Limitation: A single study conducted within a military health system; it does not represent every physical therapy program or patient background.
PubMed · PMID 32268027A trial comparing in-person physical therapy and an internet-based exercise program against a wait-list group found no significant between-group difference in WOMAC at 4 months or 12 months.
How to read this: The content, frequency, support, and adherence rate need to be checked, not only the label "exercise".
PubMed · PMID 29307722Changes seen on imaging are associated with pain, but imaging alone does not explain how severe the pain is. It is important to record symptoms and function separately from structural assessment such as radiography and MRI.
In the MOST and Framingham cohorts, an analysis comparing the left and right knees within the same person showed an association between the severity of radiographic OA and the frequency and intensity of pain.
Limitation: An association does not mean that an individual patient's pain can be predicted from imaging alone.
PubMed · PMID 19700505Among patients whose imaging findings were mild but whose pain was severe, differences were reported on quantitative sensory testing related to central sensitization.
Limitation: This is not a study that identifies a single cause of pain; factors other than sensitization also need to be assessed individually.
PubMed · PMID 22961435In a longitudinal analysis of 600 knees, a 0.1 mm loss of cartilage thickness over two years corresponded to a worsening of WOMAC pain of 0.32 points on a 0–20 scale.
How to read this: Structural change in cartilage and pain are not the same outcome, and factors such as synovitis may mediate the relationship.
PubMed · PMID 32381567PRP, bone marrow aspirate concentrate, adipose-derived cells, and culture-expanded MSCs are not the same product. Because the source, processing, dose, comparator, and disease severity differ between studies, we do not transfer the result of one trial to a different product or to the care provided at our clinic.
| Study | Comparison | Main reading |
|---|---|---|
| RESTORE | PRP vs saline | No significant between-group difference in pain or cartilage volume at 12 months |
| Mautner et al. | Three cell-based injections vs corticosteroid | No group superior at 12 months; no change in MRI scores |
| Kim et al. | Culture-expanded ADMSC vs control | Between-group difference in pain and function at 6 months; no difference in cartilage defect change on imaging |
| ADIPOA2 | Two doses of culture-expanded ADSC vs saline | No significant between-group difference in the primary endpoint or in secondary endpoints overall |
In the RESTORE trial of 288 people, neither pain nor medial tibial cartilage volume at 12 months showed a significant between-group difference.
PubMed · PMID 34812863In a randomized trial of 90 people, measures improved in both the BMAC group and the PRP group, but no between-group difference was found through 12 months. Because there was no untreated or placebo group, the effect of either intervention cannot be judged from this trial alone.
PubMed · PMID 32118081In a trial comparing BMAC, adipose SVF, umbilical cord tissue-derived MSCs, and corticosteroid, no group was superior to the others at 12 months, and there was no significant change in MRI OA scores either.
PubMed · PMID 37919438In a Phase III trial of 261 people with K-L grade 3, there was a between-group difference in VAS and WOMAC improvement at 6 months, but no significant difference in cartilage defect change on MRI.
PubMed · PMID 37345256In a Phase 2b trial that randomized 135 people and analyzed 97, no significant between-group difference was found at 6 months in the strict responder rate, in pain and function, or in the secondary endpoints overall.
PubMed · PMID 40885690In a trial of 24 people, improvement in WOMAC at 6 months was reported. This is a small, short-term result, and larger trials with longer follow-up are needed.
PubMed · PMID 30835956A Cochrane review including 25 trials and 1,341 people found, in the placebo-controlled analyses (pain: 8 trials, 459 people; function: 7 trials, 432 people), that pain and function may improve slightly, while the certainty of the evidence was rated low. Uncertainty remains regarding quality of life, serious adverse events, and structural progression.
PubMed · PMID 40169165In research on EVs (extracellular vesicles), the producing cells, culture conditions, collection and separation, storage, measuring instrument and its settings, EV-associated markers, non-vesicular components, and functional assays all need to be reported separately. NTA is a method that estimates particle size and concentration mainly from scattered light; on its own it is not a test that shows that the particles are EVs, or their purity, their contents, or their clinical effect.
MISEV2023 is a framework for reporting the methods and limitations of EV production, separation, and characterization transparently, and for confirming findings with methods that complement one another.
Note: A reference to MISEV does not imply certification of a product or clinical usefulness.
PubMed · PMID 38326288In a study comparing the NanoSight NS300 and the ZetaView, the accuracy and repeatability of concentration and size estimates differed between instruments, and neither instrument could report peaks below 60 nm.
PubMed · PMID 30988894To make the refractive index, surface molecules, size, and concentration of EVs comparable, reference materials matched to the measurement method and traceability to SI units are described as necessary.
PubMed · PMID 33062218NTA carries sources of variation that come from insufficient standardization, and calibration, dilution, and acquisition and analysis conditions need to be aligned and recorded.
PubMed · PMID 24009893Producing cells, donor, culture conditions, passage
Collection, separation, purification, storage, lot
Instrument, settings, calibration, limit of detection, replicates
EV-associated markers, non-vesicular components, functional assays
Intranasal administration means placing material in the nasal cavity. It is not the same as inhalation or nebulisation aimed primarily at the airway or lungs. Cognitive scales, hippocampal imaging or tissue findings, and mouse behavioural tests also cannot be rewritten as “conversation or speech improved.”
A three-dose exploratory study administered allogeneic adipose MSC-derived exosomes intranasally twice weekly for 12 weeks to people with mild to moderate Alzheimer’s disease.
Limit: This was a small dose-comparison study, not a placebo-controlled confirmatory trial. It did not test iPSC-derived EV and does not establish efficacy.
PubMed · PMID 37859748In 3xTg-AD mice given MSC-derived EV intranasally, the study reported distribution to brain regions including hippocampal CA1 at six hours and changes in neuroinflammation-related measures.
Limit: This was tissue and molecular work in a small number of animals. It does not demonstrate hippocampal delivery, cognition, conversation or speech improvement in people.
PubMed · PMID 32496649This study evaluated intravenously administered iPSC-derived small EV in an ischemic-stroke model in aged mice, including blood-brain-barrier and neurovascular measures.
Limit: It was neither intranasal delivery nor a human Alzheimer’s disease trial. Results cannot be generalised across route, disease model or source cell.
PubMed · PMID 36562422A 2026 study gave neural stem cell-derived EV intranasally over time to male and female 3xTg-AD mice and assessed hippocampus-dependent behaviour, neuroinflammation and amyloid-beta-related measures.
Limit: These EV were neither MSC-derived nor iPSC-derived, and this was an animal study. It does not show clinical benefit or conversation or speech change in people.
PubMed Central · PMC13188268Each link is a literature record on PubMed or PubMed Central. No figures, tables, or abstracts from the papers are reproduced in the text of this page.
This page is intended to provide general research information. It is not a diagnosis, medical advice, a treatment recommendation, or a presentation of clinical results at our clinic. The results of the studies listed here do not mean that they apply to an individual course of illness or to the care provided at our clinic.
The products, the sources of cells and blood components, the processing, the doses, the routes of administration, the participants, the comparators, and the assessment time points used in these studies all differ from one another. Please review the choice of care individually with a physician, including the standard options, what can be expected, the uncertainties, the costs, and the alternatives.
Measured values for EVs are affected by the instrument used, its settings, calibration, the limit of detection, and sample preparation. Particle count and particle size alone cannot determine the identity, purity, contents, or clinical effect of EVs.
This page does not reproduce copyrighted figures, tables, or abstracts from the papers. Please check the original text, corrections, retractions, and update status on each PubMed record and on the publisher's page.
