Objective: The purpose of this study was (1) to perform a summary of meta-analyses comparing platelet-rich plasma (PRP) injection with hyaluronic acid (HA) and placebo injection for KOA patients, (2) to determine which meta-analysis provides the best available evidence to making proposals for the use of PRP in the treatment of KOA patients, and (3) to highlight gaps in the literature that require future investigation. Material and methods: PubMed, EMBASE, and Cochrane databases search were performed for meta-analyses which compared PRP injection with HA or placebo. Clinical outcomes and adverse events were extracted from these meta-analyses. Meta-analysis quality was assessed using the Quality of Reporting of Meta-analyses (QUOROM) systems and the Oxman-Guyatt quality appraisal tool. The Jadad decision algorithm was also used to determine which meta-analysis provided the best available evidence. Results: Four meta-analyses were included in our study, and all of these articles were Level I evidence. The QUOROM score of each included meta-analysis range from 14 to 17 points (mean score 15, maximum score 18), and the Oxman-Guyatt score range from 4 to 6 points (mean score 5, maximum score 7). Three meta-analyses indicated PRP showed more benefit in pain relief and functional improvement than the control group, and the other one suggested no difference between these groups. All included meta-analyses found no statistical difference in adverse events between these groups. In addition, a meta-analysis conducted by Shen et al. got the highest methodological quality score and suggested that PRP provided better pain relief and function improvement in the treatment of KOA. Conclusions: For short-term follow-up (≤1 year), intra-articular PRP injection is more effective in terms of pain relief and function improvement in the treatment of KOA patients than HA and placebo, and there is no difference in the risk of an adverse event between PRP and HA or placebo.

Objective: The aim of this study is to compare the efficiency of different separation techniques for extracting synovial tissue-derived exosomes. Methods: The synovial tissue discarded during knee arthroscopy or total knee arthroplasty surgery was collected from the Third Affiliated Hospital of Beijing University of Chinese Medicine. Ultracentrifugation (UC), filtration combined with size exclusion chromatography (SECF), and 8% polyethylene glycol (PEG) were used to extract synovial tissue-derived exosomes. Transmission electron microscopy (TEM), nanoparticle tracer analysis (NTA), and Western Blot (WB) were used to detect the morphology, particle size, and biomarker proteins (CD9, CD63, Flotillin-1, and calnexin) of exosomes. Results: The extracts of enriched round and discoid vesicles were successfully extracted with UC, SECF, and PEG. The results of TEM have shown that all three extraction methods can extract circular or elliptical vesicles with discand cup-shaped structures from the synovial tissue, with the diameter is about 30-150 nm. NTA suggested the main peaks of three groups of exosomes are around 100-120 nm, and the concentration of the three groups of exosomes was greater than 1 × 10 10 /ml. The results of WB showed that three positive protein markers (CD9, CD63, and Flotillin-1) were highly expressed in the suspension extracted by the three methods and low in the synovial tissue. However, the negative protein (calnexin) was highly expressed in synovial tissues and PEG group, while low in UC and SECF group. Conclusion: Morphology, particle size, and labeled protein marker detection confirmed that UC, SECF, and PEG can extract exosomes derived from synovial tissue; UC and SECF are more recommended for the extraction of synovial tissue-derived exosomes, which provides a methodological basis for studying the function and mechanism of synovial tissue exosomes in the future.

Osteoarthritis (OA), as one of the top 10 causes of physical disability, is characterized by inflammation of the synovial membrane and progressive destruction of the articular cartilage. Cinnamic aldehyde (CA), an a,b-unsaturated aldehyde extracted from the traditional Chinese herbal medicine cinnamon (Cinnamomum verum J.Presl), has been reported to have anti-inflammatory, antioxidant, and anticancer properties. However, the anti-inflammatory effect of CA on OA remains unclear. The purpose of the present study was to investigate the effects of CA on inflammation, and cartilage degeneration in OA. A CCK-8 assay was performed to assess the potential toxicity of CA on cultured human OA chondrocytes. Following treatment with lipopolysaccharide (LPS) and CA, the expression of proinflammatory cytokines, including interleukin (IL)-1b, IL-6, and tumor necrosis factoralfa (TNF-a), was evaluated using quantitative real-time polymerase chain reaction (RT-qPCR) analysis, enzyme-linked immunosorbent assay, and Western blotting (WB). The production of matrix metalloproteinase-13 (MMP-13) and a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5) was also examined using RT-qPCR and WB. Furthermore, to investigate the potential anti-inflammatory mechanism of CA, biomarkers of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) pathway (p65, IKB-a) were detected using WB. The results demonstrated that CA significantly inhibited the expressions of IL-1b, IL-6, TNF-a, MMP-13, and ADAMTS-5 in LPS-induced OA chondrocytes. CA dramatically suppressed LPS-stimulated NF-kB activation. Collectively, these results suggest that CA treatment may effectively prevent OA.

Cinnamon is a wildly used traditional Chinese herbal medicine for osteoarthritis (OA) treatment, but the underlying mechanism remains ambiguous. The purpose of this study is to explore the mechanism of cinnamic aldehyde (CA), a bioactive substance extracted from Cinnamon, on synovial inflammation in OA. A total of 144 CA‐OA co‐targeted genes were identified by detect databases (PubChem, HIT, TCMSP, TTD, DrugBank and GeneCards). The results of GO enrichment analysis indicated that these co‐targeted genes have participated in many biological processes including ‘inflammatory response’, ‘cellular response to lipopolysaccharide’, ‘response to drug’, ‘immune response’, ‘lipopolysaccharide‐mediated signalling pathway’, etc. KEGG pathway analysis showed these co‐targeted genes were mainly enriched in ‘Toll‐like receptor signalling pathway’, ‘TNF signalling pathway’, ‘NF‐kappa B signalling pathway’, etc. Molecular docking demonstrated that CA could successfully bind to TLR2 and TLR4. The results of in vitro experiments showed no potential toxicity of 10, 20 and 50 μM/L CA on human OA FLS, and CA can significantly inhibit the inflammation in LPS‐induced human FLS. Further experimental mechanism evidence confirmed CA can inhibited the inflammation in LPS‐induced human OA FLS via blocking the TLR4/MyD88 signalling pathway. Our results demonstrated that CA exhibited strong anti‐inflammation effect in OA FLS through blocking the activation of TLR4/MyD88 signalling pathway, suggesting its potential as a hopeful candidate for the development of novel agents for the treatment of OA.