Extracellular vesicles (EVs)-based cell-free strategy has shown therapeutic potential in tissue regeneration. Due to their important roles in intercellular communications and their natural ability to shield cargos from degradation, EVs are also emerged as novel delivery vehicles for various bioactive molecules and drugs. Accumulating studies have revealed that EVs can be modified to enhance their efficacy and specificity for the treatment of many diseases. Engineered EVs are poised as the next generation of targeted delivery platform in the field of precision therapy. In this review, the unique properties of EVs are overviewed in terms of their biogenesis, contents, surface features and biological functions, and the recent advances in the strategies of engineered EVs construction are summarized. Additionally, we also discuss the potential applications of engineered EVs in targeted therapy of cancer and damaged tissues, and evaluate the opportunities and challenges for translating them into clinical practice.

Objective:To analyze the X-ray imaging characteristics of calcaneus in adult patients with osteoarticular diseases and its impact on disease diagnosis.Methods:Totally 78 patients (156 ankle joints) with osteoarticular diseases admitted to the Affiliated Hospital of Jining Medical University from June 2019 to June 2022 were selected as research subjects, including 72 cases of osteoarthritis and 6 cases of Kashin-Beck disease. Another 50 volunteers who underwent health examination in this hospital during the same period were selected as control group, all of them underwent calcaneal X-ray examination. Receiver operating characteristic (ROC) curve was used to analyze the diagnostic efficacy of calcaneal X-ray parameters in predicting adult osteoarticular diseases.Results:Among 72 patients with osteoarthritis, 63 cases (87.50%) showed joint surface sclerosis in the calcaneal X-ray changes. Forty-seven cases (65.28%) had narrowing of the subtalar joint space; 14 cases showed disappearance of the subtalar joint space, accounting for 19.44%. Among the 6 patients with Kashin-Beck disease, the X-ray changes of the calcaneus showed joint surface sclerosis in 6 cases, narrowing of the subtalar joint space in 4 cases, and disappearance of the subtalar joint space in 2 cases. The length, height, Bohler angle, Gissane angle, and inclination angle of the calcaneus in patients with Kashin-Beck disease were all smaller than those in the osteoarthritis group and the control group, the height to length ratio of the calcaneus was higher than that in the osteoarthritis group and the control group, and the difference was statistically significant ( P < 0.05). The length, height, Bohler angle, Gissane angle, and inclination angle of the calcaneus in patients of the osteoarthritis group were all smaller than those in the control group, and the height to length ratio of the calcaneus was higher than that in control group, and the difference was statistically significant ( P < 0.05). ROC curve analysis showed that the sensitivity of Bohler angle, Gissane angle, and the height to length ratio of the calcaneus in predicting osteoarticular diseases (72 patients with osteoarthritis) were 92.5%, 87.6% and 80.4%, respectively, with specificity of 73.0%, 68.8% and 63.1%, respectively. Conclusion:The calcaneal X-ray manifestations of adult patients with osteoarticular diseases vary greatly, among which Bohler angle, Gissane angle, and height to length ratio of the calcaneus have certain accuracy in diagnosis of osteoarthritis.