Extracellular vesicles (EVs) are crucial for facilitating intercellular communication, promoting cell migration, and orchestrating the immune response. Recently, EVs can diagnose and treat tumors. EVs can be measured as biomarkers to provide information about the type of disease and therapeutic efficacy. Furthermore, EVs with lower immunogenicity and better biocompatibility are natural carriers of chemicals and gene drugs. Herein, we review the molecular composition, biogenesis, and separation methods of EVs. We also highlight the important role of EVs from different origins as biomarkers and drug delivery systems in tumor therapy. Finally, we provide deep insights into how EVs play a role in reversing the immunosuppressive microenvironment.

Objective:To establish a real-time fluorescence-based PCR method for the rapid identification of mycobacteria in skin biopsies.Methods:Primers and probes targeting the genus Mycobacterium and 14 common Mycobacterium species were self-designed, and a real-time fluorescence-based PCR detection system/method was established. Twelve standard strains of Mycobacterium were used for in vitro validation. Tissue samples were collected from 119 patients clinically diagnosed with cutaneous mycobacterial infections at the Department of Dermatology and Venereology, Peking University First Hospital from 2019 to 2021, and were tested with the established real-time fluorescence-based PCR method. Results:In vitro testing demonstrated that the method had good sensitivity and specificity for all the 12 standard strains of Mycobacterium. Among the 119 skin biopsy samples from patients clinically diagnosed with cutaneous mycobacterial infections, the culture positivity rate was only 21.0% (25/119) ; the real-time fluorescence-based PCR yielded a positivity rate of 76.5% (91/119) for the detection of mycobacteria, and 44.5% (53/119) were identified to the species level with Mycobacterium marinum as the predominant species; 31.9% (38/119) were identified only to the genus level. Conclusion:A real-time fluorescence-based PCR method has been established for the efficient detection of mycobacteria in skin tissue samples; however, there remains a possibility of missed diagnoses, other molecular diagnostic techniques are required to be combined to improve the sensitivity and specificity.