The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points.

AIM:To perform a meta-analysis to assess whether the presence of cancer-associated fibroblasts (CAF) is a prognostic marker of oral squamous cell carcinomas (OSCC). METHODS:Immunohistochemical studies assessing the prognostic relevance of CAF (alpha smooth muscle actin (α-SMA)-positive fibroblasts) in patients with OSCC were systematically reviewed using Cochrane, Lilacs, PubMed, Scopus and Web of Science databases. The outcomes assessed were overall survival (OS) and disease-free survival (DFS). The meta-analysis was performed using the random and fixed effects model with adjusted hazard ratio (HR) and 95% confidence intervals (95% CI) as effect measures. The methodological quality of the included studies was assessed using the Meta-Analysis of Statistics Assessment and Review Instrument (MAStARI) tool and the evidence quality was assessed by the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) system. RESULTS:The presence of high levels of CAF in the stroma of OSCC predicted shortened time to DFS (HR= 3.32, 95% CI: 2.09-5.26, p<0.00001) and an overall decrease in survival (HR: 2.16, 95% CI: 1.60-2.92, p<0.00001). Moreover, high presence of CAF was frequently reported in association with parameters that worsen the prognosis in OSCC, including advanced disease stage (TNM classification), recurrence, tumor grade, depth of invasion, vascular, lymphatic and neural invasion and extranodal metastatic spread. CONCLUSION:The presence of CAF, as assessed by α-SMA-positive fibroblasts in the stroma, indicates poor prognosis in patients with OSCC.