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.

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Human embryonic stem cells (hESCs) have the ability to self-renew and differentiate into any cell lineage of the three germ layers, therefore holding great promise for regenerative medicine applications. However, directing lineage-restricted differentiation of hESCs and obtaining a homogenous differentiated cell population is still a challenge. We previously described a micromass culture system as a model system to study chondrogenic commitment of the hESCs. Using this system, various growth factors including BMP2 and TGFbeta1 direct chondrogenic differentiation and modulate cartilage-specific matrix gene expression in a distinctive manner. Furthermore, a high percentage of differentiated cells exhibit typical morphological characteristics of chondrocytes and express cartilage matrix proteins such as type II collagen and proteoglycans. Chondrogenic cells can be further isolated and cultured to form functional cartilage tissue in vitro. Here, we describe in detail our established protocols to analyze chondrogenic differentiation of hESCs, and possible isolation of chondrogenic cells to form functional cartilaginous tissue.

Human embryonic stem cells (hESCs) have the ability to self-replicate and differentiate into cells from all three embryonic germ layers, thereby holding great promise for tissue regeneration applications. However, controlling the differentiation of hESCs and obtaining homogenous differentiated cell populations still remain a challenge. We present a highly efficient and reproducible experimental system that mimics the three-dimensional (3-D) environment of in vivo chondrogenesis and that supports the directed differentiation of human embryoid body (EB)-derived cells toward the chondrogenic lineage under serum-free chondrogenic culture conditions in the presence of bone morphogenetic protein-2 (BMP-2).