ExoCarta as a resource for exosomal research

Abstract

Exosomes are a class of extracellular vesicles that are secreted by various cell types. Unlike other extracellular vesicles (ectosomes and apoptotic blebs), exosomes are of endocytic origin. The roles of exosomes in vaccine/drug delivery, intercellular communication and as a possible source of disease biomarkers have sparked immense interest in them, resulting in a plethora of studies. Whilst multidimensional datasets are continuously generated, it is difficult to harness the true potential of the data until they are compiled and made accessible to the biomedical researchers. Here, we describe ExoCarta (http://www.exocarta.org), a manually curated database of exosomal proteins, RNA and lipids. Datasets currently present in ExoCarta are integrated from both published and unpublished exosomal studies. Since its launch in 2009, ExoCarta has been accessed by more than 16,000 unique users. In this article, we discuss the utility of ExoCarta for exosomal research and urge biomedical researchers in the field to deposit their datasets directly to ExoCarta.

Keywords: Vesiclepedia; exosome resource; exosome tools; extracellular organelles; microvesicle database.

Fig. 1

Histogram of exosomal studies over the past 30 years. Immense interest in exosomes was seen during the last 7 years; more than 70% of the studies on exosomes were published (2005–2012). The statistics is generated based on PubMed indexed exosomal studies (keywords: exosomes or exosome-like) and adding the initial observations on exosomes. The resulting articles were manually verified by reading the title and abstract to ensure that the study referred exosomes, secreted vesicles of endocytic origin. Whilst each exosomal article improved our biological understanding, several articles contributed significantly. Important discoveries reported in the last 30 years are highlighted in the figure (blue – these findings moved exosomal research to a new next level; pink – trendsetting studies that formed the basis of current exosomal research): −1, discovery of exosomes (6, 47); −2, immune functions of B cell-secreted exosomes (48); −3, exosomes promote induction of antitumor immune responses in mice (49); −4, clinical trials of exosomes (50, 51); −5, discovery of exosomal RNA and transfer (12); −6, exosomes as a source of diagnostic biomarkers (52); −7, targeted delivery of siRNA through exosomes to brain (14).

Fig. 2

A snapshot of ExoCarta and interaction network of CD9. Snapshot of ExoCarta homepage is displayed. Protein interaction network of CD9 (tetraspanin family) shows its protein interactors that are identified in exosomes (pink) and not (blue). Each individual tetraspanin protein performs differently via actions through their respective interactors; for instance, CD9 and CD82 mediate metastasis inhibition by several mechanisms whereas CD151 supports tumour progression by activating MMPs (53, 54).