(A) In culture, the same cell type can produce exosomes with distinct nucleic acids and proteins above the baseline of some common protein markers. Exosome production can be dynamic, with the same cell shedding exosomes with different compositions based on their health status. (B) It has been assumed that exosomes are cellular trash bags for elimination of excess proteins, but many studies have shown that exosomes often exhibit certain specific markers, irrespective of the organ or cellular source. This suggests that certain proteins are transported to the exosomes with some degree of specificity. Additionally, distinct differences have been identified in the RNA and protein species present in exosomes, likely reflecting cellular and organ specificity. This second layer of complexity is dynamic and can change with the evolving status of the organ and cells within. Here, the pancreas is provided as an example, but this dynamism in exosomal contents presumably holds true for all organs. Therefore, exosome heterogeneity is a much more complex phenomenon than cellular heterogeneity and can be fleeting depending on stimuli and the functional status of the organ.