| Comments |
P.33 left column 2nd paragraph: "The lipid content of exosomes and their enrichment factors from cells to exosomes have been reported in several studies (Table 1). The most detailed study so far, including quantification of approximately 280 lipid species from 18 lipid classes, is [investigators’] own study with the prostate cancer cell line PC-3 [primary source 34]. However, as shown in Table 1, several studies have described the percent of different lipid classes in cells and exosomes in several cell types such as Oli-neu [primary source 35], human B-cells [primary source 36], mast cells RBL-2H3 [primary source 37], dendritic cells [primary source 37], and vesicles released during in vitro maturation of guinea pig reticulocytes [primary source 38]. In addition, Table 1 contains information about exosome preparations from biological fluids where the lipid content of the donor cells is not known. In particular, data of two different sizes (100 nm and 50 nm) of prostasomes (i.e. exosomes expected to be released from prostate cells) isolated from human seminal fluid [primary source 39], exosomes isolated from human urine [primary source 40], and exosomes secreted by a nematode parasite [primary source 41] are included. Several of the studies listed in Table 1 show 2–3 times enrichment from cells to exosomes for cholesterol, SM [sphingomyelin], glycosphingolipids and PS [phosphatidylserine]. In contrast, exosomes generally contained less PC [phosphatidylcholine] (mol% of total lipids) than their parent cells, and only small changes were reported for PE [phosphatidylethanolamine] in most studies." See notes beneath table |