Figure 1.

Matrix metalloproteinase 14 was highly concentrated in exosomes secreted by corneal fibroblasts. (A, B) Exosomal proteins were separated into 11 fractions by sucrose density gradient centrifugation and analyzed via Western blotting for the presence of MMP14 and the exosomal marker TSG101. (A) Tumor susceptibility gene 101 detected by immunoblotting (arrow) identified fractions 9 and 10 as the exosomal fractions. (B) Matrix metalloproteinase 14 (arrow) was present in the exosomal fractions 9 and 10. (C) Nonreduced and reduced cellular lysates contained low-level amounts of MMP14. Reduced exosomes showed the greatest amount of MMP14 (present as free monomer) compared to that in nonreduced exosomes (arrow). Ly, cell lysate; Exo, exosomal protein; NonRed, nonreduced conditions; Red, reduced conditions.