Lamp2

All chemicals were purchased from Sigma‐Aldrich (St. Louis, MO, USA) unless stated otherwise. The primary antibodies used for immunoblot were: Beclin‐1 (1:1000), p62 (1:1000), LC3 (1:1000), mammalian target of rapamycin (mTOR, 1:1000), p‐mTOR (Ser2448; 1:1000), AKT (1:1000), p‐AKT (Ser473; 1:1000), AMP‐activated protein kinase (AMPK, 1:1000), p‐AMPK (Thr172; 1:1000), p70 S6 kinase (P70S6K, 1:1000), p‐P70S6K (Thr389; 1:1000), UNC‐51‐like kinase 1 (ULK1, 1:1000), p‐ULK1 (Ser757; 1:1000) and high mobility group protein B 1 (HMGB1, 1:1000) purchased from Cell Signaling Technology (Danvers, MA, USA), and lysosome‐associated membrane protein‐2 (LAMP‐2, 1:500) purchased from Thermo Fisher Scientific (Rockford, IL, USA). The primary antibodies used for immunohistochemistry (IHC) and immunofluorescence (IF) were LC3 (1:200 for IHC and 1:25 for IF) purchased from Sigma‐Aldrich and LAMP‐2 (1:200 for IHC and 1:50 for IF) purchased from Thermo Fisher Scientific.

Exosome and cell lysates were separated by SDS-PAGE using precast, 4–15% gradient gels and transferred to PVDF membranes. Membranes were blocked for 2 h using 5% nonfat dry milk in Tris-buffered saline (TBS) with Tween-20 (TBST; 138 mM NaCl, 2.7 mM KCl, 50 mM Tris, pH 8.0, 0.05% Tween-20). Membranes were then incubated overnight in blocking solution containing antibodies obtained from commercial sources (CD9 [clone HI9a, BioLegend]; CD63 [clone MX-49.129.5, Santa Cruz Biotechnology], CD81 [555675, BD Pharmingen], E-cadherin [20874-1-AP, Thermo Fisher]; N-cadherin [MA1-2002, Thermo Fisher]; GRP78/BiP [PA1-014A, Thermo Fisher]; calreticulin [MA5-32131, Thermo Fisher]; ERGIC-3 [clone B5, sc-398778, Santa Cruz Biotechnology]; GM130 [PA1-077, Thermo Fisher]; HSP60 [ab190828, Abcam]; HSP90 [sc-13119; Santa Cruz Biotechnology]; Lamp2 [MA1-205, Thermo Fisher]). The next day, the membranes were washed, exposed to HRP-conjugates of goat secondary antibodies (Jackson Immunoresearch), washed again, incubated with an HRP-activated chemiluminescence detection solution (Amersham), and imaged using a GE Amersham Imager 600. Images were exported as JPEG files and assembled into figures using Adobe Illustrator and Adobe Photoshop.

EVs secreted by SD-MSCs from two different human donors (days 36-40) were lysed in RIPA buffer (Santa Cruz, Dallas, TX) and protein contents estimated using microBCA assay (Pierce, Rockford, IL) and western blot assays were performed us 10 μg of proteins. Antibodies: PDGFR-β (Santa Cruz, cat# sc-432, 1:200), LAMP2 (Thermo Scientific, cat# MA1-20798, 1:200), TIMP-1 (Chemicon, cat#AB800, 1:1000), CD90 (BD Pharmingen, cat#555596, 1:200), TIMP-2 (Chemicon, cat#AB801, 1:1000), CD9 (AbCam cat#ab2215) and CD81 (AbCam cat#ab79559).