Figure 7. TAN-derived OPN and MMP14 promote endothelial cell migration and vascular branching.
(A) Schematic of in vitro EC functional assays. (B) Representative images of the EC migration assay using cultured bEND cells with or without TAN-derived supernatant (1:1 PMN/EC ratio) or rOPN, rVEGF treatment with or without specific antibody inhibition. Scale bar: 75 μm. (C) Quantification of EC migration (relative to serum-free condition) following coincubation with TAN-conditioned media, with or without antibody-mediated inhibition of OPN (6 μg/mL) and MMP14 (10 μg/mL). (D) Representative images of EC tube formation assay using cultured bEND cells with or without TAN-derived supernatant treatment (1:3 PMN/EC ratio), or rMMP14 with the indicated antibody inhibition. Scale bar: 10μm. (E) Quantification of formed tube numbers per FOVs upon coincubation with TAN-conditioned media, with or without antibody-mediated inhibition of OPN (6 μg/mL) or MMP14 (10 μg/mL). (F) Dose-response curves of cultured murine bENDs treated with rMMP14 with or without MMP14 inhibition. (G) Dose-response curves of cultured HUVECs following stimulation with catalytic domain (CD) or full-length (FL) rMMP14 (0.01–20 μg/mL), with or without Ab-inhibition of MMP14 (10 μg/mL). For tube formation and EC migration, images are representative of n = 2 independent repeats with TAN supernatants isolated from 3 mice for each performed in duplicates. For recombinant protein, n = 3 independent repeats performed in triplicates. For all quantifications, 15–20 FOVs were analyzed for each condition. For EC transmigration assay, 2-sided student’s t test was performed to compare treatments with serum-free condition. ****P < 0.0001, ####P < 0.0001, MMP14 blockade versus nonblocking conditions. For tube formation assays in bEND or HUVEC cells, 1-way ANOVA was performed comparing Ab-blockade versus control conditions and between different concentrations of recombinant proteins. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, between treatment conditions. §§P < 0.01, §§§§P < 0.0001, selected dose(s) relative to the minimal rMMP14 dose of 0.01 μg/mL.