Fig. 4.

MSCs secrete increased levels of angiogenic and inflammatory mediators after LL-37 stimulation. (A) The concentration of LL-37 in conditioned medium taken from unstimulated MSCs in culture. (B) Serum-starved MSCs were treated with 5 μg/mL LL-37 for 48 h, then conditioned medium was analyzed by Luminex-based cytokine arrays. Values are mean ± SE. *, P < 0.05, **, P < 0.01. (C) Analysis of MSC-conditioned medium after treatment for 48 h as indicated by gelatin zymography. The representative image depicts the electrophorectic pro-MMP-2 (72 kDa) and active MMP-2 (62 kDa). MMP-9 (92 kDa) was not undetectable. (D) Quantification of zymography by densitometry. Intensity of the lower band (active MMP-2, 62 kDa) is plotted as a bar graph (n = 3). (E) Conditioned medium from untreated and LL-37-treated MSCs was added to HUVECs, then seeded onto Matrigel. Fluorescently labeled cells were monitored were for formation of capillary-like tubules. Photographs are representative of HUVECs after 2 h incubation.