MSC-derived Gal-1 influences the capillary formation of H5V endothelioma <i>in vitro</i> and increases the microvessel density of 4T1 tumors <i>in vivo</i>.

<p>(A) <i>In vitro</i> capillary assay. CM-DiI labeled wtMSCs or MSC^Gal-1−/− (red) were incubated with mouse heart capillary endothelial cells (H5V) in a ratio of 1∶1 for 3 days (left) in the presence or absence of 30 mM sucrose or TDG. Tubes were quantified in parallel samples by measuring the length of capillary-like structures in five random areas of co-cultured cells (right). **p<0.001, ***p<0.0001. (B and C) <i>In vivo</i> analysis of microvessel density in tumors. Female Balb/C mice were challenged by 4T1 (10³ cells) alone (B, left) or in combination with 10⁵ MSC^Gal-1−/− (B, middle), wtMSC (B, right), scMSC (C, left) and siMSc (C, right). The presented microscopic pictures are representative of 3 experiments. Morphometric measurement of vascularized (V) areas (B and C lower panels) was performed on paraffin-embedded primary tumor tissue sections as described in <i>Materials and methods</i>. Scale bar is 100 µm. *p<0.05.