Fig. 4

Smoothing effect of MSCs on microvessel surfaces. A Spatial distributions of the mean curvature on the microvessel surfaces under HUVEC monoculture or HUVEC–MSC co-culture after 10 days. Entire or segmented microvessel surfaces are colored with mean curvature. Gradient color bars with blue, white, and red indicate the mean surface curvature of negative, zero, and positive values, respectively. All ranges of the mean curvature values shown on the color bars are the same for (A–C). Scale bars: 200 μm. B Spatial distributions of the mean curvature on the entire microvessel surfaces. Four monoculture samples or five co-culture samples were combined to draw each histogram. The black and green lines in the graph represent monoculture and co-culture samples, respectively. Scale bars: 50 μm. C Histograms of the mean curvature on the segmented sprout surfaces. Similar to (B), datasets were combined as one, and the line colors in the graph represent culture conditions. p values in panel C were from two-sampled Kolmogorov–Smirnov tests. D Scheme of the maturation effect of MSCs on the microvessel sprouts