(a) and (b) Representative SEM images of aligned fibers with 0.46±0.14 (a) and 1.72±0.50 μm, (b) fiber diameter. Histograms represent the angle distribution of ES PCL fibers. Scale bar 20 μm, (c)–(e) hMSCs attached to aligned fibers arranged into monolayer (c) and double layer, bottom (d) and top (e) layer. Cell nuclei are stained blue and actin filaments red. Scale bar 100 μm.