Fig. 5

SGE composite hydrogels containing human fibroblasts (hNDF) and polymerized in cylindrical casts, stained for living cells using calcein AM dye. A Cell imaging at an early (day 1) and late (day 7) time point. On day 7, cylindrical scaffolds were cut in the middle to show cell distributions. B, C Scanning electron microscopy on day 7 for confirmation of fibroblasts stretching over the SGE 2–1-1 composite hydrogel. Within all other groups, no cells were detected by this method. C (i) Calcein-AM staining of human neonatal fibroblasts encapsulated at SGE 2–1-1 hydrogels at day 7. D Metabolic activity measured by Alamar Blue showed low metabolic signals of human neonatal fibroblasts in SF only and moderate metabolic signals in the SGE 2–2-0 and SGE 2–1.5–0.5 gels. The highest metabolic activity was measured in SGE 2–1-1 composite hydrogels compared to all other groups. Data are shown as mean ± SD. *** indicates significant differences of p < 0.05 between SGE 2–1-1 and all other groups