Fig. 4.

Angiogenic properties of composite hydrogel-loaded human urine-derived stem cell exosomes in vitro. （A）Live/dead assay and (B) CCK8 assay demonstrate the biocompatibility of composite hydrogels with various HAMA ratios co-cultured with EPCs. (C) Fluorescently labelled exosomes can be internalized by EPCs, observed by laser confocal scanning microscopy. (D) Observation of tube formation under the inverted light microscopy in co-culture for 5 ​h and (E) Observation of tube formation under the inverted fluorescence microscopy in co-culture for 6 ​h. (G–I) Semi-quantitative results of tube formation assays. (F) Crystalline violet staining and (M) semi-quantitative results of Transwell chambers in co-culture for 12 ​h. (J–L) Real-time fluorescence quantitative polymerase chain reaction to detect the expression level of angiogenesis-related genes in co-culture for 1 day. Data are shown as mean ​± ​standard error (n ​= ​3). (∗p ​< ​0.05, ∗∗p ​< ​0.01, ∗∗∗p ​< ​0.001.). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)