Fig. 4.

H₂O₂-controllable hydrogels for facilitating neovascularization though transient upregulation of intracellular ROS levels in ECs. A Schematic representation of in situ hydrogel formation via dual enzyme-mediated cross-linking reaction. Newly formed covalent bonds are indicated in red. Transient upregulation of intracellular ROS levels of ECs by sustained release of H₂O₂ from hydrogels. B Representative optical and fluorescent microscopic images. Scale bar is 100 μm. C Quantitative analysis of fluorescence-positive cells. The results in B are shown as an average ± s.d. Significance levels were set at *p < 0.05, **p < 0.01, and ***p < 0.001. ## indicates not significant. D In ovo angiogenic effect of the hydrogels. Histological sections of hydrogels seven days after injection, stained with α-SMA. Scale bar is 100 μm

(adapted with permission from Ref. [17]). (Color figure online)