Development of temperature and reactive oxygen species dual-responsive gelatin-PNIPAM-based hydrogels containing ferulic acid for peripheral arterial disease treatment.

Oxidative stress is considered as a key factor to accelerate the progression of peripheral arterial disease (PAD). In the study, novel temperature and reactive oxygen species (ROS) dual-responsive thioketal-linked ferulic acid (FA)-gelatin-poly(N-isopropylacrylamide) (GPTF) hydrogels were developed for PAD treatment. The prepared materials were characterized using nuclear magnetic resonance spectroscopy, ninhydrin test, 1,10-phenanthroline assay and thermogravimetry analysis. The gelation temperature of the optimized GPTF hydrogels was 32.0 °C, with a sol-gel transition occurring within 10 s at 37 °C. GPTF hydrogels exhibited the interconnected porous structure and antioxidant properties. Under H2O2-induced oxidative stress, GPTF hydrogels showed a 3.9-fold faster release of FA compared to normal conditions within the first hour. The in vitro drug release profile of developed hydrogels followed Korsmeyer-Peppas model (R2 ∼ 0.97). Post-treatment of optimized GPTF hydrogels in human umbilical vein endothelial cells exposed to H2O2 could decrease cellular ROS and improve the inflammation (IL-1α, IL-6 and MMP-3) and apoptosis, showing over 90 % cell viability. The developed hydrogels showed hemocompatibility, cytocompatibility, and no sign of inflammation after subcutaneous injection for 14 days. The in vivo anti-inflammatory and angiogenic effects of GPTF hydrogels were demonstrated in a hindlimb ischemia mouse model through mRNA gene expression, western blotting, and Masson's trichrome staining. The results suggested that this newly developed GPTF hydrogel could be delivered via injection and enable rapid drug release at the ischemia site, showing the potentials for PAD treatment.