ROS-Responsive Prodrug Micelle Co-Delivery System for Synergistic Antiatherosclerotic Therapy

Tanshinone IIA (TS-IIA) and salvianic acid A (SAA) are the main pharmacological active constituents of Danshen, which exhibit potent effects on atherosclerosis. A combination of TS-IIA and SAA might exert a synergistic antiatherosclerotic effect. However, the opposite solubility profiles of TS-IIA and SAA might lead to difficulty in achieving a synergistic combined effect of the two active components. Therefore, in this work, we fabricated a ROS-responsive prodrug micelle for the codelivery of TS-IIA and SAA (TS-IIA-PM) by self-assembling amphiphilic block copolymer PEG₅₀₀₀-SAA/PLA₁₀₀₀₀-APBA. The amphiphilic polymer was characterized by ¹H NMR, FTIR, and alizarin red S competition tests. The ROS responsiveness of TS-IIA-PM was evidenced by time-course monitoring of particle size and morphology changes and drug release behavior in the presence of 1 mM H₂O₂. We found TS-IIA-PM was stable according to its critical micelle concentration and the unchanged particle sizes in 10% FBS for 7 days. The results of in vitro and in vivo tests revealed that TS-IIA-PM was safe and biocompatible. Furthermore, it was observed that TS-IIA and prodrug micelle could produce synergistic antiatherosclerotic effect based on the results of the antioxidant study, which was further confirmed by a series of pharmocodynamics studies, such as in vitro DiI-oxLDL uptake study, oil red O staining, cholesterol efflux study, inflammatory cytokine analysis, in vivo CD68 immunostaining, and lipid disposition staining studies. Collectively, TS-IIA-PM holds great potential for the safe and efficient codelivery of TS-IIA and SAA for synergistic antiatherosclerosis.