Combating Traumatic Brain Injury: A Dual-Mechanism Hydrogel Delivering Salvianolic Acid A and Hydroxysafflor Yellow A to Block TLR4/NF-κB and Boost Angiogenesis.

Traumatic brain injury (TBI) leads to severe neurological dysfunction, disability, and even death. Surgical intervention and neurorehabilitation represent the current clinical management methods, yet there remains no effective treatment for recovery after TBI. Post-traumatic hyperinflammation and vascular injury are the key therapeutic challenges. Therefore, a novel-designed multifunctional HT/SAA/HSYA hydrogel based on hyaluronic acid (HA) co-loaded with salvianolic acid A (SAA) and hydroxysafflor yellow A (HSYA) was developed in order to simultaneously target inflammation and vascular injury, addressing key pathological processes in TBI. The HT hydrogel was formed through covalent cross-linking of tyramine-modified HA catalyzed by horseradish peroxidase (HRP). Results demonstrated that the HT hydrogel possesses a porous structure, sustained release capabilities of loaded drugs, suitable biodegradability, and excellent biocompatibility both in vitro and in vivo. WB, immunofluorescence staining, and PCR results revealed that SAA and HSYA significantly reduced the expression level of pro-inflammatory cytokines (IL-1β and TNF-α) and inhibited M1 macrophage polarization through the suppression of the TLR4/NF-κB inflammatory pathway. In vivo experiments confirmed that the HT/SAA/HSYA hydrogel exhibited remarkable pro-angiogenic effects, as evidenced by increased expression of CD31 and α-SMA. Finally, H&E staining showed that the HT/SAA/HSYA hydrogel effectively reduced the lesion volume in a mouse TBI model, and demonstrated more pronounced effects in promoting brain repair at the injury site, compared to the control and single-drug-loaded hydrogel groups. In conclusion, the HT hydrogel co-loaded with SAA and HSYA demonstrates excellent anti-inflammatory and pro-angiogenic effects, offering a promising therapeutic approach for brain repair following TBI.