Diabetic wound healing breakthrough: theaflavin-3, 3’-digallate nanoparticles@hydrogel activates the TGF-β1/SMAD3 pathway

Diabetes patients face an elevated wound infection susceptibility and delayed healing processes. Currently, no existing literature has reported on the effect and mechanism of theaflavin-3, 3'-digallate nanoparticles (TFDG NPS) and TFDG NPS@hydrogels on diabetic wounds. Given that the treatment options for diabetic wound are limited, the aim of this study is to develop an innovative therapeutic approach to address diabetic wounds. The TFDG NPS were prepared using ionic cross-linking, and they were then characterized. The biocompatibility of the TFDG NPS and TFDG NPS@hydrogel was assessed using a Cell Counting Kit-8 (CCK-8) assay and live/dead staining on HK-2 cells in vitro. Diabetic ICR mice were induced through intraperitoneal injection of streptozocin (STZ). They were then subjected to the creation of two full-thickness wounds on their dorsal areas. The effect and mechanism of the TFDG NPS and TFDG NPS@hydrogel on wound healing in diabetic mice were evaluated using a histological analysis, a western blot analysis, and molecular docking. The optimal TFDG NPS proportion was found to be TFDG:Gelatin (Gel):Chitosan (CS) = 2:1:1. Images photographed using a transmission electron microscope (TEM) revealed that the TFDG NPS appeared spherical, with a diameter of approximately 140 ± 20 nm. The favorable bio-compatibility of the TFDG NPS and TFDG NPS@hydrogel was confirmed using cell experiments. Animal studies demonstrated that both the TFDG NPS and TFDG NPS@hydrogel enhanced collagen fiber accumulation and new blood vessel density, reduced F4/80 infiltration, and upregulated the expression levels of TGF-β1, SMAD3, Collagen I, and α-SMA. The potential mechanism may involve activation of the TGF-β1/SMAD3 pathway, stimulating the secretion of Collagen I and α-SMA, and thereby facilitating wound closure in diabetic mice. The molecular docking results confirmed a high affinity between TFDG and TGF-β1/SMAD3. TFDG NPS and TFDG NPS@hydrogel promoted wound closure in diabetic mice through the TFG-β1/SMAD3 pathway, thus exhibiting promising therapeutic potential for diabetic wound treatment.