Regenerative wound dressings for accelerating diabetic wound healing

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Project Summary Diabetes affects more than 34 million people in the US alone. It is the leading cause of non-traumatic lower limb amputation, largely due to the development of chronic diabetic wounds. While various therapies have been explored to treat diabetic wounds, effective treatment remains a challenge as current therapies cannot efficiently address the key intrinsic causes of slow diabetic wound healing, i.e., chronic inflammation, abnormal skin cell functions (particularly migration), and delayed angiogenesis. To address these causes, it is crucial to control TGFβ signaling. TGFβ1/p38 pathway is directly associated with prolonged inflammation, and impaired cell migration in wounds. Meanwhile, TGFβ1/Smad2/3 pathway is required to regulate a critical cell type for wound healing, myofibroblasts. As such, inhibiting TGFβ1/p38 pathway without affecting TGFβ1/Smad2/3 pathway will simultaneously address the 3 key intrinsic causes, leading to accelerated diabetic wound healing. However, this cannot be achieved by any existing approaches. In this project, we propose to create a new wound dressing to achieve the goal. It will consist of a peptide-based TGFβ receptor II (TGFβRII) inhibitor ECG, and a reactive oxygen species (ROS)-scavenging hydrogel. The ECG will be gradually released from the hydrogel to continuously inhibit TGFβ1/p38 pathway so as to improve cell migration and decrease tissue inflammation. The enhanced endothelial cell migration will lead to accelerated angiogenesis. The hydrogel will scavenge upregulated ROS in the diabetic wounds to further decrease inflammation. Notably, ECG will not affect TGFβ1/Smad2/3 pathway under high glucose condition. To the best of our knowledge, none of the existing TGFβ receptor inhibitors have shown capability of inhibiting TGFβ1/p38 pathway without downregulating TGFβ1/Smad2/3 pathway. In our preliminary study, application of a single dose of wound dressing into excisional wounds in young diabetic mice significantly accelerated wound closure. The wounds completely closed at day 14. In contrast, the wound size remained >53% for the hydrogel-treated, and untreated wounds. The wound dressing also decreased ROS content, M1 macrophage density and p-p38 expression, and increased vessel density in the wounds. These preliminary results demonstrate that ECG-releasing wound dressing is promising for diabetic wound healing. It is yet to test whether the wound dressing can promote diabetic wound healing under aged condition, as aging itself impairs cell migration and angiogenesis. We hypothesize that the wound dressing based on ECG and ROS-scavenging hydrogel will significantly enhance skin cell migration, stimulate tissue angiogenesis, and decrease tissue inflammation, leading to accelerated healing of diabetic wounds under young and aged conditions. Aim #1 will test the hypothesis that optimal wound dressings will simultaneously scavenge ROS, increase skin cell migration, promote endothelial lumen formation, and attenuate inflammatory cytokine secretion under TGFβ and high glucose conditions. Aim #2 will test the hypothesis that the developed wound dressings will accelerate diabetic wound healing under young and aged conditions. This project is innovative because the proposed wound dressings will simultaneously address the 3 key intrinsic hurdles for diabetic wounds to heal, by differentially regulating TGFβ signaling, i.e., inhibiting TGFβ1/p38 pathway, while not affecting TGFβ1/Smad2/3 pathway that is essential for diabetic wound healing.