Indolicidin-decorated photosensitizer hydrogel accelerates diabetic wound healing by 98% in mice.
Background
Healing of diabetic wounds is severely hampered by persistent infections from multidrug-resistant bacteria and impaired regenerative processes. Current treatments, including conventional antibiotics, often fall short due to rising resistance and limited efficacy in complex wound microenvironments. While photodynamic therapy (PDT) and antimicrobial peptides (AMPs) like Indolicidin show promise, PDT suffers from short-lived, poorly diffusing reactive oxygen species (ROS), and AMPs face issues with stability, potential cytotoxicity, and resistance induction. A synergistic approach is needed to overcome these inherent limitations and address the dual challenge of infection and impaired healing.
Study Design
Researchers engineered a synergistic nanoplatform by integrating the AMP Indolicidin with the photosensitizer PTBT, encapsulated within a thermosensitive F127 hydrogel (PTBT/I@F127). This system formed uniform, highly photosensitive nanoparticles. In vitro, the team evaluated its efficacy against methicillin-resistant Staphylococcus aureus (MRSA) and E. coli. For in vivo studies, they used diabetic mouse and pig models with infected wounds, assessing wound healing rates, angiogenesis, and collagen deposition. Transcriptomic analysis was performed to elucidate the underlying molecular mechanisms, focusing on Wnt/β-catenin, NF-κB, and IL-17 signaling pathways.
Results
The PTBT/I@F127 nanoplatform demonstrated remarkable synergy in vitro, effectively killing both methicillin-resistant Staphylococcus aureus (MRSA) and E. coli. Indolicidin on the nanoparticle surface initially disrupted bacterial membranes, enhancing PTBT's contact and subsequent ROS generation under 808-nm laser irradiation. This compensated for ROS's limited diffusion and reinforced Indolicidin's antibacterial effect before degradation. In diabetic animal models, the hydrogel significantly accelerated wound closure: > Wound healing rates reached a remarkable 98% in diabetic mice and 83% in pig models. Treated wounds also exhibited remarkable angiogenesis and collagen deposition. Transcriptomic analysis revealed that Wnt/β-catenin signaling pathways were activated, promoting tissue regeneration. Concurrently, inflammation-associated pathways, specifically NF-κB and IL-17, were downregulated, leading to alleviated inflammation and a more favorable immune microenvironment for healing.
Key Findings
- PTBT/Indolicidin@F127 hydrogel effectively killed
MRSAandE. coliin vitro with remarkable synergy. - Diabetic mouse models showed 98% wound healing rates after PTBT/I@F127 treatment.
- Diabetic pig models achieved 83% wound healing rates with PTBT/I@F127.
- Treated wounds exhibited remarkable angiogenesis and collagen deposition.
Wnt/β-cateninsignaling was activated for tissue regeneration, whileNF-κBandIL-17pathways were regulated to reduce inflammation.
Why It Matters
This Indolicidin-decorated hydrogel represents a significant advance for treating chronic diabetic wounds, offering a dual-action strategy that simultaneously combats multidrug-resistant infections and promotes tissue regeneration. For peptide users and clinicians, this approach could offer a safe, controllable, and highly effective alternative to conventional antibiotics, which are increasingly failing. The synergistic design, combining AMPs with PDT, addresses key limitations of each therapy alone, suggesting a potent new protocol. While preclinical, the robust 98% healing in mice and 83% in pigs, coupled with mechanistic insights into Wnt/β-catenin activation and NF-κB/IL-17 suppression, points towards a highly translatable technology for future clinical trials, potentially revolutionizing diabetic wound care.
indolicidin
diabetic-wounds
wound-healing
antimicrobial-peptides
photodynamic-therapy
mrsa