Evaluating 3D-Patch Efficacy in Wound Healing Using the Medicinal Leech Hirudo verbana as an In Vivo Model

Skin injuries are common and can result from surgeries, burns, pressure sores, cuts, and diseases. Proper wound healing is crucial for maintaining homeostasis; wounds can be classified as acute or chronic. Acute wounds heal in four sequential phases: hemostasis, inflammation, proliferation, and remodeling. Chronic wounds arise when this process fails, often due to prolonged inflammation. Existing treatments for chronic wounds are limited, and antibiotic resistance complicates infection control, highlighting the urgent need for new therapies. Biomaterials, particularly gelatin, have gained attention for their biomimetic properties, biocompatibility, and ability to promote healing. Gelatin's ECM-like structure supports tissue metabolism, and it can be enriched with bioactive compounds to enhance tissue regeneration, collagen deposition, angiogenesis, and antimicrobial activity. This study evaluates the effectiveness of a 3D gelatin-based patch in vivo, using Hirudo verbana as a model. The patch, functionalized with chitosan and bioactive apatite nanoparticles, was implanted in injured leeches, with tissue samples collected at 72 h, 1 week, and 2 weeks. Scaffold integration, cell colonization, and healing effects were assessed through morphological, immunohistochemical, and ultrastructural analyses. The findings confirm H. verbana as a robust in vivo model for regenerative medicine and demonstrate the promising potential of gelatin-based patches.