3D Printed Human Amnion-Based Bioactive Hybrid Dressings for Effective Management of Complex Infected Wounds

Chronic wounds are often afflicted with persistent infection, excessive exudate accumulation, and delayed healing, leading to prolonged hospitalization. Excess moisture overhydrates the wound, promotes infection, and causes edema. Peri-wound skin may develop rashes, immersion injuries, and epidermal detachment. Nutrient-rich exudates foster microbial growth, increasing the infection risk. High bacterial loads lead to crust formation, continuous leakage, and foul odor, further complicating healing. To address this challenge, we developed a 3D printed amnion-based hybrid dressing comprising a regenerative layer integrated with a laminated silver-embedded polyurethane foam layer for partial and full thickness (thickness 0.12 mm-4 mm) infected wounds and burns. This dressing can suffice the varied clinical requirements of wound management by augmenting tissue regeneration, reducing bacterial load, and managing wound exudate. Human amnion was processed through decellularization and lyopreservation. Key angiogenic growth factors VEGF-A (54.12 ± 2.31 pg/mg) and PDGF-BB (3.760 ± 0.14 pg/mg) were quantified. Long-term in vitro cell viability was assessed for 20 days (as per ISO 10993-5 standards). Bioink was formulated using cryo-milled amnion particles and excipients optimized through rheology. Hybrid dressing was developed using an extrusion-based 3D printer, layering the amnion bioink onto the physical substrate, followed by lyophilization and gamma sterilization. Preclinical efficacy was assessed using a rodent Staphylococcus aureus-infected wound model, comparing the hybrid dressing to an in-house-developed amnion-mupirocin (AM) powder formulation with standard of care dressing. Both treatments demonstrated comparable wound closure rates and a significant bacterial load reduction. However, hybrid dressing offered superior healed tissue quality, increased CD31 expression, and improved neovascularization compared to AM powder treatment with a temporally regulated CD31 expression pattern mirroring the natural healing progression. This can be attributed to the hybrid construct of the dressing that provides effective exudate management, preventing its accumulation that could otherwise hinder angiogenesis, along with replenishment of wound bed with regenerative factors, aiding in mimicking the natural healing cascades.