4-aminopyridine-loaded topical gel for promoting skin regeneration in burn injuries

Burn wounds are a common traumatic injury that impair cellular function and hinder the healing process, often resulting in significant skin loss. While autologous skin grafting is considered the gold standard for treating burns, its widespread use is limited due to donor site morbidity and the requirement for large amounts of tissue. Traditional wound dressings and treatments often fail to ensure complete recovery. Being initially FDA-approved to treat multiple sclerosis, 4-aminopyridine (4-AP) has also been shown to accelerate burn wound closure by modulating keratinocytes and fibroblasts when administered systemically. However, prolonged systemic use of 4-AP can lead to significant side effects. In this study, we aimed to repurpose 4-AP for treating skin burn wounds by delivering it topically using a laponite-gelatin gel formulation. This method allows for non-invasive and localized drug delivery on the burn wound site. We evaluated the physical properties of the 4-AP gel, including shear thinning behavior, drug release kinetics, cytocompatibility, and functional wound closure (48hr) using a scratch assay (>90%). Moreover, our in vivo experiments showed that the 4-AP loaded gel accelerates wound healing by reducing inflammation, thereby enhancing re-epithelialization and angiogenesis, and promoting the transformation of fibroblasts into myofibroblasts. Burn closure in the 4-AP gel group was consistently higher than the control gel from day 6 through day 21, reaching near-complete healing by day 21, whereas control-treated wounds remained partially open. This enhanced closure correlated with accelerated collagen remodeling, as the 4-AP gel significantly increased collagen type I and III deposition and their ratio compared to controls (438% vs. 267%; 288% vs. 215%; ratio 1.7 vs. 1.2; ∗P < 0.05 to ∗∗∗P < 0.0002), indicating improved matrix maturation during burn healing. This novel application of the 4-AP gel could offer a promising alternative to current burn wound therapies, potentially leading to improved outcomes for burn patients.