Sensory nerve-secreted factors regulate basal keratinocyte function in vitro

Injuries to the skin can result in non-healing wounds, characterized by prolonged inflammation, failure to close, and chronic pain. Basal keratinocytes in the epidermis respond to signals activated following injury by proliferating, migrating, and differentiating to restore the epidermal barrier. The skin is densely innervated by peripheral sensory nerves, which contribute to the wound repair response. Although it is known that nerves are important for successful wound healing, the underlying cellular mechanisms of this phenomenon, and particularly the role of nerves in directing keratinocyte re-epithelialization, are poorly understood. To explore the relationship between sensory nerves and keratinocyte function in vitro, we cultured keratinocytes with conditioned media collected from dorsal root ganglia (DRG) in both homeostatic and post-wounding conditions and found that keratinocyte migration and proliferation, functions essential for re-epithelialization, were modulated by DRG conditioned media. Using a proteomic approach, we characterized the secretome of cultured DRG and identified key factors essential for wound healing, including extracellular matrix proteins, growth factors, and metabolic factors involved with ATP production, which was correlated with an increase in ATP rates of keratinocytes cultured in DRG conditioned medium. Our results advance our understanding of the microenvironmental cues that direct keratinocyte function during key events of cutaneous wound healing in vitro to drive the development of therapeutics that target dysregulated re-epithelialization in non-healing wounds.