Spinal Cord Injury Disrupts Inflammatory Signaling and Impairs Skin Wound Healing: Evidence from Two Models of Decubitus Ulcers

Traumatic spinal cord injury (SCI) increases the risk for skin complications, including the development of decubitus ulcers, that is, pressure sores. The mechanisms by which SCI adversely affects skin health are poorly understood. To better understand how SCI affects the normal progression of wound healing, two mouse models of cutaneous wound healing were used. Mice received a high-level (T3) SCI or sham injury (Lam) over the first week postinjury. Mice received standardized skin wounds on the dorsum below the injury level (punch biopsy or compression/ischemia wounds). Planimetric analysis revealed that wound closure was consistently delayed and impaired after SCI. Subsequent analyses of the expression of genes and proteins responsible for regulating cell migration and recruitment, particularly of neutrophils, were reduced in SCI mice as early as 1 day post-wounding. This impaired chemotactic signaling was associated with a corresponding decrease in neutrophil recruitment to the wounds of SCI mice. At later phases of healing, the expression of inflammatory genes and the accumulation of wound myeloid cells with an elevated capacity for arginine catabolism was enhanced in SCI mice relative to Lam. Overall, data in this report show that impaired wound closure in SCI mice is associated with early and prolonged disruption of the expression of genes and proteins needed to coordinate the sequential progression through all phases of wound healing. Consequently, skin wounds in SCI mice exhibit prolonged inflammation, characteristic of complicated wound healing. Thus, targeting signaling pathways during the inflammatory phase of healing of decubitus ulcers after SCI could improve wound closure and limit further complications.