Splinting Strategies to Overcome Confounding Wound Contraction in Experimental Animal Models

Significance: Clinical healing by secondary intention frequently occurs in skin that is firmly anchored to underlying (human) connective tissue. Small animals (rodents) are extensively utilized to model human cutaneous wound healing, but they heal by wound contraction, a process that is limited in the human and confounds quantitative and qualitative evaluation of experimental wound repair. Recent Advances: To alleviate wound contraction in loose-skinned species, practical solutions include choosing anatomical sites with firmly attached dermis and subcutis (e.g., rabbit ear) or performing mechanical fixation of the skin by using one of a number of devices or splints. In each case, the wound volume remains relatively constant, allowing the histomorphometric or biomolecular quantification of the cellular response under well-controlled, experimental conditions. In addition, the defined aperture of the splinted wound allows the placement of a variety of materials, including scaffolds, cells, and biologically active formulations into the wound site in an effort to potentiate the healing response and abrogate scarring. In contrast, production of larger experimental wounds or the deliberate distraction of wound margins can be used to model a hypertrophic response. Critical Issues: Device design parameters should consider ease of application, durability, and lack of interference with the normal influx of local and circulating cells to the wound site. Future Directions: Improved methods of securing flexible splints would provide a more efficient experimental platform. These devices could also incorporate optical or electronic sensors that report both the mechanical and physiological status of the healing.