Design and Standardization of a Mandibular Injury Model for the Study of Craniofacial Tissue Regeneration in the Ambystoma mexicanum Model.

Abstract

The craniofacial complex is an anatomical region that, in humans, can be affected by developmental malformations, trauma, and pathologies such as cancer, leading to the loss of affected tissues. This creates a need to seek strategies for regenerating these lost tissues. This has promoted the study of cellular and molecular mechanisms that orchestrate the regenerative response of injured craniofacial structures in regenerating species, with Ambystoma mexicanum (A. mexicanum) being a species of great interest. In accordance with the above, a reproducible surgical lesion model was designed and standardized in the jaw of axolotls to study the regenerative response of injured tissues and simulate a critical defect like those performed in humans. Thus, juvenile/adult animals between 12-15 cm were anesthetized with 0.1% tricaine for 20-30 min. Subsequently, a complete transverse amputation was performed using a four-handed technique on the distal third of the mandible, including the symphyseal and parasymphyseal region, removing skeletal structures corresponding to the dentary bone and Meckel's cartilage, as well as soft tissues such as muscle, connective tissue, nerves, and skin. Subsequently, bone remnants were regularized, and 0.5% sulfamerazine was applied. The tissue response was evaluated both macroscopically and by diaphanization. All procedures performed were approved by the animal experimentation committee of the University of Antioquia, Colombia. The results show that the amputated animals were able to regenerate the removed craniofacial structures morphologically, structurally, and functionally. Of great relevance, this work provides a reproducible surgical technique with 100% survival of amputated and reamputated animals when the collection of regenerating tissues was required. Therefore, this surgical design represents a basic input for conducting comparative analyses with other vertebrates capable of regenerating craniofacial structures and for studying the cellular and molecular mechanisms underlying this regenerative response in the future.