Injectable chondroplasty: Enzymatic reshaping of cartilage grafts.

OBJECTIVE/HYPOTHESIS: To develop an injection-based enzymatic technique that selectively softens cartilage tissue for reshaping cartilaginous structures in the head and neck. MATERIALS AND METHODS: Two groups were formed using fresh rabbit ears: (1) whole rabbit ear group; (2) composite graft group (2.5mm×3.0cm specimens sectioned from the central region of the pinna). Subperichondrial injections using three enzymes (hyaluronidase, pronase, and collagenase II) in sequence were performed for the experimental specimens from both groups. In the control specimens, phosphate buffered saline was injected in a similar fashion. The whole ear specimens were then photographed while held upright in the anatomical vertical position to evaluate for buckling, which corresponds to the integrity of the cartilage. In addition, backlight photography was performed for all specimens to further evaluate the effect of the enzymes, such that increased light intensity represents increased cartilage digestion. RESULTS: The application of the digestive enzymes resulted in marked reduction of cartilage tissue matrix resiliency, while preserving overlying skin layers. Enzymatically treated whole pinnae buckled at the site where enzymes were delivered. Backlit images revealed increased local light intensity at the regions of digestion. There was no obvious destruction of the overlying skin upon visual inspection. CONCLUSIONS: This study demonstrates the feasibility of injectable chondroplasty as a potential alternative method to conventional surgery for auricular cartilage reshaping. Sequential injection of hyaluronidase, pronase, and collagenase II into the subperichondrial space can be performed to digest and soften cartilage structure with minimal involvement of surrounding tissue. Future studies will need to include chondrocyte viability testing and optimization of delivery techniques.

The porcine and lagomorph septal cartilages: models for tissue engineering and morphologic cartilage research.

Interest in reconstruction and modification of the facial cartilaginous frameworks using advanced technology and instrumentation is growing rapidly. Despite this maturing interest, no animal model has been established to provide morphologic cartilage tissue with similar characteristics to human septum in suitable quantities. The objective of this study was to characterize porcine and lagomorph (rabbit) nasal septal cartilage tissue. Both models share great similarity with their human counterpart and provide a low-cost, high-volume, and easily obtained source of bulk cartilage tissue. We present a technique for harvesting intact septal cartilages from these species, and characterize select cellular, metabolic, and physical properties using pulse-chase radiolabeling, flow cytometry, and mechanical analysis. Our selective evaluation of key tissue properties establishes these species as appropriate animal models for nasal septal cartilaginous surgery.