Producing a flexible tissue-engineered cartilage framework using expanded polytetrafluoroethylene (ePTFE) membrane as a pseudoperichondrium

BACKGROUND: Both native and engineered cartilage is brittle and fractures easily without perichondrium. The aim of this study was to understand the role of the perichondrium and try to enhance the flexible properties of tissue-engineered cartilage using expanded polytetrafluoroethylene (ePTFE) membrane as a pseudoperichondrium. METHODS: The study was conducted in two phases. In phase I, native swine auricular cartilage of different thicknesses was studied by histologic evaluation and failure testing. Next, isolated perichondrium was bonded to native cartilage slices using fibrin glue or Dermabond and tested to failure. In phase II, swine auricular chondrocytes were suspended in fibrin glue. The chondrocyte-fibrin glue composites were then bound to expanded polytetrafluoroethylene membrane in two trilaminar configurations: In group EC-1, the membrane was in the center, whereas it was on the surfaces in group EC-2. Specimens were implanted into nude mice for 4 weeks, 8 weeks, 12 weeks, and 8 months and subjected to histologic evaluation and failure testing. RESULTS: In phase I, the results demonstrated that perichondrium securely bonded to the cartilage plays an important role in maintaining the flexible nature of elastic cartilage. In phase II, failure testing revealed that specimens in group EC-1 (expanded polytetrafluoroethylene core) were fractured during bending and destroyed after torsion, whereas those in group EC-2 (cartilage core) returned to their original shape without fracturing even after rigorous torsion. Histologic analysis demonstrated that transplanted chondrocytes penetrated into the microporous structure of expanded polytetrafluoroethylene and created a bond to it. CONCLUSION: It is possible to engineer flexible cartilage using expanded polytetrafluoroethylene as a pseudoperichondrium.