CARTILAGE RECONSTRUCTION IN HEAD AND NECK-SURGERY - COMPARISON OF RESORBABLE POLYMER SCAFFOLDS FOR TISSUE ENGINEERING OF HUMAN SEPTAL CARTILAGE

New cell culture techniques raise the possibility of creating cartilag e in vitro with the help of tissue engineering. In this study, we comp ared two resorbable nonwoven cell scaffolds, a polyglycolic acid/poly- L-lactic acid (PGA/PLLA) (90/10) copolymer (Ethisorb) and pure PLLA (V 7-2), with different degradation characteristics in their aptitude fo r cartilage reconstruction. Chondrocytes were isolated enzymatically f rom human septal cartilage. The single cells were resuspended in agaro se and transferred into the polymer scaffolds to create mechanical sta bility and retain the chondrocyte-specific phenotype. The cell-polymer constructs were then kept in perfusion culture for 1 week prior to su bcutaneous transplantation into thymusaplastic nude mice. After 6, 12, and 24 weeks, the specimens were explanted and analyzed histochemical ly on the presence of collagen (azan staining), proteoglycans (Alcian blue staining), and calcification areas (von Kossa staining). Further more, different collagen types (collagen type I, which is found in mos t tissues, but not in hyaline cartilage matrix; and collagen type II, which is cartilage specific) were differentiated immunohistochemically by the indirect immunoperoxidase technique. Vascular ingrowth was inv estigated by a factor VIII antibody, which is a endothelial marker. Qu antification of several matrix components was performed using the soft ware Photoshop. Significant differences were found between both nonwov en structures concerning matrix synthesis and matrix quality as well a s vascular ingrowth. Ethisorb, with a degradation time of approximatel y 3 weeks in vitro, showed no significant differences from normal huma n septal cartilage in the amount of collagen types I and II 24 weeks a fter transplantation. Thin fibrous tissue layers containing blood vess els encapsulated the transplants. V 7-2 constructs, which did not show strong signs of degradation even 24 weeks after transplantation, cont ained remarkably smaller amounts of cartilage-specific matrix componen ts. At the same time, there was vascular ingrowth even in central part s of the transplants. In conclusion, polymer scaffolds with a short de gradation time are suitable materials for the development of cartilage matrix products, while longer stability seems to inhibit matrix synth esis. Thus, in vitro engineering of human cartilage can result in a ca rtilage-like tissue when appropriate nonwovens are used. Therefore, th is method could be the ideal cartilage replacement method without the risk of infection and with the possibility of reconstructing large def ects with different configurations. (C) 1998 John Wiley & Sons, Inc.