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 cartilage in vitro with the help of tissue engineer- ing. In this study, we compared 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 for cartilage reconstruction. Chondrocytes were isolated en- zymatically from human septal cartilage. The single cells were resuspended in agarose and transferred into the poly- mer scaffolds to create mechanical stability and retain the chondrocyte-specific phenotype. The cell-polymer con- structs were then kept in perfusion culture for 1 week prior to subcutaneous transplantation into thymusaplastic nude mice. After 6, 12, and 24 weeks, the specimens were ex- planted and analyzed histochemically on the presence of collagen (azan staining), proteoglycans (Alcian blue stain- ing), and calcification areas (von Kossa staining). Further- more, different collagen types (collagen type I, which is found in most tissues, but not in hyaline cartilage matrix; and collagen type II, which is cartilage specific) were differ- entiated immunohistochemically by the indirect immuno- peroxidase technique. Vascular ingrowth was investigated by a factor VIII antibody, which is a endothelial marker. Quantification of several matrix components was performed using the software Photoshop. Significant differences were found between both nonwoven structures concerning ma- trix synthesis and matrix quality as well as vascular in- growth. Ethisorb, with a degradation time of approximately 3 weeks in vitro, showed no significant differences from nor- mal human septal cartilage in the amount of collagen types I and II 24 weeks after transplantation. Thin fibrous tissue layers containing blood vessels encapsulated the trans- plants. V 7-2 constructs, which did not show strong signs of degradation even 24 weeks after transplantation, contained remarkably smaller amounts of cartilage-specific matrix components. At the same time, there was vascular ingrowth even in central parts of the transplants. In conclusion, poly- mer scaffolds with a short degradation time are suitable materials for the development of cartilage matrix products, while longer stability seems to inhibit matrix synthesis. Thus, in vitro engineering of human cartilage can result in a cartilage-like tissue when appropriate nonwovens are used. Therefore, this method could be the ideal cartilage replace- ment method without the risk of infection and with the pos- sibility of reconstructing large defects with different con- figurations. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 42, 347-356, 1998.