Cartilage tissue engineering for auricular reconstruction: in vitro evaluation of potential genotoxic and cytotoxic effects of scaffold materials.

Tissue engineering of autologous cartilage transplants is suggested as a new approach in reconstruction of external auricular deformities. 1.6-Hexanediol (HD), 1.8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 6-hydroxyhexanoic acid (HHA) are matrices of the open-pored polyurethane three-dimensional scaffold. Since these bioresorbable materials may interact with the human organism, cytotoxic effects on human chondrocytes and lymphocytes and genotoxic effects on human lymphocytes were monitored. Staining with propidium iodide and fluorescence diacetate as well as the EZ4U proliferation assay served for the detection of cytotoxic effects of the materials on human chondrocytes. Trypan blue staining was used to monitor cytotoxicity on lymphocytes. Genotoxic effects on lymphocytes in terms of strand breaks, alkali labile sites and incomplete excision repair were determined by the alkaline single cell microgel electrophoresis (Comet) assay. Cytotoxic effects in chondrocytes and lymphocytes as well as genotoxic effects in lymphocytes were dose-dependent with threshold values of 5mg/mL HD, 0.5mg/mL DBU and 0.03 mg/mL HHA showing no effects. These data suggest that these matrices could be safely used for scaffolds made of polyurethane unless these compounds are not released at a rate giving higher concentrations at the site of implantation or in body fluids, respectively.

Cytotoxic and genotoxic effects of matrices for cartilage tissue engineering.

Customizing auricles with biodegradable polyurethane colonized with autologous chondrocytes as an approach for tissue engineering cartilage transplants has been suggested for the reconstruction of the external ear to repair auricular deformities. Dextrose, triethanolamine and poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-PPG-PEG) are matrices of an open-pored polyurethane three-dimensional scaffold. After release from the polymer, these compounds can be absorbed into the human organism. Therefore, cytotoxic effects on human chondrocytes and lymphocytes and genotoxic effects on human lymphocytes were determined. Propidium iodide and fluoresceine diacetate staining as well as quantitative proliferations testing with EZ4U served to detect cytotoxic effects on chondrocytes. In lymphocytes cytotoxicity was checked by trypan blue staining and the alkaline single cell microgel electrophoresis (Comet) assay was used to study genotoxic effects. Dose-dependent cytotoxicity and genotoxicity of the matrices could be shown. Concentrations up to 4.25mg/ml for dextrose, 0.15 mg/ml for PEG-PPG-PEG and 0.9 mg/ml for triethanolamine did not show cytotoxic effects in chondrocytes or genotoxic effects in lymphocytes. These data suggest that dextrose, triethanolamine and PEG-PPG-PEG could be safely used if scaffolds made of open-pored polyurethane do not release these compounds at a rate giving higher concentrations at the site of implantation or in body fluids, respectively.