Evaluating the cytotoxicity of single-walled and multi-walled carbon nanotubes as a scaffold for human chondrocyte stem cell precursors and optimizing the operational conditions

Abstract

Tissue engineering has attained great versatility and robustness, thanks to introduction of different biomaterials as scaffolds. In this study, an undifferentiated mesenchymal stem cell line was isolated from the amniotic membrane source and differentiated to human chondrocyte stem cell precursors. The differentiation was confirmed by morphological and molecular methods such as invert microscope, flow cytometry, alizarin and oil red staining. The cytotoxicity of six types of carbon nanotubes (CNTs), including pristine, carboxylic and hydroxylic single-walled and multi-walled CNTs were evaluated using MTT assay. The purity of six exploited CNTs was evaluated using inductively coupled plasma (ICP). Response surface methodology (RSM) was performed for optimizing the operational conditions to obtain the minimal toxic effects of the CNT scaffold for the isolated human chondrocyte stem cells precursors. The results of screening studies indicated that the carboxylic SWCNT and MWCNT showed the least toxicity (90%, 82% cell viability respectively, at the concentrations of 100 μg mL−1). After optimizing the operational conditions, it was suggested that a combination of 50.73 μg mL−1 SWCNT, 50.05 μg mL−1 MWCNT, and 248400 cells mL−1 will bring the minimal amount of stem cell cytotoxicity (85% viability). The model prediction of 85% stem cell viability was verified experimentally as 81%. This agreement (95%) between the predicted and observed cell viability levels confirmed the precision of the applied CCD method. Our developed protocol might be employed to stablish an acceptable strategy to exploit pristine and functionalized CNTs as the scaffold materials for potential tissue engineering of soft tissues in orthopedics.