In vitro evaluation of the biocompatibility and chondro-inductive potential of Kapton® for cartilage tissue engineering

Veterinary and human biomedical research is increasingly oriented towards the development of biocompatible implantable devices capable of supporting tissue regeneration and the development of controlled release systems. Kapton®, a polyimide known for its thermal and mechanical properties, shows potential in tissue regeneration, but its interaction with cartilage cells has not been explored in depth. This study aims to evaluate the biocompatibility, cytotoxicity and chondrocyte response on plastic materials, including polyester, polystyrene and Kapton®, by studying cell proliferation (MTT assay), morphology (optical microscopy), oxidative stress (NO and ROS assay), wound healing capacity (scratch assay) and differentiation (gene expression of specific markers), as well as immune activity in real-time qPCR. The results demonstrate that over time Kapton® supports chondrocyte adhesion, viability and proliferation in a similar manner to polystyrene (PS). Instead, the migration test on Kapton® shows wound closure approximately 3.5-fold slower at 24 h and 4d compared to PS attributable to the surface properties of the material. Furthermore, its non-toxicity is confirmed with a reduced and non-significant induction of oxidative stress. Instead, polyimide maintains the chondrocyte morphology without dedifferentiation towards the fibroblastic phenotype observed with significant differences in the expression of differentiation markers (Col2, ACAN, SOX6 and SOX9) compared to polystyrene. The stable expression of IL6 confirms the absence of significant inflammatory signals. These results confirmed the chondro-inductive activity of Kapton® and point out the potential of this material as substrate for cartilage tissue engineering and regenerative medicine due to the preserved involvement of chondrocyte phenotype in cartilage extracellular matrix synthesis.