Study of osteognesis and angiognesis genes expression of dental pulp stem cells seeded on thermosensetive injectable scaffolds based on N-Isopropylacryiamide containing VEGF and BMP2

Abstract

The use of tissue engineering promises to regenerate lost tissues using cellular products and gene therapy. Recently, similar scaffolds with different three-dimensional biological structures have been developed based on hydrogels for tissue engineering. Therefore, the aim of this study was to evaluate the expression of ossification and angiogenesis genes in dental pulp stem cells (hPDSC) transferred to temperature-sensitive injectable scaffolds containing BMP2 and VEGF. Materials and methods: In this study, electrochemical polymerization was used as a polymer scaffold fabrication method to prepare a highly porous polycaprolactone/hydroxyethyl methacrylate/N-isopropyl acrylamide (PCL-P(HEMA-NIPAAM)) hybrid copolymer for bone tissue regeneration. The characteristics of the obtained porous scaffolds were determined by FTIR, 1HNMR and SEM assays. In addition, growth factor loading and release tests, MTT and alizarin red staining were performed for bioassays of polymers containing growth factors. Finally, the expression level of growth factor VEGF was measured after exposure to the polymer. Results: Overall, we successfully developed the new hybrid copolymer PCL-P(HEMA-NIPAAM) by copolymerizing PCL, NIPAAm (heat-sensitive monomer), and HEMA via copolymerization to deliver growth factors (VEGFs or BMPs). The developed scaffolds showed many favorable advantages such as high growth factor loading capacity (85% for VEGF and 80% for BMP2) and release of heat-responsive growth factors. Growth factors were physically trapped in the structure of the hydrogel. Based on the findings of the present study, this copolymer can play an effective role by initiating various stages of bone growth, including the uptake of mesenchymal stem cells (MSCs) and their conversion to osteoblasts. In addition, the new PCL-P hybrid copolymer (HEMA-NIPAAM) showed no significant cytotoxicity for hPDSC cell lines in the MTT assay. As well as, the increase in VEGF gene expression in dental pulp stem cells was confirmed in temperature-sensitive and injectable PCL-P(HEMA-NIPAAM) containing VEGF. Conclusion: The copolymer-based scaffold PCL-P(HEMA-NIPAAm), with temperature-sensitive properties, can serve as an effective carrier for growth factors in applications related to bone tissue engineering and regenerative medicine. This biocompatible system is a promising option as a matrix for the implantation and differentiation of human dental pulp stem cells (hDPSCs) in tissue regeneration environments