The effect of electrical stimulation on the osteogenesis of MC3T3-E1 cells

Abstract

Bone and its related complications are unresolved medical issues as bones only possess limited healing and/or regeneration ability so bone tissue engineering (BTE) has emerged as an encouraging method for repairing bone defects, where scaffolds, signals and cells contribute synergistically. Since the discovery of piezoelectricity being a natural electrical property of bone, electroactive scaffolds for electrical stimulation have been increasingly researched and developed. Past research had fabricated, using vapour phase polymerisation (VPP), a polycaprolactone (PCL) film with an electrically conductive poly(3,4-ethylenedioxythiophene) tosylate (PEDOT) polymer coating conjugated with (3-glycidyloxypropyl)trimethoxysilane (GOPS) for enhanced adhesion and biocompatibility. Pulsed electromagnetic field (PEMF) could efficiently influence cell behaviours both in vitro and in vivo which resulted in direct cell activities of differentiation and proliferation. This project aims to further investigate the synergistic effect of the PEDOT-coated polycaprolactone/tricalcium phosphate (PCLTCP) film with and without pulsed electromagnetic field (PEMF) exposure on the osteogenesis of osteoblast precursor cells MC3T3-E1. The films were characterised by surface properties via Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR), Field Emission Scanning Electron Microscopy (FESEM); functional properties via four-point probe and degradation study; and cellular response via cell metabolic activity, cell proliferation, alkaline phosphatase (ALP) activity, cell mineralisation and osteogenic gene expression studies. PEDOT, conjugated with GOPS, was found to have porous morphology when coated on PCLTCP films. It exhibited comparable conductivity as human bone. The enhancement on cell metabolic activity and cell proliferation indicated biocompatibility of PCLTCP+PEDOT-GOPS film with or without PEMF exposure. Incorporation of the conductive coating promoted early cell mineralisation on day 7 but reduced late cell mineralisation on day 28. A similar effect was also observed for osteogenic gene expressions. These findings helped to understand how PEMF and the conductive PEDOT coating affect cellular behaviour individually and synergistically and can be further researched in vivo comprehensively.