Co-stimulation with piezoelectric PVDF films and low intensity pulsed ultrasound enhances osteogenic differentiation
Biranche Tandon, José Cosme, Ruikang Xue, Kasama Srirussamee, Julio Adrian Aguilar-Tadeo, Christoph Ballestrem, Jonny J. Blaker, Sarah H. Cartmell
Abstract
Bone tissue engineering has emerged as a promising approach to address the challenges of bone fracture repair and regeneration. The application of external stimuli (mechanical and electrical) can drive specific cellular responses and osteogenic differentiation, leading to the development of more effective treatments. Piezoelectric materials modulate cellular proliferation and osteogenic differentiation under both static (without mechanical stimulation) and dynamic (with mechanical stimulation) conditions, activating distinct gene expression pathways. In this work, we investigate the combinatorial effect of poly (vinylidene fluoride) (PVDF) poled and non-poled films, and low-intensity pulsed ultrasound (LIPUS) on early-stage osteogenic differentiation of mouse pre-osteoblasts. Static culture with PVDF poled films enhanced Runx2 and Col1α1 expression without impacting alkaline phosphatase (ALP) activity. Inhibition of ERK phosphorylation using U0126 in PVDF poled films resulted in a ~ 6–8-fold increase in ALP activity, suggesting the involvement of an alternative pathway in osteogenic differentiation. Dynamic culture with LIPUS generated an electric potential of approximately 500 mV across PVDF films and an electrical field of 0–10 mV mm −1 . Co-stimulation led to a ~3-fold increase of ALP activity on stimulated PVDF compared to unstimulated films. This study underscores the potential of piezoelectric materials as non-invasive electrical stimulators to enhance the efficacy of ultrasound-based therapies for bone fracture repair. • The study investigates the combined effect of piezoelectric poly(vinylidene fluoride) (PVDF) films and low-intensity pulsed ultrasound (LIPUS) on the early-stage osteogenic differentiation of mouse pre-osteoblasts (MC3T3-E1 cells). • Static Culture: PVDF poled films enhance Runx2 and Col1α1 expression, key osteogenic markers, without affecting alkaline phosphatase (ALP) activity. • ERK/MAPK Pathway: Inhibition of ERK phosphorylation with U0126 results in a 6–8-fold increase in ALP activity, indicating alternative pathways in osteogenic differentiation. • Dynamic Culture (LIPUS Stimulation): LIPUS generates an electric potential (~500 mV) across PVDF films and an electric field of 0–10 mV/mm. • Synergistic Effect of Co-Stimulation: LIPUS stimulation with PVDF poled films triples ALP activity, promoting osteogenic differentiation. • Calcium Ion Influx: ALP activity enhancement is dependent on extracellular calcium influx, as inhibition with lanthanum chloride reduces the effect.