4D piezoceramic-integrated scaffolds with bioelectric cues for skeletal muscle regeneration

Volumetric muscle loss (VML) poses a significant challenge due to the limited regenerative capacity of skeletal muscle. In this context, emerging four-dimensional (4D) regenerative strategies, which couple biomimetic scaffolds with external dynamic stimuli, have gained increasing attention for their potential to enhance repair outcomes. A novel piezoelectric scaffold based on egg white proteins (EWP) integrated with barium titanate (BTO) particles was developed using a rapid and versatile microwave-assisted method. The optimized EWP:BTO 1:1 scaffolds combine favourable porosity, mechanical compliance, and controlled degradation, closely mimicking native muscle tissue. Corona poling imparts permanent polarisation to the BTO phase, enabling localised electromechanical stimulation under ultrasound. C2C12 myoblasts cultured on these scaffolds exhibited enhanced adhesion, proliferation, infiltration and differentiation. Ultrasound stimulation synergized with polarisation to upregulate early mechanosensitive and electroactive genes. These findings highlight the capacity of piezoelectric scaffolds to integrate structural and dynamic cues, an essential feature of 4D scaffold-based approaches, promoting early myogenic signalling. A pilot in vivo study confirmed biocompatibility and structural integrity over 28 days, with no evidence of local or systemic toxicity, supporting the suitability of the scaffold for further evaluation in VML models. Overall, EWP:BTO 1:1 piezoelectric scaffolds constitute a sustainable, biocompatible, and functionally active 4D platform that converts mechanical energy into targeted electrical cues. By coupling biomimetic architecture with ultrasound-driven electromechanical activation, this approach provides a versatile and non-invasive strategy to modulate muscle regeneration and represents a promising platform for future functional muscle regeneration studies in VML.