LIPUS activated piezoelectric pPLLA/SrSiO₃ composite scaffold promotes osteochondral regeneration through P2RX1 mediated Ca²⁺ signaling pathway.

Abstract

Addressing the concurrent repair of cartilage and subchondral bone presents a significant challenge yet is crucial for the effective treatment of severe joint injuries. This study introduces a novel biodegradable composite scaffold, integrating piezoelectric poly-l-lactic acid (pPLLA) with strontium-enriched silicate bioceramic (SrSiO₃). This innovative scaffold continually releases bioactive Sr²⁺ and SiO₃^2- ions while generating an electrical charge under low-intensity pulsed ultrasound (LIPUS) stimulation, a clinically recognized method. The scaffold's unique dual action, emanating both chemical and electrical signals, activates the purinergic receptor P2X 1 (P2RX1) calcium ion channel, promoting an influx of intracellular calcium ions. This process results in a synergistic enhancement of both chondrogenic activities of rat chondrocytes (rCCs) and osteogenic activities of rat bone marrow mesenchymal stem cells (rBMSCs). Furthermore, the scaffold's effectiveness in integrating articular cartilage and subchondral bone repair is confirmed in a rat model of joint osteochondral injury. This study thereby offers a groundbreaking approach for treating severe osteoarticular cartilage defects.