Carbon nanotube fiber electrode-based implantable electroacupuncture ameliorates myocardial ischemia in rats via the FXR/SHP pathway

Abstract Myocardial ischemia (MI) remains a major clinical challenge, and the therapeutic potential of electroacupuncture (EA) is constrained in practice by repeated needle insertion, poor repeatability of acupoint localization, and limited long-term patient compliance. To overcome these barriers, we developed a minimally invasive implantable EA (IEA) system based on carbon nanotube fiber (CNTF) electrodes via a minimally invasive, ultrasound-guided procedure to establish a ‘single-implantation, long-term stimulation’ strategy, delivering both sustained mild stimulation and conventional EA at the Neiguan (PC6) acupoint. Results demonstrated that CNTFs with a diameter of 20–30 μ m, a conductivity of (2.64 ± 0.95) × 10 5 S m −1 , a charge storage capacity of 13.09 ± 2.79 mC cm −2 , and an impedance of 133.48 ± 69.88 Ω at 1 kHz represented the balanced trade-off for performance. Within the 14 d observation period, CNTF implantation at PC6 did not induce obvious local inflammatory infiltration or pathological tissue alterations. In a rat model of isoproterenol-induced MI, the IEA system markedly improved cardiac electrophysiology attenuated cardiac remodeling and reduced serum cTnT levels demonstrating superior therapeutic effects compared with conventional EA. Kinetic analysis of electrophysiological data revealed that daily IEA facilitated faster effect accumulation and consolidation, favoring acute- or subacute-phase management, whereas alternate-day IEA achieved a higher therapeutic ceiling, suggesting its superiority for maximizing long-term functional recovery. These results provided a rationale for session-frequency-personalized therapy. Furthermore, the cardioprotective effect was mediated through the downregulation of the FXR/SHP apoptotic pathway, validated by pharmacological inhibition. This work established a safe, effective, and stable platform that merged advanced bioelectronic materials with traditional acupuncture theory, providing a promising translational solution for the chronic, home-based rehabilitation of heart disease or other diseases, particular for elderly, paralyzed, or those with limited mobility and access to clinical care.