Researchers at Nanjing University of Chinese Medicine have demonstrated that remote electroacupuncture conditioning significantly protects the heart against myocardial ischemia-reperfusion injury in rats. The study, published in the journal Chinese Medicine, identifies stromal cell-derived factor-1 alpha, or SDF-1α, as the primary humoral factor mediating this cardioprotective effect. By applying electroacupuncture to the forearm, the team observed a marked reduction in infarct size and a substantial improvement in cardiac function following a simulated heart attack. This approach offers a non-invasive alternative to traditional remote ischemic conditioning, which relies on cycles of limb ischemia and reperfusion to trigger protective mechanisms in the heart.
The investigation focused on the complex and often conflicting role of the SDF-1α/CXCR4 signaling axis in the context of myocardial injury. Previous studies have produced mixed results regarding the therapeutic potential of targeting this axis, with some evidence suggesting that SDF-1α promotes cell survival while other data indicates it can exacerbate inflammatory damage. To resolve these contradictions, the researchers examined the spatiotemporal dynamics of SDF-1α signaling, specifically how its effects change over time and across different regions of the injured heart. This detailed analysis revealed that the protective benefits of electroacupuncture depend on a precise balance between pro-survival and pro-inflammatory responses.
The experimental design involved healthy male Sprague-Dawley rats subjected to a standardized model of myocardial ischemia-reperfusion injury. The researchers induced ischemia by ligating the left anterior descending coronary artery and then restored blood flow after a set period. Electroacupuncture was administered to the PC6 acupoint on the forearm, a technique previously associated with cardioprotective effects. A critical finding from the initial trials was that applying electroacupuncture immediately upon the onset of ischemia increased mortality rates, likely due to the acute stress response. However, delaying the treatment by just five minutes into the ischemic period dramatically improved survival and enhanced the protective outcomes.
At 24 hours post-reperfusion, rats treated with the delayed electroacupuncture protocol exhibited significantly better cardiac function compared to untreated controls. Echocardiographic measurements showed that left ventricular ejection fraction and fractional shortening were substantially higher in the treated group, indicating preserved pumping ability. Furthermore, the treated animals displayed a lower mortality rate and reduced levels of serum cardiac injury markers, including creatine kinase-MB and cardiac troponin I. These biochemical and functional improvements suggest that the electroacupuncture intervention effectively mitigated the acute damage caused by the restoration of blood flow to the ischemic tissue.
The study also highlighted the role of SDF-1α in modulating the inflammatory response within the infarcted myocardium. Immunofluorescence staining revealed that electroacupuncture treatment significantly reduced the infiltration of neutrophils into the injured heart tissue. More importantly, the treatment promoted the apoptosis of these neutrophils, a process essential for the resolution of inflammation. By accelerating the removal of inflammatory cells, the electroacupuncture protocol helped to limit secondary tissue damage and facilitated the transition from an acute inflammatory phase to a reparative state.
Mechanistically, the researchers found that electroacupuncture increased the concentration of SDF-1α in the infarct zone relative to the border zone. This spatial gradient was established through a dual mechanism involving both extracardiac recruitment and intracardiac stabilization. Serum levels of SDF-1α were elevated by the treatment, providing a greater supply of the chemokine to the heart. Simultaneously, the expression of CXCR7, a scavenger receptor that degrades SDF-1α, was suppressed in the infarct zone. This reduction in CXCR7 activity allowed SDF-1α to accumulate locally, creating a high-concentration environment that drove specific downstream signaling events.
The temporal dynamics of SDF-1α signaling were central to the observed cardioprotection. During the early phase of reperfusion, specifically at 15 minutes, SDF-1α binding to its receptor CXCR4 triggered the activation of the ERK pathway. This rapid signaling cascade promoted cardiomyocyte survival and attenuated apoptosis, effectively protecting heart cells from the immediate stress of reperfusion. The study confirmed that this early pro-survival effect was distinct from the later anti-inflammatory mechanisms, demonstrating that the same signaling axis can exert different beneficial effects at different time points.
As reperfusion progressed to 24 hours, the role of the SDF-1α/CXCR4 axis shifted. The sustained presence of high SDF-1α levels led to the downregulation and degradation of CXCR4 receptors. This reduction in receptor expression resulted in the suppression of downstream signaling through ERK and NF-κB p65. The inhibition of these pathways was directly linked to the promotion of neutrophil apoptosis and the resolution of inflammation. Thus, the electroacupuncture-induced elevation of SDF-1α served to fine-tune the dual role of the axis, ensuring that pro-survival signals were active early on, while anti-inflammatory signals dominated later in the recovery process.
To validate the necessity of this specific signaling mechanism, the researchers performed functional experiments using direct injections of SDF-1α and the CXCR4 antagonist AMD3100. Injecting SDF-1α directly into the infarct zone replicated the cardioprotective effects of electroacupuncture, improving cardiac function and reducing infarct size. Conversely, injecting SDF-1α into the border zone disrupted the protective gradient and diminished the benefits of the electroacupuncture treatment. These results underscore the importance of the spatial localization of SDF-1α in achieving optimal cardioprotection.
The study also examined the effects of pharmacological CXCR4 inhibition using AMD3100. While the antagonist improved cardiac function and reduced infarct size compared to untreated controls, its protective effects were weaker than those observed with electroacupuncture. The AMD3100 group exhibited higher mortality rates and larger infarct sizes than the electroacupuncture-treated group. This discrepancy suggests that simply blocking CXCR4 is insufficient to replicate the full spectrum of benefits provided by electroacupuncture, which relies on the dynamic, time-dependent modulation of the signaling pathway rather than static inhibition.
The findings suggest that remote electroacupuncture conditioning offers a feasible and safe clinical intervention for mitigating reperfusion injury. The protocol’s ability to mimic the pre-hospital window of care makes it particularly relevant for patients undergoing percutaneous coronary intervention. By initiating treatment after the initial acute stress of ischemia has stabilized, the method avoids the risks associated with immediate intervention.
The research contributes to the growing body of evidence supporting non-ischemic stimuli as effective triggers for remote cardioprotection. Electroacupuncture stands out as a green therapy due to its non-invasive nature and ease of administration. The identification of SDF-1α as a key mediator provides a clear molecular target for further investigation. Understanding how this chemokine orchestrates the spatiotemporal progression of inflammation and repair could lead to the development of novel therapeutic strategies for heart disease.
Despite the promising results, the study has limitations that should be considered. The experiments were conducted in a rat model, and the translation of these findings to human patients requires further clinical validation. Additionally, the long-term effects of this intervention on cardiac remodeling and function beyond the 24-hour mark remain to be fully elucidated.
In conclusion, this study provides a detailed mechanistic explanation for the cardioprotective effects of remote electroacupuncture conditioning. By identifying SDF-1α as a central player in the spatiotemporal regulation of the CXCR4 axis, the researchers have clarified how this non-invasive therapy balances pro-survival and anti-inflammatory responses.
Subject of Research: Mechanisms of electroacupuncture-mediated cardioprotection via SDF-1α/CXCR4 signaling in myocardial ischemia-reperfusion injury
Article Title: Remote electroacupuncture conditioning protects the heart via fine-tuning the dual role of the SDF-1α/CXCR4 axis in myocardial ischemia–reperfusion injury
Article References: Xu, S., Lian, J., Chen, S., Zuo, Y., Xiong, H., Lin, Y., Gu, Y., & Zhang, H. (2026). Remote electroacupuncture conditioning protects the heart via fine-tuning the dual role of the SDF-1α/CXCR4 axis in myocardial ischemia–reperfusion injury. Chinese Medicine, 21(1), Article 209. https://doi.org/10.1186/s13020-026-01470-5
Image Credits: AI Generated
DOI: 10.1186/s13020-026-01470-5
Keywords: electroacupuncture, cardioprotection, myocardial ischemia, reperfusion injury, SDF-1α, CXCR4, inflammation, neutrophil apoptosis, remote conditioning, cardiac function, Remote, conditioning
