Cardioprotection from ischemia-reperfusion injury by near-infrared light in rats

Abstract

Abstract Objective: Myocardial reperfusion injury can induce further cardiomyocyte death and contribute to adverse cardiovascular outcomes after myocardial ischemia, cardiac surgery, or circulatory arrest. Exposure to near-infrared (NIR) light at the time of reoxygenation protects neonatal rat cardiomyocytes and HL-1 cells from injury. We hypothesized that application of NIR at 670 nm would protect the heart against ischemia-reperfusion injury.

Methods: We assessed the protective role of NIR in in vivo and in vitro rat models of ischemia-reperfusion injury.

Results: NIR application had no effect on the function of the nonischemic isolated heart, and had no effect on infarct size when applied during global ischemia. In the in vivo model, NIR commencing immediately before reperfusion decreased infarct size by 40%, 33%, 38%, and 77%, respectively, after regional ischemic periods of 30, 20, 15, and 10 min. Serum cardiac troponin I (cTnI) was significantly reduced in the 15 min group, whereas creatine kinase (CK) and lactate dehydrogenase (LDH) levels were not affected.

Conclusions: We have demonstrated the safety of NIR application in an in vitro rat isolated model. In addition, we have demonstrated safety and efficacy when using NIR for cardioprotection in an in vivo rat ischemia model, and that this cardioprotection is dependent upon some factor present in blood, but not in perfusion buffer. RESULTS show potential for cTnI, but not CK or LDH, as a biomarker for cardioprotection by NIR. NIR may have therapeutic utility in providing myocardial protection from ischemia-reperfusion injury.

Figures

FIG. 1.

Infarct size measurements as a percentage of area at risk for various periods of ischemia duration, with or without near-infrared (NIR) treatment. Values for infarct size, control versus NIR, are: for 10 min 10.4±4.7 (n=6) versus 2.4±1.6% (n=6), for 15 min 26.8±9.7 (n=7) versus 16.2±6.2% (n=8), for 20 min 54.7±4.4 (n=5) versus 35.4±2.8% (n=7), and for 30 min 62.0±1.1 (n=6) versus 37.1±7.0% (n=7). Values given are mean±standard error. *Indicates significant difference (p<0.05) between NIR and respective control groups.

FIG. 2.

Cardiac troponin I (cTnI) levels (ng/mL) for various periods of ischemia duration, with or without near-infrared (NIR) treatment. Values, control versus NIR, are: for 10 min 34.9±4.8 (n=6) versus 34.5±3.6 (n=6), for 15 min 464±82 (n=7) versus 262±46 (n=8), for 20 min 517±116 (n=4) versus 433±112 (n=5), and for 30 min 715±48 (n=6) versus 714±101 (n=7). Values given are mean±standard error. *Indicates significant difference (p<0.05) between NIR and respective control groups.