ABSTRACT
Photobiomodulation with far-red/near-infrared (NIR) light has
been applied successfully to ameliorate cardiac injury, both in the
acute and in the chronic ischemic heart. This chapter will review the
use of NIR in the protection of the heart from ischemia or ischemia
and reperfusion injury and discuss potentially involvedmechanisms.
The prospective for translation into the clinic will also be addressed.
Coronary artery disease continues to represent an important
cause of morbidity and mortality in Western society. Restoration
of blood flow to a region of previously ischemic myocardium
(reperfusion) is a critical life-saving intervention against tissue
necrosis, but reperfusion itself also results in significant damage to
myocardium. In fact, intervention at the time of reperfusion seems
sufficient to mitigate damage, which is of higher clinical impact
compared to treatment before the ischemic event. Mitochondrial
dysfunction, Ca2+ overload, reactive oxygen species (ROS), and the inflammatory response are some of the main culprits for the
damage of reperfusion injury. Many powerful therapeutic strategies
such as ischemic and pharmacologic pre-and postconditioning
have been developed and are effective in healthy animal models,
but few have translated effectively to patients. A major reason for
the resistance to cardioprotection against infarction by physical or
pharmacological stimuli is the advanced age and/or presence of
comorbidities such as diabetes in patients [1]. Increased oxidative
stress and endothelial dysfunction with disrupted nitric oxide
synthase (NOS) activity appear to contribute to the lack of protection
by ischemic or pharmacologic postconditioning [2, 3]. An acute and
a more chronic phase can be distinguished in the protection of
myocardial damage after an ischemic event. Immediately at the time
of reperfusion, prevention of the large burst in radicals, overload
in cytosolic and mitochondrial Ca2+, and permeability transition pore opening have been shown to improve cardiac function and
decrease injury [4]. In the chronically ischemic heart, or after an
extended period of reperfusion, stimulating pro-survival signaling
pathways, extracellular matrix remodeling, and angiogenesis have
been demonstrated to lead to a better outcome [5]. Treatment of
the heart with NIR from low-energy laser or light-emitting diode
(LED) sources has been successfully used for preventing tissue
damage as well as for tissue repair in various animal models. In this
chapter, we will describe various strategies of NIR treatments of the
injured heart, discuss possible underlying mechanisms, and provide
an outlook on remaining open questions and the translatability
into human ischemic heart disease, including acute myocardial
infarction.
