[Low-level laser therapy for the treatment of male infertility and erectile dysfunction]

Low-level laser therapy (LLLT), a noninvasive photobiomodulation technique, employs red or near-infrared (NIR) light (600-1 000 nm) with power outputs ranging from 5 to 500 mW. It exerts therapeutic effects through molecular mechanisms, specifically the activation of cytochrome C oxidase (CCO) and the modulation of intracellular signaling pathways. By enhancing mitochondrial adenosine triphosphate (ATP) synthesis, LLLT mitigates oxidative stress, regulates the reactive oxygen species (ROS)/glutathione peroxidase (GSH-Px)/superoxide dismutase (SOD) axis, and activates key pathways, including phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) and mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK). These mechanisms confer antioxidant, anti-inflammatory, and pro-regenerative properties to LLLT, making it a viable intervention for dermatological conditions, oncological therapies, and musculoskeletal disorders. Recent preclinical studies underscore LLLT' s potential in male reproductive health. Specifically, it ameliorates cavernosal fibrosis and endothelial dysfunction in erectile dysfunction (ED) models by upregulating the PI3K/Akt and MAPK/ERK pathways. In the context of sperm biology, LLLT enhances motility and acrosomal integrity in both fresh and cryopreserved spermatozoa. This is achieved through mitochondrial metabolic reprogramming, such as CCO-mediated electron transport chain activation, redox homeostasis restoration, and epigenetic modulation involving DNA methylation and histone acetylation. Additionally, LLLT alleviates scrotal heat-induced oligospermia by promoting seminiferous epithelial differentiation, elevating serum testosterone levels, and suppressing lipid peroxidation. These findings highlight the translational potential of LLLT in regenerative medicine, particularly for male sexual and reproductive disorders. Future research efforts should focus on interdisciplinary collaborations spanning life sciences, engineering, and physics. The goal is to optimize laser parameters, including wavelength, irradiance, and treatment duration, and establish standardized protocols. Rigorous preclinical and clinical investigations are paramount to validate the safety, efficacy, and long-term outcomes of LLLT, ultimately paving the way for its integration into precision medicine frameworks for urological and reproductive therapies.