RESUMO
Objective: The beneficial effects of photobiomodulation (PBM) on cellular function are well characterized, principally deriving from the absorption of red to near-infrared radiation by chromophores such as cytochrome-c-oxidase. However, the effects and underlying mechanisms of PBM on non-mitochondria containing cells, such as red blood cells (RBCs), are relatively unknown. In this review, we evaluate studies that investigated the effects of PBM on RBCs in the peripheral circulation, with particular attention on changes in the structural and functional features of RBC membrane dynamics, as well as the potential implications of PBM as an intervention for pathologies related to RBC dysfunction. Methods: A literature review was performed in concordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol, using the following databases: PubMed; Ovid (OvidMedline); Scopus; Web of Science; Google Scholar; Scholar.ru; eLIBRARY.ru; Digital Library: Dissertation; and Russian State Library. Search results included publications in Russian, Ukrainian, and English languages after 1995. Eligible articles included the effects of PBM on RBC membrane morphology and function in the peripheral circulation, used either in isolation or alongside other interventions. Results: The majority of articles indicated beneficial changes in RBC structure and function following exposure to PBM, including increased osmotic resistance, normalization of membrane permeability, decreased free radical oxidation and concentration of intermediate products of lipid peroxidation, reduced phospholipase A2 membrane activity, and normalization of the viscoelastic properties of RBCs and erythrocyte deformability index. Most trials had small patient numbers with no long-term follow-up. Conclusions: The importance of RBC membrane dysfunction as a potential marker and mechanism for RBC pathologies was highlighted. PBM has shown to have membrane protective effects. Further clinical trials are recommended to provide more evidence PBM therapy to treat RBC-related diseases, which may, at the correct dose, improve RBC stability and deformability in RBC-related pathologies.