Low-Level Light Therapy Protects Red Blood Cells Against Oxidative Stress and Hemolysis During Extracorporeal Circulation

Cardiopulmonary bypass associated acute kidney injury: better understanding and better prevention

Cardiopulmonary bypass (CPB) is a common technique in cardiac surgery but is associated with acute kidney injury (AKI), which carries considerable morbidity and mortality. In this review, we explore the range and definition of CPB-associated AKI and discuss the possible impact of different disease recognition methods on research outcomes. Furthermore, we introduce the specialized equipment and procedural intricacies associated with CPB surgeries. Based on recent research, we discuss the potential pathogenesis of AKI that may result from CPB, including compromised perfusion and oxygenation, inflammatory activation, oxidative stress, coagulopathy, hemolysis, and endothelial damage. Finally, we explore current interventions aimed at preventing and attenuating renal impairment related to CPB, and presenting these measures from three perspectives: (1) avoiding CPB to eliminate the fundamental impact on renal function; (2) optimizing CPB by adjusting equipment parameters, optimizing surgical procedures, or using improved materials to mitigate kidney damage; (3) employing pharmacological or interventional measures targeting pathogenic factors.

Biphasic dose-response and effects of near-infrared photobiomodulation on erythrocytes susceptibility to oxidative stress in vitro

The effect of simultaneous application of tert-butyl hydroperoxide (tBHP) and polychromatic near-infrared (NIR) radiation on bovine blood was examined to determine whether NIR light decreases the susceptibility of red blood cells (RBCs) to oxidative stress. The study assessed various exposure methods, wavelength ranges, and optical filtering types. Continuous NIR exposure revealed a biphasic response in cell-free hemoglobin changes, with antioxidative effects observed at low fluences and detrimental effects at higher fluences. Optimal exposure duration was identified between 60 s and 15 min. Protective effects were also tested across wavelengths in the range of 750-1100 nm, with all of them reducing hemolysis, notably at 750 nm, 875 nm, and 900 nm. Comparing broadband NIR and far-red light (750 nm) showed no significant difference in hemolysis reduction. Pulse-dosed NIR irradiation allowed safe increases in radiation dose, effectively limiting hemolysis at higher doses where continuous exposure was harmful. These findings highlight NIR photobiomodulation's potential in protecting RBCs from oxidative stress and will be helpful in the effective design of novel medical therapeutic devices.

The effect of solarium light therapy on selected biological and biochemical parameters of peripheral blood in young and old horses

The aim of the study was to assess the impact of solarium light therapy on selected biological and biochemical parameters of peripheral blood in recreational horses. The study involved 10 horses divided into two groups of young (aged 5 to 7 years) and old (aged 14 to 19 years) individuals. All animals participated in light therapy sessions every other day. Blood was sampled three times during the study: before the treatment, after five light sessions, and after ten light sessions. Morphological parameters, the activity of antioxidant enzymes, TAS values, and the levels of glutathione (GSH), vitamin D3, vitamin C, and malondialdehyde (MDA) were measured in the whole blood. Light therapy contributed to an increase in MCV, HDW, MCVr, CHr and MPV indices, and simultaneously a decrease in the basophil counts, MCHC, RDW and CHCMr indices in both groups of horses (p ≤ 0.05). At the same time reticulocytes fell in older whereas white blood cells and monocytes counts expanded in younger individuals. The treatment also increased the activity of glutathione reductase (GR) and glutathione peroxidase (GPx) in young but decreased the activity of mentioned enzymes in blood plasma of old horses. The total antioxidant status (TAS) of the blood plasma rose progressively, whereas GSH levels declined in all individuals. Moreover, vitamin D3 levels did not change, whereas vitamin C levels gradually decreased during the experiment. The therapy also helped to reduce levels of MDA in the blood plasma, especially of older horses (p ≤ 0.05). In turn, GPx and GR activities as well as MDA levels significantly declined, whereas GSH levels notably elevated in erythrocytes (p ≤ 0.05). Solarium light therapy appears to have a beneficial impact on the morphological parameters and antioxidant status of blood in recreational horses in the winter season. However, the observed results could in part be attributed to the natural physiological adaptation of each individual organism to the treatment.

The effect of near-infrared low-level light on the in vitro quality of platelets during storage

BACKGROUND AND OBJECTIVES

Near-infrared (NIR) light has been successfully applied to improve the quality of mouse platelets during storage. Because it is suspected that the mitochondria contain the primary photon acceptor, we hypothesized that human platelets for transfusion may be affected similarly and could benefit from NIR light treatment.

MATERIALS AND METHODS

The optimal light dose was determined using portions of platelet concentrates (PCs) in PAS-E. A pool-and-split design was used to prepare PCs in PAS-E or plasma (n = 6). On day 1, one unit of both pairs was illuminated with 830 nm light (light-emitting diodes, 15 J/cm2). PCs were stored at 22°C and sampled regularly for analysis. Data were compared with their corresponding controls with a paired two-sided t-test.

RESULTS

Illuminated platelets in PAS-E were less activated with significantly lower CD62P expression (day 8: 10.8 ± 1.8 vs. 12.2 ± 2.6, p < 0.05) and lower Annexin A5 binding (day 8: 11.8 ± 1.9 vs. 13.1 ± 2.4, ns). They produced significantly less lactate resulting in a higher pH (days 6-10). ATP content and mitochondrial membrane potential were not affected. Although these trends were also observed for PCs in plasma, the differences did not reach statistical significance as compared with the control group.

CONCLUSION

Our study demonstrates that the glycolysis rate of human platelets can be modulated through the use of NIR, possibly through mitochondrial aerobic metabolism, but this requires confirmation. If NIR illumination can be further optimized, it may potentially become a useful tool in situations in which glycolysis and platelet activation are exacerbated.

Biochemical Changes in Cardiopulmonary Bypass in Cardiac Surgery: New Insights

Patients undergoing coronary revascularization with extracorporeal circulation or cardiopulmonary bypass (CPB) may develop several biochemical changes in the microcirculation that lead to a systemic inflammatory response. Surgical incision, post-CPB reperfusion injury and blood contact with non-endothelial membranes can activate inflammatory signaling pathways that lead to the production and activation of inflammatory cells, with cytokine production and oxidative stress. This inflammatory storm can cause damage to vital organs, especially the heart, and thus lead to complications in the postoperative period. In addition to the organic pathophysiology during and after the period of exposure to extracorporeal circulation, this review addresses new perspectives for intraoperative treatment and management that may lead to a reduction in this inflammatory storm and thereby improve the prognosis and possibly reduce the mortality of these patients.

Effects of Intravascular Photobiomodulation on Insomnia, Muscle Soreness, and Biochemistry Profiles: An Eight-Year Retrospective Cohort

BACKGROUND

Although cognitive-behavioral therapy is the first-line treatment for insomnia, pharmacotherapy is often prescribed to treat insomnia and related symptoms. In addition, muscle relaxants are commonly prescribed to alleviate muscle soreness when the pain is unbearable. However, pharmacotherapy can lead to numerous side effects. The non-drug strategy intravascular laser irradiation of blood (iPBM) has been advocated to improve pain, wound healing, blood circulation, and blood cell function to relieve insomnia and muscle soreness symptoms. Therefore, we assessed whether iPBM improves blood parameters and compared drug use before and after iPBM therapy.

METHODS

Consecutive patients who received iPBM therapy between January 2013 and August 2021 were reviewed. The associations between laboratory data, pharmacotherapies, and iPBM therapy were retrospectively analyzed. We compared patient characteristics, blood parameters, and drug use within the three months before the first treatment and the three months after the last treatment. We also compared the changes before and after treatment in patients who received ≥10 or 1-9 iPBM treatments.

RESULT

We assessed 183 eligible patients who received iPBM treatment. Of them, 18 patients reported insomnia disturbance, and 128 patients reported pain in any part of their body. After the treatment, HGB and HCT significantly increased after treatment in both the ≥10 and 1-9 iPBM treatment groups (HGB p < 0.001 and p = 0.046; HCT p < 0.001 and p = 0.029, respectively). Pharmacotherapy analysis revealed no significant differences in drug use before and after treatment, though drug use tended to decrease after iPBM.

CONCLUSIONS

iPBM therapy is an efficient, beneficial, and feasible treatment that increases HGB and HCT. While the results of this study do not support the suggestion that iPBM reduces drug use, further larger studies using symptom scales are needed to confirm the changes in insomnia and muscle soreness after iPBM treatment.

Invitro impact of a combination of red and infrared LEDs, infrared laser and magnetic field on biomarkers of oxidative stress and hemolysis of erythrocytes sampled from healthy individuals and diabetes patients

AIMS

Low-intensity infrared laser irradiation with output emissions of the laser and LED for in vitro irradiation of plasma and erythrocyte samples collected from healthy individuals and diabetes mellitus (DM) patients was used in the current study.

METHODS

The generated emission was in the range 0.85-0.89 nm with pulse duration near 130 ns and repetition rates of pulses 50, 150, 600, and 1500 Hz, average power 0, 50, or 100 mW, in the range of 1-9 min for different 30 variants of irradiation. The levels of 2-thiobarbituric-acid reactive substances (TBARS), aldehydic and ketonic derivatives of oxidatively modified proteins (OMP), total antioxidant capacity (TAC), acid-induced resistance of erythrocytes, and activities of the main antioxidant enzymes were assessed in erythrocyte and plasma samples after irradiation.

RESULTS

The low-intensity infrared laser irradiation and low-intensity light emitted by a red LED decreased the lipid peroxidation levels in the erythrocytes of both healthy individuals and DM patients. A statistically significant decrease in TBARS and OMP levels and an increase in the TAC level were observed at the irradiation energy of 34.39 and 68.79 J/cm² for samples collected from both healthy individuals and DM patients. The effects of the irradiation were accompanied by a statistically significant decrease in catalase activity of both healthy individuals and DM patients.

CONCLUSIONS

In many variants of the laser irradiation and low-intensity light emitted by a red LED used in our study, a decrease in the percent of hemolyzed erythrocytes was observed, suggesting that laser therapy protocols should take into account fluencies, frequencies, and wavelengths of the laser before the beginning of treatment, especially in DM patients.

Evaluation of selected hematological, biochemical and oxidative stress parameters in stored canine CPDA-1 whole blood

Blood transfusions are mainly given to intensive care patients; therefore, additional complications that could arise from storage lesions in preserved blood should be avoided. It has been shown that human stored red blood cells are subject to changes that are considered to be a number of interdependent processes involving metabolic disarrangement and oxidative stress. The aim of our study was to determine alterations in selected hematological and biochemical parameters and to assess whether and when oxidative stress is a significant phenomenon in stored dog CPDA-1 whole blood. Ten ½ unit bags of whole blood donated from dogs and preserved with CPDA-1 (anticoagulant containing citrate, phosphate, dextrose and adenine) were stored for 5 weeks. Each week, a 9 ml sample was drawn aseptically to measure hematological parameters, selected metabolites, free hemoglobin content, osmotic fragility, antioxidant enzyme activity, total antioxidant capacity, malondialdehyde concentration and protein carbonyl content.

The results revealed an MCV decrease in the first week of storage and then a gradual increase; osmotic fragility decreased at that time and remained low throughout the study period. Leukodepletion became significant in the fourth week of storage. The free hemoglobin concentration continuously increased, with the greatest changes observed in the last two weeks of storage. The total antioxidant capacity changed in a reverse manner. Superoxide dismutase and glutathione peroxidase activities decreased from week 0 to week 3, and catalase activity tended to decrease over time. The highest malondialdehyde concentrations in blood supernatant were measured in the first week of storage, and the carbonyl concentration increased after 35 days.

Hematological changes and oxidative stress are already present in the first week of storage, resulting in depletion of the antioxidant system and subsequent accumulation of oxidation products as well as erythrocyte hemolysis, which are most pronounced at the end of the storage period.

Effect of Near-Infrared Blood Photobiomodulation on Red Blood Cell Damage from the Extracorporeal Circuit during Hemodialysis In Vitro

The contact of blood with the bioincompatible membranes of the dialyzer, which is part of the extracorporeal circuit during hemodialysis (HD), causes upregulation of various cellular and non-cellular processes, including massive generation and release of reactive oxygen species (ROS), (which is one of the primary causes of anemia in chronic renal failure). We hypothesize that near-infrared (NIR) radiation possesses antioxidant properties and is considered to protect the red blood cell (RBC) membrane by enhancing its resilience to negative pressures. Our experimental setup consisted of an HD machine equipped with a dialyzer with a polyamide membrane; whole bovine blood was examined in vitro in blood-treated circulation. Blood samples were taken at 0, 5, 15, and 30 min during the HD therapy. We also assessed osmotic fragility, hematocrit, hemolysis, and oxidative stress as a concentration of reactive thiobarbituric acid substances (TBARS). Our results have shown that RBC membrane peroxidation increased significantly after 30 min of circulation, whereas the TBARS level in NIR-treated blood remained relatively steady throughout the experiment. The osmotic fragility of NIR-irradiated samples during dialysis was decreased compared to control samples. Our studies confirm that in vitro, blood photobiomodulation using NIR light diminishes oxidative damage during HD and can be considered a simultaneous pretreatment strategy for HD.

Near-infrared photobiomodulation of blood reversibly inhibits platelet reactivity and reduces hemolysis

Photobiomodulation (PBM) in the red/near-infrared (R/NIR) spectral range has become widely recognized due to its anti-inflammatory and cytoprotective potential. We aimed to assess the effects of blood PBM on platelets function and hemolysis in an in vitro setting. Porcine blood samples were separated into four aliquots for this study, one of which served as a control, while the other three were subjected to three different NIR PBM dosages. The platelet count and functions and the plasma free haemoglobin and osmotic fragility of red blood cells were measured during the experiment. The control group had a considerable drop in platelet number, but the NIR exposed samples had more minimal and strictly dose-dependent alterations. These modifications were consistent with ADP and collagen-induced platelet aggregation. Furthermore, red blood cells that had received PBM were more resistant to osmotic stress and less prone to hemolysis, as seen by a slightly lower quantity of plasma free hemoglobin. Here we showed under well-controlled in vitro conditions that PBM reversibly inhibits platelet activation in a dose-dependent manner and reduces hemolysis.

Therapeutic potential of intranasal photobiomodulation therapy for neurological and neuropsychiatric disorders: a narrative review

The application of photobiomodulation therapy (PBMT) for neuronal stimulation is studied in different animal models and in humans, and has shown to improve cerebral metabolic activity and blood flow, and provide neuroprotection via anti-inflammatory and antioxidant pathways. Recently, intranasal PBMT (i-PBMT) has become an attractive and potential method for the treatment of brain conditions. Herein, we provide a summary of different intranasal light delivery approaches including a nostril-based portable method and implanted deep-nasal methods for the effective systemic or direct irradiation of the brain. Nostril-based i-PBMT devices are available, using either lasers or light emitting diodes (LEDs), and can be applied either alone or in combination to transcranial devices (the latter applied directly to the scalp) to treat a wide range of brain conditions such as mild cognitive impairment, Alzheimer's disease, Parkinson's disease, cerebrovascular diseases, depression and anxiety as well as insomnia. Evidence shows that nostril-based i-PBMT improves blood rheology and cerebral blood flow, so that, without needing to puncture blood vessels, i-PBMT may have equivalent results to a peripheral intravenous laser irradiation procedure. Up to now, no studies were conducted to implant PBMT light sources deep within the nose in a clinical setting, but simulation studies suggest that deep-nasal PBMT via cribriform plate and sphenoid sinus might be an effective method to deliver light to the ventromedial part of the prefrontal and orbitofrontal cortex. Home-based i-PBMT, using inexpensive LED applicators, has potential as a novel approach for neurorehabilitation; comparative studies also testing sham, and transcranial PBMT are warranted.

Photobiomodulation Therapy as a Possible New Approach in COVID-19: A Systematic Review

COVID-19 is a viral disease characterized as a pandemic by the World Health Organization in March 2020. Since then, researchers from all over the world have been looking for ways to fight this disease. Many cases of complications arise from insufficient immune responses due to low immunity, with intense release of pro-inflammatory cytokines that can damage the structure of organs such as the lung. Thus, the hypothesis arises that photobiomodulation therapy (PBMT) with the use of a low-level laser (LLLT) may be an ally approach to patients with COVID-19 since it is effective for increasing immunity, helping tissue repair, and reducing pro-inflammatory cytokines. This systematic review was performed with the use of PubMed/MEDLINE, Web of Science, Scopus and Google Scholar databases with the following keywords: "low-level laser therapy OR photobiomodulation therapy AND COVID-19". The inclusion criteria were complete articles published from January 2020 to January 2021 in English. The exclusion criteria were other languages, editorials, reviews, brief communications, letters to the editor, comments, conference abstracts, and articles that did not provide the full text. The bibliographic search found 18 articles in the Pubmed/MEDLINE database, 118 articles on the Web of Science, 23 articles on Scopus, and 853 articles on Google Scholar. Ten articles were included for qualitative synthesis, of which four commentary articles discussed the pathogenesis and the effect of PBMT in COVID-19. Two in vitro and lab experiments showed the effect of PBMT on prevention of thrombosis and positive results in wound healing during viral infection, using the intravascular irradiation (ILIB) associated with Phthalomethyl D. Two case reports showed PBMT improved the respiratory indexes, radiological findings, and inflammatory markers in severe COVID-19 patients. One case series reported the clinical improvement after PBMT on 14 acute COVID-19 patients, rehabilitation on 24 patients, and as a preventive treatment on 70 people. One clinical trial of 30 patients with severe COVID-19 who require invasive mechanical ventilation, showed PBMT-static magnetic field was not statistically different from placebo for the length of stay in the Intensive Care Unit, but improved diaphragm muscle function and ventilation and decreased the inflammatory markers. This review suggests that PBMT may have a positive role in treatment of COVID-19. Still, the necessity for more clinical trials remains in this field and there is not sufficient research evidence regarding the effects of PBMT and COVID-19 disease, and there is a large gap.

Low-Level Laser Therapy for Diabetic Dermopathy in Patients With Type 2 Diabetes: A Placebo-Controlled Pilot Study

Introduction: Diabetic dermopathy (DD) is the most common cutaneous diabetes marker. Few studies have targeted DD using low-level laser therapy (LLLT). This pilot study aimed to evaluate the effect of LLLT on DD in patients with type 2 diabetes (T2D). Methods: 12 patients with T2D (9 men, 3 women) and bilateral DD were enrolled in this placebo controlled pilot study, and their ages ranged 50-65 years. One side was subjected to LLLT, three sessions weekly for one month (LLLT side), while the other side received the same treatment protocol with a laser device switched off as a placebo (placebo side). All patients were instructed to receive skincare for both sides, such as debridement, antibiotic creams, and dressings with betadine solution. The diameter of DD lesion and the cutaneous blood flow of the knees and ankles sites were assessed before and after one month at the end of the intervention. Results: At the baseline, no significant differences existed between LLLT and placebo sides in the DD and skin blood flow at the knee and ankle sites (P >0.05). Post-intervention, a significant improvement occurred in DD diameter and the skin blood flow of the knee and ankle sites in the LLLT side (P <0.05), while the placebo side showed a significant improvement only in DD diameter (P <0.05) and non-significant changes in skin blood flow (P >0.05). Comparing both sides, all measures significantly favored LLLT. Conclusion: The findings of this study indicate that LLLT has beneficial effects on decreasing DD in T2D patients. Also, it was approved that the short term of LLLT is a safe modality to control DD in T2D patients.

Effect of Low-Level Laser on Some Metals Related to Redox State and Histological Alterations in the Liver and Kidney of Irradiated Rats

Low-level laser therapy (LLLT) is a type of medicine that uses laser light at low levels to activate the cellular chromophores and the initiation of cellular signaling. This study aimed to evaluate the photomodulation effect of LLL against ionizing radiation (IR)-induced metal disorders related to redox state in the liver and kidney of male rats. Rats were divided into 4 groups (control, LLLT, IR (7Gy), IR+LLLT). The results showed that LLLT 870 nm one time for 3 days post-irradiation revealed redistribution of iron (Fe), copper (Cu), zinc (Zn),calcium (Ca), magnesium (Mg), manganese (Mn), and selenium (Se) in the liver and kidney tissues. Moreover, LLLT attenuated the oxidative stress manifested by a marked reduction of hydrogen peroxide (H₂O₂), 4-hydroxynonenal (4-HNE), total oxidant state (TOS), and oxidative stress index (OSI) associated with a significant increase in total antioxidant status (TAS), glutathione (GSH) content, and glutathione peroxide (GPx), glutathione reductase (GRx), superoxide dismutase(SOD), and catalase (CAT) activities. Moreover, LLLT displayed an increase in glutathione-S-transferase (GSH-T) and ceruloplasmin activities and a decrease in the activity of gamma-glutamyl transferase (γ-GT). Besides, LLLT significantly attenuated the histological changes in the liver and kidney tissues, denoted by a reduction in the necrotic and degenerative changes of hepatocytes and an improvement in the corpuscles and tubules of the kidney. In conclusion, LLLT could be used as an adjuvant treatment post-exposure to radiation, while it is not beneficial to use it on the normal tissue.

The effect of red-to-near-infrared (R/NIR) irradiation on inflammatory processes

Introduction: Near-infrared (NIR) and red-to-near-infrared (R/NIR) radiation are increasingly applied for therapeutic use. R/NIR-employing therapies aim to stimulate healing, prevent tissue necrosis, increase mitochondrial function, and improve blood flow and tissue oxygenation. The wide range of applications of this radiation raises questions concerning the effects of R/NIR on the immune system. Methods: In this review, we discuss the potential effects of exposure to R/NIR light on immune cells in the context of physical parameters of light. Discussion: The effects that R/NIR may induce in immune cells typically involve the production of reactive oxygen species (ROS), nitrogen oxide (NO), or interleukins. Production of ROS after exposure to R/NIR can either be inhibited or to some extent increased, which suggests that detailed conditions of experiments, such as the spectrum of radiation, irradiance, exposure time, determine the outcome of the treatment. However, a wide range of immune cell studies have demonstrated that exposure to R/NIR most often has an anti-inflammatory effect. Finally, photobiomodulation molecular mechanism with particular attention to the role of interfacial water structure changes for cell physiology and regulation of the inflammatory process was described. Conclusions: Optimization of light parameters allows R/NIR to act as an anti-inflammatory agent in a wide range of medical applications.

Photobiomodulation for Alzheimer's Disease: Has the Light Dawned?

Next to cancer, Alzheimer's disease (AD) and dementia is probably the most worrying health problem facing the Western world today. A large number of clinical trials have failed to show any benefit of the tested drugs in stabilizing or reversing the steady decline in cognitive function that is suffered by dementia patients. Although the pathological features of AD consisting of beta-amyloid plaques and tau tangles are well established, considerable debate exists concerning the genetic or lifestyle factors that predispose individuals to developing dementia. Photobiomodulation (PBM) describes the therapeutic use of red or near-infrared light to stimulate healing, relieve pain and inflammation, and prevent tissue from dying. In recent years PBM has been applied for a diverse range of brain disorders, frequently applied in a non-invasive manner by shining light on the head (transcranial PBM). The present review discusses the mechanisms of action of tPBM in the brain, and summarizes studies that have used tPBM to treat animal models of AD. The results of a limited number of clinical trials that have used tPBM to treat patients with AD and dementia are discussed.

Oxidative Stress and Neonatal Respiratory Extracorporeal Membrane Oxygenation

Oxidative stress is a frequent condition in critically ill patients, especially if exposed to extracorporeal circulation, and it is associated with worse outcomes and increased mortality. The inflammation triggered by the contact of blood with a non-endogenous surface, the use of high volumes of packed red blood cells and platelets transfusion, the risk of hyperoxia and the impairment of antioxidation systems contribute to the increase of reactive oxygen species and the imbalance of the redox system. This is responsible for the increased production of superoxide anion, hydrogen peroxide, hydroxyl radicals, and peroxynitrite resulting in increased lipid peroxidation, protein oxidation, and DNA damage. The understanding of the pathophysiologic mechanisms leading to redox imbalance would pave the way for the future development of preventive approaches. This review provides an overview of the clinical impact of the oxidative stress during neonatal extracorporeal support and concludes with a brief perspective on the current antioxidant strategies, with the aim to focus on the potential oxidative stress-mediated cell damage that has been implicated in both short and long-term outcomes.

Low-level light therapy reduces platelet destruction during extracorporeal circulation

Extracorporeal circulation causes many deleterious effects on blood cells. Low-level light therapy (LLLT) in the red/near-infrared spectral range is known for its cytoprotective properties but its use during cardiopulmonary bypass (CPB) has not yet been studied. We aimed to assess whether LLLT protects platelets during CPB. 24 pigs were connected to 1-hour-CPB and observed for the next 23 hours. In 12 animals, blood circulating through the oxygenator was treated with LLLT. Platelet count and function were monitored throughout the experiment. The decrease in platelet count was greater in the control group, especially during CPB and after 24 hours. In LLLT group CD62P expression remained quite stable up to the 12^th hour of the experiment, whereas in the control group it continuously decreased till the end of observation. Platelets in the control group were more prone to aggregation in the postoperative period than at the beginning of the experiment, whereas platelets in the LLLT group aggregated similarly or less intense. Limitation of platelet loss, pattern of aggregation and CD62P expression suggest that LLLT may stabilize platelet function during CPB and diminish the negative effects associated with the interaction of cells with an artificial surface.