How long does the biological effect of a red light-emitting diode last on adipose-derived mesenchymal stem cells?

This research investigated the duration of the influence of red light-emitting diodes (LED, 630 nm; output power: 2452.5 mW; laser beam: 163.5 cm2; irradiance: 15 mW/cm2; radiant exposure: 4 J/cm2) on different periods after irradiation (6, 12, 24, 48, and 72 h) on adipose-derived mesenchymal stem cells' (AdMSCs) metabolism and paracrine factors. AdMSCs were irradiated three times every 48 h. Twenty-four hours after the last irradiation, there was a higher MTT absorbance, followed by a decrease after 48 h. The cells' secretome showed increased levels of IL-6 and VEGF after 12 and 24 h, but this was reversed after 48 h. Additionally, LED irradiation resulted in higher levels of nitrite and did not affect oxidative stress markers. LED irradiation had significant effects on AdMSCs after 24 h compared to other groups and its control group.

Light-emitting Diode Can Enhance the Metabolism and Paracrine Action of Mesenchymal Stem Cells.

This study investigated the influence of red light-emitting diodes (LED, 630 nm) on different irradiation parameters and the number of applications on mesenchymal stem cells derived from adipose tissue (AdMSCs) metabolism and paracrine factors. The AdMSCs were irradiated with a LEDbox device (output power: 2452.5 mW; laser beam: 163.5 cm2 ; irradiance: 15 mW cm-2 ) using radiant exposures of 0.5, 2, and 4 J cm-2 , respectively. AdMSCs were irradiated once or every 48 h up to three irradiations. All molecular analyses were performed 24 h after the last irradiation. LED did not induce changes in cell count, DNA damage, and oxidative stress. A significant repercussion of the LED has been noticed after three irradiations with 4 J cm-2 . AdMSCs had higher levels of IL-6, IGF-1, and NOx index. A higher ATP content and MMT/Resazurin assay were identified in AdMSCs irradiated three times with 4 J cm-2 . Mitochondrial basal respiration, maximal respiration and proton leak under metabolic stress were reduced by 0.5 and 2 J cm-2 irradiations. These data showed that three LED irradiations with 4 J cm-2 may be a suitable parameter for future AdMSCs therapy because of its improved metabolic activity, ATP content, and IL-6, IGF-1, and nitric oxide secretion.

A common oral pathogen Porphyromonas gingivalis induces myocarditis in rats.

AIM: To evaluate whether Porphyromonas gingivalis (P. gingivalis) inoculation could induce cardiac remodelling in rats. MATERIALS AND METHODS: The study was conducted on 33 Wistar rats, which were distributed in the following experimental groups: not inoculated; inoculated with 1 × 108 CFU/ml of bacteria; inoculated with 3 × 108 CFU/ml of bacteria. The animals were inoculated at baseline and on the 15th day of follow-up. Blood collection was performed at baseline and 60 min after each inoculation. At 29 days, the animals were subjected to echocardiography and at 30 days to haemodynamic studies before sacrificing them. RESULTS: Impact of the bacteria was more evident in rats that received higher P. gingivalis concentration. Thus, 3 × 108 CFU/ml of bacteria increased the rectal temperature and water content in the lung as well as myocardial necrosis and fibrosis. P. gingivalis induced the intensification of DNA fragmentation and increased the levels of malondialdehyde, oxidized proteins, and macrophage expression in the myocardium. These findings were associated with lower LV isovolumetric relaxation time, +dP/dt, -dP/dt, and higher end-diastolic pressure. CONCLUSIONS: P. gingivalis bacteraemia is significantly associated with adverse cardiac remodelling and may play a biological role in the genesis of heart failure.

Post-resistance exercise photobiomodulation therapy has a more effective antioxidant effect than pre-application on muscle oxidative stress.

This study evaluated the effect of photobiomodulation therapy (PBMt) before or after a high-intensity resistance exercise (RE) session on muscle oxidative stress. Female Wistar rats were assigned to one of the following groups: Sham (non-exercised, undergoing placebo-PBMt); NLRE (exercised, undergoing placebo-PBMt); PBMt + RE (pre-exercise PBMt); RE + PBMt (post-exercise PBMt). The RE comprised four climbs bearing the maximum load with a 2 min rest between each climb. An 830-nm aluminum gallium arsenide diode laser (100 mW; 0.028 cm2; 3.57 mW/cm2; 142.8 J/cm2; 4 J; Photon Laser III, DMC, São Paulo, Brazil) was applied 60 s before or after RE in gastrocnemius muscles. Analyses were performed at 24 h after RE: lipoperoxidation using malondialdehyde (MDA) and protein oxidation (OP) on Western blot. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activity were spectrophotometrically assessed. Nitric oxide (NO) level was determined by the Griess reaction. The MDA and OP levels were significantly higher in the NLRE group. Increased OP was prevented in all PBMt groups; however, increased MDA was prevented only in the RE + PBMT group. The RE + PBMt group had higher SOD activity compared to all other groups. A higher GPx activity was observed only in the PBMT + RE compared to Sham group, and CAT activity was reduced by RE, without PBMt effect. NO levels were unchanged with RE or PBMt. Therefore, PBMt application after a RE section has a more potent antioxidant effect than previous PBMt. Rats submitted to post-RE PBMt illustrated prevention of increased lipoperoxidation and protein oxidation as well as increased SOD activity. The photobiomodulation can attenuate oxidative stress induced by resistance exercise. A more evident benefit shows to be obtained with the application after exercise, in which it has increased the activity of superoxide dismustase.

Enhancing the Therapeutic Potential of Mesenchymal Stem Cells with Light-Emitting Diode: Implications and Molecular Mechanisms.

This study evaluated the effects of light-emitting diode (LED) on mesenchymal stem cells (MSCs). An electronic search was conducted in PubMed/MEDLINE, Scopus, and Web of Science database for articles published from 1980 to February 2020. Ten articles met the search criteria and were included in this review. The risk of bias was evaluated to report quality, safety, and environmental standards. MSCs were derived from adipose tissue, bone marrow, dental pulp, gingiva, and umbilical cord. Protocols for cellular irradiation used red and blue light spectrum with variations of the parameters. The LED has been shown to induce greater cellular viability, proliferation, differentiation, and secretion of growth factors. The set of information available leads to proposing a complex signaling cascade for the action of photobiomodulation, including angiogenic factors, singlet oxygen, mitogen-activated protein kinase/extracellular signal-regulated protein kinase, Janus kinase/signal transducer, and reactive oxygen species. In conclusion, although our results suggest that LED can boost MSCs, a nonuniformity in the experimental protocol, bias, and the limited number of studies reduces the power of systematic review. Further research is essential to find the optimal LED irradiation parameters to boost MSCs function and evaluate its impact in the clinical setting.

Low-level laser therapy prevents muscle oxidative stress in rats subjected to high-intensity resistance exercise in a dose-dependent manner.

High-intensity resistance exercise (RE) increases oxidative stress leading to deleterious effects on muscle performance and recovery. The aim of this study was to assess the effect of applying low-level laser therapy (LLLT) prior to a RE session on muscle oxidative stress and to determine the possible influence of the dosimetric parameters. Female Wistar rats were assigned to non-LLLT (Ctr: non-exercised control; RNI: RE) or LLLT groups subjected to RE (radiant energy: 4 J, 8 J, and 12 J, respectively). RE consisted of four maximum load climbs. An 830-nm DMC Lase Photon III was used to irradiate three points in gastrocnemius muscles (two limbs) before exercise. Animals were euthanized after 60 min after the end of the exercise, and muscle tissue was removed for analysis of oxidative stress markers. All doses resulted in the prevention of increased lipoperoxidation; however, LLLT prevented protein oxidation only in rats that were pretreated with 8 J and 12 J of energy by LLLT. RE and LLLT did not change catalase activity. However, RE resulted in lower superoxide dismutase activity, and the opposite was observed in the LLLT group. These data indicate that LLLT prior to RE can prevent muscle oxidative stress. This study is the first to evaluate the impact of dosimetric LLLT parameters on the oxidative stress induced by RE, wherein both 8 J and 12 J of energy afforded significant protection.

Photobiomodulation therapy combined with carvedilol attenuates post-infarction heart failure by suppressing excessive inflammation and oxidative stress in rats.

The post-myocardial infarction heart failure (HF) still carries a huge burden since current therapy is unsuccessful to abrogate poor prognosis. Thus, new approaches are needed, and photobiomodulation therapy (PBMt) may be a way. However, it is not known whether PBMt added to a standard HF therapy provides additional improvement in cardiac remodeling in infarcted rats. This study sought to determine the combined carvedilol-drug and PBMt with low-level laser therapy value in HF. Rats with large infarcts were treated for 30 days. The functional fitness was evaluated using a motorized treadmill. Echocardiography and hemodynamic measurements were used for functional evaluations of left ventricular (LV). ELISA, Western blot and biochemical assays were used to evaluate inflammation and oxidative stress in the myocardium. Carvedilol and PBMt had a similar action in normalizing pulmonary congestion and LV end-diastolic pressure, attenuating LV dilation, and improving LV systolic function. Moreover, the application of PBMt to carvedilol-treated rats inhibited myocardial hypertrophy and improved +dP/dt of LV. PBMt alone prevented inflammation with a superior effect than carvedilol. Carvedilol and PBMt normalized 4-hydroxynonenal (a lipoperoxidation marker) levels in the myocardium. However, importantly, the addition of PBMt to carvedilol attenuated oxidized protein content and triggered a high activity of the anti-oxidant catalase enzyme. In conclusion, these data show that the use of PBMt plus carvedilol therapy results in a significant additional improvement in HF in a rat model of myocardial infarction. These beneficial effects were observed to be due, at least in part, to decreased myocardial inflammation and oxidative stress.

Low-level laser therapy alleviates the deleterious effect of doxorubicin on rat adipose tissue-derived mesenchymal stem cells.

Cancer is a leading cause of death worldwide, and doxorubicin (DOX) has become one of the most commonly prescribed drugs. Stem cell (SC) therapy is proving to be a promising strategy to alleviate DOX adverse effects on non-cancerous cells. However, the drug also has a toxic action on SCs, reducing the efficiency of cell therapy from a preventive view. The present study shows that the DOX toxicity in mesenchymal SCs (MSCs) can be partially overcome by low-level laser irradiation (LLLI). To achieve this, we applied the low-level red laser (wavelength: 660 nm; output power: 30 mW; laser beam: 0.028 cm2; irradiation: 1.07 mW/cm2; Ga-Al-As Photon Laser III, DMC, São Paulo, Brazil) in rat adipose tissue-derived MSCs before their exposure to different DOX concentrations. Results revealed that the DOX reduced the viability and adenosine triphosphate level of MSCs. These findings were followed by significantly increased apoptosis as well as oxidative stress in the MSCs. Interestingly, LLLI at the dose of 0.2 J alleviated the effects of DOX on cell viability and apoptosis, and inhibited oxidative stress in the MSCs. In summary, this study provides a crucial step toward the future application of LLLI as a protective approach against DOX-induced toxicity in MSCs, particularly cell death. This study also lays the groundwork for further investigation into the role of oxidative stress and inflammation as an instructive milieu for cell protection.

Predicted Equation for VO2 Based on a 20-Meter Multistage Shuttle Run Test for Children.

This study compared maximum oxygen consumption (VO2max) on a 20-meter multistage shuttle run test (20-Srt) with a cardiopulmonary exercise test (CPET) to determine a VO2max prediction equation for a 20-Srt in children aged 6-10 years. Eighty healthy children performed the CPET on a treadmill, while the 20-Srt took place on a sports court. Heart rate (HR) was measured and the expired gases were continuously measured breath-by-breath using a portable gas analyzer. The VO2max was lower (p<0.05) in CPET than 20-Srt for all, female, and male participants, respectively (46.3±7.9 vs. 48.7±4.6; 42.7±7.8 vs. 46.7±4.8; 49.3±6.8 vs. 50.4±3.9, mL·kg-1·min-1). The standard error estimates were between 3.0 and 3.6 and considered as not clinically relevant if less than 5 mL·kg-1·min-1. The intraclass correlation coefficient between the VO2 in CPET and in 20-Srt was 0.74 (CI95% 0.55-0.84) and considered moderately reliable. The linear multiple regression excluded sex, body mass index and fat-free mass and retained the maximum speed and age in the predictive equation. The 20-Srt estimates the VO2max with moderate reliability and the predictive equation was VO2maxpred=4.302+(maximum speed*5.613)-(age*1.523) for children aged 6-10 years.