Effect of laser therapy on immune cells infiltrate after excisional wounds in diabetic rats

Photobiomodulation activates undifferentiated macrophages and promotes M1/M2 macrophage polarization via PI3K/AKT/mTOR signaling pathway

Macrophages are the main mediators of the inflammatory response and play a major role in the onset and maintenance of periodontitis. Studies revealed that photobiomodulation (PBM) can change the polarization state of macrophages and inflammation reduction, although the cellular mechanisms are not fully elucidated. Here, the present study explored the effect of PBM (980 nm) on undifferentiated and M1-type macrophages and the underlying mechanism. RAW264.7 cells were exposed to laser irradiation under different laser parameters (0.5, 5.0, and 10.0 J/cm²) with or without LY294002 (an inhibitor of PI3K pathway). Then, confocal laser microscopy was used to observe cell differentiation; qPCR was performed to examine the gene expression and western blotting was used to detect the protein in the PI3K/AKT/mTOR pathway and activated macrophage markers. The obtained results revealed that 980 nm PBM increased the mRNA expression of iNOS, Il-10, Arg1, and Il-12 along with the inflammatory cytokines Tnfα, IL-1β, and Il-6 in M0-type macrophages in dose-dependent manner. More interestingly, PBM at 5 J/cm² decreased the mRNA expression of iNOS, Il-12, Tnfα, IL-1β, and Il-6 and increased the expression of Arg1 and Il-10 by M1-type macrophages, along with the elevated expression of phosphorylation of AKT and mTOR. Moreover, PBM-induced M1-type macrophage polarization was significantly attenuated via LY294002 treatment. These suggest that 980 nm PBM could activate M0-type macrophages and increase M2/M1 ratio via the PI3K/AKT/mTOR pathway.

Impact of photobiomodulation on macrophages and their polarization during diabetic wound healing: a systematic review

This review aims to providing essential information and the current knowledge about the potential role of macrophages, especially their M2 subtypes in different diabetic wounds both in clinical and pre-clinical models under the influence of photobiomodulation (PBM). The long-term goal is to advance the macrophage-based therapies to accelerate healing of diabetic foot ulcers. We reviewed all databases provided by PubMed, Google Scholar, Scopus, Web of Science, and Cochrane precisely from their dates of inception to 25/10/2021. The keywords of Diabetes mellitus diseases, wound healing, macrophage, and photobiomodulation or low-level laser therapy were used in this systematic review.A total of 438 articles were initially identified in pubmed.ncbi.nlm.nih.gov (15 articles), Google scholar (398 articles), Scopus (18 articles), and Web of Science (7 articles). Four hundred sixteen articles that remained after duplicate studies (22 articles) were excluded. After screening abstracts and full texts, 14 articles were included in our analysis. Among them, 4 articles were about the effect of PBM on macrophages in type 2 diabetes and also found 10 articles about the impact of PBM on macrophages in type 1 diabetes. The obtained data from most of the reviewed studies affirmed that the PBM alone or combined with other agents (e.g., stem cells) could moderate the inflammatory response and accelerate the wound healing process in pre-clinical diabetic wound models. However, only very few studies conducted the detailed functions of polarized macrophages and M2 subtypes in wound healing of diabetic models under the influence of PBM. Further pre-clinical and clinical investigations are still needed to investigate the role of M2 macrophages, especially its M2c subtype, in the healing processes of diabetic foot ulcers in clinical and preclinical settings.

Photobiomodulation isolated or associated with adipose-derived stem cells allograft improves inflammatory and oxidative parameters in the delayed-healing wound in streptozotocin-induced diabetic rats

The single and associated impressions of photobiomodulation (PBM) and adipose-derived stem cells (ADS) on stereological parameters (SP), and gene expression (GE) of some antioxidant and oxidative stressors of repairing injured skin at inflammation and proliferation steps (days 4 and 8) of a delayed healing, ischemic, and infected wound model (DHIIWM) were examined in type one diabetic (DM1) rats. DM1 was induced by administration of streptozotocin (40 mg/kg) in 48 rats. The DHIIWM was infected by methicillin-resistant Staphylococcus aureus (MRSA). The study comprised 4 groups (each, n = 6): Group 1 was the control group (CG). Group 2 received allograft human (h) ADSs transplanted into the wound. In group 3, PBM (890 nm, 80 Hz, 0.2 J/cm²) was emitted, and in group 4, a combination of PBM+ADS was used. At both studied time points, PBM+ADS, PBM, and ADS significantly decreased inflammatory cell count (p < 0.05) and increased granulation tissue formation compared to CG (p < 0.05). Similarly, there were lower inflammatory cells, as well as higher granulation tissue in the PBM+ADS compared to those of alone PBM and ADS (all, p < 0.001). At both studied time points, the GE of catalase (CAT) and superoxide dismutase (SOD) was remarkably higher in all treatment groups than in CG (p < 0.05). Concomitantly, the outcomes of the PBM+ADS group were higher than the single effects of PBM and ADS (p < 0.05). On day 8, the GE of NADPH oxidase (NOX) 1 and NOX4 was substantially less in the PBM+ADS than in the other groups (p < 0.05). PBM+ADS, PBM, and ADS treatments significantly accelerated the inflammatory and proliferative stages of wound healing in a DIIWHM with MRSA in DM1 rats by decreasing the inflammatory response, and NOX1 and 4 as well; and also increasing granulation tissue formation and SOD and CAT. The associated treatment of PBM+ADS was more effective than the individual impacts of alone PBM and ADS because of the additive anti-inflammatory and proliferative effects of PBM plus ADS treatments.

Assessment of wound area reduction on chronic wounds in dogs with photobiomodulation therapy: A randomized controlled clinical trial

Background and Aim

Chronic wounds are a clinical problem and require intensive standard wound care. However, this is sometimes insufficient to promote healing. Photobiomodulation therapy (PBMT) can be used as an adjunctive therapy to improve wound healing. Various PBMT devices with different properties and parameter settings as well as different animal species can influence a variety of clinical outcomes. This study aims to assess the use of 830 nm PBMT or simultaneous superpulsed and multiple wavelengths (SPMW; 660, 875, and 905 nm) PBMT on chronic wounds in client-owned dogs.

Materials and Methods

This study included 21 client-owned dogs with chronic wounds allocated into three groups: (1) Control group (C) treated with irrigated saline and without PBMT (n=7); (2) L1 group treated with irrigated saline together with the radiation of 830 nm PBMT (n=7); and (3) L2 group treated with irrigated saline together with the radiation of simultaneous SPMW-PBMT (n=7). Wound healing was assessed on the basis of wound size reduction as a percentage of wound area every 2^nd day for 15 days using image analysis software (ImageJ software^®, National Institutes of Health, Rockville, Maryland, USA).

Results

A significant difference in the percentage of wound area reduction was noted between the C and PBMT groups (L1 and L2; p<0.05). The average percentages of wound area reduction at the end of the study (15 days) were 42.39±20.58, 56.98±24.82, and 61.81±27.18 in the C, L1, and L2 groups, respectively. A steady decrease in wound size was noted in both PBMT and non-PBMT groups, and coefficients were 7.77, 8.95, and 10.01 in the C, L1, and L2 groups, respectively. The percentage of wound area reduction was found to be significantly different between the PBMT and non-BPMT groups on day 7 (p<0.05).

Conclusion

Based on the results of the current study, using either 830 nm PBMT or simultaneous SPMW-PBMT can accelerate the chronic wound healing process in dogs with a significant reduction in wound area. Therefore, it can be used as an adjunctive therapy to improve wound healing in dogs with reduced treatment duration.

Effects of the phenotypic polarization state of human leukocytes on the optical absorbance spectrum

This study evaluated the optical absorbance spectrum of human monocytes, neutrophils and lymphocytes polarized, or not, to the inflammatory or immunoregulatory phenotypes. Peripheral human blood leukocytes were isolated and polarized (10 ng/mL) with LPS or IL-4 + LPS for 2 hours. After polarization, cells were washed and incubated for an additional 24 hours (monocytes and lymphocytes) or 12 hours (neutrophils). Next, cells were collected to evaluate the optical absorbance spectrum. The three types of leukocytes exhibited absorbance in the region from 450 to 900 nm, with greater absorbance at wavelengths lower than 570 nm. Lymphocytes had a second region of greater absorbance between 770 and 900 nm. Inflammatory monocytes and lymphocytes showed increased absorbance of blue, green and yellow wavelengths (monocytes), as well as red and infrared wavelengths (monocytes and lymphocytes). Immunoregulatory polarization altered the absorbance of monocytes and lymphocytes very little. Neutrophils treated with LPS or LPS + IL-4 exhibited lower absorbance at wavelengths higher than 575 nm compared to untreated cells. The present findings showed that leukocytes exhibit greater absorbance in regions of the spectrum that have not been much used in photobiomodulation (PBM), and the polarization of these cells can affect their capacity to absorb light. Taken together, these results suggest new perspectives in the use of PBM in the clinical setting depending on the wavelengths and the stage of the inflammatory process.

Development and Characterization of Squalene-Loaded Topical Agar-Based Emulgel Scaffold: Wound Healing Potential in Full-Thickness Burn Model

Full-thickness burns pose a major challenge for clinicians to handle because of their restricted self-healing ability. Even though several approaches have been implemented for repairing these burnt skin tissue defects, all of them had unsatisfactory outcomes. Moreover, during recent years, skin tissue engineering techniques have emerged as a promising approach to improve skin tissue regeneration and overcome the shortcomings of the traditional approaches. Although previous literatures report the wound healing effects of the squalene oil, in the current study, for the first time, we developed a squalene-loaded emulgel-based scaffold as a novel approach for potential skin regeneration. This squalene-loaded agar-based emulgel scaffold was fabricated by using physical cross-linking technique using lecithin as an emulsifier. Characterization studies such as X-ray diffraction, Fourier-transform infrared spectroscopy, and field emission scanning electron microscopy revealed the amorphous nature, chemical interactions, and cross-linked capabilities of the developed emulgel scaffold. The squalene-loaded emulgel scaffold showed excellent wound contraction when compared with the agar gel and negative control. In case of the histopathology and recent immunohistochemistry findings, it was clearly evidenced that squalene-loaded emulgel promoted faster rate of the revascularization and macrophage polarization in order to enhance the burn wound healing. Moreover, the findings also revealed that the incorporation of squalene oil into the formulation enhances collagen deposition and accelerates the burnt skin tissue regeneration process. Finally, we conclude that the squalene-loaded emulgel scaffold could be an effective formulation used in the treatment of the burnt skin tissue defects.

Combined effects of metformin and photobiomodulation improve the proliferation phase of wound healing in type 2 diabetic rats

We determined the impact of Photobiomodulation (PBM) and metformin administration alone and combined on the inflammation and proliferation steps of wound healing of incisions in type two diabetes mellitus (T2DM) rats. 40 rats were divided into 4 groups (n = 10 each group). A non-genetic model of T2DM was induced in all rats, and an incision was made on each rat. There were 4 groups as follows: Group 1 was control group. Group 2 received PBM alone (890 nm, 80 Hz, 0.324 J/cm², daily). Group 3 received metformin alone (50 mg/kg, i.p., daily) and the fourth group received combination of PBM + metformin. At inflammation (day 4) and proliferation (day 7) steps, tensiometerical, stereological, and immunohistochemical examinations were performed. PBM and PBM + metformin treatments significantly increased wound strength at inflammation and proliferation steps of wound healing respectively. PBM, metformin, and PBM + metformin groups significantly decreased inflammatory cells at inflammation and proliferation steps of wound healing. PBM, metformin, and PBM + metformin groups significantly improved granulation tissue formation by increasing fibroblasts, and new blood vessel formation at inflammation and proliferation steps of wound healing. Metformin significantly increased M2 macrophages than other treatment groups at inflammation and proliferation steps of wound healing. Simultaneously, PBM significantly decreased M2 macrophages than control group. We concluded PBM and PBM + metformin treatments significantly hastened repair at the inflammation and proliferation steps of repairing skin injury in a non-genetic model of T2 DM. PBM + metformin showed a synergistic impact. There were not a positive relation between M2 macrophage number and wound strength in the studied groups. The details of the molecular mechanisms of PBM, and PBM + metformin treatments of repairing wounds in animals, and treatment of DFUs of patients with T2 DM should be elucidated by further research.

Efficacy of Biophysical Energies on Healing of Diabetic Skin Wounds in Cell Studies and Animal Experimental Models: A Systematic Review

We have systematically assessed published cell studies and animal experimental reports on the efficacy of selected biophysical energies (BPEs) in the treatment of diabetic foot ulcers. These BPEs include electrical stimulation (ES), pulsed electromagnetic field (PEMF), extracorporeal shockwave (ECSW), photo energies and ultrasound (US). Databases searched included CINAHL, MEDLINE and PubMed from 1966 to 2018. Studies reviewed include animal and cell studies on treatment with BPEs compared with sham, control or other BPEs. Information regarding the objective measures of tissue healing and data was extracted. Eighty-two studies were eventually selected for the critical appraisal: five on PEMF, four each on ES and ECSW, sixty-six for photo energies, and three about US. Based on the percentage of original wound size affected by the BPEs, both PEMF and low-level laser therapy (LLL) demonstrated a significant clinical benefit compared to the control or sham treatment, whereas the effect of US did not reveal a significance. Our results indicate potential benefits of selected BPEs in diabetic wound management. However, due to the heterogeneity of the current clinical trials, comprehensive studies using well-designed trials are warranted to confirm the results.

Improvement in infected wound healing in type 1 diabetic rat by the synergistic effect of photobiomodulation therapy and conditioned medium

We investigated the effects of photobiomodulation therapy (PBMT) and conditioned medium (CM) of human bone marrow mesenchymal stem cells (hBM-MSC) individually and/or in combination on the stereological parameters and the expression of basic fibroblast growth factor (bFGF), hypoxia-inducible factor (HIF-1α), and stromal cell-derived factor-1α (SDF-1α) in a wound model infected with methicillin-resistant Staphylococcus aureus (MRSA) in diabetic rats. CM was provided by culturing hBM-MSCs. Type 1 diabetes mellitus (T1DM) was induced in 72 rats, divided into four groups, harboring 18 rats each: group 1 served as a control group, group 2 received PBMT, group 3 received CM, and group 4 received CM + PBMT. On days 4, 7, and 15, six animals from each group were euthanized and the skin samples were separated for stereology examination and gene expression analysis by real-time polymerase chain reaction. In the CM + PBMT, CM, and PBMT groups, significant decreases were induced in the number of neutrophils (1460 ± 93, 1854 ± 138, 1719 ± 248) and macrophages (539 ± 69, 804 ± 63, 912 ± 41), and significant increases in the number of fibroblasts (1073 ± 116, 836 ± 75, 912 ± 41) and angiogenesis (15 230 ± 516, 13 318 ± 1116, 14 041 ± 867), compared with those of the control group (2690 ± 371, 1139 ± 145, 566 ± 90, 12 585 ± 1219). Interestingly, the findings of the stereological examination in the CM + PBMT group were statistically more significant than those in the other groups. In the PBMT group, in most cases, the expression of bFGF, HIF-1α, and SDF-1α, on day 4 (27.7 ± 0.14, 28.8 ± 0.52, 27.5 ± 0.54) and day 7 (26.8 ± 1.4, 29.6 ± 1.4, 28.3 ± 1.2) were more significant than those in the control (day 4, 19.3 ± 0.42, 25.5 ± 0.08, 22.6 ± 0.04; day 7, 22.3 ± 0.22, 28.3 ± 0.59, 24.3 ± 0.19) and other treatment groups. The application of PBMT + CM induced anti-inflammatory and angiogenic activities, and hastened wound healing process in a T1 DM model of MRSA infected wound.

The N-butyl alcohol extract from Hibiscus rosa-sinensis L. flowers enhances healing potential on rat excisional wounds

ETHNO-PHARMACOLOGICAL RELEVANCE

Hibiscus rosa-sinensis L. (HRS), a folk medicine named Zhujin in China, possess anti-tumor, antioxidant, antibacterial, low density lipoprotein oxidation prevention and macrophage death prevention effects. The leaves and red flowers of HRS have been traditionally used to treat with furuncle and ulceration.

AIM OF THE STUDY

To investigate the efficacy and possible mechanism of the N-butyl alcohol extract of HRS (NHRS) red flowers in wound healing by analyzing the collagen fiber deposition, angiogenic activity and macrophages action of the NHRS.

MATERIALS AND METHODS

In an excisional wound healing model in rats, different concentrations of NHRS, or recombinant bovine basic fibroblast growth factor (rbFGF), were respectively applied twice daily for 9 days. Histopathology was assessed on day 9 via hematoxylin and eosin (HE) and Masson's trichrome (MT) staining, and immunohistochemistry for vascular endothelial growth factor (VEGF), transforming growth factor-β1 (TGF-β1) and CD68. Immunomodulation by NHRS was evaluated by a carbon clearance test in mice.

RESULTS

Wound healing post-surgery was greater in the rbFGF-control, NHRS-M and MHRS-H groups than in the model and 5% dimethylsulfoxide (DMSO)-control groups after the third day. By the sixth day the wound contraction of NHRS-M and MHRS-H groups was much higher than the rbFGF-control group. HE and MT staining revealed that epithelialization, fibroblast distribution, collagen deposition of NHRS-M- and NHRS-H-control groups were significantly higher than the model group. Moreover, immunohistochemistry showed more intense staining of VEGF, TGF-β1 and CD68 in the rbFGF- and NHRS-control groups, compared to that in model and 5% DMSO-control groups. The clearance and phagocytic indices of NHRS-M- and NHRS-H-control groups were significantly higher than that of the carboxyl methyl cellulose (CMC) group in mice.

CONCLUSION

NHRS accelerates wound repair via enhancing the macrophages activity, accelerating angiogenesis and collagen fiber deposition response mediated by VEGF and TGF-β1.