Improvement of bone repair in diabetic rats subjected to ƛ780 nm low-level laser therapy

Diabetes in spotlight: current knowledge and perspectives of photobiomodulation utilization

Introduction

Diabetes is a global health concern characterized by chronic hyperglycemia resulting from insulinopenia and/or insulin resistance. The rising prevalence of diabetes and its associated complications (ulcers, periodontitis, healing of bone defect, neuropathy, retinopathy, cardiopathy and nephropathy) necessitate innovative therapeutic approaches. Photobiomodulation (PBM), involves exposing tissues and cells to low-energy light radiation, leading to biological effects, largely via mitochondrial activation.

Methods

This review evaluates preclinical and clinical studies exploring the potential of PBM in diabetes and its complications, as well all clinical trials, both planned and completed, available on ClinicalTrials database.

Results

This review highlights the variability in PBM parameters across studies, hindering consensus on optimal protocols. Standardization of treatment parameters and rigorous clinical trials are needed to unlock PBM's full therapeutic potential. 87 clinical trials were identified that investigated PBM in diabetes mellitus (with 5,837 patients planned to be treated with PBM). Clinical trials assessing PBM effects on diabetic neuropathy revealed pain reduction and potential quality of life improvement. Studies focusing on wound healing indicated encouraging results, with PBM enhancing angiogenesis, fibroblast proliferation, and collagen density. PBM's impact on diabetic retinopathy remains inconclusive however, requiring further investigation. In glycemic control, PBM exhibits positive effects on metabolic parameters, including glucose tolerance and insulin resistance.

Conclusion

Clinical studies have reported PBM-induced reductions in fasting and postprandial glycemia without an increased hypoglycemic risk. This impact of PBM may be related to its effects on the beta cells and islets in the pancreas. Notwithstanding challenges, PBM emerges as a promising adjunctive therapy for managing diabetic neuropathy, wound healing, and glycemic control. Further investigation into its impact on diabetic retinopathy and muscle recovery is warranted.

Comparison of three different dosages of low-level laser therapy on expression of cell proliferation and inflammatory markers following ovariohysterectomy in rats

The objective of the current study was to evaluate Low-level laser therapy (LLLT) on the healing of incisional wounds following ovariohysterectomy in rats, by means of subjective histopathological and immunohistochemical analysis. A total of 72 female Wistar rats were categorised into four treatment groups (Group I; sacrification 4 hours following only one LLLT application, Group II; sacrification 7 days following only one LLLT application, Group III; sacrification 4 hours after two LLLT applications, and Group IV; sacrification 7 days after two LLLT applications). Each group was further divided into four different doses subgroups (Group Control [C, off mode LLLT application], L1 [1 J/cm2], L3 [3 J/cm2], and L6 [6 J/cm2]), with equal representation in each subgroup. Ovariohysterectomy was employed using two 2-cm-length midline abdominal incisions in the left and right sides of line alba. The Group C was assigned to the left side incision to each rat in the study. After irradiation, the tissue was subjected to histopathological analysis to determine the extent of mononuclear cell infiltration, edoema, and epithelialization. Additionally, immunohistochemical analysis was performed to evaluate the expression of proliferating cell nuclear antigen (pCNA) and inducible nitric oxide synthase (iNOS). Group L1 and L3 significantly decreased mononuclear cell infiltration compared with Group C in all treatment groups (p < 0.05). Group L3 significantly decreased edoema compared with Group C in all groups except for treatment Group I (p < 0.05). Group L2 and L3 significantly increased epithelization in treatment Group IV (p < 0.05). Moreover, Group L2 and L3 significantly increased pCNA in all groups, while L2 and L3 significantly decreased iNOS expression in treatment Group II, III, and IV (p < 0.05). However, no statistical difference was found between subgroups of treatment Group I in iNOS expiration (p > 0.05). The results of the current examination demonstrated that LLLT can modulate mononuclear cell infiltration and edoema, and improve epithelization, as well as increase pCNA expression, whereas decrease iNOS expression during the wound healing process, therefore enhancing wound healing following ovariohysterectomy in rats.

An Evaluation of the Effects of Photobiomodulation Therapy on the Peri-Implant Bone Healing of Implants with Different Surfaces: An In Vivo Study

(1) Background: This study evaluates the effects of photobiomodulation (PBM) therapy on the peri-implant bone healing of implants with a machined surface (MS) and treated surface (TS). (2) Methods: Topographic characterization of the surfaces (scanning electron microscopy [SEM]- energy dispersive X-ray spectroscopy [EDX]) was performed before and after implant removal. Twenty rabbits were randomly divided into four groups: MS and TS groups (without PBM therapy) and LMS and LTS groups (with PBM therapy). After implant placement, the stability coefficient (ISQ) was measured. In the periods of 21 and 42 days, the ISQ was measured again, followed by biomechanical analysis. (3) Results: The surfaces of the TS implants showed topographic differences compared with MS implants. The ISQ values of the LMS were statistically significant when compared with those of the MS at 42 days (p < 0.001). The removal torque values of the LMS were statistically significant when compared with those of the MS at 21 days (p = 0.023) and 42 days (p = 0.023). For SEM, in general, the LMS, TS and LTS presented high bone tissue coverage when compared to MS. (4) Conclusions: The PBM therapy modulated the osseointegration process and was evidenced mainly on the machined surface.

New bone-generative effect of Salvia officinalis L. in the expanded midpalatal suture : An in vivo and in vitro study

PURPOSE

The aims of this study were to evaluate the effects of systemic administration of Salvia officinalis Linnaeus (L.) leaf extract on new bone formation in the expanded premaxillary suture in rats in vivo and to examine the antioxidant effects and phenolic profile of Salvia officinalis (SO) leaf and root extracts in vitro.

METHODS

Fourteen male Sprague Dawley rats were allocated to two groups: SO group (n = 7) and control group (n = 7). An open-loop spring was attached to the upper incisors of each rat to expand the premaxillae. A 5-day expansion period followed by a 12-day retention period was observed. The rats in the SO group received systemic administration of 20 mg SO/kg/day via the orogastric route for 17 days. Histomorphometric examinations were carried out to examine the amount of new bone formation, number of capillaries, and intensity of inflammatory cell response. Immunohistochemical analysis was conducted to examine the number of osteoblasts and osteoclasts. Leaf and root extracts of SO were also analyzed for antioxidant activity and phenolic compounds in vitro.

RESULTS

Statistical analysis showed that the following were higher in the SO group than in the control group: new bone formation, number of osteoblasts and osteoclasts, intensity of inflammatory cell response (neutrophils, lymphocytes, and macrophages), and number of capillaries. The major compound identified in SO leaf extract was rosmarinic acid, while luteolin derivatives, salvianolic acid F, and medioresinol were also present.

CONCLUSIONS

Salvia officinalis L. from leaf extract provided antioxidant effects and stimulated enhanced new bone formation in the expanded midpalatal suture after maxillary expansion in rats.

Photobiomodulation in diabetic wound healing: A review of red and near-infrared wavelength applications

The development of a painless, non-invasive, and faster way to diabetic wound healing is at the forefront of research. The complexity associated with diabetic wounds makes it a cause for concern amongst diabetic patients and the world at large. Irradiation of cells generates a photobiomodulatory response on cells and tissues, directly causing alteration of cellular processes and inducing diabetic wound repair. Photobiomodulation therapy (PBMT) using red and near-infrared (NIR) wavelengths is being considered as a promising technique for speeding up the rate of diabetic wound healing, eradication of pain and reduction of inflammation through the alteration of diverse cellular and molecular processes. This review presents the extent to which the potential of red and NIR wavelengths have been harnessed in PBMT for diabetic wound healing. Important research challenges and gaps are identified and discussed, and future directions mapped out. This review thus provides useful insights and strategies into improvement of PBMT, including its acceptance within the global medical research community.

Effect of laser photobiomodulation associated with a bioceramic cement on the repair of bone tissue in the femur of rats

This study aimed to evaluate in vivo the effect of laser photobiomodulation associated with a repair cement (MTA Repair HP™) on the process of bone repair in the femur of rats, through histological and histomorphometric assays. Forty Wistar albino rats were randomly divided into four groups, with two periods of euthanasia - 15 and 21 days (n = 5 per period). Under general anesthesia, a bone defect was made in the left femur of each animal. In the LS (Laser) group, the defect was irradiated following the parameters: λ = 808 nm, P = 100 mW, ED = 80 J/cm² per point, 22 s per point, E = 2.2 J per point. In the LM (MTA Repair HP™ + Laser) group, the defect was filled with MTA Repair HP™ and irradiated with laser in the same protocol of the LS group. In the MH (MTA Repair HP™) group, the defect was filled with MTA Repair HP™ without irradiation. In the CTR (Control) group, the bone defect received no treatment. At 15 days, the mean index of bone neoformation in the defect area was significantly lower in the CTR group as compared to the MH, LS, and LM groups. At 21 days, the LM group presented significantly greater bone neoformation than the MH group, without significant difference between LS and LM. Laser photobiomodulation therapy is promising as an adjuvant in the bone repair process, especially when associated with the use of biomaterials.

Laser acupuncture for refractory coccydynia after traumatic coccyx fracture: A case report

RATIONALE

Coccyx fracture is an injury usually caused by trauma. In most cases, the fractures recover after conservative therapy. For refractory cases that exhibit coccydynia after more than 2 months of conservative treatment, coccygectomy is indicated. However, limited information about the efficacy of this procedure is available, and it is known to have a high complication rate. As such, other therapeutic approaches are needed. Here, we report our experience using another conservative treatment option, low-level laser therapy, to successfully reduce refractory coccydynia in a patient with coccyx fracture.

PATIENT CONCERNS

A 23-year-old woman had refractory coccydynia and increased pain after a traffic accident-induced coccyx fracture.

DIAGNOSES

Initially, the patient reported transient improvement after conservative treatment with non-steroidal anti-inflammatory drugs. However, the pain increased in severity (numerical rating scale score of 8) soon after she resumed work in her office, and progressed in the following 2 months. Surgical intervention was suggested owing to the prolonged coccydynia following the failure of conservative treatment and difficulties in performing daily life activities. However, she sought other conservative therapy options, because she was concerned about the risks associated with the coccygectomy surgery.

INTERVENTIONS

The patient received low-level laser therapy once a week, for 24 weeks.

OUTCOMES

After 11 weeks of treatment, the patient reported significant improvements in her symptoms; her pain was reduced to a numerical rating scale score of 2 and bone healing was noted on radiographs. The patient could eventually perform her daily activities satisfactorily, without coccydynia, after 24 weeks of treatment.

LESSONS

Laser acupuncture produced analgesic effects in this patient with refractory coccydynia after traumatic coccyx fracture. This is the first case report to apply laser acupuncture for refractory coccydynia after traumatic coccyx fracture. Our findings imply that laser acupuncture may be a good conservative therapy option for coccyx fracture.

Effects of Different Protocols of Low-Level Laser Therapy on Collagen Deposition in Wound Healing

The low-level laser has proven successful in stimulating the production of collagen in wound healing assays. However, diversity has been observed in the protocols used. This work has evaluated the effects of three protocols of low-level laser therapy (LLLT) in the healing of open wounds in rats. Standard-sized wounds of 1 cm2 were performed with a scalpel in the middorsal region of 60 male Wistar rats weighing 225±25 g, and they were assigned into four groups (n=15): CTR (non-irradiated animals), LT1 (20 J/cm2 daily), LT2 (16 J/cm2 daily) and LT3 (20 J/cm2 daily). After 7, 14 and 21 days, five animals/day were euthanized and the wounds analyzed histologically. Data were subjected to normality analysis of distribution using Shapiro-Wilk test. Gaussian data were analyzed using ANOVA and Bonferroni tests whereas non-Gaussian data were analyzed using Kruskal-Wallis and Dunn tests, considering significant p values less than 0.05. The LLLT in all protocols reduced the inflammation and collagen deposition increased significantly (p<0.05). However, LT2 showed the highest levels of collagen in all phases of the study (p<0.05) induced faster replacement of immature collagen III by mature collagen I in the early stages of repair and early collagen remodeling promoted by providing better organization architectural beams deposited. It was concluded that all protocols induced an increase in collagen scar. However, the protocol 2 (16 J /cm2, daily application) promoted the most significant increases in collagen deposition, accelerated maturation of collagen and showed the best architecture of the final fibrous scarring.

Evaluation of the Effects of Low-Level Laser Therapy on Diabetic Bone Healing

The aim of the present study was to evaluate the effects of low-level laser therapy (LLLT) and biphasic alloplastic bone graft material on diabetic bone healing. Induction of diabetes was performed in 14 male Sprague-Dawley rats by intraperitoneal injection of a 50 mg/kg dose of streptozotocin. Two bilaterally symmetrical non-critical-sized bone defects were created in the parietal bones in each rat. Right defects were filled with biphasic alloplastic bone graft. Rats were randomly divided into 2 groups, with 1 group receiving 10 sessions of LLLT (GaAlAs, 78.5 J/cm, 100mW, 0.028 cm beam). The LLLT was started immediately after surgery and once every 3 days during postoperative period. At the end of treatment period, new bone formation and osteoblast density were determined using histomorphometry. Empty (control), graft-filled, LLLT-treated and both graft-filled and LLLT-treated bone defects were compared. New bone formation was higher in the graft treatment samples compared with the control (P = 0.009) and laser samples (P = 0.029). In addition, graft-laser combination treatment samples revealed higher bone formation than control (P = 0.008) and laser (P = 0.026) samples. Osteoblast density was significantly higher in the laser treatment (P <0.001), graft treatment (P = 0.001) and graft-laser combination treatment (P <0.001) samples than control samples. In addition, significantly higher osteoblast density was observed in the graft-laser combination treatment samples compared to the graft treatment samples (P = 0.005). The LLLT was effective to stimulate osteoblastogenesis but failed to increase bone formation. Graft augmentation for treatment of bone defects seems essential for proper bone healing in diabetes, regeneration may be supported by the LLLT to enhance osteoblastogenesis.

Role of photobiomodulation on the activation of the Smad pathway via TGF-β in wound healing

Wound healing is an essential process in which the separated or destroyed tissue attempts to restore itself into its normal state. In some instances, healing is prolonged and remains stagnant in the inflammatory phase, and is referred to as a chronic wound. At a cellular and molecular level, many factors are required during the process of successful wound healing, such as cytokines, polypeptide growth factors and components of the extracellular matrix (ECM). Transforming growth factor-beta (TGF-β) is considered as one of the essential growth factors in wound healing. Working through the Smad pathway, it is the main inducer of fibroblast differentiation which is essential for wound healing. Photobiomodulation (PBM) shows significant advantages in wound healing, and may stimulate cellular processes and tissue regeneration that results in an increase in growth factors and a decrease in inflammatory cytokines. Moreover, it leads to enhanced cell proliferation, migration, angiogenesis, and increased adenosine triphosphate (ATP) and cytochrome C oxidase (CCO) activity. In this review paper, we discuss the effects of PBM and its role on the activation of the TGF-β/Smad pathway in the process of wound healing.

Evaluation of the Effects of Photobiomodulation on Partial Osteotomy in Streptozotocin-Induced Diabetes in Rats

OBJECTIVE

We examined the effects of photobiomodulation (PBM) on stereological parameters, and gene expression of Runt-related transcription factor 2 (RUNX2), osteocalcin, and receptor activator of nuclear factor kappa-B ligand (RANKL) in repairing tissue of tibial bone defect in streptozotocin (STZ)-induced type 1 diabetes mellitus (TIDM) in rats during catabolic response of fracture healing.

BACKGROUND DATA

There were conflicting results regarding the efficacy of PBM on bone healing process in healthy and diabetic animals.

MATERIALS AND METHODS

Forty-eight rats have been distributed into four groups: group 1 (healthy control, no TIDM and no PBM), group 2 (healthy test, no TIDM and PBM), group 3 (diabetic control, TIDM and no PBM), and group 4 (diabetic test, no TIDM and PBM). TIDM was induced in the groups 3 and 4. A partial bone defect in tibia was made in all groups. The bone defects of groups second and fourth were irradiated by a laser (890 nm, 80 Hz, 1.5 J/cm²). Thirty days after the surgery, all bone defects were extracted and were submitted to stereological examination and real-time polymerase chain reaction (RT-PCR).

RESULTS

PBM significantly increased volumes of total callus, total bone, bone marrow, trabecular bone, and cortical bone, and the numbers of osteocytes and osteoblasts of callus in TIDM rats compared to those of callus in diabetic control. In addition, TIDM increased RUNX2, and osteocalcin in callus of tibial bone defect compared to healthy group. PBM significantly decreased osteocalcin gene expression in TIDM rats.

CONCLUSIONS

PBM significantly increased many stereological parameters of bone repair in an STZ-induced TIDM during catabolic response of fracture healing. Further RT-PCR test demonstrated that bone repair was modulated in diabetic rats during catabolic response of fracture healing by significant increase in mRNA expression of RUNX2, and osteocalcin compared to healthy control rats. PBM also decreased osteocalcin mRNA expression in TIDM rats.

The effects of low-level laser therapy on the healing of bone defects in streptozotocin-induced diabetic rats: A histological and morphometric evaluation

BACKGROUND

The aim of the present study was to evaluate the effects of low-level laser therapy (LLLT) on the healing of bone defects in rats with streptozotocin (STZ)-induced DM.

METHODS

28 male Sprague-Dawley rats were used in this study. 14 animals received a single dose of STZ intraperitoneally (65 mg/kg) to induce Type I DM, whereas others were injected only with sterile saline solution. Four weeks later, standard bone defects were created in the tibiae of rats. Surgical wounds in one group from each of the diabetic and non-diabetic animals were irradiated with diode laser for every other day for 4 weeks and they were described as DM + LLLT and CONT + LLLT groups, respectively. Remaining two groups received no laser treatment. New bone formation, osteoblast and blood vessel counts were calculated in histologic sections.

RESULTS

DM group had significantly smaller bone area and lower blood vessel count when compared to DM + LLLT, CONT and CONT + LLLT groups (p < 0.05 for each). CONT and CONT + LLLT groups had significantly larger bone area than DM + LLLT group (p < 0.05 for both).

CONCLUSIONS

LLLT application promoted vascularization and new bone formation in animals with DM to a limited extent, since it was unable to support the healing process up to the level of non-diabetic animals.