Effects of Two Protocols of Low-Level Laser Therapy on the Proliferation and Differentiation of Human Dental Pulp Stem Cells on Sandblasted Titanium Discs: An In Vitro Study

Photobiomodulation and low-intensity pulsed ultrasound synergistically enhance dental mesenchymal stem cells viability, migration and differentiation: an invitro study

Novel methods and technologies that improve mesenchymal stem cells (MSCs) proliferation and differentiation properties are required to increase their clinical efficacy. Photobiomodulation (PBM) and low-intensity pulsed ultrasound (LIPUS) are two strategies that can be used to enhance the regenerative properties of dental MSCs. This study evaluated the cytocompatibility and osteo/odontogenic differentiation of dental pulp, periodontal ligament, and gingival MSCs after stimulation by either PBM or LIPUS and their combined effect. MTT assay, cell migration assay, osteo/odontogenic differentiation by AR staining and ALP activity, and expression of osteo/odontogenic markers (OPG, OC, RUNX2, DSPP, DMP1) by RT-qPCR were evaluated. Statistical analysis was performed using ANOVA, followed by Tukey's post hoc test, with a p-value of less than 0.05 considered significant. The results showed that combined stimulation by PBM and LIPUS resulted in significantly the highest viability of MSCs, the fastest migration, the most dense AR staining, the most increased ALP activity, and the most elevated levels of osteogenic and odontogenic markers. The synergetic stimulation of PBM and LIPUS can be utilized in cell-based regenerative approaches to promote the properties of dental MSCs.

Effects of Semiconductor Laser Irradiation on Differentiation of Human Dental Pulp Stem Cells in Co-Culture with Dentin

This study aimed to determine the effect of photobiomodulation therapy induced by semiconductor laser irradiation on human dental pulp stem cell (hDPSC) proliferation and their differentiation into odontoblast-like cells (OLCs). The effects of various semiconductor laser irradiation conditions on hDPSCs were examined. Three groups were evaluated: a single laser irradiation at 6 h post-seeding, multiple laser irradiations up to four times every 4 days after the first dose, and a control with no laser irradiation. The cells were irradiated at 10, 30, and 150 mW using a semiconductor laser. The effect of laser irradiation on hDPSC differentiation into OLCs was also determined. Four groups were evaluated, including co-culture using basic medium and dentin discs, simple culture using OLC differentiation-inducing medium, co-culture using OLC differentiation-inducing medium and dentin discs, and control culture with basic medium. The expression of the nestin, ALP, DSPP, and DMP-1 genes was measured using real-time PCR. The multiple irradiation group irradiated at 30 mW exhibited significantly more cell proliferation than the control. The expression of nestin associated with differentiation into OLCs during each culture period tended to be lower, whereas DSPP and ALP expression was higher compared with that of the control. Multiple laser irradiations at a low power of 30 mW induced significant hDPSC proliferation and might induce differentiation into OLCs.

Infrared diode laser enhances human periodontal ligament stem cells behaviour on titanium dental implants

Low level laser treatment (LLLT) is known for its photobiostimulatory and photobiomodulatory characteristics, which stimulate cell proliferation, increase cellular metabolism, and improve cellular regeneration. The objective of the present research was to assess the possible influence of infrared diode laser irradiation on the behaviour, attachment, and osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) seeded on different types of dental implants. Two distinct types of implants, one subjected to laser surface treatment and the other treated with acid etching, were longitudinally divided into two halves and submerged in six wells culture plates. Both implants were subjected to infrared diode laser treatment, and subsequently, the morphology and attachment of cells were examined using scanning electron microscopy (SEM) after 14 and 21 days. The behaviour of (hPDLSCs) towards two types of implants, when exposed to osteogenic medium and low-level laser therapy (LLLT), was assessed using quantitative real-time polymerase chain reaction to measure the expression of stemness markers and osteogenic markers. The scanning electron microscopy (SEM) demonstrated that the application of infrared diode laser irradiation substantially improved the attachment of cells to both types of implants. The stemness gene markers were significantly down regulated in cells seeded on both surfaces when challenged with osteogenic media in relation to control. At 14 days, early osteogenic markers, were upregulated, while late osteogenic markers, were downregulated in both challenged groups. At the 21-day mark, hPDLSCs seeded on an acid-etched implant exhibited increased expression of all osteogenic markers in response to stimulation with osteogenic media and infra-red diode laser, in contrast to hPDLSCs seeded on a laser surface treated implant under the same conditions. Finally, the findings of our research revealed that when subjected to infrared diode laser, human periodontal ligament stem cells cultured on both types of implants demonstrated improved cellular attachment and differentiation. This suggested that infrared diode laser enhanced the activity of the cells surrounding the implants. Hence, the use of infrared diode laser could be pivotal in improving and expediting the clinical osseointegration process around dental implants.

Photo biomodulation of dental derived stem cells to ameliorate regenerative capacity: In vitro study

Background

Dental regeneration benefits from improving the features of dental derived stem cells. Gallium-aluminum-arsenide laser had a significant role in modification of cell behavior in different cell lines and culture conditions. Hence, exploring its mechanism and effect on dental derived stem cells would benefit prospective regenerative dental therapies.

Objectives

To assess the impact of photo biomodulation by Low-Level-Laser on isolated Dental Pulp derived Stem Cells and Periodontal Ligament derived Stem Cells regarding their proliferation and osteogenic differentiation.

Methods

Isolated DPSCs and PDLSCs from impacted third molars were subjected to Gallium-aluminum-arsenide laser for 12 sec and 3.6 J/cm2. The proliferative capacity was evaluated via 3-(4,5-dimethylthiazol-2-yl),2,5-diphenyltetrazolium bromide (MTT) Assay and Trypan blue stain. Cell osteogenic differentiation potentials were assessed by alkaline phosphatase assay and alizarin red stain, polymerase chain reaction was performed to quantify Nuclear factor Kappa gene expression.

Results

DPSCs subjected to laser bio-stimulation showed the best results regarding cell viability (MTT) and osteogenic differentiation (ALP assay), and calcium deposition at 3 intervals (3, 7, 14 days), meanwhile, PDLSCs subjected to laser bio-stimulation showed better result than control but less than DPSCs. While NF-KB gene expression was proven to be approximately comparable for both groups. Generally, the Photo-bio modulated groups showed better results than their control groups.

Conclusion

Low-level laser bio-stimulation (LLL) therapy improves DPSC and PDLSC osteogenic differentiation and proliferation via the activation of the NF-KB pathway. Also, the DPSCs outperformed PDLSCs in terms of performance.

Clinical significance

These results can be beneficial information and a reference database for more research in tissue engineering, dental therapy, and regeneration.

Evaluating the effect of strontium ranelate and photobiomodulation on cementogenic and osteogenic differentiation of buccal fat pad-derived stem cells: An in vitro study

This study aimed to analyze the impact of strontium ranelate (Str), photobiomodulation (PBM), or their combination of the proliferation, osteogenic differentiation, and cementogenic differentiation of buccal fat pad-derived stem cells. BFPdSCs were exposed to one of the following interventions: (1) PBM (660 nm), (2) PBM (660 nm) + Str, (3) PBM (880 nm), (4) PBM (880 nm) + Str, (5) Str. All study groups had significantly higher osteogenic differentiation than the control group (p < 0.05), and no significant difference existed between the 660 and 808 nm groups (p = 0.97). Compared to the Str group, 660 nm and 880 nm group samples had significantly lower osteogenic differentiation (p < 0.0001), while other groups did not show a significant difference. Regarding cementogenic differentiation, the 660 nm group showed higher values than the 808 nm group (p < 0.01). Compared with the Str group, 660 nm, 660 nm + Str, and 808 nm + Str groups showed significantly higher gene expression (p < 0.05). In the case of osteogenic differentiation, although photobiomodulation alone had a lower inducing effect than strontium ranelate, combining 808 nm diode lasers and strontium ranelate may provide the best results. Moreover, using a 660 nm diode laser and exposing stem cells to strontium ranelate can be the most effective approach to induce cementogenic differentiation.

Effect of Low-Level Laser Therapy on Differentiation and Proliferation of Human Dental Pulp Stem Cells: A Systematic Review

Introduction: Considering the positive impact of laser treatment on the proliferation of certain cell types, we opted to perform a systematic review aimed at evaluating the effects of laser therapy and photobiomodulation on the proliferation and differentiation of human dental pulp stem cells (hDPSCs). Methods: We included all research studies examining the impact of laser therapy on hDPSCs, without limitations on publication dates or article languages. The major international databases, including PubMed, ISI Web of Science, and Scopus, were searched from inception to April 2022 by the relevant keywords. Results: In total, 1886 studies were identified in the initial search from the mentioned databases and other sources. Finally, 17 relevant studies were included in the present systematic review after removing duplicates and non-relevant articles. The results indicated the useful effect of low-level laser therapy (LLLT) on the hDPSCs. Conclusion: The findings of this systematic review indicate the useful role of LLLT in cell therapy, proliferation, and differentiation associated with hDPSCs.

Effect of an low-energy Nd: YAG laser on periodontal ligament stem cell homing through the SDF-1/CXCR4 signaling pathway

BACKGROUND

The key to the success of endogenous regeneration is to improve the homing rate of stem cells, and low-energy laser is an effective auxiliary means to promote cell migration and proliferation. The purpose of this study was to observe whether low-energy neodymium (Nd: YAG) laser with appropriate parameters can affect the proliferation and migration of periodontal ligament stem cells (PDLSCs) through SDF-1/CXCR4 pathway.

METHODS

h PDLSCs were cultured and identified. CCK8 assay was used to detect the proliferation of h PDLSCs after different power (0, 0.25, 0.5, 1, and 1.5 W) Nd: YAG laser (MSP, 10 Hz, 30 s, 300 μ m) irradiation at 2th, 3rd,5th, and 7th days, and the optimal laser irradiation parameters were selected for subsequent experiments. Then, the cells were categorized into five groups: control group (C), SDF-1 group (S), AMD3100 group (A), Nd: YAG laser irradiation group (N), and Nd: YAG laser irradiation + AMD3100 group (N + A). the migration of h PDLSCs was observed using Transwell, and the SDF-1 expression was evaluated using ELISA andRT-PCR. The SPSS Statistics 21.0 software was used for statistical analysis.

RESULTS

The fibroblasts cultured were identified as h PDLSCs. Compared with the C, when the power was 1 W, the proliferation rate of h PDLSCs was accelerated (P < 0.05). When the power was 1.5 W, the proliferation rate decreased (P < 0.05). When the power was 0.25 and 0.5 W, no statistically significant difference in the proliferation rate was observed (P > 0.05). The number of cell perforations values as follows: C (956.5 ± 51.74), A (981.5 ± 21.15), S (1253 ± 87.21), N (1336 ± 48.54), and N + A (1044 ± 22.13), that increased significantly in group N (P < 0.05), but decreased in group N + A (P < 0.05). The level of SDF-1 and the expression level of SDF-1 mRNA in groups N and N + A was higher than that in group C (P < 0.05) but lower than that in group A (P < 0.05).

CONCLUSIONS

Nd: YAG laser irradiation with appropriate parameters provides a new method for endogenous regeneration of periodontal tissue. SDF-1/CXCR4 signaling pathway may be the mechanism of LLLT promoting periodontal regeneration.

Combination of Dental-Capping Agents with Low Level Laser Therapy Promotes Proliferation of Stem Cells from Apical Papilla

Background: Direct pulp capping is a vital pulp therapy, which stimulates differentiation of stem cells from apical papilla (SCAPs). SCAPs have multipotential capacity to differentiate into types of cells, contributing to the regeneration of tissues. Objective: Considering the promising effects of dental-capping materials, we aim to investigate the effect of dental dressing materials combined with laser therapy on the percentage of SCAP viability and the consequent dental regeneration capacity. Methods: We collected two immature third molar teeth and isolated SCAPs through collagenase type I enzymatic activity. Isolated SCAPs were then cultured with Dulbecco's modified Eagle's medium and α-minimum essential medium enriched with 15% and 10% fetal bovine serum, respectively. After reaching 70-80% confluency, cells were seeded in a 96-well plate and then treated with mineral trioxide aggregate (MTA), enamel matrix derivative (EMD), biodentine, and low level laser therapy (LLLT) alone and in combination for 24, 48, and 168 h. After that, cell survival rate was assessed using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay. Results: We found that combination of MTA, EMD, and LLLT as well as that of biodentine, EMD, and LLLT could lead to significant increase of SCAP viability as compared with other treatment groups. Combination of MTA and biodentine with EMD could also show increased level of SCAP proliferation and viability. However, MTA and biodentine alone reduced SCAP survival rate in all time points. Conclusions: Our conclusion is that LLLT can serve as an enhancer of SCAP proliferation and differentiation rate when added to dental-capping agents such as MTA, EMD, and biodentine. Thus, LLLT combination with effective capping materials will serve as a promising option for dental tissue repair.

Investigating effects of locally applied boric acid on fracture healing with and without low-level laser therapy

This study aimed to investigate the effects on fracture healing of locally applied boric acid (BA) with and without low-level laser therapy (LLLT). A unicortical femoral defect was surgically created on the anterolateral surface of proximal femur of each subject. The subjects, totaling 56 Wistar albino rats, were randomly allocated into four groups (n = 14 each): control, LLLT (λ = 905 μm, 10,000 Hz, 25 mW, and peak power 25 W), BA (40 mg/kg), and BA + LLLT groups. On the 30th day, the highest radiological score was recorded for the BA + LLLT group (3.63 [2-4]), followed by the BA (3.38 [2.75-3.75]), control (3 [2-3.25]), and LLLT (2.5 [1.25-3]) groups. On days 15 and 30 post-surgery, malondialdehyde levels were significantly lower among the BA + LLLT group compared to the control group (p < 0.001). On day 30, superoxide dismutase, catalase, and alkaline phosphatase levels were highest in the BA + LLLT group compared to the control group (p < 0.001). When the histopathological, immunofluorescence, and immunohistochemical findings on the 15th and 30th days were compared with the control group, a statistically significant difference was found for the BA and BA + LLLT groups (p ˂ 0.05). This study suggests that locally applied BA with LLLT may accelerate fracture healing.

A comparison of human dental pulp stem cell activity cultured on sandblasted titanium discs decontaminated with Er:YAG laser and air-powder abrasion: an in vitro study

Decontamination of implant surfaces is important to the treatment of peri-implantitis. Er:YAG laser and air-powder abrasion system are regarded as the most effective means of decontamination of implant surfaces. The aim of this in vitro study was to compare the activity of human dental pulp stem cells (hDPSCs) cultured on decontaminated sandblasted titanium discs using Er:YAG laser irradiation and air-powder abrasion. Forty-five titanium discs were contaminated with Escherichia coli (E. coli) bacteria and fifteen titanium discs served as sterile control groups. Thirty contaminated titanium discs were decontaminated with Er:YAG laser or air-powder abrasion system and fifteen contaminated discs were used as contaminated control group. Afterwards, hDPSCs were seeded on all sixty experimental titanium discs. The effects of two decontamination tools on hDPSCs viability were evaluated by MTT assay. Alkaline phosphatase (ALP) activity assay, quantitative real-time PCR analysis and alizarin red staining method were performed to assess hDPSCs osteogenic differentiation. Scanning microscope electron (SEM) was also used to evaluate the effects of two different decontaminated methods on cellular morphology. Our study showed that decontamination using Er:YAG laser caused maximum cell viability. However, the ALP activity was not different in laser and air-abrasion groups. The significant expression of an osteoblastic marker and stronger Alizarin red staining were observed in laser irradiation groups. In addition, SEM observation indicated that grown cells were more stretched and more filopodia in Er:YAG-treated discs. In the present study, Er:YAG laser and air-powder abrasion improved the activity of the cells cultured on the decontaminated titanium discs. However, in comparison with air-powder abrasion, Er:YAG laser was more effective.