Low-intensity pulsed ultrasound enhances palatal mucosa wound healing in rats

Egg white-derived peptide KPHAEVVLR promotes wound healing in rat palatal mucosa via PI3K/AKT/mTOR pathway

KPHAEVVLR (KR-9) is a peptide derived from egg white hydrolyzed, which has been found to accelerate skin wound healing in mice. However, the effect of KR-9 on wound healing on palatal mucosa in rats remains unknown, and the mechanism through which KR-9 promotes wound healing should be further explored. Herein, we aimed to investigate the effect and mechanism of KR-9 peptide on palatal mucosa wound healing. Our results showed that KR-9 reduced the wound area of palatal mucosa in rats and promoted human gingival fibroblasts(HGFs) migration and proliferation.The peptide can enter into cytoplasm. It also increased the phosphorylation of PI3K, AKT, and mTOR protein. The effect of KR-9 on HGFs migration and proliferation could be reversed by PI3K inhibitor. These results demonstrated that KR-9 peptide facilitated wound healing of palatal mucosa in rats by promoting HGFs migration and proliferation, which was mediated by PI3K/AKT/mTOR signaling pathway. This data proves that KR-9 might be used as a potential agent for wound healing treatment.

Oral wound healing models and emerging regenerative therapies

Following injury, the oral mucosa undergoes complex sequences of biological healing processes to restore homeostasis. While general similarities exist, there are marked differences in the genomics and kinetics of wound healing between the oral cavity and cutaneous epithelium. The lack of successful therapy for oral mucosal wounds has influenced clinicians to explore alternative treatments and potential autotherapies to enhance intraoral healing. The present in-depth review discusses current gold standards for oral mucosal wound healing and compares endogenous factors that dictate the quality of tissue remodeling. We conducted a review of the literature on in vivo oral wound healing models and emerging regenerative therapies published during the past twenty years. Studies were evaluated by injury models, therapy interventions, and outcome measures. The success of therapeutic approaches was assessed, and research outcomes were compared based on current hallmarks of oral wound healing. By leveraging therapeutic advancements, particularly within in cell-based biomaterials and immunoregulation, there is great potential for translational therapy in oral tissue regeneration.

Erbium, Chromium:Yttrium-Scandium-Gallium-Garnet Laser for Root Conditioning and Reduction of Postoperative Morbidity in the Treatment of Gingival Recession Defects: A Randomized Controlled Clinical Trial

Objective: This clinical trial evaluates the effect of erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) root surface biomodification and laser harvesting of de-epithelialized gingival graft (DGG) on root coverage clinical outcomes and postoperative morbidity, and compares this to the conventional blade-harvested DGG method without Er,Cr:YSGG root surface biomodification in treatment of Miller's class I, II gingival recessions (GR). Background: The application of laser technology to enhance tooth root coverage clinical outcomes as well as the impact of laser on postoperative morbidity after harvesting autogenous soft tissue grafts requires further research. Methods: This study is a randomized, single-blinded controlled trial, including 24 volunteers with isolated GR defects. They were allocated into three treatment groups to receive one of the following three interventions: blade-harvested DGG (control group: B-DGG); Er,Cr:YSGG-harvested DGG and root surface biomodified [test 1 group: L-laser-harvested DGG (L-DGG)/laser root biomodification (LRB)]; and B-DGG and Er,Cr:YSGG root surface biomodification (test 2 group: B-DGG/LRB). Clinical and radiographic parameters were recorded at baseline (1 week before surgery) and 3, 6, and 9 months postoperatively. Results: Root coverage did not show a statistically significant difference between control and test groups. Statistically significant differences were found for Visual Analog Scale on the day of surgery and day 3 and 4 postoperatively, as well as pain medication on the day of surgery favoring the L-DGG group. Conclusions: The use of Er,Cr:YSGG laser in root surface biomodification improved root coverage outcomes at 9 months. Even these changes were not statistically significant from the control group; the L-DGG technique was associated with decreased postoperative morbidity in the palatal donor site.

Stimulation of oral mucosal regeneration by low intensity pulsed ultrasound: an in vivo study in a porcine model

PURPOSE

Many studies have shown the ability of low intensity pulsed ultrasound (LIPUS) to stimulate the bone, cartilage and tendon regeneration but only a few studied LIPUS interest in the regeneration of the oral mucosa. The purpose of this study is to assess the ability of LIPUS to stimulate the regeneration of the palatal mucosa in a porcine model.

METHODS

Ten adults mini-pigs were used. Two mucosal wounds were realised on the left and right side of the palate of each pig. The right side was treated with LIPUS at 1 MHz of frequency and 300 mW/cm2 of acoustic intensity. The left side was not treated. The morphology of the wound was evaluated using a polymer silicone molding.

RESULTS

The difference between two sides was significant from day 7 with a p value < 0.0001. At day 21, the wound is completely healed on all pigs with LIPUS. The control soft tissue defect exposed a healing of 80%.

CONCLUSIONS

The present study showed that the use of LIPUS on the oral mucosa accelerates the healing of the masticatory mucosa.

Ultrasound Therapy: Experiences and Perspectives for Regenerative Medicine

Ultrasound has emerged as a novel tool for clinical applications, particularly in the context of regenerative medicine. Due to its unique physico-mechanical properties, low-intensity ultrasound (LIUS) has been approved for accelerated fracture healing and for the treatment of established non-union, but its utility has extended beyond tissue engineering to other fields, including cell regeneration. Cells and tissues respond to acoustic ultrasound by switching on genetic repair circuits, triggering a cascade of molecular signals that promote cell proliferation, adhesion, migration, differentiation, and extracellular matrix production. LIUS also induces angiogenesis and tissue regeneration and has anti-inflammatory and anti-degenerative effects. Accordingly, the potential application of ultrasound for tissue repair/regeneration has been tested in several studies as a stand-alone treatment and, more recently, as an adjunct to cell-based therapies. For example, ultrasound has been proposed to improve stem cell homing to target tissues due to its ability to create a transitional and local gradient of cytokines and chemokines. In this review, we provide an overview of the many applications of ultrasound in clinical medicine, with a focus on its value as an adjunct to cell-based interventions. Finally, we discuss the various preclinical and clinical studies that have investigated the potential of ultrasound for regenerative medicine.

Strategy of differentiation therapy: effect of dual-frequency ultrasound on the induction of liver cancer stem-like cells on a HA-based multilayer film system

Cancer stem cells (CSCs) and normal stem cells share the ability to self-renew and drive tumor formation, recurrence, and distant metastasis and are resistant to chemotherapeutic drugs. One potential therapeutic approach for targeting CSCs is to induce CSCs to differentiate into normal cancer cells to eliminate self-renewal and enhance drug sensitivity. We developed a hyaluronic acid (HA)-based multilayer film system for selecting CSC-like hepatocellular carcinoma (HCC) cell colonies. Herein, we assess the differentiation therapy of HCC CSCs using dual-frequency low-intensity ultrasound (LIUS). HA-based multilayer films of poly (allylamine hydrochloride), (PAH/HA)6, were used to isolate CSC colonies. Colony formation, maintenance, and CSC marker expression were identified. The colony-formation rate was investigated, and putative CSC markers for CD44/CD133 expression after 7 days of culture were upregulated on (PAH/HA)6 multilayer films. Dual-frequency LIUS was used to induce CSC colony differentiation, and the phenotype variation, CSC marker expression, gene expression, drug-resistance ability, and invasion ability of CSC colonies with/without LIUS stimulation were compared. The numbers of colonies and CD44/CD133 double-positive cells and the expression levels of stem cell-related genes and proteins associated with stemness all decreased due to differentiation after LIUS exposure. Furthermore, a significant reduction in CSC drug resistance and invasion ability was observed. These results indicate that dual-frequency LIUS induces CSC differentiation and reduces drug resistance and invasion ability. Differentiation of CSCs provides an alternative therapeutic strategy to reverse CSC stemness and force their loss of self-renewal ability. CSC-targeted therapy holds great promise as an effective therapeutic approach for the treatment of human tumors.

Fabrication of Multi-Layered Lidocaine and Epinephrine-Eluting PLGA/Collagen Nanofibers: In Vitro and In Vivo Study

This study developed multi-layered lidocaine- and epinephrine-eluting biodegradable poly[(d,l)-lactide-co-glyco lide] (PLGA)/collagen nanofibers. An electrospinning technique was employed to fabricate the multi-layer biodegradable drug-eluting nanofibers. After fabrication, the nanofibrous membranes were characterized. The drug release characteristics were also investigated. In addition, the in vivo efficacy of nanofibers for pain relief and hemostasis in palatal oral wounds of rabbits were evaluated. Histological examinations were also completed. The experimental results suggested that all nanofibers exhibited good biocompatibility and eluted effective levels of lidocaine and epinephrine at the initial stages of wound recovery.

High-Frequency, Low-Intensity Pulsed Ultrasound Enhances Alveolar Bone Healing of Extraction Sockets in Rats: A Pilot Study

Most studies of the beneficial effects of low-intensity pulsed ultrasound (LIPUS) on bone healing have used frequencies between 1.0 and 1.5 MHz. However, after consideration of ultrasound wave characteristics and depth of target tissue, higher-frequency LIPUS may have been more effective on superficially positioned alveolar bone. We investigated this hypothesis by applying LIPUS (frequency, 3.0 MHz; intensity, 30 mW/cm(2)) on shaved right cheeks over alveolar bones of tooth extraction sockets in rats for 10 min/d for 2 wk after tooth extraction; the control group (left cheek of the same rats) did not receive LIPUS treatment. Compared with the control group, the LIPUS group manifested more new bone growth inside the sockets on histomorphometric analysis (maximal difference = 2.5-fold on the seventh day after extraction) and higher expressions of osteogenesis-related mRNAs and proteins than the control group did. These findings indicate that 3.0-MHz LIPUS could enhance alveolar bone formation and calcification in rats.

Diode laser for harvesting de-epithelialized palatal graft in the treatment of gingival recession defects: a randomized clinical trial

AIMS

The aim of present randomized controlled clinical study was to evaluate the effects of the use of diode laser for graft harvesting and palatal wound irradiation on post-operative morbidity and root coverage outcomes after a coronally advanced flap (CAF) with de-epithelialized gingival grafts (DGG).

METHODS

Fifty-two patients with isolated recessions were treated. The CTG resulted from the de-epithelialization of a free gingival graft (FGG) with blade (control group:DGG-B) or diode laser (DL) (test group:DGG-L). The DL was used to de-epithelialize the outer part of the FGG and photo-biostimulate the palatal wound area. Post-operative morbidity was evaluated by using Oral Health-related Quality of Life (OHQoL) and Visual Analogue Scale-discomfort (VAS). Root coverage outcomes were also evaluated 6 months after operation.

RESULTS

Statistically significant differences were found for OHQoL (p = 0.0001) and VAS (p = 0.0001) at the 7th day post-operatively favouring test sites. Root coverage results did not show a statistically significant difference.

CONCLUSIONS

While both techniques were effective with regard to root coverage at 6 months, the DGG-L technique decreased post-operative morbidity associated with palatal donor-site surgery.

Proline-Rich Peptide Mimics Effects of Enamel Matrix Derivative on Rat Oral Mucosa Incisional Wound Healing

BACKGROUND

Proline-rich peptides have been shown to promote periodontal regeneration. However, their effect on soft tissue wound healing has not yet been investigated. The aim of this study is to evaluate the effect of enamel matrix derivative (EMD), tyrosine-rich amelogenin peptide (TRAP), and a synthetic proline-rich peptide (P2) on acute wound healing after a full-thickness flap procedure in an incisional rat model.

METHODS

This experimental study has a split-mouth, randomized, placebo-controlled design. Test and control wounds were created on the palatal mucosa of 54 Sprague-Dawley rats. Wounds were histologically processed, and reepithelialization, leukocyte infiltration, and angiogenesis were assessed at days 1, 3, and 7 post-surgery.

RESULTS

EMD and P2 significantly promoted early wound closure at day 1 (P <0.001 and P = 0.004, respectively). EMD maintained a significant acceleration of reepithelialization at day 3 (P = 0.004). Wounds treated by EMD and P2 showed increased angiogenesis during the first 3 days of healing (P = 0.03 and 0.001, respectively). Leukocyte infiltration was decreased in EMD-treated wounds at day 1 (P = 0.03), and P2 and TRAP induced a similar effect at days 3 (P = 0.002 and P <0.0001, respectively) and 7 (P = 0.005 and P <0.001).

CONCLUSION

EMD and P2 promoted reepithelialization and neovascularization in full-thickness surgical wounds on rat oral mucosa.

Effect of low-intensity pulsed ultrasound on biocompatibility and cellular uptake of chitosan-tripolyphosphate nanoparticles

Using low molecular weight chitosan nanoparticles (CNPs) prepared by an ionic gelation method, the authors report the effect of low-intensity pulsed ultrasound (US) on cell viability and nanoparticle uptake in cultured murine preosteoblasts. Particle size and zeta potential are measured using dynamic light scattering, and cell viability is evaluated using the of [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt; MTS] assay. Results show that 30 min delivery of CNPs at 0.5 mg/mL is able to prevent loss of cell viability due to either serum starvation or subsequent exposure to US (1 W/cm(2) or 2 W/cm(2), up to 1 min). Additionally, flow cytometry data suggest that there is a close association between cellular membrane integrity and the presence of CNPs when US at 2 W/cm(2) is administered.

Light-emitting diode irradiation promotes donor site wound healing of the free gingival graft

BACKGROUND

This study aims to evaluate the effect of light-emitting diode (LED) light irradiation on the donor wound site of the free gingival graft.

METHODS

Rat gingival fibroblasts were chosen to assess the cellular activities and in vitro wound healing with 0 to 20 J/cm(2) LED light irradiation. Seventy-two Sprague-Dawley rats received daily 0, 10 (low-dose [LD]), or 20 (high-dose [HD]) J/cm(2) LED light irradiation on the opened palatal wound and were euthanized after 4 to 28 days; the healing pattern was assessed by histology, histochemistry for collagen deposition, and immunohistochemistry for tumor necrosis factor (TNF)-α infiltration. The wound mRNA levels of heme oxygenase-1 (HO-1), TNF-α, the receptor for advanced glycation end products, vascular endothelial growth factor, periostin, Type I collagen, and fibronectin were also evaluated.

RESULTS

Cellular viability and wound closure were significantly promoted, and cytotoxicity was inhibited significantly using 5 J/cm(2) LED light irradiation in vitro. The wound closure, reepithelialization, and collagen deposition were accelerated, and sequestrum formation and inflammatory cell and TNF-α infiltration were significantly reduced in the LD group. HO-1 and TNF-α were significantly upregulated in the HD group, and most of the repair-associated genes were significantly upregulated in both the LD and HD groups at day 7. Persistent RAGE upregulation was noted in both the LD and HD groups until day 14.

CONCLUSION

LED light irradiation at 660 nm accelerated palatal wound healing, potentially via reducing reactive oxygen species production, facilitating angiogenesis, and promoting provisional matrix and wound reorganization.