Tendon Regeneration Research Articles

A 3D Dynamic In Vitro Model of Inflammatory Tendon Disease.

Three-dimensional (3D) cell cultures combining multipotent mesenchymal stromal cells (MSC), tendon extracellular matrix scaffolds, and mechanical stimulation by a bioreactor have been used to induce tenogenic differentiation in vitro. Yet, these conditions alone do not mimic the environment of acute inflammatory tendon disease adequately, thus the results of such studies are not representatives for tendon regeneration after acute injury. In this chapter, we describe two different approaches to introduce inflammatory stimuli, comprising co-culture with leukocytes and supplementation with the cytokines IL-1 β and TNF-α. The presented in vitro model of inflammatory tendon disease could be used to study musculoskeletal pathophysiology and regeneration in more depth.

Application and research of nano-biomaterials in the rehabilitation of sports tendon rupture

Nano-biomaterials have important application and development in the field of tendon fracture rehabilitation. However, with the continuous improvement of people's requirements for tendon repair, the traditional single biomaterials are difficult to meet the actual needs of tendon repair, so the biomaterials have gradually developed. Biocomposites often have the comprehensive advantages of two or more materials, which can achieve optimal and purposeful tissue repair. In this paper, the effects of nanocomposites with dual functions of tendon regeneration and barrier on the rehabilitation of exercise-induced tendon rupture will be studied. In this paper, nanowire/polylactic acid double-sided synthetic materials are mainly used in the actual preparation of biomaterials. Its main purpose is to overcome the contradiction between tendon-induced suture and adhesion of surrounding tissues in the process of tendon repair of traditional biomaterials. In the experimental part of this paper, based on the tendon rupture of a patient, the Achilles tendon suture experiment was carried out with the mixed biomaterials proposed in this paper. The experiment shows that the comprehensive biomaterials proposed in this paper have obvious rehabilitation advantages.

Collagen and chondroitin sulfate functionalized bioinspired fibers for tendon tissue engineering application

Functional tendon tissue engineering depends on harnessing the biochemical and biophysical cues of the native tendon extracellular matrix. In this study, we fabricated highly-aligned poly(L-lactic acid) (PLLA) fibers with surfaces decorated by two of the crucial tendon ECM components, type 1 collagen (COL1) and chondroitin sulfate (CS), through a coaxial stable jet electrospinning approach. Effects of the biomimetic COL1-CS (shell)/PLLA (core) fibers on the tenogenic differentiation of human mesenchymal stem cells (hMSCs) in vitro were investigated. Higher rates of cell spreading and proliferation are observed on the aligned COL1-CS/PLLA fibers compared to that on the plain PLLA fibers. Expression of the tendon-associated genes scleraxis (SCX) and COL1 as well as protein tenomodulin (TNMD) are significantly increased. Introduction of mechanical stimulation gives rise to synergistic effect on tenogenic differentiation of hMSCs. Higher expression of TGF-β2, TGFβR-II, and Smad3 by the cells on the COL1-CS/PLLA fiber substrates are observed, which indicates that COL1-CS/PLLA ultrafine fibers dictate the hMSC tenogenic differentiation through activating the TGF-β signaling pathway. Animal study in rat Achilles tendon repair model corroborated the promoting role of COL1-CS/PLLA in regenerating a tendon-like tissue. Thus, our highly aligned biomimicking fibers may serve as an efficient scaffolding system for functional tendon regeneration.

Influence of the integrity of tendinous membrane and fascicle on biomechanical characteristics of tendon-derived scaffolds

The biomechanical characteristics of tendon grafts is essential for tendon reconstructive surgery due to its great role in providing a good mechanical environment for tendon healing and regeneration. In our previous studies, the decellularized tendon slices (DTSs) and decellularized bovine tendon sheets (DBTSs) scaffolds were successfully developed. However, the influence of the integrity of tendinous membrane (endotenon and epitenon) and fascicle on biomechanical characteristics of these two scaffolds was not investigated. In this study, we assessed the integrity of tendinous membrane and fascicle of the tendon derived scaffolds and its effect on the biomechanical characteristics. The results of histological staining indicated that the DBTSs had complete endotenon and epitenon, while DTSs had no epitenon at all, only part of endotenon was remained. Furthermore, the DBTSs, and DTSs with thickness of 900 μm had complete fascicles, while DTSs with thickness less than 600 μm had almost no complete fascicles. The fibrous configuration of epitenon was well-preserved in the surface of the DBTSs but the surface ultrastructure of the DTSs was aligned collagen fibers based on scanning electron microscopy examination. The results of transmission electron microscopy showed that there was no significant difference between the DBTSs and DTSs. Mechanically, the DBTSs and DTSs with thickness of 900 μm showed similar ultimate tensile strength and stiffness to native tendon segments (NTSs). The strain at break and suture retention strength of the DBTSs showed much higher than that of the DTSs (p < 0.05). Additionally, the DBTSs showed higher ultimate load than the DTSs when these scaffolds were sutured with NTSs (p < 0.05) through the modified Kessler technique based on a uniaxial tensile test. This study demonstrated that DTSs may be used as a patch for reinforcing tendon repair, while DBTSs may be used as a bridge for reconstructing tendon defects.

Bionic Silk Fibroin Film Induces Morphological Changes and Differentiation of Tendon Stem/Progenitor Cells

Purpose Tendon injuries are common musculoskeletal system disorders, but the ability for tendon regeneration is limited. Silk fibroin (SF) film may be suitable for tendon regeneration due to its excellent biocompatibility and physical properties. This study is aimed at evaluating the application value of bionic SF film in tendon regeneration. Methods Tendon stem/progenitor cells (TSPCs) were isolated from rat Achilles tendon and characterized based on their surface marker expression and multilineage differentiation potential. SF films with smooth or bionic microstructure surfaces (5, 10, 15, 20 μm) were prepared. The morphology and mechanical properties of natural tendons and SF films were characterized. TSPCs were used as the seed cells, and the cell viability and cell adhesion morphology were analyzed. The tendongenesis-related gene expression of TSPCs was also evaluated using quantitative polymerase chain reaction. Results Compared to the native tendon, only the 10, 15, and 20 μm SF film groups had comparable maximum loading and ultimate stress, with the exception of the breaking elongation rate. The 10 μm SF film group had the highest percentage of oriented cells and the most significant changes in cell morphology. The most significant upregulations in the expression of COL1A1, TNC, TNMD, and SCX were also observed in the 10 μm SF film group. Conclusion SF film with a bionic microstructure can serve as a tissue engineering scaffold and provide biophysical cues for the use of TSPCs to achieve proper cellular adherence arrangement and morphology as well as promote the tenogenic differentiation of TSPCs, making it a valuable customizable biomaterial for future applications in tendon repair.

Bringing tendon biology to heel: Leveraging mechanisms of tendon development, healing, and regeneration to advance therapeutic strategies.

Tendons are specialized matrix-rich connective tissues that transmit forces from muscle to bone and are essential for movement. As tissues that frequently transfer large mechanical loads, tendons are commonly injured in patients of all ages. Following injury, mammalian tendons heal poorly through a slow process that forms disorganized fibrotic scar tissue with inferior biomechanical function. Current treatments are limited and patients can be left with a weaker tendon that is likely to rerupture and an increased chance of developing degenerative conditions. More effective, alternative treatments are needed. However, our current understanding of tendon biology remains limited. Here, we emphasize why expanding our knowledge of tendon development, healing, and regeneration is imperative for advancing tendon regenerative medicine. We provide a comprehensive review of the current mechanisms governing tendon development and healing and further highlight recent work in regenerative tendon models including the neonatal mouse and zebrafish. Importantly, we discuss how present and future discoveries can be applied to both augment current treatments and design novel strategies to treat tendon injuries.

SM04755, a small-molecule inhibitor of the Wnt pathway, as a potential topical treatment for tendinopathy.

The Wnt pathway is upregulated in tendinopathy, affecting inflammation and tenocyte differentiation. Given its potential role in tendinopathy, this signaling pathway may be a relevant target for treatment. The current study examined the therapeutic potential of SM04755, a topical, small‐molecule Wnt pathway inhibitor, for the treatment of tendinopathy using in vitro assays and animal models. In vitro, SM04755 decreased Wnt pathway activity, induced tenocyte differentiation, and inhibited catabolic enzymes and pro‐inflammatory cytokines in human mesenchymal stem cells, rat tendon‐derived stem cells, and human peripheral blood mononuclear cells. Evaluation of the mechanism of action of SM04755 by biochemical profiling and computational modeling identified CDC‐like kinase 2 (CLK2) and dual‐specificity tyrosine phosphorylation‐regulated kinase 1A (DYRK1A) as molecular targets. CLK and DYRK1A inhibition by siRNA knockdown or pharmacological inhibition induced tenocyte differentiation and reduced tenocyte catabolism. In vivo, topically applied SM04755 showed therapeutically relevant exposure in tendons with low systemic exposure and no detectable toxicity in rats. Moreover, SM04755 showed reduced tendon inflammation and evidence of tendon regeneration, decreased pain, and improved weight‐bearing function in rat collagenase‐induced tendinopathy models compared with vehicle control. Together, these data demonstrate that CLK2 and DYRK1A inhibition by SM04755 resulted in Wnt pathway inhibition, enhanced tenocyte differentiation and protection, and reduced inflammation. SM04755 has the potential to benefit symptoms and modify disease processes in tendinopathy.

Tendon Regeneration is Possible Even During Subtotal Isolation of the SutureSite

The process of post-traumatic regeneration of tendons is well known and described in a number of scientific articles [1-3]. There are 3 phases: inflammatory, reparative and remodeling. As a result of activation of extrinsic and intrinsic sources of regeneration, the tendon reaches its original strength 6 weeks after surgery. Afterwards the “maturation” of suture site occurs under the influence of movements for several months.

Peroneus Longus Tendon Regeneration after Anterior Cruciate Ligament Reconstruction with Magnetic Resonance Imaging Evaluation

BACKGROUND: Peroneus longus graft can be recommended as a superior graft over hamstring in anterior cruciate ligament (ACL) reconstruction. There are many studies concerning hamstring tendon regeneration, but there are few studies on the regeneration of the peroneus longus tendon after ACL reconstruction.&#x0D; AIM: This study aimed to investigate whether regeneration of the peroneus longus tendon occurs after ACL reconstruction with magnetic resonance imaging.&#x0D; METHODS: Twenty-five patients underwent ACL reconstruction with donors from the peroneus longus tendon by the same operator and were followed 12 months later with bilateral crural magnetic resonance imaging (MRI) for comparison of the donor and healthy peroneus longus tendon areas. Regeneration was assessed at 5 cm, 10 cm, and 15 cm from the ankle joint.&#x0D; RESULTS: The average age 30.4 (18-38) years old. There were 17 right and 8 left knees involved in this study. The interval between surgery and MRI was 1 year. The average regeneration presentation was located in the distal part (5 cm from the ankle joint) 66.78%, medial part (10 cm from the joint) 63.2%, and proximal part (15 cm from the ankle joint) 67.53%. There was no significant difference in the presentation of proximal, medial, and distal areas while there was a significant difference between age and regeneration of the proximal area, p &lt;0.05 (p = 0.047). Tissue regeneration was tendinous and it appeared smaller in the place where the tendons grew.&#x0D; CONCLUSION: Regeneration of the peroneus longus tendon occurred after ACL reconstruction at a 1-year follow-up according to MRI.

MOFs-Based Nitric Oxide Therapy for Tendon Regeneration

HighlightsA system that NO-loaded metal–organic frameworks encapsulated in PCL/Gel aligned coaxial scaffold is successfully constructed.The system enables to release NO slowly (1.67 nM h−1) and stably in a long period (15 d) without a burst release in the initial 48 h.The scaffold can promote the regeneration of the injured tendon with maturer collagen fibers and better mechanical properties by angiogenesis.

Bionic Silk Fibroin Film Promotes Tenogenic Differentiation of Tendon Stem/Progenitor Cells by Activating Focal Adhesion Kinase.

Background Tendon injuries are common musculoskeletal disorders in clinic. Due to the limited regeneration ability of tendons, tissue engineering technology is often used as an effective approach to treat tendon injuries. Silk fibroin (SF) films have excellent biological activities and physical properties, which is suitable for tendon regeneration. The present study is aimed at preparing a SF film with a bionic microstructure and investigating its biological effects. Methods A SF film with a smooth surface or bionic microstructure was prepared. After seeding tendon stem/progenitor cells (TSPCs) on the surface, the cell morphology, the expression level of tenogenic genes and proteins, and the focal adhesion kinase (FAK) activation were measured to evaluate the biological effect of SF films. Results The TSPCs on SF films with a bionic microstructure exhibited a slender cell morphology, promoted the expression of tenogenic genes and proteins, such as SCX, TNC, TNMD, and COLIA1, and activated FAK. FAK inhibitors blocked the enhanced expression of tenogenic genes and proteins. Conclusion SF films with a bionic microstructure may serve as a scaffold, provide biophysical cues to alter the cellular adherence arrangement and cell morphology, and enhance the tenogenic gene and protein expression in TSPCs. FAK activation plays a key role during this biological response process.

Stem Cells for the Regeneration of Tendon and Ligament: A Perspective.

Tendons are structures that connect muscles to the bones in our body and transmit the force generated by contraction of the muscles to the bones. Ligaments are structures that connect bones to bones, with histological properties similar to tendons. In tendon and ligament tissue, there are very small amounts of cells similar to mesenchymal stem cells (MSCs) called tendon stem/progenitor cells (TSPCs), or tenogenic stem cells. While the role of specific growth factors and transcription factors is well established in the osteogenic and chondrogenic differentiation of stem cells, a consensus has not been established for tenogenic differentiation. Injuries to tendons and ligaments are very common, but natural healing is very slow and inefficient due to limited vascularization. Currently, there is no adequate method for restoring extensive tendon or ligament defects. Procedures addressing the unmet need for regeneration of these tissues are needed. In this review, the current knowledge, as well as the authors’ ideas and perspective on stem cell and regenerative medicine for tendon and ligament defects are presented.

New bioreactor for mechanical stimulation of cultured tendon-like constructs: design and validation

ABSTRACT Objective: Although several different types of bioreactors are currently available with mechanical stimulation of constructs or prostheses for tendon regeneration, they are in many cases expensive and difficult to operate. This paper proposes a simple bioreactor to mechanically stimulate up to three constructs for tendon and ligament repair, composed of a stainless-steel frame and an electric motor. Methods: The deformation is produced by a cam wheel, whose eccentricity defines the maximum deformation. The test samples, braids of PLA seeded in surface with mouse fibroblasts, are immersed in the culture medium during mechanical stimulation. Results: Its advantages over existing similar bioreactor designs include: easy renewal of the culture medium and an external electric motor to avoid heating and contamination issues. After 14 days of stretching, the culture samples showed enhanced cellular proliferation and cell fiber alignment in addition to higher production of type I collagen. The cells initially seeded on the braid surface migrated to the inside of the braid. Conclusion: Although the results obtained have a poor statistical basis, they do suggest that the bioreactor could be usefully applied to stimulate constructs for tendon and ligament repair. Anyway, further experiments should be conducted in the future.

Nudt21-mediated alternative polyadenylation of HMGA2 3'-UTR impairs stemness of human tendon stem cell.

Tendon-derived stem cells (TSCs) play a primary role in tendon physiology, pathology, as well as tendon repair and regeneration after injury. TSCs are often exposed to mechanical loading-related cellular stresses such as oxidative stress, resulting in loss of stemness and multipotent differentiation potential. Cytoprotective autophagy has previously been identified as an important mechanism to protect human TSCs (hTSCs) from oxidative stress induced impairments. In this study, we found that high-mobility AT-hook 2 (HMGA2) overexpression protects hTSCs against H2O2-induced loss of stemness through autophagy activation. Evidentially, H2O2 treatment increases the expression of Nudt21, a protein critical to polyadenylation site selection in alternative polyadenylation (APA) of mRNA transcripts. This leads to increased cleavage and polyadenylation of HMGA2 3′-UTR at the distal site, resulting in increased HMGA2 silencing by the microRNA let-7 and reduced HMGA2 expression. In conclusion, Nudt21-regulated APA of HMGA2 3′-UTR and subsequent HMGA2 downregulation mediates oxidative stress induced hTSC impairments.

The Application of Mechanical Stimulations in Tendon Tissue Engineering.

Tendon injury is the most common disease in the musculoskeletal system. The current treatment methods have many limitations, such as poor therapeutic effects, functional loss of donor site, and immune rejection. Tendon tissue engineering provides a new treatment strategy for tendon repair and regeneration. In this review, we made a retrospective analysis of applying mechanical stimulation in tendon tissue engineering, and its potential as a direction of development for future clinical treatment strategies. For this purpose, the following topics are discussed; (1) the context of tendon tissue engineering and mechanical stimulation; (2) the applications of various mechanical stimulations in tendon tissue engineering, as well as their inherent mechanisms; (3) the application of magnetic force and the synergy of mechanical and biochemical stimulation. With this, we aim at clarifying some of the main questions that currently exist in the field of tendon tissue engineering and consequently gain new knowledge that may help in the development of future clinical application of tissue engineering in tendon injury.

Magnetic responsive materials modulate the inflammatory profile of IL-1β conditioned tendon cells

Tendinopathies represent half of all musculoskeletal injuries worldwide. Inflammatory events contribute to both tendon healing and to tendinopathy conditions but the cellular triggers leading to one or the other are unknown. In previous studies, we showed that magnetic field actuation modulates human tendon cells (hTDCs) behavior in pro-inflammatory environments, and that magnetic responsive membranes could positively influence inflammation responses in a rat ectopic model.Herein, we propose to investigate the potential synergistic action of the magnetic responsive membranes, made of a polymer blend of starch with polycaprolactone incorporating magnetic nanoparticles (magSPCL), and the actuation of pulsed electromagnetic field (PEMF): 5 Hz, 4mT of intensity and 50% of duty cycle, in IL-1β-treated-hTDCs, and in the immunomodulatory response of macrophages.It was found that the expression of pro-inflammatory (TNFα, IL-6, IL-8, COX-2) and ECM remodeling (MMP-1,-2,-3) markers tend to decrease in cells cultured onto magSPCL membranes under PEMF, while the expression of TIMP-1 and anti-inflammatory genes (IL-4, IL-10) increases. Also, CD16++ and CD206+ macrophages were only found on magSPCL membranes with PEMF application.Magnetic responsive membranes show a modulatory effect on the inflammatory profile of hTDCs favoring anti-inflammatory cues which is also supported by the anti-inflammatory/repair markers expressed in macrophages. These results suggest that magnetic responsive magSPCL membranes can contribute for inflammation resolution acting on both resident cell populations and inflammatory cells, and thus significantly contribute to tendon regenerative strategies.Statement of significanceMagnetically-assisted strategies have received great attention in recent years to remotely trigger and guide cell responses. Inflammation plays a key role in tendon healing but persistent pro-inflammatory molecules can contribute to tendon disorders, and therefore provide a therapeutic target for advanced treatments.We have previously reported that magnetic fields modulate the response of human tendon cells (hTDCs) conditioned to pro-inflammatory environments (IL-1β-treated-hTDCs), and that magnetic responsive membranes positively influence immune responses. In the present work, we combined pulsed electromagnetic field (PEMF) and magnetic responsive membranes to guide the inflammatory profile of IL-1β-treated-hTDCs and of macrophages. The results showed that the synergistic action of PEMF and magnetic membranes supports the applicability of magnetically actuated systems to regulate inflammatory events and stimulate tendon regeneration.

Tendon stem cell-derived exosomes regulate inflammation and promote the high-quality healing of injured tendon

BackgroundTendon stem cells (TSCs) have been reported to hold promises for tendon repair and regeneration. However, less is known about the effects of exosomes derived from TSCs. Therefore, we aimed to clarify the healing effects of TSC-derived exosomes (TSC-Exos) on tendon injury.MethodsThe Achilles tendons of Sprague-Dawley male rats were used for primary culture of TSCs and tenocytes, and exosomes were isolated from TSCs. The proliferation of tenocytes induced by TSC-Exos was analyzed using an EdU assay; cell migration was measured by cell scratch and transwell assays. We used western blot to analyze the role of the PI3K/AKT and MAPK/ERK1/2 signaling pathways. In vivo, Achilles tendon injury models were created in Sprague-Dawley rats. Rats (n = 54) were then randomly assigned to three groups: the TSC-Exos group, the GelMA group, and the control group. We used immunofluorescence to detect changes in the expression of inflammatory and apoptotic markers at 1 week after surgery. Histology and changes in expression of extracellular matrix (ECM)-related indices were assessed by hematoxylin-eosin (H&E) staining and immunohistochemistry at 2 and 8 weeks. The collagen fiber diameter of the healing tendon was analyzed at 8 weeks by transmission electron microscopy (TEM).ResultsTSC-Exos were taken up by tenocytes, which promoted the proliferation and migration of cells in a dose-dependent manner; this process may depend on the activation of the PI3K/AKT and MAPK/ERK1/2 signaling pathways. At 1 week after surgery, we found that inflammation and apoptosis were significantly suppressed by TSC-Exos. At 2 and 8 weeks, tendons treated with TSC-Exos showed more continuous and regular arrangement in contrast to disorganized tendons in the GelMA and control groups, and TSC-Exos may help regulate ECM balance and inhibited scar formation. Further, at 8 weeks, the TSC-Exos group had a larger diameter of collagen compared to the control group.ConclusionsOur data suggest that TSC-Exos could promote high-quality healing of injured tendon, which may be a promising therapeutic approach for tendon injury.

In Vitro Innovation of Tendon Tissue Engineering Strategies.

Tendinopathy is the term used to refer to tendon disorders. Spontaneous adult tendon healing results in scar tissue formation and fibrosis with suboptimal biomechanical properties, often resulting in poor and painful mobility. The biomechanical properties of the tissue are negatively affected. Adult tendons have a limited natural healing capacity, and often respond poorly to current treatments that frequently are focused on exercise, drug delivery, and surgical procedures. Therefore, it is of great importance to identify key molecular and cellular processes involved in the progression of tendinopathies to develop effective therapeutic strategies and drive the tissue toward regeneration. To treat tendon diseases and support tendon regeneration, cell-based therapy as well as tissue engineering approaches are considered options, though none can yet be considered conclusive in their reproduction of a safe and successful long-term solution for full microarchitecture and biomechanical tissue recovery. In vitro differentiation techniques are not yet fully validated. This review aims to compare different available tendon in vitro differentiation strategies to clarify the state of art regarding the differentiation process.

Tenogenic adipose-derived stem cell sheets with nanoyarn scaffolds for tendon regeneration

Tissue engineering, especially cell sheets-based engineering, offers a promising approach to tendon regeneration; however, obtaining a sufficient source of cells for tissue engineering applications is challenging. Adipose-derived stem cells (ASCs) are essential sources for tissue regeneration and have been shown to have the potential for tenogenic differentiation in vitro via induction by growth differentiation factor 5 (GDF-5). In this study, we explored the feasibility of ASCs cell sheets stimulated by GDF-5 for engineered tendon repair. As shown by quantitative polymerase chain reaction and western blotting, tenogenesis-related markers (Col I&III, TNMD, biglycan, and tenascin C) were significantly increased in GDF-5-induced ASCs cell sheets compared with the uninduced. Moreover, the levels of SMAD2/3 proteins and phospho-SMAD1/5/9 were significantly enhanced, demonstrating that GDF-5 may exert its functions through phosphorylation of SMAD1/5/9. Furthermore, the cell sheets were combined with P(LLA-CL)/Silk fibroin nanoyarn scaffolds to form constructs for tendon tissue engineering. Terminal deoxynucleotidyl transferase dUTP nick end labeling and immunofluorescence assays demonstrated favorable cell viability and tenogenesis-related marker expression in GDF-5-induced constructs. In addition, the constructs showed the potential for tendon repair in rabbit models, as demonstrated by histological, immunohistochemical, and biomechanical analyses. In our study, we successfully produced a new tissue-engineered tendon by the combination of GDF-5-induced ASCs cell sheets and nanoyarn scaffold which is valuable for tendon regeneration.

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

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