Tendon-derived Stem Cells Research Articles

Circ_0005736 promotes tenogenic differentiation of tendon-derived stem cells through the miR-636/MAPK1 axis

BackgroundTendon-derived stem cells (TDSCs) are one of stem cells characterized by greater clonogenicity, tenogenesis, and proliferation capacity. Circ_0005736 has been shown to be decreased in Rotator cuff tendinopathy. Here, we investigated the function and relationship of circ_0005736 in TDSC tenogenic differentiation.MethodsTransforming growth factor β1 (TGF-β1) was used to induce the tenogenic differentiation in TDSC. Cell proliferation, invasion and migration were evaluated by Cell Counting Kit-8, 5-Ethynyl-2′-deoxyuridine, transwell, and wound healing assays, respectively. The detection of the levels of genes and proteins was performed by qRT-PCR and Western blot. The binding between miR-636 and circ_0005736 or MAPK1 (Mitogen-Activated Protein Kinase 1) was verified using dual-luciferase reporter assay and RIP assays.ResultsTGF-β1 induced tenogenic differentiation by enhancing the production of tendon-specific markers and TDSC proliferation, invasion and migration. TGF-β1 treatment promoted circ_0005736 expression, knockdown of circ_0005736 abolished TGF-β1-induced tenogenic differentiation in TDSCs. Mechanistically, circ_0005736 acted as a sponge for miR-636 to up-regulate the expression of MAPK1, which was confirmed to be a target of miR-636 in TDSCs. Further rescue assays showed that inhibition of miR-636 could rescue circ_0005736 knockdown-induced suppression on TGF-β1-caused tenogenic differentiation in TDSCs. Moreover, forced expression of miR-636 abolished TGF-β1-caused tenogenic differentiation in TDSCs, which was rescued by MAPK1 up-regulation.ConclusionCirc_0005736 enhanced TGF-β1-induced tenogenic differentiation in TDSCs via increasing the production of tendon-specific markers and TDSC proliferation, invasion and migration through miR-636/MAPK1 axis.

Tailored modulation of S100A1 and RASSF8 expression by butanediamide augments healing of rotator cuff tears.

This investigation sought to elucidate promising treatment modalities for rotator cuff tears (RCTs) by delving into the molecular machinations instigating the affliction. The focus was on differentially expressed genes (DEGs) linked to RCTs, and the exploration of their roles and operative pathways. DEGs were discerned from GEO datasets, followed by the establishment of a protein-protein interaction (PPI) network. Subsequently, the network's core genes were determined employing a Venn diagram. Enrichment analysis facilitated the unveiling of the biological roles and signal transduction pathways of these pivotal genes, thus shedding light on molecular strategies for RCT-targeted treatment. The Discovery Studio 2019 software was employed to sift through FDA-sanctioned drugs targeting these essential proteins. Moreover, the efficaciousness of these FDA-endorsed drugs vis-à-vis RCTs was corroborated by the construction of an in vivo animal model of the injury and the in vitro cultivation of tendon-derived stem cells. Bioinformatics outcomes revealed a significant overexpression of S100A1 and RASSF8 in RCT patients. The FDA drug repository indicated that Butanediamide has a selective affinity for S100A1 and RASSF8. Subsequent in vivo and in vitro experimentation demonstrated that Butanediamide could suppress S100A1 expression and bolster TDSC proliferation, thereby facilitating RCT healing. S100A1 and RASSF8 are pivotal genes implicated in RCTs, and their roles have been elucidated. The FDA-approved compound, Butanediamide, may represent a prospective therapeutic agent for RCTs by targeting S100A1 and RASSF8, respectively.

Glycolipotoxicity conferred tendinopathy through ferroptosis dictation of tendon-derived stem cells by YAP activation.

Tendinopathy is a condition characterized by chronic, complex, and multidimensional pathological changes in the tendons. The etiology of tendinopathy is the combination of several factors, and diabetes mellitus (DM) is a risk factor. Increasing evidence has shown that the diabetic microenvironment plays an important role in tendinopathy. However, the mechanism causing tendinopathy in patients with DM remains unclear. Our study found that ferroptosis played an important role in tendinopathy in patients with DM. In vitro, high glucose and high fat treatment was used to simulate the DM microenvironment. Results showed that such a mechanism significantly increased ferroptosis, which was characterized by mass cell death, lipid peroxide accumulation, mitochondrial morphological changes, mitochondrial membrane potential decline, iron overload, and the activation of ferroptosis-related genes, in tendon-derived stem cells cultured in vitro. In the animal studies, db/db mice were used in the DM model, and the db mice had severe tendon injury and high ACSL4 and TfR1 expressions. These phenomena could be alleviated by the ferroptosis inhibitor ferrostatin-1. In conclusion, ferroptosis is associated with tendinopathy in patients with DM, and ferroptosis targeting may be a novel approach for treating diabetic tendinopathy. Our results can provide a new strategy for managing tendinopathy clinically in patients with DM.

Decellularized tendon scaffolds loaded with collagen targeted extracellular vesicles from tendon-derived stem cells facilitate tendon regeneration

Stem cell-based treatment of tendon injuries remains to have some inherent issues. Extracellular vesicles derived from stem cells have shown promising achievements in tendon regeneration, though their retention in vivo is low. This study reports on the use of a collagen binding domain (CBD) to bind extracellular vesicles, obtained from tendon-derived stem cells (TDSCs), to collagen. CBD-extracellular vesicles (CBD-EVs) were coupled to decellularized bovine tendon sheets (DBTS) to fabricate a bio-functionalized scaffold (CBD-EVs-DBTS). Our results show that thus obtained bio-functionalized scaffolds facilitate the proliferation, migration and tenogenic differentiation of stem cells in vitro. Furthermore, the scaffolds promote endogenous stem cell recruitment to the defects, facilitate collagen deposition and improve the biomechanics of injured tendons, thus resulting in functional regeneration of tendons.

Novel hybrid biocomposites for tendon grafts: The addition of silk to polydioxanone and poly(lactide-co-caprolactone) enhances material properties, in vitro and in vivo biocompatibility.

Biopolymers play a critical role as scaffolds used in tendon and ligament (TL) regeneration. Although advanced biopolymer materials have been proposed with optimised mechanical properties, biocompatibility, degradation, and processability, it is still challenging to find the right balance between these properties. Here, we aim to develop novel hybrid biocomposites based on poly(p-dioxanone) (PDO), poly(lactide-co-caprolactone) (LCL) and silk to produce high-performance grafts suitable for TL tissue repair. Biocomposites containing 1-15% of silk were studied through a range of characterisation techniques. We then explored biocompatibility through in vitro and in vivo studies using a mouse model. We found that adding up to 5% silk increases the tensile properties, degradation rate and miscibility between PDO and LCL phases without agglomeration of silk inside the composites. Furthermore, addition of silk increases surface roughness and hydrophilicity. In vitro experiments show that the silk improved attachment of tendon-derived stem cells and proliferation over 72h, while in vivo studies indicate that the silk can reduce the expression of pro-inflammatory cytokines after six weeks of implantation. Finally, we selected a promising biocomposite and created a prototype TL graft based on extruded fibres. We found that the tensile properties of both individual fibres and braided grafts could be suitable for anterior cruciate ligament (ACL) repair applications.

Tenogenic differentiation of human tendon-derived stem cells induced by long non-coding RNA LINCMD1 via miR-342-3p/EGR1 axis

ABSTRACT Background Tendon-derived stem cells (TDSCs) are proposed as a potential cell-seed for the treatment of tendon injury due to their tenogenic differentiation potential. In this work, we defined the action of long non-coding RNA (lncRNA) muscle differentiation 1 (LINCMD1) in tenogenic differentiation of human TDSCs (hTDSCs). Methods Quantitative real-time PCR (qRT-PCR) was used to assess the levels of LINCMD1, microRNA (miR)-342-3p, and early growth response-1 (EGR1) mRNA. Cell proliferation was detected by the XTT colorimetric assay. Protein expression was quantified by western blot. hTDSCs were grown in an osteogenic medium to induce osteogenic differentiation, and the extent of osteogenic differentiation was assessed by Alizarin Red Staining (ARS). The activity of alkaline phosphatase (ALP) was measured by the ALP Activity Assay Kit. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to evaluate the direct relationship between miR-342-3p and LINCMD1 or EGR1. Results Our results showed that enforced expression of LINCMD1 or suppression of miR-342-3p accelerated the proliferation and tenogenic differentiation and reduced osteogenic differentiation of hTDSCs. LINCMD1 regulated miR-342-3p expression by binding to miR-342-3p. EGR1 was identified as a direct and functional target of miR-342-3p, and knockdown of EGR1 reversed the effects of miR-342-3p suppression on cell proliferation and tenogenic and osteogenic differentiation. Furthermore, the miR-342-3p/EGR1 axis mediated the regulation of LINCMD1 on hTDSC proliferation and tenogenic and osteogenic differentiation. Conclusion Our study suggests the induction of LINCMD1 in tenogenic differentiation of hTDSCs through miR-342-3p/EGR1 axis.

LncRNA MEG3 Promotes Osteogenic Differentiation of Tendon Stem Cells Via the miR-129-5p/TCF4/β-Catenin Axis and thus Contributes to Trauma-Induced Heterotopic Ossification.

Heterotopic ossification (HO) is one of the most intractable conditions following injury to the musculoskeletal system. In recent years, much attention has been paid to the role of lncRNA in musculoskeletal disorders, but its role in HO was still unclear. Therefore, this study attempted to determine the role of lncRNA MEG3 in the formation of post-traumatic HO and further explore the underlying mechanisms. On the basis of high-throughput sequencing and qPCR validation, elevated expression of the lncRNA MEG3 was shown during traumatic HO formation. Accordingly, in vitro experiments demonstrated that lncRNA MEG3 promoted aberrant osteogenic differentiation of tendon-derived stem cells (TDSCs). Mechanical exploration through RNA pulldown, luciferase reporter gene assay and RNA immunoprecipitation assay identified the direct binding relationship between miR-129-5p and MEG3, or miR-129-5p and TCF4. Further rescue experiments confirmed the miR-129-5p/TCF4/β-catenin axis to be downstream molecular cascade responsible for the osteogenic-motivating effects of MEG3 on the TDSCs. Finally, experiments in a mouse burn/tenotomy model corroborated the promoting effects of MEG3 on the formation of HO through the miR-129-5p/TCF4/β-catenin axis. Our study demonstrated that the lncRNA MEG3 promoted osteogenic differentiation of TDSCs and thus the formation of heterotopic ossification, which could be a potential therapeutic target.

3D-printed hydrogel particles containing PRP laden with TDSCs promote tendon repair in a rat model of tendinopathy

Long-term chronic inflammation after Achilles tendon injury is critical for tendinopathy. Platelet-rich plasma (PRP) injection, which is a common method for treating tendinopathy, has positive effects on tendon repair. In addition, tendon-derived stem cells (TDSCs), which are stem cells located in tendons, play a major role in maintaining tissue homeostasis and postinjury repair. In this study, injectable gelatine methacryloyl (GelMA) microparticles containing PRP laden with TDSCs (PRP–TDSC–GM) were prepared by a projection-based 3D bioprinting technique. Our results showed that PRP–TDSC–GM could promote tendon differentiation in TDSCs and reduce the inflammatory response by downregulating the PI3K–AKT pathway, thus promoting the structural and functional repair of tendons in vivo.Graphical

NLRP3-Dependent Crosstalk between Pyroptotic Macrophage and Senescent Cell Orchestrates Trauma-Induced Heterotopic Ossification During Aberrant Wound Healing.

Heterotopic ossification (HO) represents an unwanted ossific wound healing response to the soft tissue injury which caused catastrophic limb dysfunction. Recent studies established the involvement of inflammation and cellular senescence in the tissue healing process, though their role in HO still remained to be clarified. Here, a novel crosstalk where the pyroptotic macrophages aroused tendon-derived stem cells (TDSCs) senescence is revealed to encourage osteogenic healing during trauma-induced HO formation. Macrophage pyroptosis blockade reduces the senescent cell burden and HO formation in NLRP3 knockout mice. Pyroptosis-driven IL-1β and extracellular vesicles (EVs) secretion from macrophages are determined to motivate TDSCs senescence and resultant osteogenesis. Mechanistically, pyroptosis in macrophages enhances the exosomal release of high mobility group protein 1 (HMGB1), which directly bounds TLR9 in TDSCs to trigger morbid signaling. NF-κB signaling is confirmed to be the converging downstream pathway of TDSCs in response to HMGB1-containing EVs and IL-1β. This study adds insights into aberrant regeneration-based theory for HO formation and boosts therapeutic strategy development.

Additively manufactured polyethylene terephthalate scaffolds for scapholunate interosseous ligament reconstruction

The regeneration of the ruptured scapholunate interosseous ligament (SLIL) represents a clinical challenge. Here, we propose the use of a Bone-Ligament-Bone (BLB) 3D-printed polyethylene terephthalate (PET) scaffold for achieving mechanical stabilisation of the scaphoid and lunate following SLIL rupture. The BLB scaffold featured two bone compartments bridged by aligned fibres (ligament compartment) mimicking the architecture of the native tissue. The scaffold presented tensile stiffness in the range of 260 ± 38 N/mm and ultimate load of 113 ± 13 N, which would support physiological loading. A finite element analysis (FEA), using inverse finite element analysis (iFEA) for material property identification, showed an adequate fit between simulation and experimental data. The scaffold was then biofunctionalized using two different methods: injected with a Gelatin Methacryloyl solution containing human mesenchymal stem cell spheroids (hMSC) or seeded with tendon-derived stem cells (TDSC) and placed in a bioreactor to undergo cyclic deformation. The first approach demonstrated high cell viability, as cells migrated out of the spheroid and colonised the interstitial space of the scaffold. These cells adopted an elongated morphology suggesting the internal architecture of the scaffold exerted topographical guidance. The second method demonstrated the high resilience of the scaffold to cyclic deformation and the secretion of a fibroblastic related protein was enhanced by the mechanical stimulation. This process promoted the expression of relevant proteins, such as Tenomodulin (TNMD), indicating mechanical stimulation may enhance cell differentiation and be useful prior to surgical implantation. In conclusion, the PET scaffold presented several promising characteristics for the immediate mechanical stabilisation of disassociated scaphoid and lunate and, in the longer-term, the regeneration of the ruptured SLIL.

Leucine rich repeat containing 32 accelerates tenogenic differentiation of tendon-derived stem cells and promotes Achilles tendon repair in rats.

Although many surgical or non-operative therapies have been developed to treat Achilles tendon injuries, the prognosis of which is often unsatisfactory. Recently, biologic approaches using multipotent stem cells like tendon-derived stem cells (TDSCs) pose a possible treatment option. To evaluate whether the Leucine rich repeat containing 32 (Lrrc32) affects the tenogenic differentiation of TDSCs and thus promotes Achilles tendon healing. TDSCs were infected with the recombinant Lrrc32-overexpressing lentivirus (LV-Lrrc32) and then locally injected into the injured site of rat. Four weeks after surgery, the Achilles tendon tissue (~0.5 cm) around the injured area was harvested for analysis. Pathological results showed that Lrrc32-overexpressing TDSCs significantly improved the morphological changes of the injured tendons. Specifically, the increased collagen-I expression and hydroxyproline content in extracellular matrix, and more orderly arrangement of the regenerated collagen fibers were observed in the Lrrc32 overexpression group. Moreover, 4 weeks after injection of Lrrc32-overexpressing TDSCs, the expression of tenocyte-related genes such as tenomodulin (Tnmd), scleraxis (Scx) and decorin (Dcn) were upregulated in the area of the healing tendon. These findings indicated that Lrrc32 promoted the tenogenic differentiation of TDSCs in vivo. Additionally, Lrrc32 overexpression also increased the expression of TGF-β1 and p-SMAD2/3, suggesting that the beneficial effects of Lrrc32 on tendon repair might be associated with the expression of TGF-β1 and p-SMAD2/3. Our findings collectively revealed that Lrrc32-overexpressed TDSCs promoted tendon healing more effectively than TDSCs alone.

LncRNA AC108925 promotes osteoblast differentiation of tendon-derived stem cells by targeting miR-146a-3p.

It has been reported that tendon-derived stem cells(TDSCs) conduce to the ostosis in tendon diseases, and the molecular mechanism needs to be discussed. To investigate the function and mechanism of LncRNA in tendinopathy. Tendon of tendinopathy patients and health controls were obtained, and sequencing analysis have been performed to detect the significantly expressed genes and non-coding RNAs. Moreover, to further discuss LncRNA AC108925 in tendinopathy, tendinopathy animal models have been established, and the expression of LncRNA AC108925 expression was examined by RT-qPCR methods. Furthermore, hTDSCs have been treated by osteogenic medium, and the modulating function of LncRNA AC108925 on the osteoblast differentiation of hTDSCs have been examined. Sequencing analysis showed that AC108925 a dramatically elevated LncRNA, and results of animal and cells studies confirmed the finding. Knockdown AC108925 inhibited the osteogenic differentiation of osteogenic medium treated TDSCs by decreasing the expression of osteogenic markers. Furthermore, miR-146a-3p is a target of AC108925 in TDSCs, and miR-146a-3p is a negative modulator of osteogenic differentiation of hTDSCs by inhibiting the effects of AC108925 shRNA on osteogenic differentiation of hTDSCs. AC108925 can regulate the osteogenic differentiation of hTDSCs via regulating the miR-146a-3p. Targeting the AC108925/miR-146a-3p axis might be a latent way to treat tendinopathy.

Decellularized tilapia fish skin: A novel candidate for tendon tissue engineering.

The poor regenerative ability of injured tendon tissues remains a clinical challenge. However, decellularized extracellular matrix (ECM) combined with stem cells shows promise. In contrast to bovine and porcine ECM, marine-derived decellularized ECM has several advantages; it is easily obtained, poses less biological risk, and is not contraindicated on religious grounds. This study successfully fabricated decellularized tilapia fish skin (DTFS) with copious preserved collagen fibers and natural pore structures. The outer layer is smooth and dense, while the inner layer has a soft structure with a rough surface. After crosslinking with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS), crosslinked DTFS (C-DTFS) showed improved mechanics in dry and wet conditions. In vitro, the leach liquor of crosslinked DTFS showed no cytotoxicity and promoted migration and tenonic differentiation of tendon-derived stem cells (TDSCs). Meanwhile, TDSCs seeded in the inner surface of DTFS maintained viability, differentiated, and exhibited spreading. Furthermore, cell-seeded scaffolds guided the regeneration of tendon tissue in a rat Achilles tendon defect model. Our results suggest that DTFS combined with TDSCs is a novel and promising therapeutic option for tendon tissue engineering.

Hedgehog Signalling Contributes to Trauma-Induced Tendon Heterotopic Ossification and Regulates Osteogenesis through Antioxidant Pathway in Tendon-Derived Stem Cells.

Heterotopic ossification (HO) is defined as the generation of pathological ectopic bony structures in soft tissues, but the molecular mechanisms of tendon HO are not fully revealed. Hedgehog (Hh) signalling is reportedly critical in hereditary HO. Our study focuses on the role of Hh signalling in the formation of trauma-induced tendon ossification. In this study, samples of healthy tendons and injured tendons from C57BL/6J female mice at 1, 4, 7, and 10 weeks after Achilles tenotomy were collected for quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemical analysis (IHC). At 1, 4, 7, and 10 weeks postinjury, tendon samples from the mice administered with vehicle, GANT58 (a GLI antagonist), or SAG (a smoothened agonist) were harvested for micro-CT, histological staining, qRT-PCR, and IHC. Rat tendon-derived stem cells (TDSCs) treated with vehicle, GANT58, or SAG were used to induce osteogenic and chondrogenic differentiation in vitro for qRT-PCR, alkaline phosphatase staining, Alcian blue staining, and reactive oxygen species (ROS) levels measurement. We found that Hh signalling is remarkably activated during the formation of trauma-induced tendon ossification in the model of Achilles tenotomy. The in vitro and in vivo assays both confirm that downregulation of Hh signalling significantly suppresses osteogenesis and chondrogenesis to inhibit tendon ossification, while upregulation of Hh signalling promotes this process. Under osteogenic induction, Hh signalling regulates antioxidant pathway and affects ROS generation of TDSCs. Collectively, Hh signalling contributes to trauma-induced tendon ossification and affects ROS generation through antioxidant pathway in osteogenic differentiation of TDSCs, indicating that targeting Hh signalling by GANT58 may be a potential treatment for trauma-induced tendon ossification.

VEGFA-Enriched Exosomes from Tendon-Derived Stem Cells Facilitate Tenocyte Differentiation, Migration, and Transition to a Fibroblastic Phenotype.

Tendon-derived stem cells (TDSCs) play a vital role in repair of rotator cuff tear injuries by secreting paracrine proteins that regulate resident cell functions. Secreted exosomes may play a role in tendon injury repair by mediating intercellular communication; however, the detailed mechanisms by which TDSC-derived exosomes affect tenocyte development remain unknown. Here, we examined the effects of exosomes isolated from conditioned medium of TDSCs on tenocyte differentiation, migration, and transition to a fibroblastic phenotype in vitro. Successful isolation of exosomes from TDSCs was confirmed by high expression levels of CD81, CD63, CD9, and TSG101. Treatment with TDSC-derived exosomes promoted the growth and migration of cultured rat tenocytes, and increased the levels of the fibrosis markers collagen I, collagen III, scleraxis, tenascin C, and α-smooth muscle actin. Furthermore, vascular endothelial growth factor A (VEGFA) expression was higher in TDSC-derived exosomes than in TDSCs, and genetic knockdown of VEGFA suppressed the stimulatory effect of TDSC-derived exosomes on tenocyte development. Overall, these results demonstrate that VEGFA-enriched exosomes isolated from TDSCs promote differentiation and migration of cultured tenocytes and their transition to a fibroblastic phenotype. These data provide a new potential clinical treatment strategy for tendon injury.

Enhancement of Tendon Repair Using Tendon-Derived Stem Cells in Small Intestinal Submucosa via M2 Macrophage Polarization.

(1) Background: Reconstruction of Achilles tendon defects and prevention of postoperative tendon adhesions were two serious clinical problems. In the treatment of Achilles tendon defects, decellularized matrix materials and mesenchymal stem cells (MSCs) were thought to address both problems. (2) Methods: In vitro, cell adhesion, proliferation, and tenogenic differentiation of tendon-derived stem cells (TDSCs) on small intestinal submucosa (SIS) were evaluated. RAW264.7 was induced by culture medium of TDSCs and TDSCs–SIS scaffold groups. A rat Achilles tendon defect model was used to assess effects on tendon regeneration and antiadhesion in vivo. (3) Results: SIS scaffold facilitated cell adhesion and tenogenic differentiation of TDSCs, while SIS hydrogel coating promoted proliferation of TDSCs. The expression of TGF-β and ARG-1 in the TDSCs-SIS scaffold group were higher than that in the TDSCs group on day 3 and 7. In vivo, the tendon regeneration and antiadhesion capacity of the implanted TDSCs–SIS scaffold was significantly enhanced. The expression of CD163 was significantly highest in the TDSCs–SIS scaffold group; meanwhile, the expression of CD68 decreased more significantly in the TDSCs–SIS scaffold group than the other two groups. (4) Conclusion: This study showed that biologically prepared SIS scaffolds synergistically promote tendon regeneration with TDSCs and achieve antiadhesion through M2 polarization of macrophages.

Energy-Supporting Enzyme-Mimic Nanoscaffold Facilitates Tendon Regeneration Based on a Mitochondrial Protection and Microenvironment Remodeling Strategy.

Tendon injury is a tricky and prevalent motor system disease, leading to compromised daily activity and disability. Insufficient regenerative capability and dysregulation of immune microenvironment are the leading causes of functional loss. First, this work identifies persistent oxidative stress and mitochondrial impairment in the regional tendon tissues postinjury. Therefore, a smart scaffold incorporating the enzyme mimicry nanoparticle-ceria nanozyme (CeNPs) into the nanofiber bundle scaffold (NBS@CeO) with porous, anisotropic, and enhanced mechanical properties is designed to innovatively explore a targeted energy-supporting repair strategy by rescuing mitochondrial function and remodeling the microenvironment favoring endogenous regeneration. The integrated CeNPs scavenge excessive reactive oxygen species (ROS), stabilize the mitochondria membrane potential (ΔΨm), and ATP synthesis of tendon-derived stem cells (TDSCs) under oxidative stress. In a rat Achilles tendon defect model, NBS@CeO reduces oxidative damage and accelerates structural regeneration of collagen fibers, manifesting as recovering mechanical properties and motor function. Furthermore, NBS@CeO mediates the rebalance of endogenous regenerative signaling and dysregulated immune microenvironment by alleviating senescence and apoptosis of TDSCs, downregulating the secretion of senescence-associated secretory phenotype (SASP), and inducing macrophage M2 polarization. This innovative strategy highlights the role of NBS@CeO in tendon repair and thus provides a potential therapeutic approach for promoting tendon regeneration.

The 532 nm Laser Treatment Promotes the Proliferation of Tendon-Derived Stem Cells and Upregulates Nr4a1 to Stimulate Tenogenic Differentiation.

Objective: This study aimed to verify the effect of photobiomodulation therapy (PBMT) with a wavelength of 532 nm on the proliferation and differentiation of tendon-derived stem cells (TDSCs) of Sprague-Dawley (SD) rats. Background: The combination of PBMT and stem cell transplantation with TDSCs provides a new treatment strategy for tendon injury. Nevertheless, the effect of PBMT on the biological behavior of TDSCs and its internal mechanisms remain unclear. Methods: TDSCs were isolated from Achilles tendons of SD rats and identified by cell morphology and flow cytometric analysis. Energy density gradient experiment was performed to determine the ideal energy. Then, TDSCs were treated with PBMT using a wavelength of 532 nm at a fluence of 15 J/cm2 in 532 nm laser group, and the TDSC in control group were not treated with 532 nm laser. Cell response after irradiation was observed to ascertain cell morphology and cell proliferation in the 532 nm laser group and the control group. The RNA expression levels of the key genes of TDSC differentiation, including scleraxis (Scx), tenomodulin (Tnmd), Mohawk homeobox (Mkx), Decorin (Dcn), peroxisome proliferator-activated receptor gamma (PPARγ), SRY-box transcription factor 9 (Sox9), and RUNX family transcription factor 2 (Runx2), were detected by reverse transcription-polymerase chain reaction. Then, gene chip microarray was used to detect the expression of differential genes after 532 nm laser intervention in TDSCs, and the target genes were screened out to verify the role in this process in vitro and in vivo. Results: When the 532 nm laser energy density was 15 J/cm2, the proliferation capacity of TDSCs was improved (2.73 ± 0.24 vs. 1.81 ± 0.71, p < 0.05), and the expression of genes related to tenogenic differentiation of TDSCs was significantly increased (p < 0.01). After RNA sequencing and bioinformatics analyses, we speculated that nuclear receptor subfamily 4 group A member 1 (Nr4a1) was involved in the tenogenic differentiation process of TDSCs regulated by 532 nm laser treatment. Subsequent experiments confirmed that Nr4a1 regulated the expression of the tenogenic differentiation genes Scx and Tnmd in TDSCs. Conclusions: A 532 nm laser with 15 J/cm2 regulated the process of TDSC proliferation and upregulated Nr4a1 to stimulate tenogenic differentiation.

Dual‐Phase Aligned Composite Scaffolds Loaded with Tendon‐Derived Stem Cells for Achilles Tendon Repair

AbstractTendon injury is one of the most common musculoskeletal disorders, resulting in a significant decrease in the quality of life of patients with tendon injury. With the in‐depth understanding of the anatomical structure and pathological changes that occur during tendon repair, tissue engineering methods using cells and biomaterials are widely studied. However, simulation of the aligned tissue morphology present in natural tendons remains challenging. The design of a well‐aligned scaffold would be appealing to promote better tendon regeneration. Here, a dual‐aligned composite scaffold comprising an outer layer of polycaprolactone/silk fibroin (PCL/SF) copolymer electrospun membrane and an inner layer of tendon extracellular matrix (TECM) loaded with tendon‐derived stem cells (TDSCs) is developed to promote rabbit Achilles tendon repair. As resident, tissue‐specific cells, TDSCs possess stronger tenogenic differentiation abilities. The PCL/SF electrospun membrane with a dense structure provides mechanical support and TECM with a loose porous structure provides bioactive constituents and a microenvironment for tendon repair. As shown here, the engineered scaffold facilitates TDSC proliferation and migration, favors tenogenesis‐associated gene expression, promotes tendon repair with native‐like hierarchically organized collagen fibers, and enhances the mechanical properties, indicating its potential value in the tendon tissue engineering field.

Galunisertib attenuates progression of trauma-induced heterotopic ossification via blockage of Smad2/3 signaling in mice

Heterotopic ossification (HO) is the formation of bony tissues in the extraskeletal system. To date, no effective therapy has been developed for the treatment of HO, although increasing evidences have shown that inhibition of TGF-β signaling has potential as a new therapeutic approach for attenuating HO progression. Results from previous clinical trials have demonstrated that patients with malignant tumors exhibit excellent tolerability to Galunisertib, a TGF-β receptor I kinase inhibitor. However, its therapeutic potential in preventing HO and inhibitory effect on osteogenesis remain unclear. In this study, we demonstrated that intragastrical administration of Galunisertib, at a concentration as low as 10 mg/kg, was not only fairly effective in preventing HO development in a dose-dependent manner, but also generated a non-toxic response in a novel Achilles tendon puncture-induced traumatic HO model in mice. Moreover, Galunisertib treatment in the early phases of HO development, including the inflammatory and chondrogenic period, resulted in better therapeutic effects instead of eliminating already formed bony tissues. Mechanistically, Galunisertib suppressed the osteogenic differentiation capacity of tendon-derived stem cells (TDSCs) by interfering with the Smad2/3 signaling pathway, blocking the phosphorylation of Smad2/3 translocated from cytoplasm into the nucleus to regulate the expression of both osteogenesis-related transcription factors and related proteins. Results from in vivo experiments further validated Galunisertib's effect on HO attenuation, by intercepting the TGF-β/Smad2/3 signaling pathway. In conclusion, our findings demonstrated Galunisertib's potential as a prophylactic drug for the treatment of traumatic HO or other related diseases triggered by over-expressed TGF-β.