Hypertrophic scar contracture is mediated by the TRPC3 mechanical force transducer via NFkB activation

Specific Calcium Signal Responses in Human Keloid-Derived Fibroblasts During Cyclical Stretching: Basic Research

Background

Keloids most commonly develop in the regions where the skin is constantly stretched. Although some keloid-derived fibroblasts exhibit higher single calcium spikes than normal dermal fibroblasts during short-time cyclical stretching, the calcium signal responses to long-time stretching remain unclear.

Methods

This study compared the intracellular Ca2+ dynamics induced by cyclical stretching stimuli between the control group (normal dermal fibroblasts) and the keloid group (keloid-derived fibroblasts). Each group was cyclically exposed to a two-dimensional stretch (10% strain). A confocal laser microscope was used to examine intracellular Ca2+ for 30 min fluorescently. The fluorescence intensity ratio (Fluo-8H/calcein red-orange) was used to evaluate intracellular Ca2+ concentration every 0.5 s. A calcium spike was a transient ratio increase of ≥ 20%. Receiver operating characteristic analysis was performed to determine the cutoff value of a normal calcium spike.

Results

No significant difference was observed between the keloid and control groups in the calcium signal response-positive rates (26.9% vs. 25.0%; p = 0.9). However, the calcium spike amplitudes were significantly higher in the keloid group than in the control group (1.66 vs. 1.41; p = 0.02). The cutoff value was 2.12, and 9.6% of keloid-derived fibroblasts exhibited multiple hypercalcium spikes.

Discussion

We are conducting further research based on the hypothesis that this keloid-specific subpopulation triggers the pathogenesis of keloid formation, that is, collagen overproduction, accelerated angiogenesis, and chronic inflammation.

Role of Neuropeptide B/W Signaling in Modulating Intracellular Calcium in Human Skin Fibroblasts

BACKGROUND

The neuropeptide B/W signalling system (NPB/W) has been identified in multiple body regions and is integral to several physiological processes, including the regulation of food intake and energy homeostasis. Recently, it has also been detected in human skin; however, its specific functions in this context remain to be thoroughly investigated. This study aims to identify the expression of neuropeptides B/W receptor 1 (NPBWR1) and neuropeptides B/W receptor 2 (NPBWR2) in human dermal fibroblasts of mesenchymal origin using genomic and proteomic techniques. We will also investigate the role of these receptors in cell proliferation and calcium signalling.

METHODS

The mRNAs for NPBWR1 and NPBWR2 were detected using quantitative PCR (qPCR) analysis and further validated by western blot and immunofluorescence analyses. Additionally, we synthesised ligands for these receptors, specifically hNPB (25-53) and hNPW (33-62), to investigate their effects on cell proliferation and intracellular calcium levels in human fibroblasts.

RESULTS

Our results demonstrated that hNPW (33-62) has anti-proliferative effect on human dermal fibroblasts and concentration of 0.1-μmol/L can significantly decrease intracellular calcium levels (p < 0.05).

CONCLUSION

This finding suggests a potential role for the NPB/W signalling system in pathologies associated with impaired calcium handling, such as fibrosis. Furthermore, we observed that the proliferation of human fibroblasts was not affected by hNPB (25-53). Our findings could lead to the development of new therapeutic strategies for various skin conditions and improved wound healing.

Canonical transient receptor potential channel 1 aggravates myocardial ischemia-and-reperfusion injury by upregulating reactive oxygen species

The canonical transient receptor potential channel (TRPC) proteins form Ca2+-permeable cation channels that are involved in various heart diseases. However, the roles of specific TRPC proteins in myocardial ischemia/reperfusion (I/R) injury remain poorly understood. We observed that TRPC1 and TRPC6 were highly expressed in the area at risk (AAR) in a coronary artery ligation induced I/R model. Trpc1-/- mice exhibited improved cardiac function, lower serum Troponin T and serum creatine kinase level, smaller infarct volume, less fibrotic scars, and fewer apoptotic cells after myocardial-I/R than wild-type or Trpc6-/- mice. Cardiomyocyte-specific knockdown of Trpc1 using adeno-associated virus 9 mitigated myocardial I/R injury. Furthermore, Trpc1 deficiency protected adult mouse ventricular myocytes (AMVMs) and HL-1 cells from death during hypoxia/reoxygenation (H/R) injury. RNA-sequencing-based transcriptome analysis revealed differential expression of genes related to reactive oxygen species (ROS) generation in Trpc1-/- cardiomyocytes. Among these genes, oxoglutarate dehydrogenase-like (Ogdhl) was markedly downregulated. Moreover, Trpc1 deficiency impaired the calcineurin (CaN)/nuclear factor-kappa B (NF-κB) signaling pathway in AMVMs. Suppression of this pathway inhibited Ogdhl upregulation and ROS generation in HL-1 cells under H/R conditions. Chromatin immunoprecipitation assays confirmed NF-κB binding to the Ogdhl promoter. The cardioprotective effect of Trpc1 deficiency was canceled out by overexpression of NF-κB and Ogdhl in cardiomyocytes. In conclusion, our findings reveal that TRPC1 is upregulated in the AAR following myocardial I/R, leading to increased Ca2+ influx into associated cardiomyocytes. Subsequently, this upregulates Ogdhl expression through the CaN/NF-κB signaling pathway, ultimately exacerbating ROS production and aggravating myocardial I/R injury.

Gallic Acid Treats Hypertrophic Scar in Rabbit Ears via the TGF-β/Smad and TRPC3 Signaling Pathways

Hypertrophic scars (HSs) develop due to excessive collagen deposition and abnormal fibroblast proliferation during wound healing, significantly impacting patient quality of life. Three dosages of GA ointments were administered to rabbit ear HS models to investigate the potential efficacy and mechanism of gallic acid (GA) on HS. Daily application of ointment was performed on the matrix group, the GA ointment groups, and the silicone gel group for 28 days. (No drug treatment was performed on the skin and model groups as a blank group and vehicle group, and silicone gel ointment was topically administered to the silicone gel group as a positive control group.) Scar specimens were collected for histopathology analysis, RNA sequencing analysis, real-time quantitative polymerase chain reaction, and Western blot analysis at the first, second, and fourth weeks after the treatment. Low-dose and medium-dose GA effectively suppressed HS formation and markedly decreased fibroblast infiltration levels and scar thickness. Moreover, decreased expression of TRPC3 mRNA and TGF-β1, p-Smad2/3, and Smad2/3 protein was observed in the low- and medium-dose GA groups and the silicone gel group. This study provides evidence for the efficacy of GA in treating HS and sheds light on its potential underlying pharmacological mechanisms.

Multimodal roles of transient receptor potential channel activation in inducing pathological tissue scarification

Transient receptor potential (TRP) channels are a class of transmembrane proteins that can sense a variety of physical/chemical stimuli, participate in the pathological processes of various diseases and have attracted increasing attention from researchers. Recent studies have shown that some TRP channels are involved in the development of pathological scarification (PS) and directly participate in PS fibrosis and re-epithelialization or indirectly activate immune cells to release cytokines and neuropeptides, which is subdivided into immune inflammation, fibrosis, pruritus and mechanical forces increased. This review elaborates on the characteristics of TRP channels, the mechanism of PS and how TRP channels mediate the development of PS, summarizes the important role of TRP channels in the different pathogenesis of PS and proposes that therapeutic strategies targeting TRP will be important for the prevention and treatment of PS. TRP channels are expected to become new targets for PS, which will make further breakthroughs and provide potential pharmacological targets and directions for the in-depth study of PS.

Positive feedback loops between fibroblasts and the mechanical environment contribute to dermal fibrosis

Dermal fibrosis is characterized by excessive deposition of extracellular matrix in the dermis and affects millions of people worldwide and causes limited movement, disfigurement and psychological distress in patients. Fibroblast dysfunction of plays a central role in the pathogenesis of dermal fibrosis and is controlled by distinct factors. Recent studies support the hypothesis that fibroblasts can drive matrix deposition and stiffening, which in turn can exacerbate the functional dysregulation of fibroblasts. Ultimately, through a positive feedback loop, uncontrolled pathological fibrosis develops. This review aims to summarize the phenomenon and mechanism of the positive feedback loop in dermal fibrosis, and discuss potential therapeutic targets to help further elucidate the pathogenesis of dermal fibrosis and develop therapeutic strategies. In this review, fibroblast-derived compositional and structural changes in the ECM that lead to altered mechanical properties are briefly discussed. We focus on the mechanisms by which mechanical cues participate in dermal fibrosis progression. The mechanosensors discussed in the review include integrins, DDRs, proteoglycans, and mechanosensitive ion channels. The FAK, ERK, Akt, and Rho pathways, as well as transcription factors, including MRTF and YAP/TAZ, are also discussed. In addition, we describe stiffness-induced biological changes in the ECM on fibroblasts that contribute to the formation of a positive feedback loop. Finally, we discuss therapeutic strategies to treat the vicious cycle and present important suggestions for researchers conducting in-depth research.

Stretching Promotes Wound Contraction Through Enhanced Expression of Endothelin Receptor B and TRPC3 in Fibroblasts

One factor that can contribute to the development of hypertrophic scar contracture is mechanical stress. Mechanical cyclic stretch stimuli enhance the secretion of endothelin-1 (ET-1) from keratinocyte. Cyclical stretching of fibroblasts also increases the expression level of the transient receptor potential ion channel (TRPC3), which is known to couple with the endothelin receptor and induce intracellular Ca2+ signaling via the calcineurin/nuclear factor of activated T cells (NFAT) pathway. The aim of this study was to investigate the relationship between keratinocytes and fibroblasts when they are stretched.

Methods

The conditioned medium from stretched keratinocyte was added to the fibroblast populated collagen lattice. Then, we analyzed the levels of endothelin receptor in the human hypertrophic scar tissue and stretched fibroblasts. To address the function of TRPC3, we have used an overexpression system with the collagen lattice. Finally, the TRPC3 overexpressing fibroblasts were transplanted to mouse dorsal skin, and the rate of skin wound contraction was assessed.

Results

Conditioned medium from stretched keratinocytes increased the rate of contraction of fibroblast populated collagen lattice. In human hypertrophic scar and stretched fibroblasts, endothelin receptor type B was increased. Cyclic stretching of TRPC3 overexpressing fibroblasts activated NFATc4, and stretched human fibroblasts showed more activation of NFATc4 in response to ET-1. The wound treated with TRPC3 overexpressing fibroblasts showed more contraction than control wound.

Conclusion

These findings suggest that cyclical stretching of wounds have an effect on both keratinocytes and fibroblasts, where keratinocytes secret more ET-1, and fibroblasts develop more sensitivity to ET-1 by expressing more endothelin receptors and TRPC3.

Cyclical Stretching Induces Excess Intracellular Ca2+ Influx in Human Keloid-Derived Fibroblasts In Vitro

BACKGROUND

The incidence of keloids is higher in the case of darker skin. It is more common in the parts exposed to stretching (thorax, abdomen, and joints). Cyclical stretching reportedly induced each Ca2+ spike through differential mechanosensitive channels in human synovial and dermal fibroblasts. Therefore, the authors hypothesized that cyclical stretching also induces a specific Ca2+ spike in keloid-derived fibroblasts.

METHODS

This in vitro study compared the intracellular calcium dynamics induced by cyclical stretching between control (human dermal fibroblasts) and keloid (human keloid-derived fibroblasts) groups. Each group was exposed to two-dimensional stretch using an originally developed stretch microdevice. Intracellular Ca2+ was observed for 5 minutes, including 30 seconds of baseline, under a fluorescent confocal laser microscope. The intracellular Ca2+ concentration was evaluated every 0.5 second using the fluorescence intensity ratio. A positive cellular response was defined as a rise of the ratio by greater than or equal to 20%. The normal response cutoff value was determined by receiver operating characteristic analysis.

RESULTS

The keloid groups were significantly more responsive than the control groups (15.7% versus 8.2%; P = 0.029). In the cellular response-positive cells, the keloid groups reached significantly higher intracellular Ca2+ concentration peaks than the control groups (2.20 versus 1.26; P = 0.0022). The cutoff value was 1.77, and 10.4% of the keloid-derived fibroblasts exhibited a hyper-Ca2+ spike above the normal range.

CONCLUSIONS

Keloid-derived fibroblasts with a hyper-Ca2+ spike might constitute a keloid-specific subpopulation. Hereafter, the authors will study whether the normalization of excessive intracellular Ca2+ concentration leads to keloid treatment in vivo.

CLINICAL RELEVANCE STATEMENT

This study result provided a clue to the onset mechanism of keloids, which the authors hope will lead to the development of new therapy in the future.

Mechanotransduction in skin wound healing and scar formation: Potential therapeutic targets for controlling hypertrophic scarring

Hypertrophic scarring (HTS) is a major source of morbidity after cutaneous injury. Recent studies indicate that mechanical force significantly impacts wound healing and skin regeneration which opens up a new direction to combat scarring. Hence, a thorough understanding of the underlying mechanisms is essential in the development of efficacious scar therapeutics. This review provides an overview of the current understanding of the mechanotransduction signaling pathways in scar formation and some strategies that offload mechanical forces in the wounded region for scar prevention and treatment.

Skin biomechanics: a potential therapeutic intervention target to reduce scarring

Pathological scarring imposes a major clinical and social burden worldwide. Human cutaneous wounds are responsive to mechanical forces and convert mechanical cues to biochemical signals that eventually promote scarring. To understand the mechanotransduction pathways in cutaneous scarring and develop new mechanotherapy approaches to achieve optimal scarring, the current study highlights the mechanical behavior of unwounded and scarred skin as well as intra- and extracellular mechanisms behind keloid and hypertrophic scars. Additionally, the therapeutic interventions that promote optimal scar healing by mechanical means at the molecular, cellular or tissue level are extensively reviewed. The current literature highlights the significant role of fibroblasts in wound contraction and scar formation via differentiation into myofibroblasts. Thus, understanding myofibroblasts and their responses to mechanical loading allows the development of new scar therapeutics. A review of the current clinical and preclinical studies suggests that existing treatment strategies only reduce scarring on a small scale after wound closure and result in poor functional and aesthetic outcomes. Therefore, the perspective of mechanotherapies needs to consider the application of both mechanical forces and biochemical cues to achieve optimal scarring. Moreover, early intervention is critical in wound management; thus, mechanoregulation should be conducted during the healing process to avoid scar maturation. Future studies should either consider combining mechanical loading (pressure) therapies with tension offloading approaches for scar management or developing more effective early therapies based on contraction-blocking biomaterials for the prevention of pathological scarring.

Healing Mechanisms in Cutaneous Wounds: Tipping the Balance

Acute and chronic cutaneous wounds pose a significant health and economic burden. Cutaneous wound healing is a complex process that occurs in four distinct, yet overlapping, highly coordinated stages: hemostasis, inflammation, proliferation, and remodeling. Postnatal wound healing is reparative, which can lead to the formation of scar tissue. Regenerative wound healing occurs during fetal development and in restricted postnatal tissues. This process can restore the wound to an uninjured state by producing new skin cells from stem cell reservoirs, resulting in healing with minimal or no scarring. Focusing on the pathophysiology of acute burn wounds, this review highlights reparative and regenerative healing mechanisms (including the role of cells, signaling molecules, and the extracellular matrix) and discusses how components of regenerative healing are being used to drive the development of novel approaches and therapeutics aimed at improving clinical outcomes. Important components of regenerative healing, such as stem cells, growth factors, and decellularized dermal matrices, are all being evaluated to recapitulate more closely the natural regenerative healing process.

Expression of NF-κB-p65 and α-SMA in the Study of Capsules formed by Surface Textured Implants Versus Foam Covered Silicone Implants in a Rat Model

BACKGROUND

We aimed to compare inflammatory and intercellular transcription responses induced by surface textured (ST) implants versus foam covered (FC) silicone implants placed on the dorsal aspect of rats.

METHODS

We utilized 80 female rats of the Wistar lineage. The rats were divided into four subgroups of 20 with one type of implant placed in the dorsum per rat. Analysis was carried out on peri-implant capsules at 90 d and at 180 d post-surgery with microscopic evaluation of inflammatory and immuno-histochemical response of NF-κB-p65 and α-SMA in fibroblasts. This study was carried out at the Evangelical Faculty of Parana and at the Ivo Pitanguy Institute, Brazil in 2015.

RESULTS

The FC exhibited higher levels of acute and chronic inflammation on evaluation in both time frames. The capsule surrounding the ST implants was significantly thicker with well-organized collagen fibres. NFκB-p65 expression in the capsule surrounding the FC implant was more pronounced. There was higher and more significant α-SMA expression in the capsules of the surface textured (ST) silicone implants compared to the foam-covered (FC) silicone implants.

CONCLUSION

Activation of NFκB-p65 plays a key role in the evolution of capsule formation and maintenance of inflammation by regulating the healing process. Similarly, higher and more prolonged levels of inflammation (increased NF-κB-p65 results in increased inflammation) and lower α-SMA (higher α-SMA is protective against capsular contracture) did not directly translate to a thicker capsule and ultimately, capsular contracture in foam covered silicone implants.

Treatment of Severe Postburn Contracture of the Elbow via Distraction With External Circular Frame in Pediatric Patient

BACKGROUND

Although external circular frame (ECF) has been widely used for the correction of knee and ankle deformities, few studies reported the use of ECF for the treatment of severe postburn elbow contracture and stiffness (SPECS). The purpose of this retrospective study was to investigate the effectiveness and safety of the distraction using ECF in treating SPECS.

METHODS

After institutional review board approval, we implemented a retrospective single-center case series study composed of consecutive patients treated for SPECS at Chinese PLA General Hospital between January 2010 and January 2018. After scar release and skin grafting, distraction with ECF was performed for 4 to 6 weeks, and the frame was retained for 2 more weeks before removal. Four weeks of splinting and at least 1 year of rehabilitation were recommended. Patient demographics, active and passive range of motion (ROM) of the elbow at different time points (preoperative, postdistraction, and final follow-up), and complications were collected from the electronic medical record. The primary outcome was the long-term improvement of the ROM. Other outcomes included complications and recurrence.

RESULTS

The ECF was used to treat SPECS in 6 patients (3 males and 3 females, average age of 11.7 ± 2.6 years). Scar release and distraction with ECF significantly increased both active (from 3° preoperative to 38.7° postdistraction) and passive (from 3.5° preoperative to 48.3° postdistraction) ROM over an average distraction duration of 5.2 weeks. The long-term improvement of active and passive ROM was 38° ± 13.4° and 46° ± 14.7°, respectively, over a median follow-up of 4.1 years. Pin-tract infection occurred in 2 patients and were treated with local wound care and oral antibiotics. A tendon readhesion developed in 1 of the 6 patients because of noncompliance with splinting and physiotherapy, and was treated with revision surgery.

CONCLUSIONS

The 3C strategy (i.e., contracture release, coverage of the defect with skin grafting, and correction of articular angle with gradual distraction using the ECF) is able to increase the ROM with minor complications. We recommend distraction with ECF as part of the treatment arsenal, particularly for severe contractures in which 1-stage correction is unfeasible because of considerable soft tissue shortening.

[Roles of interleukin-6/signal transduction and activator of transcription 3 pathway and -catenin in mechanical stress-induced hypertrophic scar formation in mice]

Objective: To establish mechanical stress-induced hypertrophic scar mouse models, and to examine the roles of interleukin-6/signal transduction and activator of transcription 3 (IL-6/STAT3) pathway and β-catenin. Methods: The experimental research method was used. Sixteen female C57/BL6 mice of 12-week-old were collected and two straight full-thickness skin incisions of 2 cm in length were inflicted on the back of each mouse. On the fourth day post injury, the two wounds on the back of each mouse were divided into mechanical traction group and blank control group according to the random number table method, with 16 wounds in each group. The wounds in mechanical traction group were given continuous mechanical traction for 14 days, while the wounds in blank control group were given no treatment. After 14 days of mechanical traction for wounds in mechanical traction group, the appearances of the scar tissue in wounds of 2 groups were visually observed, and the areas of scars were measured; the morphological changes of the scar tissue in wounds of 2 groups were observed by hematoxylin-eosin staining, and the cross-sectional areas of scars were measured; the content of IL-6 in supernatant of the scar tissue in wounds of 2 groups was detected by enzyme-linked immunosorbent assay; the protein expression of phosphorylated STAT3 (p-STAT3) of the scar tissue in wounds of 2 groups was detected by Western blotting; and the expression of β-catenin of the scar tissue in wounds of 2 groups was detected by immunohistochemistry. Data were statistically analyzed with paired sample t test. Results: Red hairless area similar to human scar tissue formed in wounds of mechanical traction group after 14 days of mechanical traction, with large area of scar, thickened local area, hardened texture, and some even slightly raised, while scar in wounds of blank control group was linear and not obvious. After 14 days of mechanical traction for wounds in mechanical traction group, the scar area of wounds in mechanical traction group was (5.65±0.95) mm2, which was significantly larger than (1.07±0.28) mm2 in blank control group (t=26.333, P<0.01). After 14 days of mechanical traction for wounds in mechanical traction group, the skin appendages of scar tissue were absent, and the dermis hyperplasia was active and obviously thickened, while skin appendages of scar tissue of wounds in blank control group were still present, with unconspicuous dermis hyperplasia; the cross-sectional area of scar in wounds of mechanical traction group was (0.82±0.23) mm2, which was significantly larger than (0.29±0.07) mm2 of blank control group (t=8.879, P<0.01). After 14 days of mechanical traction for wounds in mechanical traction group, the content of IL-6 in the supernatant of scar tissue and the protein expression of p-STAT3 in scar tissue of wounds in mechanical traction group were significantly higher than those in blank control group (t=37.552, 25.863, P<0.01). The expression of β-catenin was high in the scar tissue of wounds in mechanical traction group after 14 days of mechanical traction, while that in blank control group was low. Conclusions: The study successfully establishes mechanical stress-induced hypertrophic scar mouse models. Mechanical stress can participate in wound healing and induce scar hyperplasia of mice wounds through continuous or overexpression of IL-6/STAT3 pathway, and β-catenin can also promote the formation of hypertrophic scar.

TRPV4 integrates matrix mechanosensing with Ca2+ signaling to regulate extracellular matrix remodeling

In healthy connective tissues, mechanosensors trigger the generation of Ca²⁺ signals, which enable cells to maintain the structure of the fibrillar collagen matrix through actomyosin contractile forces. Transient receptor potential vanilloid type 4 (TRPV4) is a mechanosensitive Ca²⁺ -permeable channel that, when expressed in cell-matrix adhesions of the plasma membrane, regulates extracellular matrix (ECM) remodeling. In high prevalence disorders such as fibrosis and tumor metastasis, dysregulated matrix remodeling is associated with disruptions of Ca²⁺ homeostasis and TRPV4 function. Here, we consider that ECM polymers transmit cell-activating mechanical signals to TRPV4 in cell adhesions. When activated, TRPV4 regulates fibrillar collagen remodeling, thereby altering the mechanical properties of the ECM. In this review, we integrate functionally connected processes of matrix remodeling to highlight how TRPV4 in cell adhesions and matrix mechanics are reciprocally regulated through Ca²⁺ signaling.

Modulation of Extracellular Matrix by Scrophularia striata Extract in Vitro: A Potential Antiscarring Agent

Background: Hypertrophic scars are the consequences of the aberration of normal wound healing. To date, therapeutic strategies for abnormal scarring have been unsuccessful. ‎‏The abnormal extracellular‎ matrix is one of the most important contributing factors to ‎hypertrophic scars. ‏Scrophularia striata has been used in Iranian folk medicine for the treatment of burn wounds. ‏The plant extract accelerates wound healing and attenuates scar formation. Objectives: The study was performed to investigate the effects of Scrophularia striata hydroalcoholic extract (SSE) on MMP1, MMP8, fibronectin, collagen type I, and total collagen produced by human skin fibroblasts in the culture medium. Methods: The effects of SSE on the expression of MMP1, MMP8, fibronectin, and collagen type I in human skin fibroblast (HSF) were evaluated using Q-PCR and Western blotting methods. In addition, the effect of SSE on the total collagen content was measured in cultured HSF using Red Sirius Kit. Results: SSE significantly induced the expression of MMP1 and suppressed the production of fibronectin at the mRNA and protein levels. The total collagen content was significantly lower in SSE-treated cells than in untreated cells. SSE did not have any significant effect on MMP8 and collagen type I expression. Conclusions: The results of this study revealed that SSE could modulate the extracellular matrix turnover and had the potential for the prevention and treatment of hypertrophic scars.

Mechanical stretching of pulmonary vein stimulates matrix metalloproteinase-9 and transforming growth factor-β1 through stretch-activated channel/MAPK pathways in pulmonary hypertension due to left heart disease model rats

Pulmonary hypertension due to left heart disease (PH-LHD) is a momentous pulmonary hypertension disease, and left heart disease is the most familiar cause. Mechanical stretching may be a crucial cause of vascular remodeling. While, the underlining mechanism of mechanical stretching-induced in remodeling of pulmonary vein in the early stage of PH-LHD has not been completely elucidated. In our study, the PH-LHD model rats were successfully constructed. After 25 days, doppler echocardiography and hemodynamic examination were performed. In addition, after treatment, the levels of matrix metalloproteinase-9 (MMP-9) and transforming growth factor-β1 (TGF-β1) were determined by ELISA, immunohistochemistry and western blot assays in the pulmonary veins. Moreover, the pathological change of pulmonary tissues was evaluated by H&E staining. Our results uncovered that left ventricular insufficiency and interventricular septal shift could be observed in PH-LHD model rats, and the right ventricular systolic pressure (RVSP) and mean left atrial pressure (mLAP) were also elevated in PH-LHD model rats. Meanwhile, we found that MMP-9 and TGF-β1 could be highly expressed in PH-LHD model rats. Besides, we revealed that stretch-activated channel (SAC)/mitogen-activated protein kinases (MAPKs) signaling pathway could be involved in the upregulations of MMP-9 and TGF-β1 mediated by mechanical stretching in pulmonary vein. Therefore, current research revealed that mechanical stretching induced the increasing expressions of MMP-9 and TGF-β1 in pulmonary vein, which could be mediated by activation of SAC/MAPKs signaling pathway in the early stage of PH-LHD.

Evidence-based therapy in hypertrophic scars: An update of a systematic review

Hypertrophic scars are still a major burden for numerous patients, especially after burns. Many treatment options are available; however, no evidence-based treatment protocol is available with recommendations mostly emerging from experience or lower quality studies. This review serves to discuss the currently available literature. A systematic review was performed and the databases PubMed and Web of Science were searched for suitable publications. Only original articles in English that dealt with the treatment of hypertrophic scars in living humans were analyzed. Further, studies with a level of evidence lower than 1 as defined by the American Society of Plastic Surgeons were excluded. After duplicate exclusion, 1638 studies were screened. A qualitative assessment yielded 163 articles eligible for evidence grading. Finally nine studies were included. Four of them used intralesional injections, four topical therapeutics and one assessed the efficacy of CO₂ -laser. Intralesional triamcinolone + fluorouracil injections, and topical pressure and/or silicone therapy revealed significant improvements in terms of scar height, pliability, and pigmentation. This systematic review showed that still few high-quality studies exist to evaluate therapeutic means and their mechanisms for hypertrophic scars. Among these, most of them assessed the efficacy of intralesional triamcinolone injections with the same treatment protocol. Intralesional injection appears to be the best option for hypertrophic scar treatment. Future studies should focus on a possible optimization of infiltrative therapies, consistent end-point evaluations, adequate follow-up periods, and possibly intraindividual treatments.

Calcium in Cell-Extracellular Matrix Interactions

In multicellular organisms, the cells are surrounded by persistent, dynamic extracellular matrix (ECM), the largest calcium reservoir in animals. ECM regulates several aspects of cell behavior including cell migration and adhesion, survival, gene expression and differentiation, thus playing a significant role in health and disease. Calcium is reported to be important in the assembly of ECM, where it binds to many ECM proteins. While serving as a calcium reservoir, ECM macromolecules can directly interact with cell surface receptors resulting in calcium transport across the membrane. This chapter mainly focusses on the role of cell-ECM interactions in cellular calcium regulation and how calcium itself mediates these interactions.

Hyaluronic acid hydrogel loaded by adipose stem cells enhances wound healing by modulating IL-1β, TGF-β1, and bFGF in burn wound model in rat

Application of hydrogels can be an effective technique in transferring the adipose-derived stem cells (ASCs) to injured tissue and their protection from further complications. Besides, acellular dermal matrix (ADM) has successfully been used in treatment of wounds. In this study, a combination of hylauronic acid (HA) and ASCs (HA/ASCs) was applied on burn wounds and the injured area was then covered by an ADM dressing in a rat model (ADM-HA/ASCs). Wound healing was evaluated by histopathological, histomorphometrical, molecular, biochemical, and scanning electron microscopy assessments on days 7, 14, and 28 post-wounding. ADM-HA/ASCs stimulated healing significantly more than the ADM-HA and ADM treated wounds, as it led to reduced inflammation, and improved angiogenesis and enhanced granulation tissue formation. Expression of interleukin-1β (IL-1β) and transforming growth factor-β1 (TGF-β1) was lower in the ADM-HA/ASCs treated wounds than the ADM-HA and ADM groups, at the seventh post-wounding day. ADM-HA/ASCs also enhanced the expression level of TGF-β1 mRNA at 14 day post-wounding that was parallel to the experimental data from histological and biochemical assessments and confirmed the positive role of ASCs in repair of burn wounds. Additionally, increase in basic fibroblast growth factor (bFGF) expression and decreased TGF-β1 level on the 28th post-wounding day indicated the anti-scarring activity of ASCs. HA loaded by adipose stem cells can represent a promising strategy in accelerating burn wound healing.

Aligned Carbon Nanotubes Reduce Hypertrophic Scar via Regulating Cell Behavior

Hypertrophic scars, characterized by excessive cell proliferation, disordered cell growth, and aberrant deposition of collagens, could cause significant clinical problems. Herein, aligned carbon nanotubes (ACNTs) were synthesized via chemical vapor deposition, and bulk ACNTs were pulled out from the arrays. The capacity of the ACNTs to reduce hypertrophic scar formation was evaluated both in vitro and in vivo. The results demonstrated that the ACNTs suppressed the overproliferation of fibroblast cells, directed their growth, and inhibited collagen expression in vitro without cell cytotoxicity. Moreover, in vivo evaluation in a rabbit ear model indicated relieved scar hypertrophy after the ACNTs treatment. The gene expression microarray was further used to understand the mechanism, which showed that ACNTs could inhibit the TGFβ pathway to alter the components in the extracellular matrix, cell proliferation, cell cytoskeleton, and cell motility. These findings may provide a potent strategy of using carbon nanotubes in the bioengineering field.

Mechanobiological Feedback in Pulmonary Vascular Disease

Vascular stiffening in the pulmonary arterial bed is increasingly recognized as an early disease marker and contributor to right ventricular workload in pulmonary hypertension. Changes in pulmonary artery stiffness throughout the pulmonary vascular tree lead to physiologic alterations in pressure and flow characteristics that may contribute to disease progression. These findings have led to a greater focus on the potential contributions of extracellular matrix remodeling and mechanical signaling to pulmonary hypertension pathogenesis. Several recent studies have demonstrated that the cellular response to vascular stiffness includes upregulation of signaling pathways that precipitate further vascular remodeling, a process known as mechanobiological feedback. The extracellular matrix modifiers, mechanosensors, and mechanotransducers responsible for this process have become increasingly well-recognized. In this review, we discuss the impact of vascular stiffening on pulmonary hypertension morbidity and mortality, evidence in favor of mechanobiological feedback in pulmonary hypertension pathogenesis, and the major contributors to mechanical signaling in the pulmonary vasculature.

TRPV2 channel inhibitors attenuate fibroblast differentiation and contraction mediated by keratinocyte-derived TGF-β1 in an in vitro wound healing model of rats

BACKGROUND

Keratinocytes release several factors that are involved in wound contracture and scar formation. We previously reported that a three-dimensional reconstruction model derived from rat skin represents a good wound healing model.

OBJECTIVE

We characterized the role of transient receptor potential (TRP) channels in the release of transforming growth factor (TGF)-β1 from keratinocytes and the differentiation of fibroblasts to identify possible promising pharmacological approaches to prevent scar formation and contractures.

METHODS

The three-dimensional culture model was made from rat keratinocytes seeded on a collagen gel in which dermal fibroblasts had been embedded.

RESULTS

Among the TRP channel inhibitors tested, the TRPV2 inhibitors SKF96365 and tranilast attenuated most potently keratinocyte-dependent and - independent collagen gel contraction due to TGF-β signaling as well as TGF-β1 release from keratinocytes and α-smooth muscle actin production in myofibroblasts. Besides the low amounts detected in normal dermis, TRPV2 mRNA and protein levels were increased after fibroblasts were embedded in the gel. TRPV2 was also expressed in the epidermis and keratinocyte layers of the model. Both inhibitors and TRPV2 siRNA attenuated the intracellular increase of Ca²⁺ induced by the TRPV agonist 2-aminoethoxydiphenyl borate in TGF-β1-pretreated fibroblasts.

CONCLUSION

This is the first study to show that compounds targeting TRPV2 channels ameliorate wound contraction through the inhibition of TGF-β1 release and the differentiation of dermal fibroblasts in a culture model.

Inactivation of Beclin-1-dependent autophagy promotes ursolic acid-induced apoptosis in hypertrophic scar fibroblasts

A hypertrophic scar (HS) is caused by abnormal proliferation of dermal fibroblasts. Thus, promoting hypertrophic scar fibroblast (HSFB) apoptosis is an effective strategy for HS therapy. Ursolic acid (UA) has been widely used as an inducer of apoptosis in diverse cancers. However, whether UA plays an inhibitory role in HS formation is still unknown. In our study, UA was used to treat HSFBs and the cell viability, apoptosis, and collagen synthesis were determined by a Cell Counting Kit 8 assay, flow cytometry, and an H3 -proline incorporation assay, respectively. Autophagy activity was detected by LC3 immunoblotting and electron microscopy, and siRNAs targeting Beclin-1 were used to inhibit autophagy. Western blotting was performed to investigate the molecular changes in HSFBs after various treatments. We found that UA inhibited collagen synthesis and induced cell apoptosis in HSFBs, evidenced by the deregulated expression of Bim, Bcl-2 and Cyto C. Furthermore, we demonstrated that UA induced autophagy and inactivation of autophagy promoted UA-induced apoptosis and collagen synthesis inhibition in HSFBs. Molecular investigation indicated that UA-induced autophagy through upregulation of Beclin-1 and knockdown of Beclin-1 prevent UA-induced autophagy. Overexpression of Bcl-2 prevents UA-induced autophagy, Beclin-1 upregulation, apoptosis and collagen synthesis inhibition in HSFBs. Collectively, our study demonstrated that UA is a novel agent for inhibiting HS formation by promoting apoptosis, especially in combination with an autophagy inhibitor. Our results provide strong evidence of the application of UA in clinical HS treatment.

Activation of TRPV3 Regulates Inflammatory Actions of Human Epidermal Keratinocytes

Transient receptor potential (TRP) ion channels were first characterized on neurons, where they are classically implicated in sensory functions; however, research in recent decades has shown that many of these channels are also expressed on nonneuronal cell types. Emerging findings have highlighted the role of TRP channels in the skin, where they have been shown to be important in numerous cutaneous functions. Of particular interest is TRPV3, which was first described on keratinocytes. Its functional importance was supported when its gain-of-function mutation was linked to Olmsted syndrome, which is characterized by palmoplantar keratoderma, periorifacial hyperkeratosis, diffuse hypotrichosis and alopecia, and itch. Despite these exciting results, we have no information about the role and functionality of TRPV3 on keratinocytes at the cellular level. In this study, we identified TRPV3 expression both on human skin and cultured epidermal keratinocytes. TRPV3 stimulation was found to function as a Ca²⁺-permeable ion channel that suppresses proliferation of epidermal keratinocytes and induces cell death. Stimulation of the channel also triggers a strong proinflammatory response via the NF-κB pathway. Collectively, our data show that TRPV3 is functionally expressed on human epidermal keratinocytes and that it plays a role in cutaneous inflammatory processes.

Inflammatory cytokine IL6 cooperates with CUDR to aggravate hepatocyte-like stem cells malignant transformation through NF-κB signaling

Inflammatory cytokines and lncRNAs are closely associated with tumorigenesis. Herein, we reveal inflammatory cytokines IL6 cooperates with long noncoding RNA CUDR to trigger the malignant transformation of human embryonic stem cells-derived hepatocyte-like stem cells. Mechanistically, IL6 cooperates with CUDR to cause MELLT3 to interact with SUV39h1 mRNA3′UTR and promote SUV39h1 expression. Moreover, the excessive SUV39h1 also increases tri-methylation of histone H3 on nineth lysine (H3K9me3). Intriguingly, under inflammatory conditions, H3K9me3 promotes the excessive expression and phosphorylation of NF-κB, and in turn, phorsphorylated NF-κB promotes the expression and phosphorylation of Stat3. Furthermore, that the phosphorylated Stat3 loads onto the promoter region of miRs and lncRNAs. Ultimately, the abnormal expression of miRs and lncRNAs increased telomerase activity, telomere length and microsatellite instability (MSI), leading to malignant transformation of hepatocyte-like stem cells.