Mechanism Of Scar Formation Research Articles

Mechanism of scar formation following Roux-en-Y choledochojejunostomy in a novel rat model of obstructive jaundice.

BackgroundThe present study aimed to analyze the scar formation mechanism following Roux-en-Y choledochojejunostomy (CJS) in a novel rat model of obstructive jaundice.MethodsThe biliary obstruction model of Sprague-Dawley (SD) rats was established in advance, and 24 rats were randomly divided into 4 groups (control group, 1-day ligation group, 3-day ligation group, and 5-day ligation group). Changes in postoperative weight, common bile duct diameter, and laboratory indexes were analyzed to determine the best operation time. Roux-en-Y CJS in rats was studied based on the model, and the rats were randomly divided into 4 groups [control group, 3-day choledochojejunostomy (CJS) group, 7-day CJS group, and 30-day CJS group]. The same indexes were analyzed, and the characteristics of scar formation were evaluated by histopathology and polymerase chain reaction examination.ResultsThe third day after common bile duct ligation is the best time for a Roux-en-Y CJS. The common bile duct diameter expands to 4.2 mm on average, and these physiological characteristics are consistent with current standard clinical findings. After completing CJS, the rats’ weight returned to normal levels, and alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TB), direct bilirubin (DB), and C-reactive protein (CRP) indexes gradually decreased (P<0.05). Anastomotic stoma diameter tended to narrow with time and was significantly narrower on day 30 than preoperation. After CJS, the expression of α-smooth muscle actin (α-SMA) peaked in the early stage and was still higher than that of the control group in the bile duct wall 1 month postoperatively (P<0.05). Transforming growth factor-β1 (TGF-β1) expression gradually increased and was higher than that of the control group at each stage postoperatively (P<0.05).ConclusionsThe rat Roux-en-Y CJS model is more in line with our surgical model, and the clinical condition has potential applicability for the study of CJS scar formation. Scar formation following CJS in rats is characterized by the activation of fibroblasts caused by early inflammatory stimulation, which leads to the proliferation of collagen and smooth muscle fibers, resulting in scars.

IL-10 alleviates lipopolysaccharide-induced skin scarring via IL-10R/STAT3 axis regulating TLR4/NF-κB pathway in dermal fibroblasts.

Hypertrophic scar (HS) is a severe fibrotic skin disease. It has always been a major problem in clinical treatment, mainly because its pathogenesis has not been well understood. The roles of bacterial contamination and prolonged wound inflammation were considered significant. IL‐10 is a potent anti‐inflammatory cytokine and plays a pivotal role in wound healing and scar formation. Here, we investigate whether IL‐10 alleviates lipopolysaccharide (LPS)‐induced inflammatory response and skin scarring and explore the possible mechanism of scar formation. Our results showed that the expression of TLR4 and pp65 was higher in HS and HS‐derived fibroblasts (HSFs) than their counterpart normal skin (NS) and NS‐derived fibroblasts (NSFs). LPS could up‐regulate the expression of TLR4, pp65, Col I, Col III and α‐SMA in NSFs, but IL‐10 could down‐regulate their expression in both HSFs and LPS‐induced NSFs. Blocking IL‐10 receptor (IL‐10R) or the phosphorylation of STAT3, their expression was up‐regulated. In addition, in vitro and in vivo models results showed that IL‐10 could alleviate LPS‐induced fibroblast‐populated collagen lattice (FPCL) contraction and scar formation. Therefore, IL‐10 alleviates LPS‐induced skin scarring via IL‐10R/STAT3 axis regulating TLR4/NF‐κB pathway in dermal fibroblasts by reducing ECM proteins deposition and the conversion of fibroblasts to myofibroblasts. Our results indicate that IL‐10 can alleviate the LPS‐induced harmful effect on wound healing, reduce scar contracture, scar formation and skin fibrosis. Therefore, the down‐regulation of inflammation may lead to a suitable scar outcome and be a better option for improving scar quality.

The Roles of Inflammation in Keloid and Hypertrophic Scars

The underlying mechanisms of wound healing are complex but inflammation is one of the determining factors. Besides its traditional role in combating against infection upon injury, the characteristics and magnitude of inflammation have dramatic impacts on the pathogenesis of scar. Keloids and hypertrophic scars are pathological scars that result from aberrant wound healing. They are characterized by continuous local inflammation and excessive collagen deposition. In this review, we aim at discussing how dysregulated inflammation contributes to the pathogenesis of scar formation. Immune cells, soluble inflammatory mediators, and the related intracellular signal transduction pathways are our three subtopics encompassing the events occurring in inflammation associated with scar formation. In the end, we enumerate the current and potential medicines and therapeutics for suppressing inflammation and limiting progression to scar. Understanding the initiation, progression, and resolution of inflammation will provide insights into the mechanisms of scar formation and is useful for developing effective treatments.

New research advances and clinical treatment of scar

Scar formation is the abnormal healing process of skin after being damaged. The mechanism of scar formation is not clear, and many studies have shown that it is affected by many factors. Based on the over deposition of collagen in scars, many researchers have carried out studies on the mechanism, pathological manifestation, and treatment method of scars. In the treatment aspect of scar, the combination of traditional and new treatment methods has been well accepted and achieved good results. To understand the new advances of scar research and combine it with clinical treatment transformation could lead to the development of more effective prophylactic and therapeutic strategies for scar treatment in the future.

Reconsideration of burn scar treatment

Since the mechanisms of scar formation are not fully understood, at least to date, there is no ideal method to prevent and treat scar after burn. In recent years, on the basis of conventional treatments, such as pressure therapy, external use of silicone gel, and intralesional injections of corticosteroids, the therapeutic approaches of fractional carbon dioxide laser treatment, injection of anti-vascular endothelial growth factor antibody, autologous fat transplantation, injection of botulinum toxin A, radiation therapy etc., have been gradually applied to treat burn scars. It is very important to select various methods individually and comprehensively according to the specific conditions of patients and scars. Meanwhile, it is necessary to continue to study and explore the possibility of targeted therapy in scar management.

Abstract 17995: Inhibition of Myofibroblast Differentiation by FOXO3a - Implications for Acute Myocardial Infarction and Cardiac Remodeling

Introduction: Transdifferentiation of cardiac fibroblasts into myofibroblasts regulated by TGFβ/SMAD3 signaling is a major mechanism of scar formation and adverse remodeling following myocardial infarction. Hypothesis: We hypothesized that the transcription factor FOXO3a, a key regulator of cell differentiation, cycle and size, might inhibit this process. Methods: Acute myocardial infarction was induced in FOXO3-/- and WT mice (FVB) by permanent LAD ligation and myofibroblast transdifferentiation markers were assessed. FOXO3a-/- and WT cardiac fibroblasts were investigated in transdifferentiation assays ex vivo. FOXO3a gene transfer was performed with gain of function adenoviral vectors. IP/IF and Western blotting were used to test for a direct interaction between FOXO3a and SMAD3. Results: FOXO3a-/- mice had significantly higher survival rates compared to WT mice due to reduced rates of ventricle perforation. Myocardial expression of alpha smooth muscle actin (ASMA) and Collagen1A1 (Col1A1) was significantly enhanced in FOXO3a-/- mice 3 and 14 days post infarction. Moreover, Foxo3a-/- mice showed larger fibrotic areas following MI. In line with these results, cardiac fibroblasts isolated from FOXO3a-/- mice showed significantly enhanced expression levels of Col1A1 and ASMA 24 hours following stretch or TGF-β stimulation when compared to WT cells in vitro. Furthermore supernatants of FOXO3a -/- fibroblasts showed significantly higher protein expression of Col1A1 in (p&lt;0.01) while FOXO3a gene-transfer dose-dependently downregulated Col1A1. Immunfluorescence staining for ASMA protein was significantly attenuated following FOXO3a gene transfer in cardiac fibroblasts. Mechanistically, immunoprecipitation showed direct interaction of FOXO3a with SMAD3a that was enhanced following activation of the transcription factor leading to diminished SMAD3 downstream gene expression. Conclusions: Our results identify FOXO3a as a direct inhibitor of TGF- β regulated matrix remodeling via FOXO3a-SMAD3 interaction. FOXO3a regulates fibrosis and scar formation following myocardial infarction and thus targeting the FOXO3a-SMAD3 axis might be of therapeutic interest.

Human Gingival Fibroblasts Display a Non-Fibrotic Phenotype Distinct from Skin Fibroblasts in Three-Dimensional Cultures

Scar formation following skin injury can be a major psychosocial and physiological problem. However, the mechanisms of scar formation are still not completely understood. Previous studies have shown that wound healing in oral mucosa is faster, associates with a reduced inflammatory response and results to significantly reduced scar formation compared with skin wounds. In the present study, we hypothesized that oral mucosal fibroblasts from human gingiva are inherently distinct from fibroblasts from breast and abdominal skin, two areas prone to excessive scar formation, which may contribute to the preferential wound healing outcome in gingiva. To this end, we compared the phenotype of human gingival and skin fibroblasts cultured in in vivo-like three-dimensional (3D) cultures that mimic the cells' natural extracellular matrix (ECM) niche. To establish 3D cultures, five parallel fibroblast lines from human gingiva (GFBLs) and breast skin (SFBLs) were seeded in high density, and cultured for up to 21 days in serum and ascorbic acid containing medium to induce expression of wound-healing transcriptome and ECM deposition. Cell proliferation, morphology, phenotype and expression of wound healing and scar related genes were analyzed by real-time RT-PCR, Western blotting and immunocytochemical methods. The expression of a set of genes was also studied in three parallel lines of human abdominal SFBLs. Findings showed that GFBLs displayed morphologically distinct organization of the 3D cultures and proliferated faster than SFBLs. GFBLs expressed elevated levels of molecules involved in regulation of inflammation and ECM remodeling (MMPs) while SFBLs showed significantly higher expression of TGF-β signaling, ECM and myofibroblast and cell contractility-related genes. Thus, GFBLs display an inherent phenotype conducive for fast resolution of inflammation and ECM remodeling, characteristic for scar-free wound healing, while SFBLs have a profibrotic, scar-prone phenotype.

Abstract 353: Hdac Class I Inhibition Diminished Cd90+ Cardiac Fibroblast Activation Via Gsk3b/β-catenin Pathway.

Myofibroblast activation is one of the major mechanisms of scar formation and interstitial myocardial fibrosis after myocardial infarction (MI) and subsequent heart failure. Elucidating the mechanisms of myofibroblast activation will provide a strategy to treat heart failure. Histone Deacetylases (HDAC) were reported to regulate myofibroblast differentiation and extracellular matrix deposition in lung, kidney and liver fibrosis. Furthermore, HDAC inhibitors were shown to retard myocardial remodeling, interstitial fibrosis and improve cardiac function after MI. However, the mechanisms are unclear. Here we examined whether HDAC1/2 are up-regulated after MI, identify which myocardial cell type is predominately expressing HDAC, and examine the effects of HDAC inhibition on myocardial fibrosis. MI was created in rats by ligation of the left coronary artery. We found that, in sham rats, HDACs were uniformly expressed in both right and left ventriculars. On the other hand, we observed up-regulation of both HDAC1 and 2 in the infarcted LV following MI. In addition, HDAC1 and 2 were co-localized with cardiac fibroblast markers CD90, Vimentin, and αSMA in the infarcted area. Treatment of CD90+ cells isolated from both CHF and sham atrial culture with pan HDAC inhibitor (100 nM, or 300 nM) TSA diminished cardiac fibroblasts activation as indicated by the decrease in αSMA and the increase in E-cadherin gene expressions. Similarly, treatment of CD90 cells with a specific HDAC class I inhibitor (2 μM, Mocetinostat) upregulated E-cadherin and diminished the markers of fibrosis (αSMA, MMP-2, and Collagen III).The decrease in fibroblast activation by HDAC inhibition was associated with increase in p-Gsk3β/Gsk3β ratio and β-catenin protein content. In addition, Mocetinostat treatment of CD90+ cells up-regulated cleaved-Caspase3, an indicator of apoptosis. Taken together, diminishing cardiac fibroblast activation using HDAC class I inhibitor appears to be dependent on Gsk3β/β-catenin pathway.

The research of fibroblasts from human hypertrophic scar showing a mesenchymal stem cell phenotype and multilineage differentiation potentialities

To explore the CD phenotypic, protein expression and pluripotent differentiation of human hypertrophic scar fibroblasts cultured in vitro, so as to study the mechanisms of scar formation. Fibroblasts were isolated and cultured from human hypertrophic scar of 3 cases. The cells morphology was observed by inverted microscope, and the growing state of the third passage was detected by the cell counting meter of Vi-CELL. The cell surface markers CD105, CD14, CD73, CD34, CD44, CD45 and CD90 were identified by flow cytometry. The expression of CK19, Oct-4, Nanog and vimentin was detected by immunocytochemistry, and the expression of alpha-smooth muscle actin(alpha-SMA) was tested by immunofluorescence. The differentiated potential of fibroblasts of the third passage into adipogenic, osteogenic and chondrogenic lineages was assayed. The primary passage fibroblasts showed the shape of spindle shaped or irregular polygon with a radiated or circinate of growing arrangement. The growth curve showed the cells growth was slow on the first and second day, and quick during the third to fifth day, which reached platform stage on the sixth or seventh day. The fibroblasts highly expressed mesenchymal stem cell surface markers-CD73, CD105, CD44, CD90, but not expressed hematopoietic stem cell surface markers-CD14, CD34, CD45 by flow cytometry. And positive expression of vimentin, Oct-4 and negative expression of CK19 were detected by Immunocytochemistry. Positive expression of alpha-SMA was also detected by immunofluorescence. Multidirectional differentiation induction indicated that the third passage cells could differentiate into adipogenic, osteogenic and chondrogenic lineages. Human hypertrophic scar-derived fibroblasts show the biologic characteristics of mesenchymal stem cells, which may play an important role in wound healing and hypertrophic scar formation.

Effects of transforming growth factor-β2 on human Tenon fibroblasts transformation and scarring after glaucoma filtration surgery

Background Research showed that transforming growth factor-β2 (TGF-β2) promotes scar formation.But its mechanism in scarring after glaucoma filtration surgery is worthy of studying.Objective This study was to investigate the effect of TGF-β2 on myofibroblast transition of human Tenon fibroblasts (HTFs) and scarring after glaucoma filtration surgery.Methods Tenon capsular tissue was obtained from 3 patients with strabismus during the surgery and was incubated in DMEM with 10％ fetal bovine serum (FBS).The cells were collected and passaged in the free-serum medium for 24 hours,and then 1,2,5,10,20 μg/L TGF-β2 was added into the medium respectively,to induce the transformation of HTFs,and 2 μg/L or 5 μg/L TGF-β2 was used to treat the HTFs for 6,24,48 and 72 hours.The control group was not treated with TGF-β2.The expressions of α-smooth muscle actin (α-SMA) and phosphorylation of the signaling proteins (pSmad2) in HTFs were detected by Western blot assay.The expressions of α-SMA and F-actin were located by cell immunofluorescine technique under the confocal immunofluorescence microscopy.Cell contractility was determined by collagen gel contraction assays.This study was approved by Ethic Committee of Institute of Surgery Research of Daping Hospital,and informed consent was obtained from each patient or custodian initial of the study.Results The expression of α-SMA protein in the HTFs was increased significantly after the treatment of TGF-β2 in comparison with the control group and reached a peak at 24-48 hours.The α-SMA expression was gradually weakened in the 10 μg/L TGF-β2 groups.Little of α-SMA and F-actin were expressed in the control group.However,strong staining for α-SMA and F-actin were observed in the 1,2 and 5 μg/L TGF-β2 groups and then the staining weakened at the concentration of 10 μg/L.In addition,pSmad2 showed a stronger expression in the 2 μg/L TGF-β2 group than that in the PBS group and FBS group,with the strongest expression in 30 minutes through 2 hours.The untreated gel contracted (78.00±3.13)％ from its initial size,and contraction in the 1,2,5,10 μg/L TGF-β2 group were (63.88±1.78)％,(20.69±0.65)％,(19.49-±0.54)％,(16.24±0.84) ％,respectively,TGF-β2 increased HTFs contraction significantly (Fgroup =859.400,P =0.000).Conclusions TGF-β2 can induce transdifferentiation of Tenon fibroblast into myofibroblast and increase cell contractility,with a concentration-dependent and time-dependent pattern to an extent.It may be the mechanism of scar formation after glaucoma filter surgery. Key words: Transforming growth factor-β2 ; Glaucoma/filtering surgery; Scar; Tenon fibroblast; α-Smooth muscle actin

Effect of adenoviral mediated overexpression of fibromodulin on human dermal fibroblasts and scar formation in full-thickness incisional wounds

Fibromodulin, a member of the small leucine-rich proteoglycan family, has been recently suggested as a biologically significant mediator of fetal scarless repair. To assess the role of fibromodulin in the tissue remodeling, we constructed an adenoviral vector expressing human fibromodulin cDNA. We evaluated the effect of adenovirus-mediated overexpression of fibromodulin in vitro on transforming growth factors and metalloproteinases in fibroblasts and in vivo on full-thickness incisional wounds in a rabbit model. In vitro, we found that Ad-Fibromodulin induced a decrease of expression of TGF-beta(1) and TGF-beta(2) precursor proteins, but an increase in expression of TGF-beta(3) precursor protein and TGF-beta type II receptor. In addition, fibromodulin overexpression resulted in decreased MMP-1 and MMP-3 protein secretion but increased MMP-2, TIMP-1, and TIMP-2 secretion, whereas MMP-9 and MMP-13 were not influenced by fibromodulin overexpression. In vivo evaluation by histopathology and tensile strength demonstrated that Ad-Fibromodulin administration could ameliorate wound healing in incisional wounds. In conclusion, although the mechanism of scar formation in adult wounds remains incompletely understood, we found that fibromodulin overexpression improves wound healing in vivo, suggesting that fibromodulin may be a key mediator in reduced scarring.