Current potential therapeutic strategies targeting the TGF-β/Smad signaling pathway to attenuate keloid and hypertrophic scar formation

Aberrant scar formation, which includes keloid and hypertrophic scars, is associated with a pathological disorganized wound healing process with chronic inflammation. The TGF-β/Smad signaling pathway is the most canonical pathway through which the formation of collagen in the fibroblasts and myofibroblasts is regulated. Sustained activation of the TGF-β/Smad signaling pathway results in the long-term overactivation of fibroblasts and myofibroblasts, which is necessary for the excessive collagen formation in aberrant scars. There are two categories of therapeutic strategies that aim to target the TGF-β/Smad signaling pathway in fibroblasts and myofibroblasts to interfere with their cellular functions and reduce cell proliferation. The first therapeutic strategy includes medications, and the second strategy is composed of genetic and cellular therapeutics. Therefore, the focus of this review is to critically evaluate these two main therapeutic strategies that target the TGF-β/Smad pathway to attenuate abnormal skin scar formation.

Where do you insert a drain tube during breast reconstruction?

PURPOSE

A drain tube is commonly inserted during breast reconstruction surgery. This leads to a scar in addition to the scar on the breast. This study was performed to investigate how patients feel about the drain scar and to clarify its ideal location.

METHODS

A questionnaire survey about the drain scar was distributed to 38 consecutive breast reconstruction patients and a total of 104 female doctors and nurses engaged in breast reconstruction. The drain scars were evaluated using the Japan Scar Workshop (JSW) Scar Scale.

RESULTS

A total of 32% of the patients expressed some anxiety about the drain scar. Patients who were anxious about the drain scar had higher scores on the JSW Scar Scale than those who were not anxious. Younger doctors and nurses preferred the drain scar to be on the side of the chest, while older doctors and nurses preferred the drain scars to be at the axilla.

CONCLUSIONS

About a third of the patients had some anxiety associated with their drain scar after breast reconstruction surgery, and this anxiety level was correlated with objective assessment of the scar. Thus, more patient involvement or the provision of more information regarding drain placement is required.

A highly simulated scar model developed by grafting human thin split-thickness skin on back of nude mouse: The remodeling process, histological characteristics of scars

A predictive scar animal model is needed in order to study the mechanism and assess the therapies before its use in humans. However, due to the differences in wound healing patterns and regeneration ability, none of the existing models can fully simulate the characteristics of human scar. The aim of this study was to build a model that recapitulated the developing process and outcomes of human hypertrophic scar (HS). Nude mice were grafted with thin split-thickness human skins. The dynamic changes and final outcomes of the grafts were investigated. The results showed that human skin grafts survived and underwent progressive scarring remodeling in morphology and histology. Scar related markers (α-SMA, CD34, Collage I, TGF-β1) were positive in immunohistology. Protein expressions in TGF-β1/Smad2/3 pathway were increased in accordance with HS during the development process by western blotting. It was finally proved that scar reconstructed by this model matches a real-world human HS. This is a stable, easy to reproduce model for studying the scar formation process and its properties.

[Clinical effect of Zhang's super tension-relieving suture for high-tension wound closure]

Objective: To investigate the clinical effect of Zhang's super tension-relieving suture applied in high-tension wound closure. Methods: From January to August 2019, 19 eligible patients with scar or black hairy nevus were treated with Zhang's super tension-relieving suture for outpatient operation in the Department of Plastic and Reconstructive Surgery of Shanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine. The patients were composed of 6 males and 13 females, aged 10-68 years, with 8 keloids, 3 hypertrophic scars, 5 atrophic scars, and 3 black hairy nevus. The operation sites included lower jaw in 2 cases, neck in 3 cases, chest in 4 cases, abdomen in 2 cases, and limbs in 8 cases. The size of scars and black hairy nevus before surgery ranged from 1.4 cm×1.1 cm to 10.0 cm×4.0 cm. All the lesions underwent excision alone with both sides of the incision undermined for 1 to 2 cm, and the wound size ranged from 2.6 cm×2.6 cm to 12.6 cm×6.8 cm. Zhang's super tension-relieving suture was applied with barbed suture, and the wound edges were naturally jointed with relaxation and low tension by pushing normal skin on both sides to the middle. Two patients with keloids underwent superficial radiotherapy within 24-hour interval after the surgery, with a total of 20 Gy delivered in 4 times, once a day. All the patients were followed up at outpatient clinics, with tension-relieving duration and adverse effects recorded. Six months after operation, the Vancouver Scar Scale (VSS) was used to evaluate scar appearance, while scar width and recurrence were recorded. Results: All the wounds of 19 patients healed completely after surgeries. Two patients experienced transient hyperpigmentation at puncture points and recovered without intervention, and one of them had hypertrophic scar at the puncture point, which was relieved after intralesional injections of corticosteroids. One patient underwent transient erythema, dry desquamation, and hyperpigmentation after radiotherapy, which recovered without intervention. Follow-up time ranged from 7.1 to 13.6 months, with an average of 9.6 months. Tension-relieving duration ranged from 4 to 26 weeks, with an average of 11.2 weeks. Two patients underwent Zhang's super tension-relieving suture again 8 weeks after operation due to their short tension-relieving duration which lasted for only 4 weeks after the first suture. Six months after operation, liner scars were achieved in all the patients with an average width of 2.2 mm (0.8 to 7.0 mm) and an average VSS score of 2.1 points (1.0 to 4.3 points). Three keloid patients had local recurrence 3 months after surgery for not receiving radiotherapy, which was obviously relieved following laser treatment in combination with intralesional injections of corticosteroids and 5-fluorouracil, etc. Conclusions: Zhang's super tension-relieving suture technique with barbed suture is able to effectively relieve the tension on wound edges, extend the tension-relieving duration, and reduce the hypertrophic scar risk when applied in high-tension wound.

[Expressions and effects of autophagy-related genes in bleomycin-induced skin fibrosis of mice]

Objective: To investigate the expressions and effects of autophagy-related genes in bleomycin-induced skin fibrosis of mice. Methods: (1) Totally 72 male BALB/c mice aged 6 weeks were divided into blank control group, simple phosphate buffer solution (PBS) group, and bleomycin group according to the random number table, with 24 mice in each group. Mice in blank control group received no treatment, and 100 μL of PBS and bleomycin (1 mg/mL) were respectively injected subcutaneously in the back skin of mice in simple PBS and bleomycin group, once a day for 28 days. On injection day (ID) 7, 14, 21, and 28, 6 mice in each group were collected to observe the skin change on the back of mice with naked eyes. After the observation, the mice were sacrificed and skin tissue on the back was taken. Skin tissue of mice on ID 28 was collected to measure the thickness of skin tissue by routine hematoxylin-eosin staining and observe skin tissue morphology by Masson staining. Skin tissue on ID 7, 14, 21, and 28 was taken to detect content of hydroxyproline by enzyme linked immunosorbent assay, and mRNA and protein expressions of p62, microtubule-associated protein 1 light chain 3 Ⅱ (LC3 Ⅱ) and Beclin-1 were detected by real-time fluorescent quantitative reverse transcription polymerase chain reaction and Western blotting, respectively. (2) Skin tissue of mice in blank control group in experiment (1) was taken to culture fibroblasts (Fbs) in 3rd-6th passages. The cells were divided into blank control group, simple PBS group, and bleomycin group according to the random number table, with 6 wells in each group. Cells in blank control group were not stimulated, and cells in simple PBS group and bleomycin group were stimulated with 20 μL of PBS and bleomycin (1 mg/mL) for 72 h, respectively. Cellular immunofluorescence staining was used to observe the expression of LC3 Ⅱ. Data were statistically analyzed with analysis of variance of factorial design, one-way analysis of variance, t test, and Bonferroni correction. Results: (1) Skin on the back of mice in blank control group and simple PBS group was thin and ruddy, and the veins were clear on ID 7, 14, 21, and 28. Several raised ridges were visible on the puncture site of mice in simple PBS group from ID 14. Skin on the back of mice was ruddy, with several raised ridges visible on the puncture site of mice in bleomycin group on ID 7, the skin turned slightly white on ID 14, the skin turned white obviously with unclear surrounding blood vessels on ID 21, and the skin turned white and the surrounding blood vessels could not be recognized on ID 28. (2) On ID 28, the skin thicknesses of mice in blank control group and simple PBS group were similar (t=0.79, P>0.05). Compared with that in blank control group and simple PBS group, the skin thickness of mice in bleomycin group was significantly increased (t=0.50, 0.50, P<0.01). (3) On ID 28, the skin tissue structure of mice in blank control group and simple PBS group was similar, with a small amount of orderly arranged collagen and evenly distributed hair follicle; the number of collagen of skin in mice of bleomycin group was increased obviously and arranged disorderly, and the number of hair follicle was decreased significantly. (4) On ID 7, 14, 21, and 28, the content of hydroxyproline in the skin tissue of mice in bleomycin group was significantly higher than that in blank control group and simple PBS group (t=0.99, 0.98, 0.50, 0.51, 0.50, 0.50, 0.52, 0.51, P<0.05 or P<0.01). (5) On ID 7, p62 mRNA expression in the skin tissue of mice in bleomycin group was significantly lower than that in simple PBS group (t=0.93, P<0.05). On ID 14 and 21, the mRNA expressions of p62, LC3 Ⅱ, and Beclin-1 in the skin tissue of mice in bleomycin group were significantly higher than those in blank control group (t=0.74, 0.70, 0.58, 0.49, 0.51, 0.74, P<0.05) and simple PBS group (t=0.94, 0.65, 0.65, 0.77, 0.49, 0.51, P<0.05). On ID 28, the mRNA expressions of p62 and Beclin-1 in the skin tissue of mice in bleomycin group were significantly lower than those in blank control group (t=0.50, 0.44, P<0.05) and simple PBS group (t=0.97, 0.55, P<0.05), and that of LC3 Ⅱ was significantly higher than that in blank control group and simple PBS group, respectively (t=0.51, 0.98, P <0.01). (6) On ID 7, 14, 21, and 28, the protein expressions of LC3 Ⅱ in blank control group, simple PBS group, and bleomycin group were 0.167±0.042, 0.122±0.016, 0.553±0.078, 0.118±0.035, 0.120±0.023, 0.117±0.061, 0.581±0.039, 0.159±0.065, 0.233±0.027, 0.304±0.031, 1.020±0.010, 0.089±0.045. On ID 14, the protein expressions of p62 and Beclin-1 in the skin tissue of mice in bleomycin group were significantly higher than those in blank control group (t=0.86, 0.89, P<0.05) and simple PBS group (t=0.42, 0.89, P<0.05). On ID 21, the protein expressions of p62, LC3 Ⅱ, and Beclin-1 in the skin tissue of mice in bleomycin group were significantly higher than those in blank control group and simple PBS group (t=0.82, 0.45, 0.50, 0.79, 0.51, 0.50, P<0.01). On ID 28, the protein expressions of p62, LC3 Ⅱ, and Beclin-1 in the skin tissue of mice in bleomycin group were significantly lower than those in blank control group and simple PBS group (t=0.77, 0.54, 0.52, 0.50, 0.51, 0.50, P<0.05). (7) After culture for 72 h, the expression of LC3 Ⅱ in Fbs of bleomycin group was significantly lower than that of blank control group and simple PBS group, respectively. Conclusions: In the process of bleomycin stimulating skin fibrosis, autophagy-related genes increase firstly and then decrease. When the autophagy process is activated, it is expected to reverse the process of skin fibrosis.

Targeted apoptosis of myofibroblasts by elesclomol inhibits hypertrophic scar formation

Background

Hypertrophic scar (HS) is characterized by the increased proliferation and decreased apoptosis of myofibroblasts. Myofibroblasts, the main effector cells for dermal fibrosis, develop from normal fibroblasts. Thus, the stimulation of myofibroblast apoptosis is a possible treatment for HS. We aimed to explore that whether over-activated myofibroblasts can be targeted for apoptosis by anticancer drug elesclomol.

Methods

4′,6-diamidino-2-phenylindole staining, flow cytometry, western blotting, collagen gel contraction and immunofluorescence assays were applied to demonstrate the proapoptotic effect of elesclomol in scar derived myofibroblasts and TGF-β1 induced myofibroblasts. The therapeutic potential of elesclomol was investigated by establishing rabbit ear hypertrophic scar models.

Findings

Both 4′,6-diamidino-2-phenylindole staining and flow cytometry indicated that elesclomol targets myofibroblasts in vitro. Collagen gel contraction assay showed that elesclomol inhibited myofibroblast contractility. Flow cytometry and western blot analysis revealed that elesclomol resulted in excessive intracellular levels of reactive oxygen species(ROS), and caspase-3 and cytochrome c proteins. Moreover, compared with the control group, the elesclomol group had a significantly lower scar elevation index in vivo. Immunofluorescence assays for TUNEL and α-smooth muscle actin indicated that elesclomol treatment increased the number of apoptotic myofibroblasts.

Interpretation

The above results indicate that elesclomol exerted a significant inhibitory effect on HS formation via targeted myofibroblast apoptosis associated with increased oxidative stress. Thus, elesclomol is a promising candidate drug for the treatment of myofibroblast-related diseases such as HS.

Modulating cationicity of chitosan hydrogel to prevent hypertrophic scar formation during wound healing

It is of great clinical significance to design wound dressing materials with combined excellent wound healing properties and superior capability to suppress hypertrophic scar formation. This study aimed to examine if and how the cationicity of chitosan would affect the hypertrophic scar-related outcomes, through preparing carboxymethyl chitosan hydrogels with different genipin concentrations (2.5%, 5%, 10% and 15%, respectively). An optimum window of chitosan cationicity (5% in our case) demonstrated potential to mitigate hypertrophic scar in wound healing by suppressing the expression of a-smooth muscle actin (a-SMA) and promoting secretion of type I matrix metalloproteinases (MMP-1). In vivo, the CMCS-5% hydrogel again showed smaller, thinner and smoother wound appearance. Moreover, the CMCS-5% sample with additional incorporation of 2% (V/V) Aloe vera gel exhibited further improved performance in scar inhibition. Overall, such findings might have important implications in chitosan-based wound dressing design for high-quality wound repair and effective scar inhibition.

MiR-486-5p inhibits the hyperproliferation and production of collagen in hypertrophic scar fibroblasts via IGF1/PI3K/AKT pathway

Background: This study explored the function and mechanism of miR-486-5p in HSFBs.Methods: Qualitative real-time-polymerase chain reaction (qRT-PCR) was performed to detect the expression of miR-486-5p in HS and hypertrophic scar fibroblasts (HSFBs). Viability, migration, invasion ability, apoptosis, and expressions of Collagen I, Collagen III, α-SMA and Cleaved caspase-3 in HSFBs after transfection with miR-486-5p mimic or inhibitor were measured by CCK-8, wound-healing, transwell, and Western blot, respectively. Interaction between miR-486-5p and IGF1 was predicted by Targetscan version 7.2 and further confirmed by dual-luciferase assay, and functional rescue experiments were conducted to verify the predicted molecular mechanism. The activation of PI3K/AKT pathway was also analyzed by Western blot.Results: MiR-486-5p was low-expressed in HS and HSFBs, and that overexpression of miR-486-5p suppressed the viability, migration, invasion, and expressions of Collagen I, Collagen III, and α-SMA of HSFBs, meanwhile, it also promoted apoptosis and Cleaved caspase-3 expression in HSFBs. Moreover, IGF1 was targeted by miR-486-5p, and increased viability, migration, invasion, and collagens expressions, the activation of PI3K/Akt pathway, and decreased apoptosis and Cleaved caspase-3 induced by miR-486-5p inhibitor could be partly alleviated by siIGF1.Conclusions: Overexpressed miR-486-5p inhibited the hyperproliferation and excessive production of collagen in HSFBs via IGF1/PI3K/AKT pathway.

Comparative Efficacy and Safety of Common Therapies in Keloids and Hypertrophic Scars: A Systematic Review and Meta-analysis

OBJECTIVES

At present, there are many therapies for treating keloids and hypertrophic scars, but there is still a lack of treatments that are relatively balanced in efficacy and safety. The study aims to evaluate comprehensively efficacy and safety of common therapies in keloids and hypertrophic scars.

METHODS

The literature search was conducted up to May 2019. The traditional meta-analysis was performed on 17 therapies. Bayesian network meta-analysis was conducted on the four most common treatments. The outcome indicators were the numbers of patients with good-to-excellent effect, Vancouver Scar Scale (VSS) and adverse events.

RESULTS

There was no significant difference in the efficacy of triamcinolone acetonide (TAC) compared with other monotherapies except for silicone gel sheet and neodymium-yttrium-aluminum-garnet in primary indicator. The combination therapies were superior to TAC, and the results were consistent after the pooled analysis (RR = 0.522, 95% CI 0.332-0.823). The level of VSS in TAC group was higher than that in 5-flurouracil (5-FU) and TAC + 5-FU group, but lower than that in verapamil (VER) group. And the patients treated with TAC were less safe than those treated with verapamil (P = 0.013). Surface under cumulative ranking ranked verapamil and TAC + 5-FU as the favorable efficacy therapies in terms of primary indicator and ranked TAC + 5-FU as the best therapy for VSS, while VER was ranked as the worst.

CONCLUSION

This meta-analysis showed that TAC + 5-FU may be the most effective therapy, while verapamil may be a better therapeutic strategy for safety.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Strategies to prevent hypertrophic scar formation: a review of therapeutic interventions based on molecular evidence

Once scar tissues mature, it is impossible for the surrounding tissue to regenerate normal dermal tissue. Therefore, it is essential to understand the fundamental mechanisms and establish effective strategies to inhibit aberrant scar formation. Hypertrophic scar formation is considered a result of the imbalance between extracellular matrix synthesis and degradation during wound healing. However, the underlying mechanisms of hypertrophic scar development are poorly understood. The purpose of this review was to outline the management in the early stage after wound healing to prevent hypertrophic scar formation, focusing on strategies excluding therapeutic agents of internal use. Treatment aimed at molecular targets, including cytokines, will be future options to prevent and treat hypertrophic scars. More basic studies and clinical trials, including combination therapy, are required to investigate the mechanisms and prevent hypertrophic scar formation.

Investigating the potential of LSKL peptide as a novel hypertrophic scar treatment

Hypertrophic scar (HTS) is a common pathologic dermal fibroproliferative disease after skin injury. Transforming growth factor β (TGF-β) plays a central role in HTS formation and development. Thrombospondin-1 (TSP-1) activates latent TGF-β by binding to latency-associated peptide-β on TGF-β structure. So far, LSKL peptide was shown to selectively antagonize TSP-1. In this study, TSP-1 was first confirmed to be highly expressed in HTS. LSKL peptide was proven to inhibit the overexpression of extracellular matrix and contractile ability of HTS fibroblasts. In vivo, LSKL could attenuate the thickness of HTS, distortion of collagen alignment and fibrogenesis. Results also demonstrated that LSKL peptide not only remarkably attenuated cell proliferation and migration, but also induced cell apoptosis of HTS fibroblasts. Western blot analysis further revealed that LSKL peptide significantly suppressed the phosphorylation of PI3K, AKT, and mTOR, while not affecting the phosphorylation of Smad2/3 and MEK/ERK. These findings suggested that LSKL might be a promising anti-fibrosis agent to HTS through PI3K/AKT/mTOR signaling pathway.

The role of macrophages in the formation of hypertrophic scars and keloids

Numerous studies have shown that macrophages can orchestrate the microenvironment from the early stage of wound healing to the later stages of scar formation. However, few reviews have highlighted the significance of macrophages during the formation of abnormal scars. The purpose of this review was to outline the polarization of macrophages from early to late stage of pathological scar formation, focusing on spatiotemporal diversity of M1 and M2 macrophages. In this review, the role of macrophages in the formation of hypertrophic scars and keloids is summarized in detail. First, an increased number of M2 cells observed before injuries are significantly associated with susceptibility to abnormal scar pathogenesis. Second, decreased expression of M1 at the early stage and delayed expression of M2 at the late stage results in pathological scar formation. Third, M2 cells are highly expressed at both the margin and the superficial region, which is consistent with the invasive property of keloids. Finally, this review helps to characterize strategies for the prediction and prevention of pathological scar formation.

Topical application of silk fibroin-based hydrogel in preventing hypertrophic scars

Current medications for the treatment of hypertrophic scars suffer from bottlenecks of limited therapeutic efficacy and a slow recovery rate. Silk fibroin (SF) has gained attention for its ability to promote wound healing in burns and cutaneous wounds, but its therapeutic effects against hypertrophic scar have not been thoroughly investigated. We prepared SF-based hydrogels (SFHs) with various SF concentrations (1.5 %, 3 %, and 6 %) and characterized their physicochemical properties. Cell experiments showed that these SFHs had favorable biocompatibility in vitro. Further animal experiments in rabbits revealed that the SFH (3 %)-treated group achieved scars on their ears that were thinner and significantly lighter in color compared with the negative control group. Moreover, treatment with SFHs reduced the density and led to the orderly arrangement of collagen fibers. It was found that the therapeutic effects of SFHs were attributed to the reduced expression levels of α-smooth muscle actin. These results are the first to demonstrate that SFH can be exploited as an effective therapeutic agent for the treatment of hypertrophic scars.

Emerging evidence for the roles of peptide in hypertrophic scar

Hypertrophic scar is a dermal fibroproliferative disorder characterized by excess collagen deposition. There are many existing treatment modalities, but none works perfectly in all individuals. Recently, evidence is increasing that peptides can play crucial roles in the prevention or treatment of hypertrophic scar. The peptides may be derived from growth factors, hormones, and intracellular products of proteolysis. In vitro and in vivo studies have revealed that a number of peptides, usually topically applied, have beneficial effects on fibroblasts in rat, mouse, hamster, pig and rabbit scar models. The length of such peptides typically ranges between 10 and 15 amino acids (aa). Peptides may reduce scar progenitors, prevent excessive scarring, decrease scar growth, speed re-epithelialization and promote scar maturation through multiple mechanisms. They may target TGF-β signaling, fibroblast function or collagen modulation, inflammation, renin angiotensin system, gap junction and other pathways. However, there is a paucity of evidence regarding specific binding sites for these peptides in scar models. Here, we review current research progress on the roles of peptides and underlying mechanisms in hypertrophic scar. We also discuss the clinical potential of peptides as therapeutic agents in scarring. Finally, the functions of several peptide-related compounds in hypertrophic scar are summarized.

Wnt4 negatively regulates the TGF-β1-induced human dermal fibroblast-to-myofibroblast transition via targeting Smad3 and ERK

Abnormal activation of Wnt signaling has been demonstrated in the wound healing process and the pathogenesis of fibrotic disorders, with Wnt4 specifically identified as having a key role in the pathogenesis of renal, pulmonary and liver fibrosis. Wnt4 also was found to be upregulated by transforming growth factor-β1 (TGF-β1) in fetal and postnatal murine fibroblasts and bone marrow mesenchymal cells, suggesting an underlying cooperation between Wnt4 and TGF-β1 in fibrosis. However, the specific roles of Wnt4 in TGF-β1-induced skin myofibroblast transition and hypertrophic scar formation remain unclear. In the present study, we first observed reduced Wnt4 expression in hypertrophic scar tissue compared with that in normal skin tissue. Following upregulation by TGF-β1, Wnt4 inhibited the TGF-β1-induced transdifferentiation of fibroblasts into myofibroblasts. Using fibroblast-populated collagen lattice contraction assays, we showed that the increased contractility induced by TGF-β1 was significantly blocked by exogenous Wnt4 and the α-smooth muscle actin (α-SMA) expression was decreased in fibroblasts in the collagen lattices. In addition, knockdown of Wnt4 resulted in further increases in α-SMA and collagen I expressions. Further investigation showed that Wnt4 could inhibit the autocrine effect of TGF-β1 as well as block the phosphorylation of Smad3 and ERK but not of AKT or JNK. Lastly, using hypertrophic scar-derived fibroblasts, we showed that the elevated α-SMA and collagen I levels were markedly reduced after treatment with Wnt4. Taken together, our results suggest that Wnt4 negatively regulates TGF-β1-induced fibroblast activation, which may represent a novel therapeutic strategy for the treatment and prevention of hypertrophic scars.

Smad interacting protein 1 influences transforming growth factor-β1/Smad signaling in extracellular matrix protein production and hypertrophic scar formation

The transforming growth factor (TGF)-β/Smad signal transduction pathway is closely associated with hypertrophic scar (HS) formation. Smad interacting protein 1 (SIP1) is a cytoplasmic protein that efficiently regulates Smad2-/3-dependent signaling within the TGF-β₁ pathway. SIP1 influences collagen synthesis in the HS through a heretofore unknown mechanism. This study investigated the role of the SIP1-mediated TGF-β₁/Smad signaling pathway in extracellular matrix (ECM) protein production and hypertrophic scarring. SIP1 expression was markedly lower in HS vs. normal skin (NS) tissue, and α-smooth muscle actin (α-SMA) content and collagen I/III (Col I/III) synthesis were inversely correlated with SIP1 expression. Furthermore, SIP1 inhibited Smad2/3 phosphorylation in vitro, and improved the collagen-based architecture of the scar while reducing collagen expression and overall scar formation in a rabbit ear model of HS. Based on these findings, we propose that SIP1 acts as a molecular modulator capable of altering Smad2-/3-facilitated signaling through the control of Smad phosphorylation, thus inhibiting α-SMA and collagen upregulation in fibroblasts and, ultimately, HS formation. The low SIP1 content in scar tissue also suggests that SIP1 (and positive regulation thereof) is a prospective target for selective HS drug therapy.

Effect of Keratinocytes on Myofibroblasts in Hypertrophic Scars

Myofibroblasts play a central role in matrix formation and wound contraction during wound healing and undergo apoptosis at the end of the healing. Hypertrophic scarring is a pathologic condition in which myofibroblasts persist in the tissue. It has been hypothesized that abnormalities in epidermal-dermal crosstalk underlie this pathology. Therefore, in this study, we investigated whether myofibroblasts are affected by keratinocytes. Transforming growth factor beta-induced myofibroblasts (Imyo) and myofibroblasts from hypertrophic scar tissue (Hmyo) were characterized using microarrays. Keratinocytes were co-cultured with myofibroblasts, and quantitative PCR analysis was performed. We found that numerous extracellular matrix- and smooth muscle cell-associated genes were upregulated in Imyo and Hmyo respectively, and these findings suggest that Hmyo are fully differentiated myofibroblasts and that Imyo are less differentiated than Hmyo. Decreased collagen type 1 gene expression was found in keratinocytes co-cultured with Imyo and Hmyo; further, α-smooth muscle actin expression in Imyo increased in the presence of keratinocytes. These observations indicate that keratinocytes play a role in the development of pathological fibrosis in hypertrophic scar tissue by regulating the behavior of dermal fibroblasts and myofibroblasts. We believe that this study provides the basis for understanding the pathophysiology of hypertrophic scarring and identifying new therapeutic approaches for this dysfunction.No Level Assigned This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors - www.springer.com/00266 .

Botulinum toxin type A suppresses pro-fibrotic effects via the JNK signaling pathway in hypertrophic scar fibroblasts

Hypertrophic scar is a dermal fibroproliferative disease characterized by the overproduction and deposition of extracellular matrix, and the hyperproliferation and enhanced angiogenesis of fibroblasts, along with their enhanced differentiation to myofibroblasts. Botulinum toxin type A shows potential for prevention of hypertrophic scar formation; however, its effectiveness in attenuating skin fibrosis and the related mechanism are unclear. In this study, human scar fibroblasts were cultured and stimulated with botulinum toxin type A, and the changes in fibroblast proliferation, migration, and protein expression of pro-fibrotic factors were evaluated with colorimetric, scratch, and enzyme-linked immunosorbent assays and western blotting, respectively. Botulinum toxin type A treatment decreased the proliferation and migration of human scar fibroblasts compared with those of untreated controls. Protein expression levels of pro-fibrotic factors (transforming growth factor β1, interleukin-6, and connective tissue growth factor) were also inhibited by botulinum toxin type A, whereas the JNK phosphorylation level was increased. Activation of the JNK pathway demonstrated the inhibitory effects of the toxin on human scar fibroblast proliferation and production of pro-fibrotic factors, suggesting that the suppressive effects of botulinum toxin type A are closely associated with JNK phosphorylation. Overall, this study showed that botulinum toxin type A has a suppressive effect on extracellular matrix production and scar-related factors in human scar fibroblasts in vitro, and that regulation of JNK signaling plays an important role in this process. Our results provide a theoretical basis, at the cellular level, for the therapeutic use of botulinum toxin type A.

[Secondary surgical and medical treatment of scars]

The authors, through their experience, take stock of current secondary management of scars whether they are pathological (hypertrophic, cheloid) or dystrophic (enlarged, hypo- or hyper-pigmented, adherent) by presenting surgical or medical solutions.

Bone marrow concentrate-induced mesenchymal stem cell conditioned medium facilitates wound healing and prevents hypertrophic scar formation in a rabbit ear model

Background

Hypertrophic scars (HSs) are formed via an aberrant response to the wound healing process. HSs can be cosmetic or can result in functional problems. Prolonged proliferation and remodeling phases disrupt wound healing, leading to excessive collagen production and HS formation. However, there are currently no satisfactory drugs to prevent HS formation. Mesenchymal stem cell (MSC) conditioned medium (CM) has therapeutic effects on wound healing and preventing HS formation. Bone marrow concentrate (BMC) contains various growth factors and cytokines that are crucial for regeneration and has been applied in the clinical setting. In this study, we evaluated the effects of BMC-induced MSC CM on HS formation in a rabbit ear model.

Methods

We established a rabbit ear wound model by generating full-thickness wounds in the ears of rabbits (n = 12) and treated wounds with MSC CM, BMC CM, or BMC-induced MSC CM. Dermal fibroblasts from human hypertrophic scar were stimulated with transforming growth factor beta 1 (TGF-β1) for 24 h and cultured in each culture medium for 72 h. We measured the hypertrophic scar (HS) formation during the skin regeneration by measuring the expression of several remodeling molecules and the effect of these conditioned media on active human HS fibroblasts.

Results

Our results showed that BMC-induced MSC CM had greater antifibrotic effects than MSC CM and BMC CM significantly attenuated HS formation in rabbits. BMC-induced MSC CM accelerated wound re-epithelization by increasing cell proliferation. Additionally, BMC-induced MSC CM also inhibited fibrosis by decreasing profibrotic gene and protein expression, promoting extracellular matrix turnover, inhibiting fibroblast contraction, and reversing myofibroblast activation.

Conclusions

BMC-induced MSC CM modulated the proliferation and remodeling phases of wound healing, representing a potential wound healing agent and approach for preventing HS formation.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1383-x) contains supplementary material, which is available to authorized users.

Effect of artesunate and relation with TGF-β1 and SMAD3 signaling on experimental hypertrophic scar model in rabbit ear

Artesunate (ART) is the derivative of artemisinin isolated from the traditional Chinese medicine qinghao. Although several studies reported the efficiency of artesunate in the treatment of malaria, inhibiting fibroblasts and collagen synthesis, the association between artesunate and scar formation is unclear. The research was designed to study the significance of artesunate (ART) on the expression of transforming growth factor (TGF-β1) and small mother against decapentaplegic (SMAD3) in rabbit's ear hypertrophic scar model. Twenty-four New Zealand white rabbits were randomly divided into six groups: control group, matrix group, low-concentration artesunate group (0.48%), medium-concentration artesunate group (0.96%), high-concentration artesunate group (1.92%) and silicone gel group. Punched defects were established on each rabbit’s ear which resulted in a hypertrophic scar. On the 28th day, topical artesunate creams were applied twice a day except on the control group. On the 56th day, scar samples were collected for histopathology and immunoassay. Hematoxylin and eosin staining, Van Gieson staining, immunohistochemistry and Western blot analysis were done. Amongst the six groups, findings showed that the medium-concentration artesunate group (0.92%) efficiently decreased hypertrophic scar formation and significantly reduced fibroblasts and collagen synthesis. The results had also shown a decrease in the expression of transforming growth factor (TGF-β1) and declined small signal mother against decapentaplegic (Smad3). The overall study shows efficacy and mechanism of artesunate. It concluded that the medium concentration of artesunate (0.92%) could be an effective therapeutic agent for hypertrophic scars.

Combination of mesenchymal stem cell-conditioned medium and botulinum toxin type A for treating human hypertrophic scars

BACKGROUND

Both mesenchymal stem cell-conditioned medium (MSC CM) and Botox have demonstrated therapeutic effects for hypertrophic scar (HS). It is unclear whether a synergistic effect occurs when these treatments are used in combination. We aimed to investigate the therapeutic effects of MSC CM and Botox alone when compared with those of a combined regimen on HS.

METHODS

Fibroblasts from human HS were isolated and treated with Dulbecco's modified Eagle's medium (DMEM), MSCCM, or Botox alone or a combination of MSCCM and Botox. We also used an in vivo HS-buried null mice model to investigate the efficacy of combination treatment.

RESULTS

The results demonstrated that the combination of MSC CM and Botox downregulated both mRNA and protein levels of type I collagen, type III collagen, and alpha-smooth muscle actin (α-SMA) in HS fibroblasts. The combined regimen also suppressed fibroblast proliferative activity, increased apoptosis, and displayed significant inhibitory effects on the contractile ability of HS fibroblasts compared to MSC CM, Botox, or DMEM alone. Using an in vivo HS-buried null mice model, significant scar weight reduction, cell apoptosis, and less α-SMA expression were observed from the combined regimen of MSC CM and Botox compared to those from the other groups. The combined regimen also significantly improved arrangement and deposition of collagen fibers.

CONCLUSIONS

This study demonstrates that a combination of MSC CM and Botox exhibited a significant therapeutic effect compared to monotherapy. Clinical translation of this therapy should be further considered.

Quantification of Pediatric Burn Scar Stiffness Using Acoustic Radiation Force Impulse Ultrasound Elastography

The purpose of this study was to quantify the stiffness of hypertrophic scars using acoustic radiation force impulse ultrasound elastography. Sixteen pediatric patients with hypertrophic scars resulting from burn injuries participated in this study (mean age: 5.13, standard deviation: 3.20). Values for the elastic modulus (E) of scar and control sites were obtained. Scarred areas were found to be almost four times stiffer than control sites (scar E_mean = 39.29 kPa compared with control E_mean = 10.19 kPa) (p = 0.0004). Correlations between scar stiffness and clinician-reported subjective scar scale scores were not observed (r_s = 0.30, p = 0.27 and r_s = 0.25, p = 0.35 respectively). We found that acoustic radiation force impulse imaging can discriminate between hypertrophic scars and normal skin and should be considered a potentially valuable tool in the armamentarium of objective scar measures. Future research should focus on evaluating the technology's ability to detect scar change over time in order to determine responsiveness to treatment.

A dose-ranging, parallel group, split-face, single-blind phase II study of light emitting diode-red light (LED-RL) for skin scarring prevention: study protocol for a randomized controlled trial

BACKGROUND

Skin fibrosis is a significant global health problem that affects over 100 million people annually and has a profoundly negative impact on quality of life. Characterized by excessive fibroblast proliferation and collagen deposition, skin fibrosis underlies a wide spectrum of dermatologic conditions ranging from pathologic scars secondary to injury (e.g., burns, surgery, trauma) to immune-mediated diseases. Effective anti-scarring therapeutics remain an unmet need, underscoring the importance of developing novel approaches to treat and prevent skin fibrosis. Our in vitro data show that light emitting diode-red light (LED-RL) can modulate key cellular and molecular processes involved in skin fibrosis. In two phase I clinical trials (STARS 1 and STARS 2), we demonstrated the safety and tolerability of LED-RL at fluences of 160 J/cm² up to 480 J/cm² on normal human skin.

METHODS/DESIGN

CURES (Cutaneous Understanding of Red-light Efficacy on Scarring) is a dose-ranging, randomized, parallel group, split-face, single-blind, mock-controlled phase II study to evaluate the efficacy of LED-RL to limit post-surgical skin fibrosis in subjects undergoing elective mini-facelift surgery. Thirty subjects will be randomly allocated to three treatment groups to receive LED-RL phototherapy or temperature-matched mock irradiation (control) to either periauricular incision site at fluences of 160 J/cm², 320 J/cm², or 480 J/cm². Starting one week post-surgery (postoperative days 4-8), treatments will be administered three times weekly for three consecutive weeks, followed by efficacy assessments at 30 days, 3 months, and 6 months. The primary endpoint is the difference in scar pliability between LED-RL-treated and control sites as determined by skin elasticity and induration measurements. Secondary outcomes include clinical and photographic evaluations of scars, 3D skin imaging analysis, histological and molecular analyses, and adverse events.

DISCUSSION

LED-RL is a therapeutic modality of increasing importance in dermatology, and has the potential to limit skin fibrosis clinically by decreasing dermal fibroblast activity and collagen production. The administration of LED-RL phototherapy in the early postoperative period may optimize wound healing and prevent excessive scarring. The results from this study may change the current treatment paradigm for fibrotic skin diseases and help to pioneer LED-RL as a safe, non-invasive, cost-effective, portable, at-home therapy for scars.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03795116 . Registered on 20 December 2018.

MicroRNA-130a has pro-fibroproliferative potential in hypertrophic scar by targeting CYLD

Hypertrophic scars are dermal fibrosis diseases that protrude from the surface of the skin and irregularly extend to the periphery, seriously affecting the appearance and limb function of the patient. In this study, we found that microRNA-130a (miR-130a) was increased in hypertrophic scar tissues and derived primary fibroblasts, accompanied by up-regulation of collagen1/3 and α-SMA. Inhibition of miR-130a in hypertrophic scars fibroblasts suppressed the expression of collagen1/3 and α-SMA as well as the cell proliferation. Bioinformatics analysis combined with luciferase reporter gene assay results indicated that CYLD was a target gene of miR-130a, and the miR-130a mimic could reduce the level of CYLD. In contrast to miR-130a, the expression of CYLD was downregulated in hypertrophic scars and their derived fibroblasts. Overexpressing CYLD inhibited the expression of collagen 1/3 and α-SMA, slowed cell proliferation, and inhibited Akt activity. As expected, further study showed that the overexpression of CYLD could prevent the pro-fibroproliferative effects of miR-130a. Consistent with the in vitro results, the inhibitor of miR-130a effectively ameliorated excessive collagen deposition in bleomycin-induced skin fibrosis mouse model. Taken together, our results indicate that miR-130a promotes collagen secretion, myofibroblast transformation and cell proliferation by targeting CYLD and enhancing Akt activity. Therefore, the miR-130a/CYLD/Akt pathway may serve as a novel entry point for future skin fibrosis research.