Hypertrophic scar formation following burns and trauma: new approaches to treatment

A review of potential biomarkers for assessing physical and psychological trauma in paediatric burns

Biological markers that evaluate physical healing as well as psychological impact of a burn are essential for effective treatment of paediatric burns. The objective of this review is to summarize the evidence supporting the use of biomarkers in children with burns. An extensive review of the literature was performed using PubMed. A total of 59 biomarkers were identified relating to burn presence, specifically relating to processes involved in inflammation, wound healing, growth and metabolism. In addition, biomarkers involved in the stress response cascade following a burn trauma were also identified. Although many biomarkers have been identified that are potentially associated with burn-related physical and psychological trauma, an understanding of burn biology is still lacking in children. We propose that future research in the field of children’s burns should be conducted using broad screening methods for identifying potential biomarkers, examine the biological interactions of different biomarkers, utilize child-appropriate biological fluids such as urine or saliva, and include a range of different severity burns. Through further research, the biological response to burn injury may be fully realized and clinically relevant diagnostic tests and treatment therapies utilizing these biomarkers could be developed, for the improvement of healing outcomes in paediatric burn patients.

Mechanotransduction in Wound Healing: From the Cellular and Molecular Level to the Clinic

GENERAL PURPOSE

To review the various mechanical forces that affect fibroblasts, keratinocytes, endothelial cells, and adipocytes at the cellular and molecular level as well as scar-reducing mechanical devices currently in clinical use.

TARGET AUDIENCE

This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.

LEARNING OBJECTIVES/OUTCOMES

After participating in this educational activity, the participant will:1. Compare and contrast the responses of various types of cells to mechanical forces.2. Identify the mechanical devices and techniques that can help restore skin integrity.

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.

Attenuation of Abnormal Scarring Using Spherical Nucleic Acids Targeting Transforming Growth Factor Beta 1

Abnormal scarring is a consequence of dysregulation in the wound healing process, with limited options for effective and noninvasive therapies. Given the ability of spherical nucleic acids (SNAs) to penetrate skin and regulate gene expression within, we investigated whether gold-core SNAs (AuSNAs) and liposome-core SNAs (LSNAs) bearing antisense oligonucleotides targeting transforming growth factor beta 1 (TGF-β1) can function as a topical therapy for scarring. Importantly, both SNA constructs appreciably downregulated TGF-β1 protein expression in primary hypertrophic and keloid scar fibroblasts in vitro. In vivo, topically applied AuSNAs and LSNAs downregulated TGF-β1 protein expression levels and improved scar histology as determined by the scar elevation index. These data underscore the potential of SNAs as a localized, self-manageable treatment for skin-related diseases and disorders that are driven by increased gene expression.

MicroRNA-9-5p inhibits proliferation and induces apoptosis of human hypertrophic scar fibroblasts through targeting peroxisome proliferator-activated receptor β

Hypertrophic scar (HS) is a dermal fibro-proliferative disorder result from abnormal wound healing after skin injury. MicroRNA-9-5p (miR-9-5p) has been reported to be upregulated and closely related to collagen proteins in human dermal fibroblasts. However, the correlation and possible mechanism between miR-9-5p and HS require further investigation. The expressions of miR-9-5p in HS tissues and HS fibroblasts were detected by quantitative real-time PCR (RT-qPCR). The expression level of peroxisome proliferator-activated receptor β (PPARβ) was measured by RT-qPCR assay. The protein levels of PPARβ, α-SMA, Vimentin, COL1A, cyclin D1, bcl-2, and bax were detected by western blot assay. The effect of miR-9-5p and PPARβ on HS fibroblasts proliferation and apoptosis were detected by cell counting kit-8 (CCK-8) and flow cytometry assays. The interaction between miR-9-5p and PPARβ was predicted by TargetScan, and then confirmed by dual-luciferase reporter assay. MiR-9-5p expression was downregulated in HS tissues and HS fibroblasts. MiR-9-5p inhibited the levels of extracellular matrix-associated genes (α-SMA, Vimentin, COL1A) in HS fibroblasts. MiR-9-5p repressed proliferation and induced apoptosis of HS fibroblasts. PPARβ is a target gene of miR-9-5p. The silencing of PPARβ expression hindered proliferation and expedited apoptosis of HS fibroblasts. MiR-9-5p suppressed proliferation and promoted apoptosis of HS fibroblasts by targeting PPARβ. In this paper, we firstly disclosed that miR-9-5p hampered extracellular matrix deposition and proliferation, and induced apoptosis by targeting PPARβ in HS fibroblasts. Our findings provided a new role of miR-9-5p/PPARβ in the occurrence and development of HS fibroblasts, promising a new target for HS.

Summary: Our findings provided a new role of miR-9-5p/PPAR in the occurrence and development of HS fibroblasts, promising a new target for HS.

Scar Quality of Skin Graft Borders: A Prospective, Randomized, Double-Blinded Evaluation

Prominent scars may remain around the border of a mature skin graft (SG) at the interface of the SG with normal skin. The border of a SG may be constructed by either exactly approximating (A) or slightly overlapping (O) the edge of the SG on the wound margin. The purpose of this study was to evaluate whether A or O affects the quality of the border scar of SGs applied to burn patients. This prospective study was a within-border design in which adult burn patients requiring SGs served as their own control. Half of each study border was fashioned using O and the immediately adjacent other half was made using A. We randomly assigned O or A to the proximal or distal halves of vertical borders and the medial and lateral halves of horizontal borders. Both halves of the study border were identically fixated with staples or sutures and were managed in the same fashion postoperatively. Blinded evaluations at 3, 6, and 12 months of O and A borders were performed using the Vancouver Scar Scale (VSS), the observer component of the Patient and Observer Scar Assessment Scale (POSAS), and a global binary assessment of which half of the study border "looked better." Blinded patients also rated each half of the study border with a 10-point Likert scale. Values are reported as the mean ± SD or median (interquartile range), as appropriate. There were 34 borders studied in 15 subjects (46.7% female, age 29 [22,57], % TBSA burn 9.7 ± 5.3, and no inhalation injuries). Study borders were constructed at 7 (5,11) days postburn, had a total length of 12 (9.3,14.5) cm, and all involved split thickness SGs of thickness 13 (12,14)/1000th of an inch. Sheet grafts were applied in 27% and meshed grafts in 73%. SGs were applied immediately after excision in 75% or after allografting in 25%. Border scars matured between 3 and 12 months with reductions in total VSS from 8 (7,8) to 4 (3,6) for O borders (P < .001) and from 8 (7,9) to 4 (1,6) for A borders (P < .001). However, there were no significant differences between O and A borders in total VSS at 3 months (P = .165), 6 months (P = .602), and 12 months (P = .358) or in total OSAS at 3 months (P = .681), 6 months (P = .890), or 12 months (P = .601). At 12 months, 60% of O borders and 40% of A borders were globally rated as "better" (P = .258). There were no significant differences in the patients' subjective ratings of the O and A borders at 3 months (P = .920), 6 months (P = .960), and 12 months (P = .66). The scar quality at the border of a skin graft does not appear to be affected by the surgical technique used to construct the border at the time of grafting.

MiR-3613-3p inhibits hypertrophic scar formation by down-regulating arginine and glutamate-rich 1

Hypertrophic scar (HS) is a severe skin disorder characterized by excessive extracellular matrix production and abnormal function of fibroblasts. Recent studies have demonstrated that microRNAs (miRNAs) play critical roles in HS formation. This study aims to investigate the role of miR-3613-3p in the formation of HS. The mRNA and miRNA levels were measured by quantitative RT-PCR analysis. The protein levels were examined by Western blot assay. Cell proliferation was determined by Cell Counting Kit-8 assay. The Caspase-3 and Caspase-9 activities were measured using flow cytometry assay. Dual-luciferase activity reporter assay and mRNA-miRNA pulldown assay were conducted to validate the target of miR-3613-3p. miR-3613-3p was downregulated, while arginine and glutamate-rich 1 (ARGLU1) was upregulated in HS fibroblasts (HSFs) and tissues. Overexpression of miR-3613-3p or knockdown of ARGLU1 markedly inhibited the expression of extracellular matrix (ECM) production-associated proteins and promoted Caspase-3 and Caspase-9 activations in HSFs. ARGLU1 was further identified as a direct target of miR-3613-3p. Restoration of ARGLU1 abrogated the suppressive effect of miR-3613-3p on cell proliferation and ECM protein expression of HSFs. Our results demonstrated that miR-3613-3p inhibited HS formation via targeting ARGLU1, which may provide potential therapeutic targets for the management of HS.

Novel application of autologous micrografts in a collagen-glycosaminoglycan scaffold for diabetic wound healing

BACKGROUND

Therapeutic strategies that successfully combine two techniques-autologous micrografting and biodegradable scaffolds-offer great potential for improved wound repair and decreased scarring. In this study we evaluate the efficacy of a novel modification of a collagen-glycosaminoglycan scaffold with autologous micrografts using a murine dorsal wound model.

METHODS

db/db mice underwent dorsal wound excision and were treated with a collagen-glycosaminoglycan scaffold (CGS), a modified collagen-glycosaminoglycan scaffold (CGS+MG) or simple occlusive dressing (Blank). The modified scaffold was created by harvesting full thickness micrografts and transplanting these into the collagen-glycosaminoglycan membrane. Parameters of wound healing, including cellular proliferation, collagen deposition, keratinocyte migration, and angiogenesis were assessed.

RESULTS

The group treated with the micrograft-modified scaffold healed at a faster rate, showed greater cellular proliferation, collagen deposition, and keratinocyte migration with higher density and greater maturity of microvessels. The grafts remained viable within the scaffold with no evidence of rejection. Keratinocytes were shown to migrate from the wound border and from the micrograft edges towards the center of the wound, while cellular proliferation was present both at the wound border and wound bed.

CONCLUSION

We report successful treatment of diabetic wounds with a novel collagen-glycosaminoglycan scaffold modified with full-thickness automicrografts. Differences in cellular migration and proliferation offer maiden evidence on the mechanisms of wound healing. Clinically, the successful scaffold engraftment, micrograft viability and improved wound healing offer promising results for the development of a new therapeutic modality for wound repair.

Inflammation as an orchestrator of cutaneous scar formation: a review of the literature

Inflammation is a key phase in the cutaneous wound repair process. The activation of inflammatory cells is critical for preventing infection in contaminated wounds and results in the release of an array of mediators, some of which stimulate the activity of keratinocytes, endothelial cells, and fibroblasts to aid in the repair process. However, there is an abundance of data suggesting that the strength of the inflammatory response early in the healing process correlates directly with the amount of scar tissue that will eventually form. This review will summarize the literature related to inflammation and cutaneous scar formation, highlight recent discoveries, and discuss potential treatment modalities that target inflammation to minimize scarring.

Personalized Computational Models of Tissue-Rearrangement in the Scalp Predict the Mechanical Stress Signature of Rotation Flaps

OBJECTIVE

To elucidate the mechanics of scalp rotation flaps through 3D imaging and computational modeling. Excessive tension near a wound or sutured region can delay wound healing or trigger complications. Measuring tension in the operating room is challenging, instead, noninvasive methods to improve surgical planning are needed.

DESIGN

Multi-view stereo allows creation of 3D patient-specific geometries based on a set of photographs. The patient-specific 3D geometry is imported into a finite element (FE) platform to perform a virtual procedure. The simulation is compared with the clinical outcome. Additional simulations quantify the effect of individual flap parameters on the resulting tension distribution.

PARTICIPANTS

Rotation flaps for reconstruction of scalp defects following melanoma resection in 2 cases are presented. Rotation flaps were designed without preoperative FE preparation.

MAIN OUTCOME MEASURE

Tension distribution over the operated region.

RESULTS

The tension from FE shows peaks at the base and distal ends of the scalp rotation flap. The predicted geometry from the simulation aligns with postoperative photographs. Simulations exploring the flap design parameters show variation in the tension. Lower tensions were achieved when rotation was oriented with respect to skin tension lines (horizontal tissue fibers) and smaller rotation angles.

CONCLUSIONS

Tension distribution following rotation of scalp flaps can be predicted through personalized FE simulations. Flaps can be designed to reduce tension using FE, which may greatly improve the reliability of scalp reconstruction in craniofacial surgery, critical in complex cases when scalp reconstruction is essential for coverage of hardware, implants, and/or bone graft.

Current and Emerging Topical Scar Mitigation Therapies for Craniofacial Burn Wound Healing

Burn injury in the craniofacial region causes significant health and psychosocial consequences and presents unique reconstructive challenges. Healing of severely burned skin and underlying soft tissue is a dynamic process involving many pathophysiological factors, often leading to devastating outcomes such as the formation of hypertrophic scars and debilitating contractures. There are limited treatment options currently used for post-burn scar mitigation but recent advances in our knowledge of the cellular and molecular wound and scar pathophysiology have allowed for development of new treatment concepts. Clinical effectiveness of these experimental therapies is currently being evaluated. In this review, we discuss current topical therapies for craniofacial burn injuries and emerging new therapeutic concepts that are highly translational.

Recapitulation of normal collagen architecture in embryonic wounded corneas

Wound healing is characterized by cell and extracellular matrix changes mediating cell migration, fibrosis, remodeling and regeneration. We previously demonstrated that chick fetal wound healing shows a regenerative phenotype regarding the cellular and molecular organization of the cornea. However, the chick corneal stromal structure is remarkably complex in the collagen fiber/lamellar organization, involving branching and anastomosing of collagen bundles. It is unknown whether the chick fetal wound healing is capable of recapitulating this developmentally regulated organization pattern. The purpose of this study was to examine the three-dimensional collagen architecture of wounded embryonic corneas, whilst identifying temporal and spatial changes in collagen organization during wound healing. Linear corneal wounds that traversed the epithelial layer, Bowman´s layer, and anterior stroma were generated in chick corneas on embryonic day 7. Irregular thin collagen fibers are present in the wounded cornea during the early phases of wound healing. As wound healing progresses, the collagen organization dramatically changes, acquiring an orthogonal arrangement. Fourier transform analysis affirmed this observation and revealed that adjacent collagen lamellae display an angular displacement progressing from the epithelium layer towards the endothelium. These data indicate that the collagen organization of the wounded embryonic cornea recapitulate the native macrostructure.

Long non-coding RNA H19 promotes the proliferation, migration and invasion while inhibits apoptosis of hypertrophic scarring fibroblasts by targeting miR-3187-3p/GAB1 axis

BACKGROUND

It had been reported that long non-coding RNA (lncRNA) H19 was associated with the proliferation of fibroblasts. However, the regulatory mechanism of H19 remains unclear. Thus, the study was designed to explore the underlying mechanism of H19 in the process of Hypertrophic scarring (HS).

METHODS

The expression levels of H19, miR-3187-3p, and growth factor receptor binding 2-associated binding protein 1 (GAB1) in HS tissues and HS fibroblasts were measured by real-time quantitative polymerase chain reaction (RT-qPCR) assay. The biological behaviors of HS fibroblasts, such as cell proliferation, apoptosis, migration, and invasion were assessed by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazol-3-ium bromide (MTT), colony formation, flow cytometry, and transwell assays, respectively. The protein expression level was quantified by western blot assay. The interaction association between miR-3187-3p and H19 or GAB1 was predicted by Starbase database analysis and confirmed by dual-luciferase reporter assay, respectively.

RESULTS

H19 was significantly increased in HS tissues and HS fibroblasts. Loss-of-functional experiments revealed that knockdown of H19 inhibited the development of HS. Moreover, silencing of H19 impeded the proliferation, migration, and invasion, while enhanced apoptosis of HS fibroblasts by increasing miR-3187-3p expression. In addition, overexpression of GAB1 could abolish miR-3187-3p overexpression-induced effects on cell proliferation, apoptosis, migration, and invasion of HS fibroblasts. Mechanistically, H19 could act as a sponge of miR-3187-3p to upregulate the expression of GAB1 in HS fibroblasts.

CONCLUSION

Collectively, our results revealed that H19 promoted the proliferation, migration, and invasion, while impeded apoptosis of HS fibroblasts by targeting miR-3187-3p/GAB1 axis.

Gene expression profile analysis on different stages of hypertrophic scarring in a rabbit ear model

Hypertrophic scarring (HS) is one of the most common skin disorders. The study aimed to investigate the gene expression profile at day 10 (Stage 1), 21 (Stage 2), and day 40 (Stage 3) post-wounding of HS using RNA-sequencing of a scar model from rabbit ears. A total of 17,386 unigenes were annotated using the eggNOG Functional Category database. The study identified significantly differentially expressed genes (DEGs) including 261, 141, and 247 upregulated ones as well as 253, 272, and 58 downregulated ones in three stages respectively. The DEGs varies among each stage measured by Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. DEGs were enriched in 'immune system process' and 'proteinaceous extracellular matrix' in Stage 1, 'anatomical structure development', 'cell differentiation', 'cell adhesion'and some other terms in Stage 2, 'cancers', 'proteinaceous extracellular matrix' and 'signal transduction' in Stage 3. Furthermore, the Wnt signaling pathway was found to play a pivotal role in regression of HS. In conclusion, we revealed comprehensively the gene expression profiles during HS formation providing probable targets in HS treatment.

The Japanese Experience with Basic Fibroblast Growth Factor in Cutaneous Wound Management and Scar Prevention: A Systematic Review of Clinical and Biological Aspects

INTRODUCTION

Basic fibroblast growth factor (bFGF) plays several key roles in wound healing. Over the last 2 decades, clinical and basic research on bFGF has been actively conducted in Japan with reports on its potent efficacy in accelerating the healing of chronic ulcers and burn wounds by stimulating key cellular players in the skin. However, its efficacy remains unrecognized internationally. Thus, this study reviews current knowledge about the therapeutic value of bFGF in wound management and scar prevention accumulated in Japan over the last 2 decades.

METHODS

We review the Japanese literature that demonstrates the anti-scarring effects of bFGF and exhaustively assess how these effects are exerted. Using the search terms "bFGF OR growth factors AND wound healing in Japan" and "bFGF AND scar prevention in Japan," we conducted a search of the PubMed database for publications on the role of bFGF in wound and scar management in Japan. All eligible papers published between 1988 and December 2019 were retrieved and reviewed.

RESULTS

Our search yielded 208 articles; 82 were related to the application of bFGF for dermal wound healing in Japan. Of these, 27 fulfilled all inclusion criteria; 11 were laboratory studies, 7 were case reports, 4 were clinical studies, and 5 were randomized controlled trials.

CONCLUSION

Further research, with recognition of the therapeutic value of bFGF in wound and scar management and its clinical applications, is needed to provide additional clinical advantages while improving wound healing and reducing the risk of post-surgical scar formation.

Efficacy of stem cell therapy for burn wounds: a systematic review and meta-analysis of preclinical studies

BACKGROUND

Burns remain a serious public health problem with high morbidity and mortality rates worldwide. Although there are various treatment options available, there is no consensus on the best treatment for severe burns as of yet. Stem cell therapy has a bright prospect in many preclinical studies of burn wounds. The systematic review was performed for these preclinical studies to assess the efficacy and possible mechanisms of stem cells in treating burn wounds.

METHODS

Twenty-two studies with 595 animals were identified by searching PubMed, EMBASE, Web of Science, and Cochrane Library databases from inception to 13 May 2020. In addition, a manual search of references of studies was performed to obtain potential studies. No language or time restrictions were enforced. RevMan 5.3 was used for all data analysis.

RESULTS

The overall meta-analysis showed that stem cell therapy significantly improved burn healing rate (SMD 3.06, 95% CI 1.98 to 4.14), irrespective of transplant type, burn area, and treatment method in the control group. Subgroup analyses indicated that hair follicle stem cells seemed to exert more beneficial effects on animals with burn wounds (SMD 7.53, 95% CI 3.11 to 11.95) compared with other stem cells. Furthermore, stem cell therapy seemed to exert more beneficial effects on burn wounds with second-degree (SMD 7.53, 95% CI 3.11 to 11.95) compared with third-degree (SMD 2.65, 95% CI 1.31 to 4.00).

CONCLUSIONS

Meta-analysis showed that stem cell therapy exerts a healing function for burn wounds, mainly through angiogenesis and anti-inflammatory actions. These findings also demonstrate the need for considering variations in future clinical studies using stem cells to treat a burn wound in order to maximize the effectiveness. In general, stem cells can potentially become a novel therapy candidate for burn wounds.

The impact of non-toxic blue light (453 nm) on cellular antioxidative capacity, TGF-β1 signaling, and myofibrogenesis of human skin fibroblasts

Studies have demonstrated that blue light induces biological effects, such as cell death, and inhibition of proliferation and differentiation. Since blue light at longer wavelength (>440 nm) exerts less injurious effects on cells than at shorter wavelengths, (400-440 nm), we have investigated the impact of non-toxic (LED) blue light at 453 nm wavelength on human skin fibroblasts (hsFBs). We found that besides its decreasing effects on the proliferation rate, repeated blue light irradiations (80 J/cm²) also significantly reduced TGF-β1-induced myofibrogenesis as shown by diminished α-SMA and EDA-FN expression accompanied by reduced protein expression and phosphorylation of ERK 1/2, SMAD 2/3, and p38-key players of TGF-β1-induced myofibrogenesis. In parallel, catalase protein expression, intracellular FAD concentrations as well as NADP⁺/NADPH ratio were reduced, whereas intracellular reactive oxygen species (ROS) were increased. We postulate that as a molecular mechanism downregulation of catalase and photoreduction of FAD induce intracellular oxidative stress which, in turn, affects the signaling factors of myofibrogenesis leading to a lower rate of α-SMA and EDA-FN expression and, therefore, myofibroblast formation. In conclusion, blue light even at longer wavelengths shows antifibrotic activity and may represent a suitable and safe approach in the treatment of fibrotic skin diseases including hypertrophic scarring and scleroderma.

Regenerative Scar-Free Skin Wound Healing

IMPACT STATEMENT

Millions of people every year develop scars in response to skin injuries after surgery, trauma, or burns with significant undesired physical and psychological effects. This review provides an update on engineering strategies for scar-free wound healing and discusses the role of different cell types, growth factors, cytokines, and extracellular components in regenerative wound healing. The use of pro-regenerative matrices combined with engineered cells with less intrinsic potential for fibrogenesis is a promising strategy for achieving scar-free skin tissue regeneration.

Adipose mesenchymal stem cell exosomes promote wound healing through accelerated keratinocyte migration and proliferation by activating the AKT/HIF-1α axis

Accelerating wound healing is a key consideration for surgeons. The three stages of wound healing include the inflammatory response, cell proliferation and tissue repair, and much research has focused on the migration and proliferation of epidermal cells, since this is one of the most important steps in wound healing. Studies have shown that adipose mesenchymal stem cells (ADSCs) can promote wound healing by releasing exosomes, although the specific mechanism remains unclear. To clarify the role of adipose mesenchymal stem cell exosomes (ADSCs-exo), we constructed a HaCaT cells model and a mouse wound healing model to examine the effects of ADSCs-exo on wound healing. CCK8 assays and the scratch test showed that ADSCs-exo could promote the proliferation and migration of HaCaT cells. Western blotting and real-time PCR showed that ADSCs-exo upregulated the phosphorylation of AKT and the expression of HIF-1α in HaCaT cells. HIF-1α expression was reduced by inhibiting AKT phosphorylation,and the migration of HaCaT cells simultaneously slowed. These results were also confirmed in vivo. In conclusion, we confirmed that ADSCs-exo promote the proliferation and migration of HaCaT cells by regulating the activation of the AKT/HIF-1α signaling pathway, thus promoting wound healing.

Free tissue transfer for burns reconstruction: A single-site experience

This study reviews free tissue transfer (FTT) surgery for both acute wound and reconstructive scar management of burn injuries at a UK burns unit over a 10-year period. Thirty eight patients underwent 46 FTTs, or free flaps, as part of their burn injury pathway. For the cohort of patients, there was one flap failure, which occurred for a secondary scar reconstruction. It is noted that FTT was successful for all seven acute or primary interventions. Anterolateral thigh flap was the most frequently performed (57%); followed by parascapular flaps (22%) of which 43% were pre-expanded. A method of pre-expansion for neck contractures and a novel technique of anchoring this flap to the pre-tracheal fascia are described here. This can provide the patient with good neck contouring by using the capsule to hitch the flap into a good position. It is clear that further work is required to study the prevention of hypertrophic scarring that can occur at the interface between flap and adjacent skin, where occurrence rate in this cohort was 17%. It is proposed that FTT now provides a viable solution both to the coverage of complex burn wounds and to the revision of scar contractures. Consensus over an FTT protocol for the primary management of open burn wounds is seen as the logical next step for this surgical intervention.

Cutaneous endocannabinoid system: Does it have a role on skin wound healing bearing fibrosis?

INTRODUCTION

Recently, the endocannabinoid system has been identified in skin and it has been linked with the formation of skin fibrosis and wound healing. We aimed to find and analyse reported data on compounds acting in the endocannabinoid system with significant effect in skin fibrosis.

METHODS

A literature search on PUBMED was conducted for studies published in English until February 2020 on cannabinoids and skin fibrosis. The initial search was performed with terms: "cannabinoid" AND "skin". This search retrieved 296 publications from which 18 directly related to skin fibrosis or wound healing process were included in this review.

RESULTS

CB1 receptor inactivation and CB2 receptor activation show anti-fibrotic effects on cellular and animal experimental models of cutaneous fibrosis. CB2 receptor activation also promotes re-epithelization. Other cannabinoid related receptors, like adenosine A2A receptors and PPAR-γ, are also involved. Their activation lead to a pro-fibrotic and anti-fibrotic effect, respectively.

CONCLUSION

Several molecular drug targets for endocannabinoid system were identified in skin. It may be a promising approach for the treatment of excessive skin fibrosis disorders.

Tetramethylpyrazine Induces Apoptosis and Inhibits Proliferation of Hypertrophic Scar-Derived Fibroblasts via Inhibiting the Phosphorylation of AKT

Hypertrophic scar (HS) is a serious fibrotic skin disease and often considered as a kind of benign skin tumor. Tetramethylpyrazine (TMP), the main chemical composition of the traditional Chinese medicine Chuanxiong Rhizoma, has shown significant clinical benefits in the treatment of fibrosis disease and tumor, while the role in HS and the concrete mechanisms remain elusive. Herein, the protective effects of TMP in the treatment of HS was investigated and the results showed that the protein expression levels of type I collagen (Col I), type III collagen (Col III), and α-smooth muscle actin (α-SMA) were all inhibited remarkably after addition of TMP in HS-derived fibroblasts (HFs). Moreover, TMP also suppressed fibroblast proliferative and induced cell apoptosis. The protein expression levels of Caspase-3 and Bcl-2 were all decreased comparing with the control group while proapoptotic proteins Bax and Cleaved Caspase-3 were increased. In addition, TMP treatment markedly reduced the phosphorylation levels of AKT. Taken together, our investigations demonstrated that TMP could down-regulate the expression of fibrosis-related molecules, inhibit scar fibroblast proliferation and activate cell apoptosis, during which AKT pathway was involved. Thus, this study shed more light on the pharmacological mechanisms of TMP, and provided a novel therapeutic alternative for prevention and treatment of HS.

The Unsuccessful Twiddler: A Case of Twiddler's Syndrome Without Deep Brain Stimulator Lead Breakage

The authors present the case of a 78-year-old right-handed female with a past medical history of Parkinson's disease, treated with implantation of a left-sided subthalamic nucleus St. Jude Medical Infinity® (Abbott Medical, Austin, TX) deep brain stimulator, who presented with lead-associated discomfort, or “bowstringing”. Further investigation by chest X-ray revealed an extensive case of distal lead coiling. However, it was surprising that, despite the extensive coiling, the lead stayed intact without hardware failure as proven by patient remaining asymptomatic from her Parkinson's disease and intraoperative impedance testing demonstrating normal results. After revision surgery, the patient remained asymptomatic. Due to paucity of cases of this disease in the literature, specific predictive risk factors are not known, but certain patient characteristics may help take precautions.

Comparison of botulinum toxin type A and aprotinin monotherapy with combination therapy in healing of burn wounds in an animal model

Burns are one of the most common injuries that are complicated by many challenges including infection, severe inflammatory response, excessive expression of proteases, and scar formation. The aim of this study was to investigate the effect of botulinum toxin type A (BO) and aprotinin (AP) separately or in combination (BO-AP) in healing process. Four burn wounds were created in each rat and randomly filled with silver sulfadiazine (SSD), BO, AP and BO-AP. The rats were euthanized after 7, 14, and 28 days, and their harvested wound samples were evaluated by gross pathology, histopathology, gene expression, biochemical testing, and scanning electron microscopy. Both BO and AP significantly reduced expression of interleukin-1β (IL-1β) and transforming growth factor-β1 (TGF-β1) at the 7th post wounding day. Moreover, they inhibited scar formation by reducing the TGF-β1 level and increasing basic fibroblast growth factor (bFGF) at the 28th day. AP by decreasing protease production showed more effective role than BO in wound regeneration. AP increased tissue organization and maturation and improved cosmetic appearance of wounds, at 28 days. The best results gained when combination of BO and AP were used in healing of burn wounds. Treatment by BO-AP significantly subsided inflammation compared to the BO, AP, and SSD treated wounds. Treatment with BO-AP also reduced collagen density and led to minimal scar formation. Combination of botulinum toxin type A and aprotinin considerably increased structural and functional properties of the healing wounds by reducing scar formation and decreasing production of proteases.

In Vivo Models for the Study of Fibrosis

Significance: Fibrosis and scar formation pose a substantial physiological and psychological burden on patients and a significant public health burden on the economy, estimated to be up to $12 billion a year. Fibrosis research is heavily reliant on in vivo models, but variations in animal models and differences between animal and human fibrosis necessitates careful selection of animal models to study fibrosis. There is also an increased need for improved animal models that recapitulate human pathophysiology. Recent Advances: Several murine and porcine models, including xenograft, drug-induced fibrosis, and mechanical load-induced fibrosis, for different types of fibrotic disease have been described in the literature. Recent findings have underscored the importance of mechanical forces in the pathophysiology of scarring. Critical Issues: Differences in skin, properties of subcutaneous tissue, and modes of fibrotic healing in animal models and humans provide challenges toward investigating fibrosis with in vivo models. While porcine models are typically better suited to study cutaneous fibrosis, murine models are preferred because of the ease of handling and availability of transgenic strains. Future Directions: There is a critical need to develop novel murine models that recapitulate the mechanical cues influencing fibrosis in humans, significantly increasing the translational value of fibrosis research. We advocate a translational pipeline that begins in mouse models with modified biomechanical environments for foundational molecular and cellular research before validation in porcine models that closely mimic the human condition.

Functional Skin Grafts: Where Biomaterials Meet Stem Cells

Skin tissue engineering has attained several clinical milestones making remarkable progress over the past decades. Skin is inhabited by a plethora of cells spatiotemporally arranged in a 3-dimensional (3D) matrix, creating a complex microenvironment of cell-matrix interactions. This complexity makes it difficult to mimic the native skin structure using conventional tissue engineering approaches. With the advent of newer fabrication strategies, the field is evolving rapidly. However, there is still a long way before an artificial skin substitute can fully mimic the functions and anatomical hierarchy of native human skin. The current focus of skin tissue engineers is primarily to develop a 3D construct that maintains the functionality of cultured cells in a guided manner over a period of time. While several natural and synthetic biopolymers have been translated, only partial clinical success is attained so far. Key challenges include the hierarchical complexity of skin anatomy; compositional mismatch in terms of material properties (stiffness, roughness, wettability) and degradation rate; biological complications like varied cell numbers, cell types, matrix gradients in each layer, varied immune responses, and varied methods of fabrication. In addition, with newer biomaterials being adopted for fabricating patient-specific skin substitutes, issues related to escalating processing costs, scalability, and stability of the constructs under in vivo conditions have raised some concerns. This review provides an overview of the field of skin regenerative medicine, existing clinical therapies, and limitations of the current techniques. We have further elaborated on the upcoming tissue engineering strategies that may serve as promising alternatives for generating functional skin substitutes, the pros and cons associated with each technique, and scope of their translational potential in the treatment of chronic skin ailments.

Beneath the Surface: A Review of Laser Remodeling of Hypertrophic Scars and Burns

Significance: Hypertrophic scars, keloids, and burn injuries of the skin have a significant impact on patients' lives and impact the health care system tremendously. Treating skin wounds and lesions can be challenging, with a variety of choices available for treatment. Scar and burn managements range from invasive, surgical options such as scar excision to less invasive, nonsurgical alternatives such as laser therapy or topical drug application. Recent Advances: Laser treatment has become increasingly popular, with a growing body of research supporting its use for scars and burns. Numerous methods are available for the treatment of these skin diseases, including different nonsurgical laser therapies. Critical Issues: To date, the optimal treatment method for scars, keloids, and burn injuries of the skin has not yet been established, although it is an area of increasing clinical concern. Future Directions: This review provides an updated summary of the treatment of scars and burn wounds of the skin using different laser treatments, including the most recent technologies. It addresses their indications, mechanisms of action, differences, efficacies, and complications.

Comparative regenerative biology of spiny (Acomys cahirinus) and laboratory (Mus musculus) mouse skin

Wound-induced hair follicle neogenesis (WIHN) has been demonstrated in laboratory mice (Mus musculus) after large (>1.5 × 1.5 cm2 ) full-thickness wounds. WIHN occurs more robustly in African spiny mice (Acomys cahirinus), which undergo autotomy to escape predation. Yet, the non-WIHN regenerative ability of the spiny mouse skin has not been explored. To understand the regenerative ability of the spiny mouse, we characterized skin features such as hair types, hair cycling, and the response to small and large wounds. We found that spiny mouse skin contains a large portion of adipose tissue. The spiny mouse hair bulge is larger and shows high expression of stem cell markers, K15 and CD34. All hair types cycle synchronously. To our surprise, the hair cycle is longer and less frequent than in laboratory mice. Newborn hair follicles in anagen are more mature than C57Bl/6 and demonstrate molecular features similar to C57Bl/6 adult hairs. The second hair cycling wave begins at week 4 and lasts for 5 weeks, then telogen lasts for 30 weeks. The third wave has a 6-week anagen, and even longer telogen. After plucking, spiny mouse hairs regenerate in about 5 days, similar to that of C57Bl/6. After large full-thickness excisional wounding, there is more de novo hair formation than C57Bl/6. Also, all hair types are present and pigmented, in contrast to the unpigmented zigzag hairs in C57Bl/6 WIHN. These findings shed new light on the regenerative biology of WIHN and may help us understand the control of skin repair vs regeneration.

Ointment of Ximenes americana promotes acceleration of wound healing in rats1

Purpose

To evaluate the healing potential of the Ximenia americana hydroalcoholic extract in 10% cream in excisional wound models in rats.

Methods

Sixty male adults Wistar rats were submitted to skin and subcutaneous tissue surgery in the right and left thoracic regions, divided into three experimental groups: Standard submitted to treatment with only the base vehicle, Treated wounds treated with hydroalcoholic extract of X. americana applied on 10%, Lanette base and Control, untreated wounds. The treatment was performed daily and the wounds evaluated microscopically by the quantification of fibroblasts, collagen fibers and blood vessels.

Results

The histomorphometric analysis showed a significant increase in the number of fibroblasts, collagen fibers and blood vessels in the treated group.

Conclusion

The topical action of the cream based on Ximenia americana shows angiogenic effects and improves the replacement of collagen, suggesting its use for the development of herbal remedy in the treatment of cutaneous wound healing.

Dihydromyricetin attenuates hypertrophic scar formation by targeting activin receptor-like kinase 5

Hypertrophic scar (HPS) is a manifestation of abnormal tissue repair, representing excessive extracellular matrix production and abnormal function of fibroblasts, for which no satisfactory treatment is available at present. Here we identified a natural product of flavonoid, dihydromyricetin, could effectively attenuate HPS formation. We showed that local intradermal injection of dihydromyricetin (50 μM) reduced the gross scar area, cross-sectional size of the scar and the scar elevation index in a mechanical load-induced mouse model. In addition, dihydromyricetin treatment also markedly decreased collagen density of the scar tissue. Furthermore, both in vitro and in vivo study both demonstrated that dihydromyricetin inhibited the proliferation, activation, contractile and migration abilities of hypertrophic scar-derived fibroblasts (HSFs) but did not affect HSFs apoptosis. Western blot analysis revealed that dihydromyricetin could down-regulate the phosphorylation of Smad2 and Smad3 of TGF-β signaling. Such bioactivity of dihydromyricetin may result from its selective binding to the catalytic region of activin receptor-like kinase 5 (ALK5), as suggested by the molecular docking study and kinase binding assay (12.26 μM). Above all, dihydromyricetin may prove to be a promising agent for the treatment of HPS and other fibroproliferative disorders.

Macrophages significantly enhance wound healing in a vascularized skin model

Tissue-engineered dermo-epidermal skin grafts could be applied for the treatment of large skin wounds or used as an in vitro wound-healing model. However, there is currently no skin replacement model that includes both, endothelial cells to simulate vascularization, and macrophages to regulate wound healing and tissue regeneration. Here, we describe for the first time a tissue-engineered, fully vascularized dermo-epidermal skin graft based on a fibrin hydrogel scaffold, using exclusively human primary cells. We show that endothelial cells and human dermal fibroblasts form capillary-like structures within the dermis whereas keratinocytes form the epithelial cell layer. Macrophages played a key role in controlling the number of epithelial cells and their morphology after skin injury induced with a CO₂ laser. The activation of selected cell types was confirmed by mRNA analysis. Our data underline the important role of macrophages in vascularized skin models for application as in vitro wound healing models or for skin replacement therapy. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1340-1350, 2019.

miR-181b-5p promotes proliferation and inhibits apoptosis of hypertrophic scar fibroblasts through regulating the MEK/ERK/p21 pathway

Hypertrophic scar (HS) is a common skin disorder occurring during the wound healing process, and the pathogenesis of HS remains unclear. Previous studies indicated that miRNAs may be involved in the onset and progression of HS. In the present study, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting were used to investigate the expression of miR-181b-5p and decorin in HS tissues. Direct interaction between miR-181b-5p and decorin was confirmed using a dual-luciferase assay. Human HS fibroblasts (HSFbs) were cultured and transfected with miR-181b-5p mimics, and MTT assay and Annexin V fluorescein isothiocyanate/propidium iodide staining were performed to investigate the role of miR-181b-5p in the proliferation and apoptosis of HSFbs. Subsequently, the expression levels of mitogen-activated protein kinase kinase (MEK), phospho (p)-extracellular signal-regulated kinase (ERK) and p21 were determined in HSFbs transfected with miR-181b-5p mimics and untransfected cells using RT-qPCR and western blotting. The results indicated upregulation of miR-181b-5p and downregulation of decorin expression in HS tissues compared with normal skin samples. miR-181b-5p may regulate the expression of decorin through direct binding to the 3′-untranslated region, as demonstrated by the results of the dual-luciferase assay. Transfection with miR-181b-5p mimics in HSFbs enhanced cell proliferation, reduced apoptosis and increased the expression of MEK, p-ERK and p21. Furthermore, treatment with MEK inhibitor in HSFbs transfected with miR-181b-5p mimics partially inhibited miR-181b-5p-induced antiapoptotic effects. Taken together, increased expression of miR-181b-5p may serve important roles in the pathogenesis of HS through regulating the MEK/ERK/p21 pathway, suggesting that miR-181b-5p may be a therapeutic target for the treatment of HS.

Wild-type p53-modulated autophagy and autophagic fibroblast apoptosis inhibit hypertrophic scar formation

Hypertrophic scarring is a serious fibrotic skin disease, and the abnormal activation of hypertrophic scar fibroblasts (HSFs) intensifies its pathogenesis. Our previous studies have demonstrated that the dysregulation of autophagy in HSFs is associated with fibrosis. However, knowledge regarding the regulation of HS fibrosis by p53-modulated autophagy is limited. Here, we investigated the effect of p53-modulated autophagy on HS fibrosis. The overexpression of wtp53 (Adp53) promoted autophagic capacity and inhibited collagen and α-SMA expression in HSFs. In contrast, LC3 (AdLC3) overexpression did not suppress Col 1, Col 3, or α-SMA expression, but LC3 (shLC3) knockdown downregulated collagen expression. Adp53-modulated autophagy altered Bcl-2 and Bcl-xL expression, but AdLC3 affected only Bcl-xL expression. Silencing Bcl-xL suppressed collagen expression, but autophagy was also inhibited. Flow cytometry showed that the silencing of Bcl-2 (sibcl-2), Bcl-xL (sibcl-xL), and Adp53 significantly increased apoptosis in the HSFs. Therefore, wtp53 inhibited fibrosis in the HSFs by modulating autophagic HSF apoptosis; moreover, the inhibition of autophagy by sibcl-xL had antifibrotic effects. In addition, treatment with Adp53, AdLC3, shLC3, sibcl-2, and sibcl-xL reduced scar formation in a rabbit ear scar model. These data confirm that wtp53-modulated autophagy and autophagic HSF apoptosis can serve as potential molecular targets for HS therapy.

Development of a Topical 48-H Release Formulation as an Anti-scarring Treatment for Deep Partial-Thickness Burns

The purpose of this study was to develop pirfenidone (PF) ointment formulations for a dose finding study in the prophylactic treatment of deep partial-thickness burns in a mouse model. A preformulation study was performed to evaluate the solubility of PF in buffers and different solvents and its stability. Three different formulations containing 1, 3.5, and 6.5% w/w PF were prepared and optimized for their composition for testing in mice. Optimized formulations showed promising in vitro release profiles, in which 20-45% of PF was released in the first 7 h and 70-90% released within 48 h. The rheological properties of the ointment remained stable throughout storage at 25 ± 2°C/60% RH. Animal studies showed treatments of burn wounds during the inflammatory stage of wound healing with PF ointments at different drug concentrations had no adverse effects on reepithelization. Moreover, 6.5% PF ointment (F3) reduced the expression of pro-inflammatory cytokines IL-12p70 and TNFα. This study suggests that hydrocarbon base ointment could be a promising dosage form for topical delivery of PF in treatment of deep partial-thickness burns.

Efficacy of Topical Enalapril in Treatment of Hypertrophic Scars

BACKGROUND

Angiotensin II activation by angiotensin-converting enzyme (ACE) is a significant mediator in wound healing and collagen production. In this study, the effect of topical application of ACE on hypertrophic scar formation has been studied in a clinical trial.

METHODS

Thirty patients with hypertrophic scar and itching after treatment of 2^nd or 3^rd degree burns participated in this double-blinded clinical trial. Subjects had two same-degree scars on symmetrical sites of body which were randomly allocated into two groups. One side was treated with 1% enalapril ointment and the other side with placebo twice daily. During a 6-months follow-up, a scoring table for itching was completed on a daily basis by patients. Furthermore, a single surgeon measured size of scars once a month. The mean size, thickness and itching score were calculated for each scar and compared between medication and placebo-treated scars.

RESULTS

The mean size of scars in enalapril treated side was significantly less than scars in the placebo side. Additionally, enalapril treated scars had significantly lower itching scores compared to the placebo group.

CONCLUSION

Topical enalapril significantly decreases the clinical parameters of hypertrophic scar and also itching as an indirect indicative of scar improvement. Furthermore, enalapril proved to be clinically safe for patients with low incidence of adverse drug reactions and acceptable cost effectiveness.

Silver Sulfadiazine Retards Wound Healing and Increases Hypertrophic Scarring in a Rabbit Ear Excisional Wound Model

This study evaluated the effects of topical use of silver sulfadiazine cream (SSD) on wound healing and subsequent scarring in a rabbit ear wound model. Seven millimeter full-thickness excisional wounds were created in rabbit ears. Twenty-four rabbits were randomized into four groups in which each group received base cream, 0.01% SSD, 0.1% SSD, or 1% SSD, respectively. Each treatment was applied at 2-day intervals from postoperative days (PODs) 2 to 14. At POD 7, half of the rabbits from each group were killed and tissues were harvested to measure wound healing parameters that included epithelial gap and granulation area. At POD 28, the remaining rabbits from each group were assessed for hypertrophic scarring. Epithelial gaps in SSD-treated groups at concentrations of 0.1 and 1% were significantly larger than those of base cream-treated controls. In contrast, analysis of granulation areas that represent volume of granulation tissue formed during healing did not show any statistical differences between the base cream-treated group and all three SSD-treated groups. At POD 28, when compared to the base cream-treated group (1.44 ± 0.03), SSD-treated-groups (0.1 and 1%) had more (P < .05) hypertrophic scar formation (scar elevation index = 1.65 ± 0.04, 0.1%; 1.63 ± 0.06, 1%). The results of this study demonstrate that SSD treatment contributes not only to impaired reepithelialization but also to a greater hypertrophic scar formation. These results also indicate that caution should be exercised when using SSD clinically to prevent or treat wound infections.

Computational analysis identifies putative prognostic biomarkers of pathological scarring in skin wounds

Background

Pathological scarring in wounds is a prevalent clinical outcome with limited prognostic options. The objective of this study was to investigate whether cellular signaling proteins could be used as prognostic biomarkers of pathological scarring in traumatic skin wounds.

Methods

We used our previously developed and validated computational model of injury-initiated wound healing to simulate the time courses for platelets, 6 cell types, and 21 proteins involved in the inflammatory and proliferative phases of wound healing. Next, we analysed thousands of simulated wound-healing scenarios to identify those that resulted in pathological (i.e., excessive) scarring. Then, we identified candidate proteins that were elevated (or decreased) at the early stages of wound healing in those simulations and could therefore serve as predictive biomarkers of pathological scarring outcomes. Finally, we performed logistic regression analysis and calculated the area under the receiver operating characteristic curve to quantitatively assess the predictive accuracy of the model-identified putative biomarkers.

Results

We identified three proteins (interleukin-10, tissue inhibitor of matrix metalloproteinase-1, and fibronectin) whose levels were elevated in pathological scars as early as 2 weeks post-wounding and could predict a pathological scarring outcome occurring 40 days after wounding with 80% accuracy.

Conclusion

Our method for predicting putative prognostic wound-outcome biomarkers may serve as an effective means to guide the identification of proteins predictive of pathological scarring.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1406-x) contains supplementary material, which is available to authorized users.

MicroRNA-519d inhibits proliferation and induces apoptosis of human hypertrophic scar fibroblasts through targeting Sirtuin 7

MicroRNAs (miRNAs) play critical roles in various pathological processes, including hypertrophic scar (HS) formation. However, the precise role of miRNAs in HS formation remains largely unknown. In this study, we aimed to investigate the role of miR-519d in HS formation. We found that miR-519d expression was significantly downregulated in HS tissues and fibroblasts. Overexpression of miR-519d inhibited the expression of type I collagen (Col I), type III collagen (Col III) and α-smooth muscle actin (α-SMA) in HS fibroblasts. Moreover, overexpression of miR-519d reduced the proliferation and induced the apoptosis of HS fibroblasts. In contrast, suppression of miR-519d showed the opposite effects. Interestingly, Sirtuin 7 (SIRT7) was identified as a target gene of miR-519d. The results showed that miR-519d directly targeted the 3'-untranslated region of SIRT7 and negatively regulated its expression. Furthermore, miR-519d regulated the expression of TGF-β type I receptor (TGFBRI) and the phosphorylation of Smad2. Knockdown of SIRT7 by siRNA inhibited the expression of Col I, Col III and α-SMA, and reduced the proliferation and induced the apoptosis of HS fibroblasts. Overexpression of SIRT7 abrogated the effects mediated by miR-519d overexpression in HS fibroblasts. Overall, these results suggest that miR-519d inhibits the expression of extracellular matrix-associated genes, reduces the proliferation and induces the apoptosis of HS fibroblasts by targeting SIRT7, implying a suppressive role of miR-519d in HS formation. This study suggests that miR-519d may serve as a promising therapeutic target for treatment of human HS.

Mechanical Forces in Cutaneous Wound Healing: Emerging Therapies to Minimize Scar Formation

Significance: Excessive scarring is major clinical and financial burden in the United States. Improved therapies are necessary to reduce scarring, especially in patients affected by hypertrophic and keloid scars. Recent Advances: Advances in our understanding of mechanical forces in the wound environment enable us to target mechanical forces to minimize scar formation. Fetal wounds experience much lower resting stress when compared with adult wounds, and they heal without scars. Therapies that modulate mechanical forces in the wound environment are able to reduce scar size. Critical Issues: Increased mechanical stresses in the wound environment induce hypertrophic scarring via activation of mechanotransduction pathways. Mechanical stimulation modulates integrin, Wingless-type, protein kinase B, and focal adhesion kinase, resulting in cell proliferation and, ultimately, fibrosis. Therefore, the development of therapies that reduce mechanical forces in the wound environment would decrease the risk of developing excessive scars. Future Directions: The development of novel mechanotherapies is necessary to minimize scar formation and advance adult wound healing toward the scarless ideal. Mechanotransduction pathways are potential targets to reduce excessive scar formation, and thus, continued studies on therapies that utilize mechanical offloading and mechanomodulation are needed.

Extracorporeal Shock Wave Therapy Alters the Expression of Fibrosis-Related Molecules in Fibroblast Derived from Human Hypertrophic Scar

Extracorporeal shock wave therapy (ESWT) considerably improves the appearance and symptoms of post-burn hypertrophic scars (HTS). However, the mechanism underlying the observed beneficial effects is not well understood. The objective of this study was to elucidate the mechanism underlying changes in cellular and molecular biology that is induced by ESWT of fibroblasts derived from scar tissue (HTSFs). We cultured primary dermal fibroblasts derived from human HTS and exposed these cells to 1000 impulses of 0.03, 0.1, and 0.3 mJ/mm². At 24 h and 72 h after treatment, real-time PCR and western blotting were used to detect mRNA and protein expression, respectively, and cell viability and mobility were assessed. While HTSF viability was not affected, migration was decreased by ESWT. Transforming growth factor beta 1 (TGF-β1) expression was reduced and alpha smooth muscle actin (α-SMA), collagen-I, fibronectin, and twist-1 were reduced significantly after ESWT. Expression of E-cadherin was increased, while that of N-cadherin was reduced. Expression of inhibitor of DNA binding 1 and 2 was increased. In conclusion, suppressed epithelial-mesenchymal transition might be responsible for the anti-scarring effect of ESWT, and has potential as a therapeutic target in the management of post-burn scars.