A preliminary study on ultrasound techniques applied to evaluate the curative effect of botulinum toxin type a in hypertrophic scars.

Objective: To validate the feasibility of ultrasound in assessing the curative effect of botulinum toxin type A (BTXA) in treating hypertrophic scar (HS). Methods: Eight healthy New Zealand long-eared rabbits were utilized in the study. Four wounds, each measuring 1.0 cm in diameter, were created on both ears of each rabbit. Immediately after surgery, each of these wounds received an injection containing a distinct concentration of BTXA. On postoperative week 6, scar thickness, vascularity, and hardness were assessed based on high frequency ultrasound (HFUS), superb microvascular imaging (SMI), shear wave elastography (SWE), Masson staining, and immunohistochemical staining for CD31. Results: All wounds healed well, and HSs formed after 6 weeks post-surgery. Scar thickness based on HFUS presented a significant decrease with increasing BTXA concentration (p < 0.05), aligning with the gross morphology. Simultaneously, scar stiffness, evaluated using SWE, showed a significant decrease in accordance with the variation of the collagen volume fraction, which refers to the ratio of the collagen positive area to the total area (p < 0.05). Although the vascularity index obtained by SMI did not exhibit a statistically significant change across different BTXA concentrations, this technique effectively illustrated the microvascular perfusion in HS. Immunohistochemical staining for CD31 revealed that BTXA inhibited angiogenesis. Conclusion: HFUS and SWE displayed excellent performance in evaluating HS thickness and stiffness. SMI showed a good performance in reflecting microvascular signals in HS. These ultrasound techniques have great potential in assessing the therapeutic effect of BTXA in HS.

Adipose-derived mesenchymal stem cells suppress fibroblast proliferation of hypertrophic scar through CCL5 and CXCL12.

BACKGROUND AND OBJECTIVE: Adipose-derived mesenchymal stem cells (ADSCs) can accelerate wound healing, reduce scar formation, and inhibit hypertrophic scar (HTS). ADSCs can secrete a large amount of CCL5, and CCL5 has been proved to be pro-inflammatory and pro-fibrotic. CXCL12 (SDF-1) is a key chemokine that promotes stem cell migration and survival. Therefore, this study selected normal skin and HTS conditioned medium to simulate different microenvironments, and analyzed the effects of different microenvironments on the expression of CCL5 and CXCL12 in human ADSCs (hADSCs). MATERIALS AND METHODS: hADSCs with silenced expression of CCL5 and CXCL12 were co-cultured with hypertrophic scar fibroblasts to verify the effects of CCL5 and CXCL12 in hADSCs on the proliferation ability of hypertrophic scar fibroblasts. A mouse model of hypertrophic scar was established to further confirm the effect of CCL5 and CXCL12 in hADSCs on hypertrophic scar formation. RESULTS: CCL5 level was found to be significantly high in hADSCs cultured in HTS conditioned medium. CXCL12 in HTS group was prominently lowly expressed compared with the normal group. Inhibition of CCL5 in hADSCs enhanced the effects of untreated hADSCs on proliferation of HTS fibroblasts while CXCL12 knockdown exerted the opposite function. Inhibition of CCL5 in hADSCs increased the percentage of HTS fibroblasts in the G0/G1 phase while down-regulation of CXCL12 decreased those. Meanwhile, the down-regulated levels of fibroblast markers including collagen I, collagen III, and α-SMA induced by CCL5 knockdown were significantly up-regulated by CXCL12 inhibition. hADSCs alleviate the HTS of mice through CCL5 and CXCL12. CONCLUSION: In summary, our results demonstrated that hADSCs efficiently cured HTS by suppressing proliferation of HTS fibroblasts, which may be related to the inhibition of CXCL12 and elevation of CCL5 in hADSCs, suggesting that hADSCs may provide an alternative therapeutic approach for the treatment of HTS.

Hepatocyte growth factor-modified adipose-derived mesenchymal stem cells inhibit human hypertrophic scar fibroblast activation.

PURPOSE: Nucleoside-modified messenger RNA (modRNA) holds the potential for facilitating genetic enhancement of stem cells. In this study, modRNA encoding hepatocyte growth factor (modHGF) was used to chemically modify adipose-derived mesenchymal stem cells (ADSCs) and the effect of modified ADSCs on the activation of hypertrophic scar fibroblasts (HSFs) was evaluated. METHODS: CCK-8, wound healing, and transwell assays were utilized to evaluate the viability and migratory potential of modHGF-engineered ADSCs and their effect on HSF activation. Reverse transcription-polymerase chain reaction, western blot, and immunofluorescence staining were performed to detect the expression of collagen-I (Col I), collagen-III (Col III), alpha-smooth muscle actin (α-SMA), matrix metallopeptidase 1 (MMP-1), and MMP-3. RESULTS: Transfection of ADSCs with modHGF (HGF-ADSC) resulted in enhanced production of HGF. Meanwhile, modHGF modification enhanced the viability and migration of ADSCs. Notably, culture media from HGF-ADSCs exhibited a more potent inhibitory effect on the proliferation and migration of HSFs. In addition, culture media from HGF-ADSCs inhibited extracellular matrix synthesis of HSFs, as evidenced by reduced expression levels of Col I, Col III, and α-SMA, while increasing expression of MMP-1 and MMP-3. Conversely, neutralization experiments confirmed that these effects could be effectively alleviated by blocking HGF activity. CONCLUSION: modHGF modification optimizes the inhibitory effect of ADSCs on HSF activation, which provides a promising alternative for preventing and treating hyperplastic scars.

Skin fibrosis is accompanied by increased expression of secreted frizzled-related protein-2.

Dermal fibrosis is a consequence of damage to skin and is accompanied by dysfunction and cosmetic disfigurement. Improved understanding of the pathological factors driving skin fibrosis is critical to development of therapeutic modalities. Here, we describe that the Wnt signalling antagonist SFRP2 is upregulated in organotypic keratinocyte cultures upon experimental reduced hydration, a model that simulates the aberrant epidermal barrier state characteristic of several skin pathologies, including those that manifest in development of fibrosis. Consistent with this, we find that SFRP2 is overexpressed in both the dermis and epidermis of human hypertrophic scar tissue and lesional tissue of a mouse scleroderma model. Knockdown of SFRP2 expression in human fibroblasts antagonises proliferation and myofibroblast differentiation, including deposition of type I collagen, suggesting that SFRP2 signalling in fibroblasts may contribute to propagation of fibrosis in hypertrophic scar, as well as in other clinical indications characterised by skin fibrosis.

Evidence of a causal relationship between blood pressure and pathological scars: a bidirectional Mendelian randomization study.

Background: Recent advancements in basic medicine and epidemiology suggest a potential influence of blood pressure on scar formation, yet the specifics of this relationship are not fully understood. This study aims to clarify the causal link between blood pressure and the development of pathological scars using Mendelian randomization (MR). Methods: This study employed genetic variants closely linked to blood pressure as instrumental variables to explore the relationship between blood pressure and pathological scars. The inverse variance weighted (IVW) method was used for analysis. Results: Our analysis identified a notable association where higher blood pressure was correlated with a lower risk of pathological scars. Specifically, an increase in diastolic blood pressure (odds ratio [OR] per standard deviation increase: 0.67 [95% Confidence Interval [CI], 0.49-0.99]), systolic blood pressure (OR per standard deviation increase: 0.66 [95% CI, 0.46-0.93]), and hypertension (pooled OR: 0.39 [95% CI, 0.18-0.85]) were significantly associated with a reduced risk of keloids. Similarly, a genetic predisposition to hypertension (pooled OR: 0.31 [95% CI, 0.11-0.89]) was significantly associated with a reduced risk of hypertrophic scars. Neither reverse MR analysis nor Steiger's test indicated a significant reverse causal relationship between hypertension and either keloids or hypertrophic scars. Conclusion: The findings suggest a protective role of higher blood pressure against the development of pathological scars, including keloids and hypertrophic scars. However, the inconsistency observed across different MR methods warrants cautious interpretation and underscores the need for further investigation to confirm these findings.

Zinc-Alpha-2-Glycoprotein Peptide Downregulates Type I and III Collagen Expression via Suppression of TGF-ß and p-Smad 2/3 Pathway in Keloid Fibroblasts and Rat Incisional Model.

BACKGROUND: Keloids and hypertrophic scars result from abnormal collagen accumulation and the inhibition of its degradation. Although the pathogenesis remains unclear, excessive accumulation of the extracellular matrix (ECM) is believed to be associated with the TGF-ß/SMAD pathway. Zinc-alpha-2-glycoprotein (ZAG) inhibits TGF-ß-mediated epithelial-to-mesenchymal transdifferentiation and impacts skin barrier functions. In this study, we investigated the potential of a small ZAG-derived peptide against hypertrophic scars and keloids. METHODS: The study examined cell proliferation and mRNA expression of collagen types I and III in human dermal fibroblast (HDF) cell lines and keloid-derived fibroblasts (KF) following ZAG peptide treatment. A rat incisional wound model was used to evaluate the effect of ZAG peptide in scar tissue. RESULTS: Significantly lower mRNA levels of collagen types I and III were observed in ZAG-treated fibroblasts, whereas matrix metalloproteinase (MMP)-1 and MMP-3 mRNA levels were significantly increased in HDFs and KFs. Furthermore, ZAG peptide significantly reduced protein expression of collagen type I and III, TGF-ß1, and p-Smad2/3 complex in KFs. Rat incisional scar models treated with ZAG peptide presented narrower scar areas and reduced immature collagen deposition, along with decreased expression of collagen type I, α-SMA, and p-Smad2/3. CONCLUSION: ZAG peptide effectively suppresses the TGF-ß and p-Smad2/3 pathway and inhibits excessive cell proliferation during scar formation, suggesting its potential therapeutic implications against keloids and hypertrophic scars.

Role of Dermatix in the Management of Eyelid Hypertrophic Scars After Facial Trauma.

Facial trauma can cause skin wounds with uneven and discoloured edges that require healing by secondary intention. These wounds often produce excess collagen fibres, leading to fibrosis and hypertrophic scars that can cause discomfort and negatively impact the patient's quality of life. A man suffered facial trauma due to a motor vehicle accident, resulting in a fracture of the left zygomatic-maxillary complex. He underwent surgery to fix the fracture and reconstruct his eyelid but developed a hypertrophic scar during recovery that caused eye dryness and discomfort. To treat the scar, Dermatix silicone gel (SG) (Viatris, Canonsburg, PA) was applied twice a day. After two months of treatment, the scar had improved significantly, and the patient's eyelid function had also improved. This case describes the use of Dermatix SG to treat a patient with a traumatic hypertrophic scar of the eyelid associated with eyelid malposition. Silicone gel is a non-invasive treatment for scars and has been shown to be effective in reducing scar elevation and erythema. However, there is a gap in the literature regarding the routine use of SG to preserve functionality and aesthetics in traumatic hypertrophic scars of complex anatomical structures. Further studies are needed to understand the principles of using SG for these types of scars to improve functional and aesthetic outcomes. Applying Dermatix SG twice a day for 60 days corrected a patient's functional and aesthetic issues. More studies should be conducted to investigate the product's effectiveness further.

Addressing Burn Hypertrophic Scar Symptoms Earlier: Laser Scar Revision May Begin as Early as 3-6 Months After Injury.

OBJECTIVES: Fractional ablative CO2 laser (FLSR) is used to treat hypertrophic scars (HTSs) resulting from burn injuries, which are characterized by factors, such as erythema, contracture, thickness, and symptoms of pain and itch. Traditionally, waiting a year after injury for scar maturation before starting laser treatment has been recommended; however, the potential benefits of earlier intervention have gained popularity. Still, the optimal timing for beginning laser intervention in patients with HTSs remains uncertain. This study aims to evaluate the ideal timing for the initiation of FLSR for HTSs using several qualitative and quantitative assessment measures. It was hypothesized that early intervention would lead to similar improvement trends as later intervention, however, would be more ideal due to the shortened time without symptom relief for patients. METHODS: Patients who received three or more laser treatment sessions and completed both pre- and posttreatment evaluations were included in this analysis (n = 69). FLSR treatment was administered at 4-8-week intervals. Patients starting treatment before 6 months after injury were classified as the early-stage intervention group and those beginning treatment at 6-12 months after injury were classified as the late-stage intervention group. Demographic data, including the age of patients at the time of first treatment, age of scars at the time of first treatment, biological sex, ethnicity, Fitzpatrick skin type, and use of laser-assisted drug delivery, were collected by retrospective chart review. Patients were evaluated on six subjective scales and objectively for scar stiffness with durometry. For all scales, higher scores indicate worse scars. A two-way ANOVA, Student's t-test, and Mann-Whitney U-test were used to compare scores from the pre- to posttreatment evaluations. RESULTS: There were no significant differences between the groups for any of the demographic or scar-specific variables; thus, differences in outcome can be attributed to the timing of intervention. Both groups demonstrated an improvement in scars with treatment over time (p < 0.05). Both early- and middle-stage initiation showed scar symptom improvement in five out of six scales. In the late-stage intervention, the Patient and Observer Scar Assessment Scale-Patient average score did not show improvement. In the early-stage intervention, the Vancouver Scar Scale total did not show improvement. Quantitative evaluation of scar stiffness by durometry did not show symptom improvement in either group. The Scar Comparison Scale demonstrated the greatest improvement across groups. CONCLUSION: Laser treatment led to scar improvement in at least one scale at each stage of initiation. Both intervention timelines resulted in equivalent outcomes, and early intervention should be considered when initiating FLSR treatment in burn scars to alleviate symptoms earlier.

Exploring the potential mechanism of WuFuYin against hypertrophic scar using network pharmacology and molecular docking.

BACKGROUND: Hypertrophic scar (HTS) is dermal fibroproliferative disorder, which may cause physiological and psychological problems. Currently, the potential mechanism of WuFuYin (WFY) in the treatment of HTS remained to be elucidated. AIM: To explore the potential mechanism of WFY in treating HTS. METHODS: Active components and corresponding targets were retrieved from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform. HTS-related genes were obtained from the GeneCards, DisGeNET, and National Center for Biotechnology Information. The function of targets was analyzed by performing Gene Ontology and Kyoto Encyclopaedia of Genes and Genome (KEGG) enrichment analysis. A protein + IBM-protein interaction (PPI) network was developed using STRING database and Cytoscape. To confirm the high affinity between compounds and targets, molecular docking was performed. RESULTS: A total of 65 core genes, which were both related to compounds and HTS, were selected from multiple databases. PPI analysis showed that CKD2, ABCC1, MMP2, MMP9, glycogen synthase kinase 3 beta (GSK3B), PRARG, MMP3, and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit gamma (PIK3CG) were the hub targets and MOL004941, MOL004935, MOL004866, MOL004993, and MOL004989 were the key compounds of WFY against HTS. The results of KEGG enrichment analysis demonstrated that the function of most genes were enriched in the PI3K-Akt pathway. Moreover, by performing molecular docking, we confirmed that GSK3B and 8-prenylated eriodictyol shared the highest affinity. CONCLUSION: The current findings showed that the GSK3B and cyclin dependent kinase 2 were the potential targets and MOL004941, MOL004989, and MOL004993 were the main compounds of WFY in HTS treatment.

Exosomes Derived from Hypertrophic Scar Fibroblasts Suppress Melanogenesis in Normal Human Epidermal Melanocytes.

Post-burn hypertrophic scars often exhibit abnormal pigmentation. Exosomes play important roles in maintaining normal physiological homeostasis and in the pathological development of diseases. This study investigated the effects of the exosomes derived from hypertrophic scar fibroblasts (HTSFs) on melanocytes, which are pigment-producing cells. Normal fibroblasts (NFs) and HTSFs were isolated and cultured from normal skin and hypertrophic scar (HTS) tissue. Both the NF- and HTSF-exosomes were isolated from a cell culture medium and purified using a column-based technique. The normal human epidermal melanocytes were treated with both exosomes at a concentration of 100 µg/mL at different times. The cell proliferation, melanin content in the medium, apoptotic factors, transcription factors, melanin synthesis enzymes, signaling, signal transduction pathways, and activators of transcription factors (STAT) 1, 3, 5, and 6 were investigated. Compared with the Dulbecco's phosphate-buffered saline (DPBS)-treated controls and NF-exosomes, the HTSF-exosomes decreased the melanocyte proliferation and melanin secretion. The molecular patterns of apoptosis, proliferation, melanin synthesis, Smad and non-Smad signaling, and STATs were altered by the treatment with the HTSF-exosomes. No significant differences were observed between the DPBS-treated control and NF-exosome-treated cells. HTSF-derived exosomes may play a role in the pathological epidermal hypopigmentation observed in patients with HTS.

Decorin attenuates hypertrophic scar fibrosis via TGFß/Smad signalling.

The management of hypertrophic scars (HSs), characterized by excessive collagen production, involves various nonsurgical and surgical interventions. However, the absence of a well-defined molecular mechanism governing hypertrophic scarring has led to less-than-ideal results in clinical antifibrotic treatments. Therefore, our study focused on the role of decorin (DCN) and its regulatory role in the TGF-ß/Smad signalling pathway in the development of HSs. In our research, we observed a decrease in DCN expression within hypertrophic scar tissue and its derived cells (HSFc) compared to that in normal tissue. Then, the inhibitory effect of DCN on collagen synthesis was confirmed in Fc and HSFc via the detection of fibrosis markers such as COL-1 and COL-3 after the overexpression and knockdown of DCN. Moreover, functional assessments revealed that DCN suppresses the proliferation, migration and invasion of HSFc. We discovered that DCN significantly inhibits the TGF-ß1/Smad3 pathway by suppressing TGF-ß1 expression, as well as the formation and phosphorylation of Smad3. This finding suggested that DCN regulates the synthesis of collagen-based extracellular matrix and fibrosis through the TGF-ß1/Smad3 pathway.

Isorhamnetin inhibits hypertrophic scar formation through TGF-ß1/Smad and TGF-ß1/CREB3L1 signaling pathways.

Background: Hypertrophic scar (HS) is a common fibrotic skin disease that occurs secondary to burns or injuries. The activation of the TGF-ß signaling pathway contributes immensely to HS formation. Isorhamnetin (ISO) is a type of flavonoid compound that exerts an antifibrotic effect via TGF-ß signaling suppression. However, whether ISO can inhibit HS formation via TGF-ß signaling is yet to be elucidated. This study aimed to examine the influence of ISO on HS pathogenesis and TGF-ß signaling, especially the downstream molecules and networks of TGF-ß signaling that facilitate HS formation. Methods: Hypertrophic scar fibroblasts (HSFBs) were isolated from human HS tissues. The in vitro proliferation, migration, contractile ability, cell cycle, and apoptosis of HSFBs after ISO treatment were determined using cell viability assay, EdU staining, wound healing assay, collagen gel contraction assay, and flow cytometry. The expressions of genes and proteins involved in TGF-ß signaling and its downstream molecules in ISO-treated HSFBs were determined using quantitative PCR (qPCR), immunofluorescence, and western blotting. In vivo, a rabbit HS model was established, and the effects of ISO on rabbit HS formation were investigated using histological analysis, immunohistochemical staining, and qPCR. Results: In vitro studies indicated that ISO treatment suppressed the proliferation, migration, and contractile ability of HSFBs; attenuated the expressions of COL Ⅰ, COL Ⅲ, and α-SMA; and inhibited TGF-ß1 signaling-induced activation of HSFBs by decreasing the levels of phosphorylated Smad2/3 and cleaved CREB3L1 in a dose-dependent manner. Furthermore, ISO augmented apoptosis and G2 phase cell cycle arrest of HSFBs by upregulating the expressions of the proapoptotic proteins Bax and cleaved caspase-3 and downregulating the expression of the antiapoptotic protein Bcl-2. In vivo studies revealed that ISO ameliorated HS formation in the rabbit ear by lowering the scar elevation index, attenuating the collagen density, facilitating the regular arrangement of collagen fibers, and downregulating the expressions of TGF-ß1, CREB3L1, COL Ⅰ, COL Ⅲ, and α-SMA. Conclusions: ISO suppressed HS pathogenesis by dampening TGF-ß1/Smad and TGF-ß1/CREB3L1 signaling pathways, which suggests that it may serve as a candidate inhibitor of TGF-ß1 signaling and a promising anti-HS drug with a high therapeutic potential.

Graphene Quantum Dots Reduce Hypertrophic Scar by Inducing Myofibroblasts To Be a Quiescent State.

Contrary to the initial belief that myofibroblasts are terminally differentiated cells, myofibroblasts have now been widely recognized as an activation state that is reversible. Therefore, strategies targeting myofibroblast to be a quiescent state may be an effective way for antihypertrophic scar therapy. Graphene quantum dots (GQDs), a novel zero-dimensional and carbon-based nanomaterial, have recently garnered significant interest in nanobiomedicine, owing to their excellent biocompatibility, tunable photoluminescence, and superior physiological stability. Although multiple nanoparticles have been used to alleviate hypertrophic scars, a GQD-based therapy has not been reported. Our in vivo studies showed that GQDs exhibited significant antiscar efficacy, with scar appearance improvement, collagen reduction and rearrangement, and inhibition of myofibroblast overproliferation. Further in vitro experiments revealed that GQDs inhibited α-SMA expression, collagen synthesis, and cell proliferation and migration, inducing myofibroblasts to become quiescent fibroblasts. Mechanistic studies have demonstrated that the effect of GQDs on myofibroblast proliferation blocked cell cycle progression by disrupting the cyclin-CDK-E2F axis. This study suggests that GQDs, which promote myofibroblast-to-fibroblast transition, could be a novel antiscar nanomedicine for the treatment of hypertrophic scars and other types of pathological fibrosis.

Integrative Analysis of Lactylome and Proteome of Hypertrophic Scar To Identify Pathways or Proteins Associated with Disease Development.

Lactylation (Kla), a recently discovered post-translational modification derived from lactate, plays crucial roles in various cellular processes. However, the specific influence of lactylation on the biological processes underlying hypertrophic scar formation remains unclear. In this study, we present a comprehensive profiling of the lactylome and proteome in both hypertrophic scars and adjacent normal skin tissues. A total of 1023 Kla sites originating from 338 nonhistone proteins were identified based on lactylome analysis. Proteome analysis in hypertrophic scar and adjacent skin samples revealed the identification of 2008 proteins. It is worth noting that Kla exhibits a preference for genes associated with ribosome function as well as glycolysis/gluconeogenesis in both normal skin and hypertrophic scar tissues. Furthermore, the functional enrichment analysis demonstrated that differentially lactyled proteins are primarily involved in proteoglycans, HIF-1, and AMPK signaling pathways. The combined analysis of the lactylome and proteome data highlighted a significant upregulation of 14 lactylation sites in hypertrophic scar tissues. Overall, our investigation unveiled the significant involvement of protein lactylation in the regulation of ribosome function as well as glycolysis/gluconeogenesis, potentially contributing to the formation of hypertrophic scars.

The potential of RNA therapeutics in dermatology.

Ribonucleic acid (RNA) therapeutics hold great potential for the advancement of dermatological treatments due to, among other reasons, the possibility of treating previously undruggable targets, high specificity with minimal side effects, and ability to include multiple RNA targets in a single product. Although there have been research relating to RNA therapeutics for decades, there have not been many products translated for clinical use until recently. This may be because of challenges to the application of RNA therapeutics, including the dearth of effective modes of delivery to the target, and rapid degradation of RNA in the human body and environment. This article aims to provide insight on (1) the wide-ranging possibilities of RNA therapeutics in the field of dermatology as well as (2) how key challenges can be addressed, so as to encourage the development of novel dermatological treatments. We also share our experience on how RNA therapeutics have been applied in the management of hypertrophic and keloid scars.

Effect of black cloth ointment on hypertrophic scar formation: An investigation using integrated network pharmacology and animal assay.

BACKGROUND: Hypertrophic scars (HS) are a common disfiguring condition in daily clinical encounters which brings a lot of anxieties and concerns to patients, but the treatment options of HS are limited. Black cloth ointment (BCO), as a cosmetic ointment applicable to facial scars, has shown promising therapeutic effects for facial scarring. However, the molecular mechanisms underlying its therapeutic effects remain unclear. MATERIAL AND METHODS: Network pharmacology was first applied to analyze the major active components of BCO and the related signaling pathways. Subsequently, rabbit ear scar model was successfully established to determine the pharmacological effects of BCO and its active component ß-elemene on HS. Finally, the molecular mechanism of BCO and ß-elemene was analyzed by Western blot. RESULTS: Through the network pharmacology, it showed that ß-elemene was the main active ingredient of BCO, and it could significantly improve the pathological structure of HS and reduce collagen deposition. BCO and ß-elemene could increase the expression of ER stress-related markers and promote the increase of apoptotic proteins in the Western blot experiment and induce the apoptosis of myofibroblasts. CONCLUSIONS: Our findings indicate that the material basis for the scar-improving effects of the BCO is ß-elemene, and cellular apoptosis is the key mechanism through which the BCO and ß-elemene exert their effects.

A Nude Mouse Model of Xenografted Hypertrophic Scar Cells to Test Therapeutics in the Skin.

BACKGROUND: Existing animal models for testing therapeutics in the skin are limited. Mouse and rat models lack similarity to human skin in structure and wound healing mechanism. Pigs are regarded as the best model with regards to similarity to human skin; however, these studies are expensive, time-consuming, and only small numbers of biologic replicates can be obtained. In addition, local-regional effects of treating wounds that are closely adjacent to one-another with different treatments make assessment of treatment effectiveness difficult in pig models. Therefore, here, a novel nude mouse model of xenografted porcine hypertrophic scar (HTS) cells was developed. This model system was developed to test if supplying hypo-pigmented cells with exogenous alpha melanocyte stimulating hormone (α-MSH) will reverse pigment loss in vivo. METHODS: Dyschromic HTSs were created in red Duroc pigs. Epidermal scar cells (keratinocytes and melanocytes) were derived from regions of hyper-, hypo-, or normally pigmented scar or skin and were cryopreserved. Dermal fibroblasts (DFs) were isolated separately. Excisional wounds were created on nude mice and a grafting dome was placed. DFs were seeded on day 0 and formed a dermis. On day 3, epidermal cells were seeded onto the dermis. The grafting dome was removed on day 7 and hypo-pigmented xenografts were treated with synthetic α-MSH delivered with microneedling. On day 10, the xenografts were excised and saved. Sections were stained using hematoxylin and eosin hematoxylin and eosin (H&E) to assess xenograft structure. RNA was isolated and quantitative real-time polymerase chain reaction (qRT-PCR) was performed for melanogenesis-related genes TYR, TYRP1, and DCT. RESULTS: The seeding of HTSDFs formed a dermis that is similar in structure and cellularity to HTS dermis from the porcine model. When hyper-, hypo-, and normally-pigmented epidermal cells were seeded, a fully stratified epithelium was formed by day 14. H&E staining and measurement of the epidermis showed the average thickness to be 0.11 ± 0.07 µm vs. 0.06 ± 0.03 µm in normal pig skin. Hypo-pigmented xenografts that were treated with synthetic α-MSH showed increases in pigmentation and had increased gene expression of TYR, TYRP1, and DCT compared to untreated controls (TYR: 2.7 ± 1.1 vs. 0.3 ± 1.1; TYRP1: 2.6 ± 0.6 vs. 0.3 ± 0.7; DCT 0.7 ± 0.9 vs. 0.3 ± 1-fold change from control; n = 3). CONCLUSIONS: The developed nude mouse skin xenograft model can be used to study treatments for the skin. The cells that can be xenografted can be derived from patient samples or from pig samples and form a robust dual-skin layer containing epidermis and dermis that is responsive to treatment. Specifically, we found that hypo-pigmented regions of scar can be stimulated to make melanin by synthetic α-MSH in vivo.

Minimally invasive surgical approach to model hypertrophic scarring in the rabbit ear.

BACKGROUND: Current strategies for hypertrophic scar prevention and treatment are limited. OBJECTIVE: To facilitate these efforts, a minimally invasive hypertrophic scar model was created in a rabbit ear for the first time based on previous methods used to induce ischemia. METHODS: Six New Zealand white rabbits (12 ears total) were studied. First, ischemia was achieved by ligating the cranial artery, cranial vein and central artery, while preserving the caudal artery, caudal vein and central vein, respectively. The relative level of ischemia induced at time of surgery, both baseline and maximum perfusion, was assessed with a fluorescent light-assisted angiography and demonstrated lower rates of perfusion in the ischemic ears. Following vascular injury, a 2-cm full thickness linear wound was created on the ventral ear and closed with 4 - 0 Nylon sutures under high tension. For each rabbit, one ear received a combination of ischemia and wounding with suture tension (n = 6), while the other ear was non-ischemic with wounding and suture tension alone (n = 6). RESULTS: Four weeks post-operatively, ischemic ears developed scar hypertrophy (histological scar thickness: 1.1 ± 0.2 mm versus 0.5 ± 0.1 mm, p < 0.05). CONCLUSION: Herein, we describe a novel, prototypical minimally invasive rabbit ear model of hypertrophic scar formation that can allow investigation of new drugs for scar prevention.

The role of circulating metabolites and gut microbiome in hypertrophic scar: a two-sample Mendelian randomization study.

Hypertrophic scarring is a fibro-proliferative disorder caused by abnormal cutaneous wound healing. Circulating metabolites and the gut microbiome may be involved in the formation of these scars, but high-quality evidence of causality is lacking. To assess whether circulating metabolites and the gut microbiome contain genetically predicted modifiable risk factors for hypertrophic scar formation. Two-sample Mendelian randomization (MR) was performed using MR-Egger, inverse-variance weighting (IVW), Mendelian Randomization Pleiotropy RESidual Sum and Outlier, maximum likelihood, and weighted median methods. Based on the genome-wide significance level, genetically predicted uridine (P = 0.015, odds ratio [OR] = 1903.514, 95% confidence interval [CI] 4.280-846,616.433) and isovalerylcarnitine (P = 0.039, OR = 7.765, 95% CI 1.106-54.512) were positively correlated with hypertrophic scar risk, while N-acetylalanine (P = 0.013, OR = 7.98E-10, 95% CI 5.19E-17-0.012) and glycochenodeoxycholate (P = 0.021, OR = 0.021 95% CI 0.003-0.628) were negatively correlated. Gastranaerophilales and two unknown gut microbe species (P = 0.031, OR = 0.378, 95% CI 0.156-0.914) were associated with an decreased risk of hypertrophic scarring. Circulating metabolites and gut microbiome components may have either positive or negative causal effects on hypertrophic scar formation. The study provides new insights into strategies for diagnosing and limiting hypertrophic scarring.

MALAT1 Knockdown Inhibits the Proliferation, Migration, and Collagen Deposition of Human Hypertrophic Scar Fibroblasts via Targeting miR-29a-3p/Smurf2 Axis.

Purpose: Hypertrophic scarring (HS) is commonly described as an abnormal post-traumatic tissue repair characterized by excessive hypercellularity and extracellular matrix (ECM) deposition. Mounting evidence suggests that MALAT1 is maladjusted in many fibrotic diseases, but its contribution to HS progression remains poorly understood. Hence, we sought to elucidate the fundamental role of MALAT1 in HS. Methods: The expression of MALAT1, miR-29a-3p, and Smurf2 in skin tissues and fibroblasts was assessed by RT-qPCR and Western blotting. Furthermore, lentiviruses, RNAi, or plasmids were utilized to transfect hypertrophic scar fibroblasts (HSFs) for gene overexpression or downregulation. The biological behaviors of HSFs were quantified by the CCK-8 assay, wound healing assay, transwell assay, and flow cytometry. Mechanistically, bioinformatics analysis, dual-luciferase reporter assays, and rescue experiments were performed to verify the relationship between miR-29a-3p and MALAT1 or Smurf2. Results: Our data indicate that MALAT1, Smurf2 were overexpressed while miR-29a-3p was suppressed in HS tissues and fibroblasts. Downregulation of MALAT1 may lead to decreased proliferation, migration, and invasion of fibroblasts, accompanied by enhanced apoptosis, reduced TGF-ß signal transduction, and ECM accumulation in HSFs, by enhancing miR-29a-3p and suppressing Smurf2 expression. Mechanistically, MALAT1 acted as a sponge for miR-29a-3p, while miR-29a-3p directly targeted Smurf2. More importantly, rescue experiments suggested that MALAT1 downregulation induced impact on the proliferation, migration, and invasion of HSFs could be partially overturned through miR-29a-3p knockdown or Smurf2 overexpression. Conclusion: MALAT1 knockdown inhibits the proliferation, migration, invasion, and collagen deposition of HSFs via targeting the miR-29a-3p/Smurf2 axis, which may reveal a promising therapeutic exploitable vulnerability to HS.