Hypertrophic and keloid scars fail to progress from the CD34- /α-smooth muscle actin (α-SMA)+ immature scar phenotype and show gradient differences in α-SMA and p16 expression

HSFAS mediates fibroblast proliferation, migration, trans-differentiation and apoptosis in hypertrophic scars via interacting with ADAMTS8

Hypertrophic scar (HS) is one of the most common sequelae of patients, especially after burns and trauma. The roles of regulatory long noncoding RNAs (lncRNAs) in mediating HS remain underexplored. Human hypertrophic scar-derived fibroblasts (HSFBs) have been shown to exert more potent promoting effects on extracellular matrix (ECM) accumulation than normal skin-derived fibroblasts (NSFBs) and are associated with enhanced HS formation. The purpose of this study is to search for lncRNAs enriched in HSFBs and investigate their roles and mechanisms. LncRNA MSTRG.59347.16 is one of the most highly expressed lncRNAs in HS detected by lncRNA-seq and qRT-PCR and named as hypertrophic scar fibroblast-associated lncRNA (HSFAS). HSFAS overexpression significantly induces fibroblast proliferation, migration, and myofibroblast trans-differentiation and inhibits apoptosis in HSFBs, while knockdown of HSFAS results in augmented apoptosis and attenuated proliferation, migration, and myofibroblast trans-differentiation of HSFBs. Mechanistically, HSFAS suppresses the expression of A disintegrin and metalloproteinase with thrombospondin motifs 8 (ADAMTS8). ADAMTS8 knockdown rescues downregulated HSFAS-mediated fibroblast proliferation, migration, myofibroblast trans-differentiation and apoptosis. Thus, our findings uncover a previously unknown lncRNA-dependent regulatory pathway for fibroblast function. Targeted intervention in the HSFAS-ADAMTS8 pathway is a potential therapy for HS.

Mechanically Robust Hemostatic Hydrogel Membranes with Programmable Strain-Adaptive Microdomain Entanglement for Wound Treatment in Dynamic Tissues

Supramolecular hydrogels emerge as a promising paradigm for sutureless wound management. However, their translation is still challenged by the insufficient mechanical robustness in the context of complex wounds in dynamic tissues. Herein, we report a tissue-adhesive supramolecular hydrogel membrane based on biocompatible precursors for dressing wounds in highly dynamic tissues, featuring robust mechanical resilience through programmable strain-adaptive entanglement among microdomains. Specifically, the hydrogels are synthesized by incorporating a long-chain polyurethane segment into a Schiff base-ligated short-chain oxidized cellulose/quaternized chitosan network via acylhydrazone bonding, which readily establishes interpenetrating entangled microdomains in dynamic cross-linked hydrogel matrices to enhance their tear and fatigue resistance against extreme mechanical stresses. After being placed onto dynamic tissues, the hydrogel dressing could efficiently absorb blood to achieve rapid hemostasis. Moreover, metal ions released from ruptured erythrocytes could be scavenged by the Schiff base linkers to form additional ionic bonds, which would trigger the cross-linking of the short-chain components and establish abundant crystalline microdomains, eventually leading to the in situ stiffening of the hydrogels to endure heavy mechanical loads. Benefiting from its hemostatic capacity and strain adaptable mechanical performance, this hydrogel wound dressing shows promise for the clinical management of various traumatic wounds.

From Histopathology to High-Resolution Ultrasound Imaging of Skin Scars

Nowadays, modern ultrasound machines and high-frequency transducers allow us to accurately assess the superficial soft tissues of the human body. In this sense, sonographic evaluation of the skin and related pathologies is progressively growing in the pertinent literature. To the best of our knowledge, a standardized sonographic protocol focused on the assessment of pathological skin scars is still lacking. As such, the main purpose of the present study was to propose a technical guide to sonographically assess skin scars in the daily practice of clinicians-starting from knowledge on their histopathological features. In order to standardize the ultrasound examination, a superficial-to-deep, layer-by-layer approach has been proposed to optimize its reproducibility and to promote a common language among the different healthcare providers.

Fibrosis in burns: an overview of mechanisms and therapies

Scar development remains a common occurrence and a major healthcare challenge affecting the lives of millions of patients annually. Severe injuries to the skin, such as burns can lead to pathological wound healing patterns, often characterized by dermal fibrosis or excessive scarring, and chronic inflammation. The two most common forms of fibrotic diseases following burn trauma are hypertrophic scars (HSCs) and keloids, which severely impact the patient's quality of life. Although the cellular and molecular mechanisms are similar, HSC and keloids have several distinct differences. In this review, we discuss the different forms of fibrosis that occur postburn injury, emphasizing how the extent of burn influences scar development. Moreover, we highlight how a systemic response induced by a burn injury drives wound fibrosis, including both the role of the inflammatory response, as well as the fate of fibroblast during skin healing. Finally, we list potential therapeutics aimed at alleviating pathological scar formation. An understanding of the mechanisms of postburn fibrosis will allow us to effectively move studies from bench to bedside.

Assessment of the quality of the healing process in experimentally induced skin lesions treated with autologous platelet concentrate associated or unassociated with allogeneic mesenchymal stem cells: preliminary results in a large animal model

Regenerative medicine for the treatment of skin lesions is an innovative and rapidly developing field that aims to promote wound healing and restore the skin to its original condition before injury. Over the years, different topical treatments have been evaluated to improve skin wound healing and, among them, mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) have shown promising results for this purpose. This study sought to evaluate the quality of the healing process in experimentally induced full-thickness skin lesions treated with PRP associated or unassociated with MSCs in a sheep second intention wound healing model. After having surgically created full-thickness wounds on the back of three sheep, the wound healing process was assessed by performing clinical evaluations, histopathological examinations, and molecular analysis. Treated wounds showed a reduction of inflammation and contraction along with an increased re-epithelialization rate and better maturation of the granulation tissue compared to untreated lesions. In particular, the combined treatment regulated the expression of collagen types I and III resulting in a proper resolution of the granulation tissue contrary to what was observed in untreated wounds; moreover, it led to a better maturation and organization of skin adnexa and collagen fibers in the repaired skin compared to untreated and PRP-treated wounds. Overall, both treatments improved the wound healing process compared to untreated wounds. Wounds treated with PRP and MSCs showed a healing progression that qualitatively resembles a restitutio ad integrum of the repaired skin, showing features typical of a mature healthy dermis.

UCHL1 aggravates skin fibrosis through an IGF-1-induced Akt/mTOR/HIF-1α pathway in keloid

Keloid is a heterogeneous disease featured by the excessive production of extracellular matrix. It is a great challenge for both clinicians and patients regarding the exaggerated and uncontrolled outgrowth and the therapeutic resistance of the disease. In this study, we verified that UCHL1 was drastically upregulated in keloid fibroblasts. UCHL1 had no effects on cell proliferation and migration, but instead promoted collagen I and α-SMA expression that was inhibited by silencing UCHL1 gene and by adding in LDN-57444, a pharmacological inhibitor for UCHL1 activity as well. The pathological process was mediated by IGF-1 promoted Akt/mTOR/HIF-1α signaling pathway because inhibition of any of them could reduce the expression of collagen I and α-SMA driven by UCHL1 in fibroblasts. Also, we found that UCHL1 expression in keloid fibroblasts was promoted by M2 macrophages via TGF-β1. These findings extend our understanding of the pathogenesis of keloid and provide potential therapeutic targets for the disease.

Comparison of the efficacy of seven types of microneedles for treating a rabbit hypertrophic scar model

Microneedle technology can effectively suppress the formation of hypertrophic scarring in both animals and humans. Our previous research has revealed that this is due to the physical contact inhibition effect by using microneedles made of liquid-crystal polymers as the model device. One important factor we didn't study is the influence of the fabrication materials of microneedles. Therefore, this article examines this key point on a rabbit ear hypertrophic scar model. We monitor the thickness of the scars, and the expression of α-SMA and Ki-67 protein, and TGF-β1 mRNA in a period of 42 days. Among microneedles made of 6 polymeric materials and stainless steel, polymethylmethacrylate microneedles present superiority in all aspects including the reduction of tissue fibrosis, and the expression of α-SMA, Ki-67 protein and TGF-β1 mRNA. On the other hand, polycarbonates, polyurethane, and polylactic-co-glycolic acid microneedles could suppress three biomarker expressions.

Defining invasion in breast cancer: the role of basement membrane

Basement membrane (BM) is an amorphous, sheet-like structure separating the epithelium from the stroma. BM is characterised by a complex structure comprising collagenous and non-collagenous proteoglycans and glycoproteins. In the breast, the thickness, density and composition of the BM around the ductal lobular system vary during differing development stages. In pathological conditions, the BM provides a physical barrier that separates proliferating intraductal epithelial cells from the surrounding stroma, and its absence or breach in malignant lesions is a hallmark of invasion and metastases. Currently, diagnostic services often use special stains and immunohistochemistry (IHC) to identify the BM in order to distinguish in situ from invasive lesions. However, distinguishing BM on stained sections, and differentiating the native BM from the reactive capsule or BM-like material surrounding some invasive malignant breast tumours is challenging. Although diagnostic use of the BM is being replaced by myoepithelial cell IHC markers, BM is considered by many to be a useful marker to distinguish in situ from invasive lesions in ambiguous cases. In this review, the structure, function and biological and clinical significance of the BM are discussed in relation to the various breast lesions with emphasis on how to distinguish the native BM from alternative pathological tissue mimicking its histology.

MicroRNA-182-5p Inhibits Hypertrophic Scar Formation by Inhibiting the Proliferation and Migration of Fibroblasts via SMAD4 Pathway

Introduction

Secondary to war wounds, trauma, etc., hypertrophic scar formation is the cause of an excessive proliferation of fibroblasts and accumulation of collagen fibers, which might affect cosmetic appearance, and could cause malignant transformation. miRNAs play an important role in disease regulation via inhibiting post-transcriptional protein translation by targeting and binding to the 3' UTR region of mRNA. Here we explore the mechanism and interventions of scar formation from the perspective of miRNA.

Methods

Hypertrophic scar-associated differential miRNAs were screened by analyzing sequencing data of normal skin and hypertrophic scar, and verified by RT-qPCR. Signaling pathways that may be influenced by differentially miRNAs were analyzed using KEGG and GO. miRNA mimics were used to explore the effects of miRNAs on SMAD signaling pathway proteins. Dual-luciferase assays were used to explore the targeted binding of miRNAs. The mimics of the miRNA were used to explore the impact of miRNAs on the proliferation, migration, apoptosis and collagen synthesis levels of hypertrophic scar fibroblasts. The scar model of rabbit ear was used to verify the influence of miRNA on wound healing and scar formation in vivo.

Results

Expression of miR-182-5p was found to be considerably decreased in hypertrophic scars and fibroblasts. miR-182-5p was found to act mainly by targeting the 3'UTR region of SMAD4, but not SMAD1 or SMAD3. miR-182-5p overexpression may drastically suppress the proliferation and migration of fibroblasts, accompanied by enhanced apoptosis and reduced collagen fiber synthesis. The overexpression of miR-182-5p in in vivo experiments could effectively inhibit hypertrophic scar formation without affecting the speed and quality of wound healing.

Conclusion

miR-182-5p inhibits hypertrophic scar formation by decreasing the proliferation and migration of fibroblasts via SMAD4 pathway, and is expected to become a novel hypertrophic scar therapeutic target.

Platycodin D inhibits the proliferation and migration of hypertrophic scar-derived fibroblasts and promotes apoptosis through a caspase-dependent pathway

Abnormal fibroblast proliferation and excessive extracellular matrix (ECM) deposition lead to the formation of hypertrophic scars (HSs). However, there is no satisfactory method to inhibit the occurrence and development of HSs. In our study, platycodin D (PD), a natural compound extracted from Platycodon grandiflorus, inhibited HSs formation both in vitro and in vivo. First, qRT-PCR and Western blot were used to confirm PD dose-dependently downregulated the expression of Col I, Col III and α-SMA in human hypertrophic scar-derived fibroblasts (HSFs) (p < 0.05). Second, cck-8, transwell and wound healing assays verified PD suppressed the proliferation (p < 0.05) and migration of HSFs (p < 0.05), and inhibited the differentiation of HSFs into myofibroblasts. Moreover, PD-induced HSFs apoptosis were analyzed by flow cytometry and the apoptosis was activated through a caspase-dependent pathway. The rabbit ear scar model was used to further confirm the inhibitory effect of PD on collagen and α-SMA deposition. Finally, Western blot analysis showed that PD reduced TGF-β RI expression (p < 0.05) and affected matrix metalloproteinase 2 (MMP2) protein levels (p < 0.05). In conclusion, our study showed that PD inhibited the proliferation and migration of HSFs by inhibiting fibrosis-related molecules and promoting apoptosis via a caspase-dependent pathway. The TGF-β/Smad pathway also mediated the inhibition of HSFs proliferation and HSFs differentiation into myofibroblasts. Therefore, PD is a potential therapeutic agent for HSs and other fibrotic diseases.

Bioinformatics analysis and identification of dysregulated POSTN in the pathogenesis of keloid

Keloid is a benign fibro-proliferative dermal tumour formed by an abnormal scarring response to injury and characterised by excessive collagen accumulation and invasive growth. The pathophysiology of keloids is complex, and the treatment for keloids is still an unmet medical need. Here, we investigated the transcriptional gene that influences keloid development by comparing keloid, non-lesioned keloid skin and normal skin as well as keloid fibroblast and normal fibroblast (GSE83286, GSE92566, GSE44270). Based on the analysis, 146 up-regulated genes and 48 down-regulated genes were found in keloid tissue compared with normal skin and keloid no-lesioned skin. Eleven genes were further identified by overlapping the DEGs from keloid tissue described previously with DEGs in keloid fibroblast. The overlapped genes included PRR16, SFRP2, EDIL3, GERM1, POSTN, PDE3A, GALNT5, F2RL2, EYA4, ZFHX4, and AIM2. POSTN is the most crucial node in PPI network, which mainly correlate to collagen-related genes. Moreover, siRNA knockdown identified POSTN is a crucial regulatory gene that regulates keloid fibroblast migration and collagen I, collagen III expression level. In conclusion, our study identified 11 hub genes that play crucial role in keloid formation and provided insights for POSTN to be the therapeutic target for keloid through bioinformatic analysis of three datasets. Additionally, our results would support the development of future therapeutic strategies.

Skin fibrosis associated with keloid, scleroderma and Jorge Lobo's disease (lacaziosis): An immuno-histochemical study

Fibrosis is a common pathophysiological response of many tissues and organs subjected to chronic injury. Despite the diverse aetiology of keloid, lacaziosis and localized scleroderma, the process of fibrosis is present in the pathogenesis of all of these three entities beyond other individual clinical and histological distinct characteristics. Fibrosis was studied in 20 samples each of these three chronic cutaneous inflammatory diseases. An immunohistochemical study was carried out to explore the presence of α-smooth muscle actin (α-SMA) and vimentin cytoskeleton antigens, CD31, CD34, Ki67, p16; CD105, CD163, CD206 and FOXP3 antigens; and the central fibrotic cytokine TGF-β. Higher expression of vimentin in comparison to α-SMA in all three lesion types was found. CD31- and CD34-positive blood vessel endothelial cells were observed throughout the reticular dermis. Ki67 expression was low and almost absent in scleroderma. p16-positive levels were higher than ki67 and observed in reticular dermis of keloidal collagen in keloids, in collagen bundles in scleroderma and in the external layers of the granulomas in lacaziosis. The presence of α-actin positive cells and rarely CD34 positive cells, observed primarily in keloids, may be related to higher p16 antigen expression, a measure of cell senescence. Low FOXP3 expression was observed in all lesion types. CD105-positive cells were mainly found in perivascular tissue in close contact with the adventitia in keloids and scleroderma, while, in lacaziosis, these cells were chiefly observed in conjunction with collagen deposition in the external granuloma layer. We did not find high involvement of CD163 or CD206-positive cells in the fibrotic process. TGF-β was notable only in keloid and lacaziosis lesions. In conclusion, we have suggested vimentin to be the main myofibroblast general marker of the fibrotic process in all three studied diseases, while endothelial-to-mesenchymal transition (EndoMT) and mesenchymal stem cells (MSCs) and M2 macrophages may not play an important role.

Bone marrow-derived vasculogenesis leads to scarless regeneration in deep wounds with periosteal defects

Deep skin wounds with periosteal defects, frequently caused by traffic accidents or radical dissection, are refractory. Transplant surgery is frequently performed, but patients are subjected to stress for long operation periods, the sacrifice of donor regions, or several complications, such as flap necrosis or intractable ulcers. Even if the defects are covered, a scar composed of fibrous tissue remains in the body, which can cause itching, dysesthesia, or repeated ulcers because of the lack of distribution of peripheral nerves or hair follicles. Thus, treatments with the aim of regenerating lost tissue for deep wounds with periosteal defects are needed. Here, we show that the use of gelatin sponges (GS), which have been used as haemostatic materials in clinical practice, allowed the regeneration of heterogeneous tissues, including periosteum, skin, and skin appendages, when used as scaffolds in deep wounds with periosteal defects in rats. Bone marrow transplantation in rats revealed the mechanism by which the microenvironment provided by GS enabled bone marrow-derived cells (BMDCs) to form a vascular niche, followed by regeneration of the periosteum, skin, or skin appendages such as hair follicles by local cells. Our findings demonstrated that vascular niche formation provided by BMDCs is crucial for heterogeneous tissue regeneration.

The m6A-methylated mRNA pattern and the activation of the Wnt signaling pathway under the hyper-m6A-modifying condition in the keloid

Purpose: The present study was carried out to investigate the global m⁶A-modified RNA pattern and possible mechanisms underlying the pathogenesis of keloid. Method: In total, 14 normal skin and 14 keloid tissue samples were first collected on clinics. Then, three samples from each group were randomly selected to be verified with the Western blotting to determine the level of methyltransferase and demethylase. The total RNA of all samples in each group was isolated and subjected to the analysis of MeRIP sequencing and RNA sequencing. Using software of MeTDiff and htseq-count, the m⁶A peaks and differentially expressed genes (DEGs) were determined within the fold change >2 and p-value < 0.05. The top 10 pathways of m⁶A-modified genes in each group and the differentially expressed genes were enriched by the Kyoto Encyclopedia of Genes and Genomes signaling pathways. Finally, the closely associated pathway was determined using the Western blotting and immunofluorescence staining. Results: There was a higher protein level of WTAP and Mettl3 in the keloid than in the normal tissue. In the keloid samples, 21,020 unique m⁶A peaks with 6,573 unique m⁶A-associated genetic transcripts appeared. In the normal tissue, 4,028 unique m⁶A peaks with 779 m⁶A-associated modified genes appeared. In the RNA sequencing, there were 847 genes significantly changed between these groups, transcriptionally. The genes with m⁶A-methylated modification and the upregulated differentially expressed genes between two tissues were both mainly related to the Wnt signaling pathway. Moreover, the hyper-m⁶A-modified Wnt/β-catenin pathway in keloid was verified with Western blotting. From the immunofluorescence staining results, we found that the accumulated fibroblasts were under a hyper-m⁶A condition in the keloid, and the Wnt/β-Catenin signaling pathway was mainly activated in the fibroblasts. Conclusion: The fibroblasts in the keloid were under a cellular hyper-m⁶A-methylated condition, and the hyper-m⁶A-modified highly expressed Wnt/β-catenin pathway in the dermal fibroblasts might promote the pathogenesis of keloid.

Cellular Senescence in Aging, Tissue Repair, and Regeneration

SUMMARY

Society and our healthcare system are facing unprecedented challenges due to the expansion of the older population. As plastic surgeons, we can improve care of our older patients through understanding the mechanisms of aging that inevitably impact their outcomes and well-being. One of the major hallmarks of aging, cellular senescence, has recently become the focus of vigorous research in academia and industry. Senescent cells, which are metabolically active but in a state of stable cell cycle arrest, are implicated in causing aging and numerous age-related diseases. Further characterization of the biology of senescence revealed that it can be both detrimental and beneficial to organisms depending on tissue context and senescence chronicity. Here, we review the role of cellular senescence in aging, wound healing, tissue regeneration, and other domains relevant to plastic surgery. We also review the current state of research on therapeutics that modulate senescence to improve conditions of aging.

Glabridin from Glycyrrhiza glabra Possesses a Therapeutic Role against Keloid via Attenuating PI3K/Akt and Transforming Growth Factor-β1/SMAD Signaling Pathways

Glabridin (Gla) is a typical flavonoid isolated from the Glycyrrhiza glabra with various bioactivities and is a common additive in many cosmetics. In our study, we evaluated the antiscarring effect of Gla from G. glabra in a rabbit ear hyperplastic scar model. Hematoxylin and eosin staining and Masson staining were applied to determine the pathological changes and collagen fibers of scar tissue in rabbits. The results suggested that Gla could reduce rabbit ear scar hyperplasia, inhibit inflammation, and decrease collagen production. Furthermore, the in vitro cell experiments were applied to determine the effects of Gla on human keloid fibroblasts (HKFs), and we observed that Gla suppressed the HKF cells' proliferation via inducing apoptosis. Subsequently, we found that Gla reduced collagen production in HKF cells. The further molecular mechanisms investigations suggested that Gla played a therapeutic role against keloid by attenuating PI3K/Akt and TGFβ1/SMAD pathways. Our study would be beneficial for extending the applications of the known sweet plant of G. glabra.

Downregulation of PLK4 expression induces apoptosis and G0/G1-phase cell cycle arrest in keloid fibroblasts

Objectives

Keloids are benign fibroproliferative tumors that display many cancer‐like characteristics, such as progressive uncontrolled growth, lack of spontaneous regression, and extremely high rates of recurrence. Polo‐like kinase 4 (PLK4) was recently identified as a master regulator of centriole replication, and its aberrant expression is closely associated with tumorigenesis. This study aimed to investigate the expression and biological role of PLK4 in the pathogenesis of keloids.

Materials and Methods

We evaluated the expression of PLK4 in keloids and adjacent normal skin tissue samples. Then, we established PLK4 knockdown and overexpression cell lines in keloid fibroblasts (KFs) and normal skin fibroblasts (NFs), respectively, to investigate the roles of PLK4 in the regulation of proliferation, migration, invasion, apoptosis, and cell cycle in KFs. Centrinone B (Cen‐B), a highly selective PLK4 inhibitor, was used to inhibit PLK4 activity in KFs to evaluate the therapeutic effect on KFs.

Results

We discovered that PLK4 was overexpressed in keloid dermal samples and KFs compared with adjacent normal skin samples and NFs derived from the same patients. High PLK4 expression was positively associated with the proliferation, migration, and invasion of KFs. Furthermore, knockdown of PLK4 expression or inhibition of PLK4 activity by Cen‐B suppressed KF growth, induced KF apoptosis via the caspase‐9/3 pathway, and induced cell cycle arrest at the G0/G1 phase in vitro.

Conclusions

These findings demonstrate that PLK4 is a critical regulator of KF proliferation, migration, and invasion, and thus, Cen‐B is a promising candidate drug for keloid treatment.

Fibroblasts in Scar Formation: Biology and Clinical Translation

Scarring, which develops due to fibroblast activation and excessive extracellular matrix deposition, can cause physical, psychological, and cosmetic problems. Fibroblasts are the main type of connective tissue cells and play important roles in wound healing. However, the underlying mechanisms of fibroblast in reaching scarless wound healing require more exploration. Herein, we systematically reviewed how fibroblasts behave in response to skin injuries, as well as their functions in regeneration and scar formation. Several biocompatible materials, including hydrogels and nanoparticles, were also suggested. Moreover, factors that concern transformation from fibroblasts into cancer-associated fibroblasts are mentioned due to a tight association between scar formation and primary skin cancers. These findings will help us better understand skin fibrotic pathogenesis, as well as provide potential targets for scarless wound healing therapies.

Histology and Vascular Architecture Study of Keloid Tissue to Outline the Possible Terminology of Keloid Skin Flaps

BACKGROUND

Using the keloid "epidermis" to cover a wound is widely used during treatment for keloids. Many flap terminologies have been used in literature. However, the definition of the flap is not well established. Here, we refined the definition of the flap and associated terminology and explored the survival mechanism of the 'flap' through histological analysis and blood supply studying.

METHODS

Histology and vascular study of keloid was carried out with keloid and its surrounding normal skin tissue which were collected from keloid patients following keloid resection operations. The histological structures and thicknesses of epidermal and subepidermal of the keloids were analyzed and measured using hematoxylin & eosin (H&E) staining. Vascular density and blood perfusion in the subepidermal layer of keloids (KDS) were analyzed using CD31 immunohistochemical staining and a laser speckle contrast imaging system (LSCI), respectively. The vascular network in KDS was visualized by CD31 immunofluorescence staining and three-dimensional reconstruction.

RESULTS

29 pieces of keloid and its surrounding normal skin tissue sample from ten patients were collected. Keloid samples were about 2 cm wide and 5 cm long. The normal skin samples were about 2 to 3 mm in width. The thickness of epidermal layer of keloids was (136.4 ± 35.3) μm, and the thickness of epidermal layer of surrounding normal skin was (78.8 ± 13.9) μm. There was statistical thickness difference between the two layers, t(20) = 7.469, P < 0.001. The total thickness of keloid epidermal and subepidermal layers was 391.4 ± 2.3 μm. The vascular density (13.9 ± 3.4/field) and blood flow perfusion (132.7 ± 31.3) PU in KDS were greater than that of surrounding normal skin (7.8 ± 2.3/field, 73.9 ± 17.9 PU), P < 0.001. Horizontally distributed vessels with several vertical branches were observed in 3D vascular network reconstruction.

CONCLUSION

The epidermal layer of keloid is thicker than that of surrounding normal skin. There is a vascular network structure under it. The vessels mainly locate at a depth of about 150 to 400 μm from the surface of keloid epidermis, randomly distribute and run parallel to the epidermis. Based on these characteristics which may ensure an adequate blood supply, we propose the concept of a "keloid subepidermal vascular network flap."

LEVEL OF EVIDENCE V

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Dermal Fibroblast Heterogeneity and Its Contribution to the Skin Repair and Regeneration

Significance: Dermal fibroblasts are the major cell type in the skin's dermal layer. These cells originate from distinct locations of the embryo and reside in unique niches in the dermis. Different dermal fibroblasts exhibit distinct roles in skin development, homeostasis, and wound healing. Therefore, these cells are becoming attractive candidates for cell-based therapies in wound healing. Recent Advances: Human skin dermis comprises multiple fibroblast subtypes, including papillary, reticular, and hair follicle-associated fibroblasts, and myofibroblasts after wounding. Recent studies reveal that these cells play distinct roles in wound healing and contribute to diverse healing outcomes, including nonhealing chronic wound or excessive scar formation, such as hypertrophic scars (HTS) and keloids, with papillary fibroblasts having antiscarring and reticular fibroblast scar-forming properties. Critical Issues: The identities and functions of dermal fibroblast subpopulations in many respects remain unknown. In this review, we summarize the current understanding of dermal fibroblast heterogeneity, including their defined cell markers and dermal niches, dynamic changes, and contributions to skin wound healing, with the emphasis on scarless healing, healing with excessive scars (HTS and keloids), chronic wounds, and the potential application of this heterogeneity for developing cell-based therapies that allow wounds to heal faster with less scarring. Future Directions: Heterogeneous dermal fibroblast populations and their functions are poorly characterized. Refining and advancing our understanding of dermal fibroblast heterogeneity and their participation in skin homeostasis and wound healing may create potential therapeutic applications for nonhealing chronic wounds or wounds that heal with excessive scarring.

[Morphogenetic and pathogenetic features of hypertrophic and keloid scars of the head and neck]

OBJECTIVE

Evaluate the morphogenetic and pathogenetic features of hypertrophic and keloid scars of the head and neck.

MATERIAL AND METHODS

The study included 286 patients, among them 176 (61.5%) patients with hypertrophic and 110 (38.5%) with keloid scars aged 18 to 65 years with a disease duration from 1 month to 2 years. Material for histological and immunohistochemical (IHC) studies of scar tissue was fixed in 10% buffered formalin. Serial paraffin sections were stained with H&E, according to Van Gieson and Weigert. IHC was performed using monoclonal mouse antibodies to collagen type I (clone 3G3, Santa Cruz, dilution 1:100), collagen type III (clone B-4, Santa Cruz, dilution 1:50), collagen type IV (clone COL-94, Santa Cruz, dilution 1:50), MMP-1 (clone 3B6, Santa Cruz, dilution 1:100), α-SMA1 (clone 1A4, Dako Agilent, dilution 1:100) and rabbit polyclonal anti-TGFβ antibodies (clone 3C11, Santa Cruz, 1:100 dilution).

RESULTS

Pathogenetic, morphological and immunohistochemical differences in hypertrophic and keloid scars were established depending on their degree of maturity. In the formation of hypertrophic scars, the key factor in sclerotic processes is TGF-b on the background of low MMP1 activity. Keloid scars were distinguished not only by the accumulation of hard-to-degrade collagens, but also by the development of an osteoclast-like reaction with a high content of MMP1. Immature scar tissue was characterized by the presence of myofibroblastic α-SMA1 positive focus and center of inflammatory changes.

CONCLUSIONS

The data obtained allow substantiating new approaches to the treatment of patients with hypertrophic and keloid scars.

Correlation between elastic modulus and clinical severity of pathological scars: a cross-sectional study

Though widely used to assess pathological scars, the modified Vancouver Scar Scale (mVSS) is neither convenient nor objective. Shear wave elastography (SWE) is used to evaluate the stiffness of pathological scars. We aimed to determine the correlation between mVSS score and elastic modulus (EM) measured by SWE for pathological scars. Clinical information including ultrasound (US) results of the enrolled patients with pathological scars was analyzed. The clinical severity of the pathological scars was evaluated by mVSS. Skin stiffness, as represented by EM, was calculated using SWE. The average EM of the whole scar (EM_WHOLE), hardest part of the scar (EM_HARDEST), and normal appearance of the skin around the scar (EM_NORMAL) were also recorded. Enrolled in this study were 69 pathological scars, including 28 hypertrophic scars and 41 keloids. The univariable regression analyses showed that the EM of pathological scars was closely related to mVSS score, while the linear multivariable regression analyses showed no significantly correlation. Curve fitting and threshold effect analysis revealed that when EM_WHOLE was less than 166.6 kPa or EM_HARDEST was less than 133.07 kPa, EM was positively correlated with mVSS score. In stratified analysis, there was no significant linear correlation and threshold effect between EM_WHOLE and mVSS score in hypertrophic scars or keloids. However, the fully adjusted smooth curves presented a linear association between mVSS score and EM_HARDEST in keloids (the adjusted β [95% CI] was 0.010 [0.001, 0.018]), but a threshold and nonlinear association were found in hypertrophic scars. When EM_HARDEST was less than 156.13 kPa, the mVSS score increased along with the hardest scar part stiffness; the adjusted β (95% CI) was 0.024 (0.009, 0.038). In conclusion, EM of pathological scars measured by SWE were correlated with mVSS within a threshold range, and showed different association patterns in hypertrophic scars and keloids.

Fibrous Demineralized Bone Matrix (DBM) Improves Bone Marrow Mononuclear Cell (BMC)-Supported Bone Healing in Large Femoral Bone Defects in Rats

Regeneration of large bone defects is a major objective in trauma surgery. Bone marrow mononuclear cell (BMC)-supported bone healing was shown to be efficient after immobilization on a scaffold. We hypothesized that fibrous demineralized bone matrix (DBM) in various forms with BMCs is superior to granular DBM. A total of 65 male SD rats were assigned to five treatment groups: syngenic cancellous bone (SCB), fibrous demineralized bone matrix (f-DBM), fibrous demineralized bone matrix densely packed (f-DBM 120%), DBM granules (GDBM) and DBM granules 5% calcium phosphate (GDBM5%Ca2+). BMCs from donor rats were combined with different scaffolds and placed into 5 mm femoral bone defects. After 8 weeks, bone mineral density (BMD), biomechanical stability and histology were assessed. Similar biomechanical properties of f-DBM and SCB defects were observed. Similar bone and cartilage formation was found in all groups, but a significantly bigger residual defect size was found in GDBM. High bone healing scores were found in f-DBM (25) and SCB (25). The application of DBM in fiber form combined with the application of BMCs shows promising results comparable to the gold standard, syngenic cancellous bone. Denser packing of fibers or higher amount of calcium phosphate has no positive effect.

Immunohistological Analysis of CD34-Positive Dermal Dendritic Cells and Microvessel Density in the Genital and Extragenital Lichen Sclerosus

BACKGROUND

Lichen sclerosus (LiS) is a chronic scleroatrophic condition that usually affects the anogenital area and occasionally the extragenital sites. CD34-positive dermal dendritic cells (DDCs) contribute to the maintenance of the dermal microarchitecture and modulation of the immune response. p53 is a tumor suppressor gene important for the regulation of the cell cycle and apoptosis. Similar to morphea (a LiS-closely related scleroatrophic condition), dermal sclerosis, alterations of DDCs, and dermal microvasculature may be important underlying pathogenetic mechanisms in LiS.

OBJECTIVES

To examine the profile of CD34-positive DDCs, microvessel density (MVD), and p53 protein in LiS.

MATERIALS AND METHODS

The immunohistological profiles of DDCs, MVD, and p53 were examined in 19 cases of LiS and their age- and sex-matched normal skin (10 specimens), using antibodies against CD34 and p53.

RESULTS

There was a markedly decreased counts (1.7 ± 0.5/mm2) or complete loss of CD34-positive DDCs in LiS against their abundance in the normal skin (23.4 ± 2.1/mm2, p = 0.000). MVD was markedly increased in LiS lesions (20 ± 0.47) as compared to normal skin (5.50 ± 0.20, p = 0.000). Discontinuous single-cell p53 weakly positive nuclear staining was seen in the epidermal basal cell keratinocytes in normal skin and LiS lesions.

CONCLUSIONS

To the best of this author's knowledge, this is the first study analyzing DDCs, MVD, and p53 profiles together in LiS. The findings suggest that alterations of DDCs and MVD have roles in the pathogenesis of LiS.

Notch-ing up knowledge on molecular mechanisms of skin fibrosis: focus on the multifaceted Notch signalling pathway

Fibrosis can be defined as an excessive and deregulated deposition of extracellular matrix proteins, causing loss of physiological architecture and dysfunction of different tissues and organs. In the skin, fibrosis represents the hallmark of several acquired (e.g. systemic sclerosis and hypertrophic scars) and inherited (i.e. dystrophic epidermolysis bullosa) diseases. A complex series of interactions among a variety of cellular types and a wide range of molecular players drive the fibrogenic process, often in a context-dependent manner. However, the pathogenetic mechanisms leading to skin fibrosis are not completely elucidated. In this scenario, an increasing body of evidence has recently disclosed the involvement of Notch signalling cascade in fibrosis of the skin and other organs. Despite its apparent simplicity, Notch represents one of the most multifaceted, strictly regulated and intricate pathways with still unknown features both in health and disease conditions. Starting from the most recent advances in Notch activation and regulation, this review focuses on the pro-fibrotic function of Notch pathway in fibroproliferative skin disorders describing molecular networks, interplay with other pro-fibrotic molecules and pathways, including the transforming growth factor-β1, and therapeutic strategies under development.

Keloid tissue analysis discredits a role for myofibroblasts in disease pathogenesis

Myofibroblasts, renowned for their contractility and extracellular matrix production, are widely considered the key effector cells for nearly all scars resulting from tissue repair processes, ranging from normal scars to extreme fibrosis. For example, it is often assumed that myofibroblasts underpin the characteristics of keloid scars, which are debilitating pathological skin scars lacking effective treatments because of a poor understanding of the disease mechanisms. Here, we present primary and published transcriptional and histological evidence that myofibroblasts are not consistently present in primary keloid lesions, and when alpha-smooth muscle actin (αSMA)-positive cells are detected, they are not greater in number or expressing more αSMA than in normal or hypertrophic scars. In conclusion, keloid scars do not appear to require αSMA-positive myofibroblasts; continuing to consider keloids on a quantitative spectrum with normal or hypertrophic scars, with αSMA serving as a biomarker of disease severity, is hindering advancement of understanding and therapy development.

A Prototype Skin Substitute, Made of Recycled Marine Collagen, Improves the Skin Regeneration of Sheep

Simple Summary

Marine ecosystems are a huge source of unexplored “blue” materials for different applications. The edible part of sea urchin is limited, and the vast majority of the product ends up as waste. Our studies intend to fully recycle wastes from the food industry and reconvert them in high added-value products, as innovative biocompatible skin substitutes for tissue regeneration. The aim of the present work is to apply the pioneering skin substitute in in vivo experimental wounds to test its regenerative potential and compare it, in a future study, to the available commercial membranes produced with collagen of bovine, porcine, and equine origin. Results are encouraging since the skin substitute made with marine collagen reduced inflammation, promoted the deposition of granulation tissue, and enhanced a proper re-epithelialization with the adequate development of skin appendages. In summary, our findings might be of great interest for processing industries and biotech companies which transform waste materials in high-valuable and innovative products for Veterinary advanced applications.

Abstract

Skin wound healing is a complex and dynamic process that aims to restore lesioned tissues. Collagen-based skin substitutes are a promising treatment to promote wound healing by mimicking the native skin structure. Recently, collagen from marine organisms has gained interest as a source for producing biomaterials for skin regenerative strategies. This preliminary study aimed to describe the application of a collagen-based skin-like scaffold (CBSS), manufactured with collagen extracted from sea urchin food waste, to treat experimental skin wounds in a large animal. The wound-healing process was assessed over different time points by the means of clinical, histopathological, and molecular analysis. The CBSS treatment improved wound re-epithelialization along with cell proliferation, gene expression of growth factors (VEGF-A), and development of skin adnexa throughout the healing process. Furthermore, it regulated the gene expression of collagen type I and III, thus enhancing the maturation of the granulation tissue into a mature dermis without any signs of scarring as observed in untreated wounds. The observed results (reduced inflammation, better re-epithelialization, proper development of mature dermis and skin adnexa) suggest that sea urchin-derived CBSS is a promising biomaterial for skin wound healing in a “blue biotechnologies” perspective for animals of Veterinary interest.

Analysis of HOX gene expression and the effects of HOXA9 overexpression in fibroblasts derived from keloid lesions and normal skin

Keloids are fibroproliferative lesions resulting from an abnormal wound healing process due to pathological mechanisms that remain incompletely understood. Keloids tend to occur more frequently in anterior versus posterior body regions (e.g., ears, face, upper torso); this has been attributed to higher skin tension in those areas, although this has not yet been conclusively proven. Previous studies reported reduced expression of multiple homeobox (HOX) genes in keloid versus normal fibroblasts, suggesting a role for HOX genes in keloid pathology. However, HOX genes are differentially expressed along the anterior-posterior axis. Hypothetically, differential HOX expression may be due to differences in body sites, as matched donor sites are often unavailable for keloids and normal skin. To better understand the basis for differential HOX gene expression in cells from keloids compared with normal skin, we compared HOXA7, HOXA9, HOXC8 and HOXC11 expression in keloid and normal skin-derived fibroblasts from various body sites. When keloid (N = 20) and normal (N = 12) fibroblast cell strains were evaluated, expression of HOXA7, HOXA9 and HOXC8 was significantly lower in keloid versus normal fibroblasts. However, HOX gene expression was lower in fibroblasts from more anterior versus posterior body sites. When keloid and normal cells from similar body sites were compared, differential HOX expression was not observed. To investigate the phenotypic relevance of HOX expression, HOXA9 was overexpressed in keloid and normal fibroblasts. HOXA9 overexpression did not affect proliferation but significantly reduced fibroblast migration and altered gene expression. The results suggest that differential HOX expression may be due to differences in positional identity between keloid and normal fibroblasts. However, HOX genes can potentially regulate fibroblast phenotype, suggesting that differential HOX gene expression may play a role in keloid development in anterior body sites.

Immunohistological Analysis of CD34-Positive Dermal Dendritic Cells and Microvessel Density in the Genital and Extragenital Lichen Sclerosus

BACKGROUND

Lichen sclerosus (LiS) is a chronic scleroatrophic condition that usually affects the anogenital area and occasionally the extragenital sites. CD34-positive dermal dendritic cells (DDCs) contribute to the maintenance of the dermal microarchitecture and modulation of the immune response. p53 is a tumor suppressor gene important for the regulation of the cell cycle and apoptosis. Similar to morphea (a LiS-closely related scleroatrophic condition), dermal sclerosis, alterations of DDCs, and dermal microvasculature may be important underlying pathogenetic mechanisms in LiS.

OBJECTIVES

To examine the profile of CD34-positive DDCs, microvessel density (MVD), and p53 protein in LiS.

MATERIALS AND METHODS

The immunohistological profiles of DDCs, MVD, and p53 were examined in 19 cases of LiS and their age- and sex-matched normal skin (10 specimens), using antibodies against CD34 and p53.

RESULTS

There was a markedly decreased counts (1.7±0.5/mm2) or complete loss of CD34-positive DDCs in LiS against their abundance in the normal skin (23.4±2.1/mm2, p=0.000). MVD was markedly increased in LiS lesions (20±0.47) as compared to normal skin (5.50±0.20, p=0.000). Discontinuous single-cell p53 weakly positive nuclear staining was seen in the epidermal basal cell keratinocytes in normal skin and LiS lesions.

CONCLUSIONS

To the best of this author's knowledge, this is the first study analyzing DDCs, MVD, and p53 profiles together in LiS. The findings suggest that alterations of DDCs and MVD have roles in the pathogenesis of LiS.

Ameliorating Fibrotic Phenotypes of Keloid Dermal Fibroblasts through an Epidermal Growth Factor-Mediated Extracellular Matrix Remodeling

Keloid and hypertrophic scars are skin fibrosis-associated disorders that exhibit an uncontrollable proliferation of fibroblasts and their subsequent contribution to the excessive accumulation of extracellular matrix (ECM) in the dermis. In this study, to elucidate the underlying mechanisms, we investigated the pivotal roles of epidermal growth factor (EGF) in modulating fibrotic phenotypes of keloid and hypertrophic dermal fibroblasts. Our initial findings revealed the molecular signatures of keloid dermal fibroblasts and showed the highest degree of skin fibrosis markers, ECM remodeling, anabolic collagen-cross-linking enzymes, such as lysyl oxidase (LOX) and four LOX-like family enzymes, migration ability, and cell–matrix traction force, at cell–matrix interfaces. Furthermore, we observed significant EGF-mediated downregulation of anabolic collagen-cross-linking enzymes, resulting in amelioration of fibrotic phenotypes and a decrease in cell motility measured according to the cell–matrix traction force. These findings offer insight into the important roles of EGF-mediated cell–matrix interactions at the cell–matrix interface, as well as ECM remodeling. Furthermore, the results suggest their contribution to the reduction of fibrotic phenotypes in keloid dermal fibroblasts, which could lead to the development of therapeutic modalities to prevent or reduce scar tissue formation.

Could cold plasma act synergistically with allogeneic mesenchymal stem cells to improve wound skin regeneration in a large size animal model?

Skin wound healing may sometimes lead to open sores that persist for long periods and expensive hospitalization is needed. Among different kinds of therapeutic innovative approaches, mesenchymal stem cells (MSCs) and low-temperature atmospheric pressure cold plasma (ionized gas) have been recently tested to improve this regenerative process. To optimize wound healing the present study intended to combine, for the first time, these two novel approaches in a large size animal wound healing model with the aim of assessing the putative dual beneficial effects. Based on clinical, histopathological, and molecular results a synergistic action in a second intention healing wound in sheep has been observed. Experimental wounds treated with cold plasma and MSCs showed a slower but more effective healing compared to the single treatment, as observed in previous studies. The combined treatment improved the correct development of skin appendages and structural proteins of the dermis showing the potential of the dual combination as a safe and effective tool for skin regeneration in the veterinary clinical field.

Hypertrophic scars and keloids: Overview of the evidence and practical guide for differentiating between these abnormal scars

Although hypertrophic scars and keloids both generate excessive scar tissue, keloids are characterized by their extensive growth beyond the borders of the original wound, which is not observed in hypertrophic scars. Whether or not hypertrophic scars and keloids are two sides of the same coin or in fact distinct entities remains a topic of much debate. However, proper comparison between the two ideally occurs within the same study, but this is the exception rather than the rule. For this reason, the goal of this review was to summarize and evaluate all publications in which both hypertrophic scars and keloids were studied and compared to one another within the same study. The presence of horizontal growth is the mainstay of the keloid diagnosis and remains the strongest argument in support of keloids and hypertrophic scars being distinct entities, and the histopathological distinction is less straightforward. Keloidal collagen remains the strongest keloid parameter, but dermal nodules and α-SMA immunoreactivity are not limited to hypertrophic scars alone. Ultimately, the current hypertrophic scars-keloid differences are mostly quantitative in nature rather than qualitative, and many similar abnormalities exist in both lesions. Nonetheless, the presence of similarities does not equate the absence of fundamental differences, some of which may not yet have been uncovered given how much we still have to learn about the processes involved in normal wound healing. It therefore seems pertinent to continue treating hypertrophic scars and keloids as separate entities, until such a time as new findings more decisively convinces us otherwise.

Keloid disorder: Fibroblast differentiation and gene expression profile in fibrotic skin diseases

Keloid disorder, a group of fibroproliferative skin diseases, is characterized by unremitting accumulation of the extracellular matrix (ECM) of connective tissue, primarily collagen, to develop cutaneous tumors on the predilection sites of skin. There is a strong genetic predisposition for keloid formation, and individuals of African and Asian ancestry are particularly prone. The principal cell type responsible for ECM accumulation is the myofibroblast derived from quiescent resident skin fibroblasts either through trans-differentiation or from keloid progenitor stem cells with capacity for multi-lineage differentiation and self-renewal. The biosynthetic pathways leading to ECM accumulation are activated by several cytokines, but particularly by TGF-β signalling. The mechanical properties of the cellular microenvironment also play a critical role in the cell's response to TGF-β, as demonstrated by culturing of fibroblasts derived from keloids and control skin on substrata with different degrees of stiffness. These studies also demonstrated that culturing of fibroblasts on tissue culture plastic in vitro does not reflect their biosynthetic capacity in vivo. Collectively, our current understanding of the pathogenesis of keloids suggests a complex network of interacting cellular, molecular and mechanical factors, with distinct pathways leading to myofibroblast differentiation and activation. Keloids can serve as a model system of fibrotic diseases, a group of currently intractable disorders, and deciphering of the critical pathogenetic steps leading to ECM accumulation is expected to identify targets for pharmacologic intervention, not only for keloids but also for a number of other, both genetic and acquired, fibrotic diseases.

Effect of THBS1 on the Biological Function of Hypertrophic Scar Fibroblasts

Hypertrophic scarring is a skin collagen disease that can occur following skin damage and is unlikely to heal or subside naturally. Since surgical treatment often worsens scarring, it is important to investigate the pathogenesis and prevention of hypertrophic scarring. Thrombospondin-1 (THBS1) is a matrix glycoprotein that can affect fibrosis by activating TGF-β1, which plays a key role in wound repair and tissue regeneration; therefore, we investigated the effects of THBS1 on the biological function of hypertrophic scar fibroblasts. THBS1 expression was measured in hypertrophic scars and adjacent tissues as well as normal fibroblasts, normal scar fibroblasts, and hypertrophic scar fibroblasts. In addition, THBS1 was overexpressed or silenced in hypertrophic scar fibroblasts to determine the effects of THBS1 on cell proliferation, apoptosis, and migration, as well as TGF-β1 expression. Finally, the role of THBS1 in hypertrophic scarring was confirmed in vivo using a mouse model. We found that THBS1 expression was increased in hypertrophic scar tissues and fibroblasts and promoted the growth and migration of hypertrophic scar fibroblasts as well as TGF-β1 expression. Interestingly, we found that si-THBS1 inhibited the occurrence and development of bleomycin-induced hypertrophic scars in vivo and downregulated TGF-β1 expression. Together, our findings suggest that THBS1 is abnormally expressed in hypertrophic scars and can induce the growth of hypertrophic scar fibroblasts by regulating TGF-β1. Consequently, THBS1 could be an ideal target for treating hypertrophic scarring.

Cryosurgery as a Single Agent and in Combination with Intralesional Corticosteroids Is Effective on Young, Small Keloids and Induces Characteristic Histological and Immunohistological Changes: A Prospective Randomized Trial

BACKGROUND

As the pathogenesis of keloids is poorly understood, there is no sound biological basis of keloid management. Few controlled therapeutic studies have been published, and recurrences are a major reason for treatment failure.

OBJECTIVE

To detect efficacy and safety of cryosurgery regimens on keloids and the occurring biological changes caused by the treatment.

METHODS

This prospective randomized study compared efficacy and tolerability as well as histological/immunohistochemical effects of liquid nitrogen contact cryosurgery as a single regimen (group A) and combined with intralesional corticosteroids (group B) on young (<2 years old), small (≤10 cm2) keloids in 40 patients (2-sided effect, α-error 1%, power 95%).

RESULTS

Marked flattening of the lesions was achieved by both regimens. Median lesional volumes decreased from 106 to 7 mm3 in group A (p = 0.001) and from 138 to 6 mm3 in group B (p < 0.0001; ns, between groups). Good to excellent responses were registered in 83.3 and 90% of patients in groups A and B, respectively, by evaluating the lesional volume, in 80 and 95% of patients by the physician's evaluation and in 95% of patients in either group by the patient's assessment. Follow-up of 6-36 months revealed no further significant changes. Cryosurgery was generally well tolerated, with minor pain during treatment not requiring (27.5%) or requiring local anaesthesia (5%) - but not analgesics -, and hypopigmentation (25%). Histological examination showed increased vessel number and lumen dilatation after treatment in group B and reduction of rete ridge length in both groups with more prominent changes in group A. Tenascin C staining demarcated keloids from normal skin before therapy, while after therapy the entire treated tissue was labelled. Interferon-γ expression was significantly decreased after therapy both regarding positively stained cells and intensity in both groups.

CONCLUSION

Cryosurgery without and with intralesional corticosteroids is effective and safe on young, small keloids not only as a destructive physical procedure, but also by inducing biochemical and immunological scar rejuvenation.

miR-205 inhibits the development of hypertrophic scars by targeting THBS1

Increasing evidence shows that miRNAs are involved in the growth and development of hypertrophic scars. However, the specific mechanism of miR-205 is unclear. Here, we investigated the relationship between miR-205, thrombospondin 1 (THBS1) expression, and hypertrophic scars, and showed that miR-205 inhibits cell proliferation and migration and induces apoptosis. Double luciferase analysis, Western blot, and real-time polymerase chain reaction showed that miR-205 downregulates THBS1 expression and activity. Compared to the control group, miR-205 inhibited hypertrophic scar development. Our findings contribute to a better understanding of the miR-205-THBS1 pathway as a promising therapeutic target for reducing hypertrophic scars.

Effects of the circ_101238/miR-138-5p/CDK6 axis on proliferation and apoptosis keloid fibroblasts

The formation of keloid scars is normally induced by cutaneous injuries, however, the detailed mechanisms underlying keloid formation remain largely unknown. The present study aimed to investigate the effects of circular RNA_101238 (circ_101238) on the proliferation and apoptosis of keloid fibroblasts and to identify the underlying molecular mechanisms of these effects. Reverse transcription-quantitative (RT-q)PCR was performed to determine the expression levels of circ_101238, microRNA (miRNA/miR)-138-5p and cyclin-dependent kinase 6 (CDK6) in keloids and normal skin tissues. Following transfection with short hairpin (sh)-circ_101238, LV-circ_101238, miR-138-5p mimics, miR-138-5p inhibitors and small interfering (si)-CDK6, cell proliferation was assessed using a cell counting kit-8 assay. Furthermore, cell apoptosis was evaluated via flow cytometric analysis, while a dual-luciferase assay was performed to confirm interactions between circ_101238, miR-138-5p and CDK6. The expression levels of the proliferation marker, CDK6 and apoptosis marker, caspase-3 were determined via RT-qPCR and western blot analyses. The results demonstrated that expression levels of circ_101238 and CDK6 were significantly increased in keloid samples, while miR-138-5p expression was reduced in comparison to normal skin. Furthermore, circ_101238 was demonstrated to bind miR-138-5p, which subsequently targeted CDK6. Proliferative activity and CDK6 expression were significantly decreased in keloid fibroblasts following transfection with sh-circ_101238 or miR-138-5p mimics, while cell apoptosis was markedly increased. Furthermore, co-transfection with miR-138-5p mimics reversed the effects caused by overexpression of circ_101238. Treatment of keloid fibroblasts with si-CDK6 counteracted the biological behavior changes induced by miR-138-5p inhibitors. Additionally, transfection with LV-CDK6 reversed the effects caused by miR-138-5p mimics. Taken together, the results of the present study demonstrated that circ_101238 was upregulated in keloid tissues in comparison with normal tissues and that circ_101238 knockdown inhibited cell proliferation, while promoting apoptosis of keloid fibroblasts via the miR-138-5p/CDK6 axis. These results suggest that circ_101238 may serve as a promising therapeutic candidate for keloid therapy and that circ_101238/miR-138-5p/CDK6 signaling has the potential to regulate the growth of keloid fibroblasts.

The Keloid Disorder: Heterogeneity, Histopathology, Mechanisms and Models

Keloids constitute an abnormal fibroproliferative wound healing response in which raised scar tissue grows excessively and invasively beyond the original wound borders. This review provides a comprehensive overview of several important themes in keloid research: namely keloid histopathology, heterogeneity, pathogenesis, and model systems. Although keloidal collagen versus nodules and α-SMA-immunoreactivity have been considered pathognomonic for keloids versus hypertrophic scars, conflicting results have been reported which will be discussed together with other histopathological keloid characteristics. Importantly, histopathological keloid abnormalities are also present in the keloid epidermis. Heterogeneity between and within keloids exists which is often not considered when interpreting results and may explain discrepancies between studies. At least two distinct keloid phenotypes exist, the superficial-spreading/flat keloids and the bulging/raised keloids. Within keloids, the periphery is often seen as the actively growing margin compared to the more quiescent center, although the opposite has also been reported. Interestingly, the normal skin directly surrounding keloids also shows partial keloid characteristics. Keloids are most likely to occur after an inciting stimulus such as (minor and disproportionate) dermal injury or an inflammatory process (environmental factors) at a keloid-prone anatomical site (topological factors) in a genetically predisposed individual (patient-related factors). The specific cellular abnormalities these various patient, topological and environmental factors generate to ultimately result in keloid scar formation are discussed. Existing keloid models can largely be divided into in vivo and in vitro systems including a number of subdivisions: human/animal, explant/culture, homotypic/heterotypic culture, direct/indirect co-culture, and 3D/monolayer culture. As skin physiology, immunology and wound healing is markedly different in animals and since keloids are exclusive to humans, there is a need for relevant human in vitro models. Of these, the direct co-culture systems that generate full thickness keloid equivalents appear the most promising and will be key to further advance keloid research on its pathogenesis and thereby ultimately advance keloid treatment. Finally, the recent change in keloid nomenclature will be discussed, which has moved away from identifying keloids solely as abnormal scars with a purely cosmetic association toward understanding keloids for the fibroproliferative disorder that they are.

Histopathology and immunohistochemical analysis of 5-fluorouracil and triamcinolone treated keloids in double-blinded randomized controlled trial

Keloids are a major complication related to surgical wound healing and very challenging condition to treat. Many treatment options are available, but the efficacy of the treatment is poor in most of cases and some keloids do not respond to the treatment at all. We compared the efficacy of intralesional 5-fluorouracil (5-FU) and triamcinolone (TAC) injections in a double-blind randomized controlled trial (RCT). Forty-three patients with 50 keloid scars were treated with either intralesional TAC or 5-FU-injections over 6 months. We wanted to find out whether biological features (cell density, cell proliferation rate, vascular density, myofibroblast numbers, steroid hormone receptor expression) in keloids could be used to predict the response to therapy and define the biological changes that take place in patients receiving a response. As there was no statistically significant difference in the remission rate between TAC and 5-FU treatments, all patients were combined and analyzed as responders and nonresponders. Although responders have slightly more myofibroblasts than the nonresponders in their keloids in the pretreatment biopsy samples, we could not identify a single predictive factor that could identify those patients that respond to drug injections. The good clinical response to therapy is associated with the simultaneous reduction of myofibroblasts in the keloid. This study demonstrates that myofibroblasts are reduced in number in those keloids that were responsive to therapy, and that both 5-FU and TAC injections are useful for keloid treatment.