Where we stand with human hypertrophic and keloid scar models

miR-96 promotes collagen deposition in keloids by targeting Smad7

The abnormal upregulation of transforming growth factor-β (TGF-β) signaling has been demonstrated to initiate keloid formation and progression. Keloid is a type of benign skin tumor that may occur following sustaining skin injury. microRNA-96 (miR-96) serves an important role in the progression of various malignant diseases. Using reverse transcription quantitative polymerase chain reaction (RT-qPCR), the present study demonstrated that miR-96 was overexpressed in keloid-derived fibroblasts (KFs). Luciferase reporter assay revealed mothers against decapentaplegic homolog (Smad)7, which is one of the important inhibitory factors in the TGF-β pathway, as a direct target of miR-96. miR-96 was initially observed to be correlated with the deposition of type I collagen in KFs in vitro. The miR-96 antagomir, was directly added into the keloid organ culture (OC) to find its significant antifibrotic potential, such as keloid OC shrinkage, exhibited by its dry weight loss and improved dermis architecture, exhibited by Masson's staining. Following miR-96 antagomir treatment, a reduction in the mRNA and protein expression levels of collagen type I α 1 chain and collagen type 3 α 1 chain within keloid OC tissues was observed. The present study revealed that miR-96 serves an important role in pathogenic keloid formation, suggesting that miR-96 antagomir has the potential to prevent keloid progression.

The effectiveness of pressure therapy (15-25 mmHg) for hypertrophic burn scars: A systematic review and meta-analysis

Although pressure therapy (PT) represents the standard care for prevention and treatment of hypertrophic scar (HS) from burns, its practice is largely based on empirical evidence and its effectiveness remains controversial. To clarify the effect of PT (15-25 mmHg) for HS, we performed the systematic review and meta-analysis. Several electronic databases were screened to identify related randomized controlled trials (RCTs). 12 RCTs involving 710 patients with 761 HS resulting from burn injuries were included. Compared with non/low-PT, cases treated with PT (15-25 mmHg) showed significant differences in Vancouver Scar Scale score (MD = -0.58, 95% CI = -0.78--0.37), thickness (SMD = -0.25, 95% CI = -0.40--0.11), brightness (MD = 2.00, 95% CI = 0.59-3.42), redness (MD = -0.79, 95% CI = -1.52--0.07), pigmentation (MD = -0.16, 95% CI = -0.32--0.00) and hardness (SMD = -0.65, 95% CI = -1.07--0.23). However, there was no difference in vascularity (MD = 0.03, 95% CI = -0.43-0.48). Our analysis indicated that patients with HS who were managed with PT (15-25 mmHg) showed significant improvements. Due to limitations, more large and well-designed studies are needed to confirm our findings and the side-effects of the PT may also need to be evaluated.

3D modeling of keloid scars in vitro by cell and tissue engineering

Keloids are pathologic scars defined as dermal fibrotic tumors resulting from a disturbance of skin wound healing process. Treatments against keloids are multiple, sometimes empirical and none of them really provides an effective tool for physicians. The lack of effective treatments is correlated with the poor understanding of keloid pathogenesis. To fill this gap, researchers need strong models mimicking keloids as closely as possible. The objective of this study was to establish in vitro a new reconstructed keloid model (RKM), by combining fibroblasts extracted from the three major area of a keloid (center, periphery, non-lesional) in a three-dimensional biomaterial. To this aim, fibroblasts of three keloid locations were extracted and characterized, and then integrated in a hydrated collagen gel matrix during a three-step procedure. The heterogeneity of fibroblasts was assessed according to their proliferative and remodeling capacities. RKMs were further visualized and characterized by both light and scanning electron microscopy. This reconstructed keloid model should be very useful for investigating keloid fibroblasts function in conditions mimicking in vivo situation. Moreover, RKM should also be a suitable model for either drug study and discovery or innovative approaches using medical devices both during cancer and cancer-like disease investigation.

Functional analysis of keratinocyte and fibroblast gene expression in skin and keloid scar tissue based on deviation analysis of dynamic capabilities

The aim of the present study was to select key genes that are associated with fibroblasts and keratinocytes during keloid scar progression and development. The gene expression profile of GSE44270, which includes 32 samples, was downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) in case samples compared with control samples were screened using the Limma R package followed by hierarchical clustering analysis. Protein-protein interaction (PPI) networks of the total selected DEGs were constructed using Cytoscape. Moreover, the Gene Ontology biological processes and significant Kyoto Encyclopedia of Genes and Genomes pathways of the total selected DEGs were enriched using the Database for Annotation, Visualization and Integrated Discovery. Significant pathways that may be associated with keloid scar were analyzed using deviation analysis of dynamic capabilities. There were 658 DEGs in fibroblast keloid vs. normal, 112 DEGs in fibroblast non-lesion vs. normal, 439 DEGs in fibroblast keloid vs. non-lesion, 523 DEGs in keratocyte keloid vs. normal, 186 DEGs in keratocyte non-lesion vs. normal, and 963 DEGs in keratocyte keloid vs. non-lesion groups. HOXA9, BMP4, CDKN1A and SMAD2 in fibroblasts, and HOXA7, MCM8, PSMA4 and PSMB2 in keratinocytes were key genes in the PPI networks. Moreover, the amino sugar and nucleotide sugar metabolism pathway, cell cycle, and extracellular matrix (ECM)-receptor interaction pathway were significant pathways. This study suggests that several key genes (BMP4, HOXA9, SMAD2, CDKN1A, HOXA7, PSMA4 and PSMB2) that participate in some significant pathways (cell cycle and ECM-receptor interaction pathways) may be potential therapeutic targets for keloid scars.

The Northwestern Abdominoplasty Scar Model: A Novel Human Model for Scar Research and Therapeutics

There is a growing interest in the development and evaluation of therapeutic agents that improve the cosmetic appearance of scars. Existing nonhuman animal models to study scarring, while valuable, have well-acknowledged limitations, as it is accepted that the biology of human scarring differs significantly from scarring in other species. Moreover, human clinical trials of scarring require large numbers of subjects to achieve statistical power and are plagued by inherent intersubject variability because of the complex nature of wound healing in human beings. As a better alternative, we have developed the Northwestern Abdominoplasty Scar Model—a novel human clinical model that permits analysis of up to 20 cutaneous scars in a single subject and allows for not only visual scar comparison, but also histologic and molecular analyses of factors involved in scarring and wound healing. We have utilized this model in 5 early phase clinical trials designed to test the safety and efficacy of a variety of scar therapeutics without any complications to date. The model not only is applicable to scar therapeutics, but also can be utilized for other applications, such as the testing of implantable biomaterials, injectable products, therapies such as lasers, or even for in vivo study of wound healing processes in humans.