Collagen IV in Normal Skin and in Pathological Processes

Collagen as the extracellular matrix biomaterials in the arena of medical sciences

Collagen is a multipurpose material that has several applications in the health care, dental care, and pharmaceutical industries. Crosslinked compacted solids or lattice-like gels can be made from collagen. Biocompatibility, biodegradability, and wound-healing properties make collagen a popular scaffold material for cardiovascular, dentistry, and bone tissue engineering. Due to its essential role in the control of several of these processes, collagen has been employed as a wound-healing adjunct. It forms a major component of the extracellular matrix and regulates wound healing in its fibrillar or soluble forms. Collagen supports cardiovascular and other soft tissues. Oral wounds have been dressed with resorbable forms of collagen for closure of graft and extraction sites, and to aid healing. This present review is concentrated on the use of collagen in bone regeneration, wound healing, cardiovascular tissue engineering, and dentistry.

Hybrid Hydroxyapatite-Metal Complex Materials Derived from Amino Acids and Nucleobases

Calcium phosphates (CaPs) and their substituted derivatives encompass a large number of compounds with a vast presence in nature that have aroused a great interest for decades. In particular, hydroxyapatite (HAp, Ca10(OH)2(PO4)6) is the most abundant CaP mineral and is significant in the biological world, at least in part due to being a major compound in bones and teeth. HAp exhibits excellent properties, such as safety, stability, hardness, biocompatibility, and osteoconductivity, among others. Even some of its drawbacks, such as its fragility, can be redirected thanks to another essential feature: its great versatility. This is based on the compound's tendency to undergo substitutions of its constituent ions and to incorporate or anchor new molecules on its surface and pores. Thus, its affinity for biomolecules makes it an optimal compound for multiple applications, mainly, but not only, in biological and biomedical fields. The present review provides a chemical and structural context to explain the affinity of HAp for biomolecules such as proteins and nucleic acids to generate hybrid materials. A size-dependent criterium of increasing complexity is applied, ranging from amino acids/nucleobases to the corresponding macromolecules. The incorporation of metal ions or metal complexes into these functionalized compounds is also discussed.

Chromosome-level genome sequencing and multi-omics of the Hungarian White Goose (Anser anser domesticus) reveals novel miRNA-mRNA regulation mechanism of waterfowl feather follicle development

The Hungarian White Goose (Anser anser domesticus) is an excellent European goose breed, with high feather and meat production. Despite its importance in the poultry industry, no available genome assembly information has been published. This study aimed to present Chromosome-level and functional genome sequencing of the Hungarian White Goose. The results showed that the genome assembly has a total length of 1115.82 Mb, 39 pairs of chromosomes, 92.98% of the BUSCO index, and contig N50 and scaffold N50 were up to 2.32 Mb and 60.69 Mb, respectively. Annotation of the genome assembly revealed 19550 genes, 286 miRNAs, etc. We identified 235 expanded and 1,167 contracted gene families in this breed compared with the other 16 species. We performed a positive selection analysis between this breed and four species of Anatidae to uncover the genetic information underlying feather follicle development. Further, we detected the function of miR-199-x, miR-143-y, and miR-23-z on goose embryonic skin fibroblast. In summary, we have successfully generated a highly complete genome sequence of the Hungarian white goose, which will provide a great resource to improve our understanding of gene functions and enhance the studies on feather follicle development at the genomic level.

Transcriptome and proteome revealed the differences in 3 colors of earlobe in Jiangshan Black-bone chicken

The earlobe is a featherless, exposed thickening located beneath the ear canal of chickens, which plays a visual signaling role in age, performance, mental vitality, reproduction, and other aspects. However, despite its importance, there have been few studies on the color differences and formation mechanisms of chicken earlobes, particularly the structurally blue earlobes characteristic of the Jiangshan black-bone chicken. In this study, we explored the physiological mechanisms that may influence the formation of differently colored earlobes using 3 types of earlobes from Jiangshan black-bone chickens: light peacock green (Green group), dark peacock green (Blue group), and dark reddish purple (Black group). All 3 earlobe colors exhibited positive melanin Masson-Fontana staining, and the thickness of collagen fibers in the dermis decreased in the order of Green, Blue, and Black groups. A total of 1,953 differentially expressed genes (DEGs) were detected in the 3 earlobes through mRNA sequencing, among which the GO term "collagen trimer" was significantly enriched in DEGs between groups. Additionally, 716 differentially expressed proteins (DEPs) were identified in the 3 earlobes using 4D-DIA proteomics, with the term "collagen fibril organization" being significantly enriched in DEPs between the Green and Black groups. Integrated analysis of transcriptome and proteome data revealed that 12 DEGs and DEPs were commonly differentially expressed between the Green and Black groups, including the gene LUM (corneal keratan sulfate proteoglycan), which was significantly enriched in the "collagen fibril organization" GO term. In conclusion, our study suggests that LUM plays a crucial role in the formation of peacock green earlobes in Jiangshan black-bone chickens. The high level of LUM in peacock green (Green and Blue groups) may affect collagen nanostructures, leading to a stronger effect of melanin-supported dermal collagen on the production of non-iridescent structural colors through coherent scattering, resulting in a bright structural blue color in Jiangshan black-bone chickens. In contrast, the low expression of LUM in dark reddish purple (Black group) reduces the reflection of non-iridescent structural colors, making the earlobe color appear almost black, similar to melanin.

Unveiling the mechanism of high sugar diet induced advanced glycosylation end products damage skin structure via extracellular matrix-receptor interaction pathway

BACKGROUND

AGEs accumulate in the skin as a result of a high-sugar diet and play an important role in the skin aging process.

OBJECTIVES

The aim of this study was to characterize the mechanism underlying the effect of a high-sugar diet on skin aging damage at a holistic level.

METHODS

We established a high-sugar diet mouse model to compare and analyze differences in physiological indexes. The effect of a high-sugar diet on skin aging damage was analyzed by means of a transcriptome study and staining of pathological sections. Furthermore, the differences in the protein expression of AGEs and ECM components between the HSD and control groups were further verified by immunohistochemistry.

RESULTS

The skin in the HSD group mice tended toward a red, yellow, dark, and deep color. In addition, the epidermis was irregular with anomalous phenomena, the epidermis was thinned, and the dermis lost its normal structure and showed vacuolated changes. Transcriptomics results revealed significant downregulation of the ECM-receptor interaction pathway, significant upregulation of the expression of AGEs and significant downregulation of the expression levels of COLI, FN1, LM5, and TNC, among others ECM proteins and ECM receptors.

CONCLUSIONS

High-sugar diets cause skin aging damage by inducing the accumulation of AGEs, disrupting the expression of ECM proteins and their receptors, and downregulating the ECM-receptor interaction pathway, which affects cellular behavioral functions such as cell proliferation, migration, and adhesion, as well as normal skin tissue structure.

Current Prognostic Biomarkers for Abdominal Aortic Aneurysm: A Comprehensive Scoping Review of the Literature

Abdominal aortic aneurysm (AAA) is a progressive dilatation of the aorta that can lead to aortic rupture. The pathophysiology of the disease is not well characterized but is known to be caused by the general breakdown of the extracellular matrix within the aortic wall. In this comprehensive literature review, all current research on proteins that have been investigated for their potential prognostic capabilities in patients with AAA was included. A total of 45 proteins were found to be potential prognostic biomarkers for AAA, predicting incidence of AAA, AAA rupture, AAA growth, endoleak, and post-surgical mortality. The 45 proteins fell into the following seven general categories based on their primary function: (1) cardiovascular health, (2) hemostasis, (3) transport proteins, (4) inflammation and immunity, (5) kidney function, (6) cellular structure, (7) and hormones and growth factors. This is the most up-to-date literature review on current prognostic markers for AAA and their functions. This review outlines the wide pathophysiological processes that are implicated in AAA disease progression.

The Tumor Stroma of Squamous Cell Carcinoma: A Complex Environment That Fuels Cancer Progression

The tumor microenvironment (TME), a complex assembly of cellular and extracellular matrix (ECM) components, plays a crucial role in driving tumor progression, shaping treatment responses, and influencing metastasis. This narrative review focuses on the cutaneous squamous cell carcinoma (cSCC) tumor stroma, highlighting its key constituents and their dynamic contributions. We examine how significant changes within the cSCC ECM-specifically, alterations in fibronectin, hyaluronic acid, laminins, proteoglycans, and collagens-promote cancer progression, metastasis, and drug resistance. The cellular composition of the cSCC TME is also explored, detailing the intricate interplay of cancer-associated fibroblasts (CAFs), mesenchymal stem cells (MSCs), endothelial cells, pericytes, adipocytes, and various immune cell populations. These diverse players modulate tumor development, angiogenesis, and immune responses. Finally, we emphasize the TME's potential as a therapeutic target. Emerging strategies discussed in this review include harnessing the immune system (adoptive cell transfer, checkpoint blockade), hindering tumor angiogenesis, disrupting CAF activity, and manipulating ECM components. These approaches underscore the vital role that deciphering TME interactions plays in advancing cSCC therapy. Further research illuminating these complex relationships will uncover new avenues for developing more effective treatments for cSCC.

A chemiluminescence immunoassay for type IV collagen as a promising marker for liver fibrosis and cirrhosis

Herein, a magnetic bead-based chemiluminescence assay is reported to detect type IV collagen (col-IV) in serum samples. Magnetic beads (MBs) exhibit biocompatibility. Taking advantage of this property, they were conjugated with the col-IV antibody. For the determination of col-IV, the interaction of the col-IV sample, anti-(col-IV)-alkaline phosphatase (anti-(col-IV)-ALP) and anti-col-IV-magnetic beads (anti-(col-IV)-MBs) was performed to generate chemiluminescence. Under the optimized conditions, the developed method displayed good linearity in the concentration range of 20-2000 ng mL-1 with the limit of 0.79 ng mL-1. The repeatability coefficient of variation (CV) for col-IV detection ranged from 3.16% to 7.50%. The col-IV level in samples collected from a hospital was assessed by the chemiluminescence assay. Satisfactory recoveries were obtained ranging from 93.30% to 100.14%. In conclusion, the magnetic bead-based chemiluminescence assay may be used as a routine and efficient tool to detect type IV collagen in clinical diagnosis.

Elucidating the Role of Transcriptomic Networks and DNA Methylation in Collagen Deposition of Dezhou Donkey Skin

DNA methylation represents a predominant epigenetic modification with broad implications in various biological functions. Its role is particularly significant in the process of collagen deposition, a fundamental aspect of dermal development in donkeys. Despite its critical involvement, the mechanistic insights into how DNA methylation influences collagen deposition in donkey skin remain limited. In this study, we employed whole genome bisulfite sequencing (WGBS) and RNA sequencing (RNA-seq) to investigate the epigenetic landscape and gene expression profiles in the dorsal skin tissues of Dezhou donkeys across three developmental stages: embryonic (YD), juvenile (2-year-old, MD), and mature (8-year-old, OD). Our analysis identified numerous differentially methylated genes that play pivotal roles in skin collagen deposition and overall skin maturation, including but not limited to COL1A1, COL1A2, COL3A1, COL4A1, COL4A2, GLUL, SFRP2, FOSL1, SERPINE1, MMP1, MMP2, MMP9, and MMP13. Notably, we observed an inverse relationship between gene expression and DNA methylation proximal to transcription start sites (TSSs), whereas a direct correlation was detected in regions close to transcription termination sites (TTSs). Detailed bisulfite sequencing analyses of the COL1A1 promoter region revealed a low methylation status during the embryonic stage, correlating with elevated transcriptional activity and gene expression levels. Collectively, our findings elucidate key genetic markers associated with collagen deposition in the skin of Dezhou donkeys, underscoring the significant regulatory role of DNA methylation. This research work contributes to the foundational knowledge necessary for the genetic improvement and selective breeding of Dezhou donkeys, aiming to enhance skin quality attributes.

Mechanisms of Pathogenic Escherichia coli Attachment to Meat

Escherichia coli are present in the human and animal microbiome as facultative anaerobes and are viewed as an integral part of the whole gastrointestinal environment. In certain circumstances, some species can also become opportunistic pathogens responsible for severe infections in humans. These infections are caused by the enterotoxinogenic E. coli, enteroinvasive E. coli, enteropathogenic E. coli and the enterohemorrhagic E. coli species, frequently present in food products and on food matrices. Severe human infections can be caused by consumption of meat contaminated upon exposure to animal feces, and as such, farm animals are considered to be a natural reservoir. The mechanisms by which these four major species of E. coli adhere and persist in meat postslaughter are of major interest to public health and food processors given their frequent involvement in foodborne outbreaks. This review aims to structure and provide an update on the mechanistic roles of environmental factors, curli, type I and type IV pili on E. coli adherence/interaction with meat postslaughter. Furthermore, we emphasize on the importance of bacterial surface structures, which can be used in designing interventions to enhance food safety and protect public health by reducing the burden of foodborne illnesses.

A sustainable strategy for generating highly stable human skin equivalents based on fish collagen

Tissue engineered skin equivalents are increasingly recognized as potential alternatives to traditional skin models such as human ex vivo skin or animal skin models. However, most of the currently investigated human skin equivalents (HSEs) are constructed using mammalian collagen which can be expensive and difficult to extract. Fish skin is a waste product produced by fish processing industries and identified as a cost-efficient and sustainable source of type I collagen. In this work, we describe a method for generating highly stable HSEs based on fibrin fortified tilapia fish collagen. The fortified fish collagen (FFC) formulation is optimized to enable reproducible fabrication of full-thickness HSEs that undergo limited contraction, facilitating the incorporation of human donor-derived skin cells and formation of biomimetic dermal and epidermal layers. The morphology and barrier function of the FFC HSEs are compared with a commercial skin model and validated with immunohistochemical staining and transepithelial electrical resistance testing. Finally, the potential of a high throughput screening platform with FFC HSE is explored by scaling down its fabrication to 96-well format.

Light Sheet-Based Laser Patterning Bioprinting Produces Long-Term Viable Full-Thickness Skin Constructs

Tissue engineering holds great promise for biomedical research and healthcare, offering alternatives to animal models and enabling tissue regeneration and organ transplantation. 3D bioprinting stands out for its design flexibility and reproducibility. Here, an integrated fluorescent light sheet bioprinting and imaging system is presented that combines high printing speed (0.66 mm3 /s) and resolution (9 µm) with light sheet-based imaging. This approach employs direct laser patterning and a static light sheet for confined voxel crosslinking in photocrosslinkable materials. The developed bioprinter enables real-time monitoring of hydrogel crosslinking using fluorescent recovery after photobleaching (FRAP) and brightfield imaging as well as in situ light sheet imaging of cells. Human fibroblasts encapsulated in a thiol-ene click chemistry-based hydrogel exhibited high viability (83% ± 4.34%) and functionality. Furthermore, full-thickness skin constructs displayed characteristics of both epidermal and dermal layers and remained viable for 41 days. The integrated approach demonstrates the capabilities of light sheet bioprinting, offering high speed, resolution, and real-time characterization. Future enhancements involving solid-state laser scanning devices such as acousto-optic deflectors and modulators will further enhance resolution and speed, opening new opportunities in light-based bioprinting and advancing tissue engineering.

Sulfilimine bond formation in collagen IV

The collagen IV network plays a crucial role in providing structural support and mechanical integrity to the basement membrane and surrounding tissues. A key aspect of this network is the formation of intra- and inter-collagen fibril crosslinks. One particular crosslink, an inter-residue sulfilimine bond, has been found, so far, to be unique to collagen IV. More specifically, these crosslinks are primarily formed between methionine and lysine or hydroxylysine residues and can occur within a single collagen fibril or between different collagen fibrils. Due to its significance as the major crosslink in the collagen IV network, the sulfilimine bond plays critical roles in tissue development and various human diseases. While the proposed reaction mechanism for sulfilimine bond formation is supported by experimental evidence, the precise nature of this bond remained uncertain until computational studies were conducted. The process involves the reaction of hypohalous acids (e.g., HOBr, HOCl), produced by a peroxidasin enzyme in the basement membrane, with the sidechain sulfur of methionine or sidechain nitrogen of lysine/hydroxylysine residues in collagen IV, to form halosulfonium or haloamine intermediates, respectively. The halosulfonium/haloamine then reacts with the sidechain amine/sulfide of the lysine (or hydroxylysine) or methionine respectively, eventually resulting in the formation of the sulfilimine (MetSNLys/Hyl) crosslink. The sulfilimine product formed not only plays a crucial role in physiological processes but also finds applications in various industrial and pharmaceutical contexts. In this review, we provide a comprehensive summary of existing studies, including our own research, aimed at understanding the reaction mechanism, protonation states, characteristic nature, and dynamic behavior of the sulfilimine bond in collagen IV. The goal is to offer readers an overview of this critically important biochemical bond.

Identifying Bone Marrow Microenvironmental Populations in Myelodysplastic Syndrome and Acute Myeloid Leukemia

The bone marrow microenvironment consists of distinct cell populations, such as mesenchymal stromal cells, endothelial cells, osteolineage cells, and fibroblasts, which provide support for hematopoietic stem cells (HSCs). In addition to supporting normal HSCs, the bone marrow microenvironment also plays a role in the development of hematopoietic stem cell disorders, such as myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). MDS-associated mutations in HSCs lead to a block in differentiation and progressive bone marrow failure, especially in the elderly. MDS can often progress to therapy-resistant AML, a disease characterized by a rapid accumulation of immature myeloid blasts. The bone marrow microenvironment is known to be altered in patients with these myeloid neoplasms. Here, a comprehensive protocol to isolate and phenotypically characterize bone marrow microenvironmental cells from murine models of myelodysplastic syndrome and acute myeloid leukemia is described. Isolating and characterizing changes in the bone marrow niche populations can help determine their role in disease initiation and progression and may lead to the development of novel therapeutics targeting cancer-promoting alterations in the bone marrow stromal populations.

In vitro comparison of human plasma-based and self-assembled tissue-engineered skin substitutes: two different manufacturing processes for the treatment of deep and difficult to heal injuries

Background

The aim of this in vitro study was to compare side-by-side two models of human bilayered tissue-engineered skin substitutes (hbTESSs) designed for the treatment of severely burned patients. These are the scaffold-free self-assembled skin substitute (SASS) and the human plasma-based skin substitute (HPSS).

Methods

Fibroblasts and keratinocytes from three humans were extracted from skin biopsies (N = 3) and cells from the same donor were used to produce both hbTESS models. For SASS manufacture, keratinocytes were seeded over three self-assembled dermal sheets comprising fibroblasts and the extracellular matrix they produced (n = 12), while for HPSS production, keratinocytes were cultured over hydrogels composed of fibroblasts embedded in either plasma as unique biomaterial (Fibrin), plasma combined with hyaluronic acid (Fibrin-HA) or plasma combined with collagen (Fibrin-Col) (n/biomaterial = 9). The production time was 46-55 days for SASSs and 32-39 days for HPSSs. Substitutes were characterized by histology, mechanical testing, PrestoBlue™-assay, immunofluorescence (Ki67, Keratin (K) 10, K15, K19, Loricrin, type IV collagen) and Western blot (type I and IV collagens).

Results

The SASSs were more resistant to tensile forces (p-value < 0.01) but less elastic (p-value < 0.001) compared to HPSSs. A higher number of proliferative Ki67+ cells were found in SASSs although their metabolic activity was lower. After epidermal differentiation, no significant difference was observed in the expression of K10, K15, K19 and Loricrin. Overall, the production of type I and type IV collagens and the adhesive strength of the dermal-epidermal junction was higher in SASSs.

Conclusions

This study demonstrates, for the first time, that both hbTESS models present similar in vitro biological characteristics. However, mechanical properties differ and future in vivo experiments will aim to compare their wound healing potential.

Material matters: exploring the interplay between natural biomaterials and host immune system

Biomaterials are widely used for various medical purposes, for instance, implants, tissue engineering, medical devices, and drug delivery systems. Natural biomaterials can be obtained from proteins, carbohydrates, and cell-specific sources. However, when these biomaterials are introduced into the body, they trigger an immune response which may lead to rejection and failure of the implanted device or tissue. The immune system recognizes natural biomaterials as foreign substances and triggers the activation of several immune cells, for instance, macrophages, dendritic cells, and T cells. These cells release pro-inflammatory cytokines and chemokines, which recruit other immune cells to the implantation site. The activation of the immune system can lead to an inflammatory response, which can be beneficial or detrimental, depending on the type of natural biomaterial and the extent of the immune response. These biomaterials can also influence the immune response by modulating the behavior of immune cells. For example, biomaterials with specific surface properties, such as charge and hydrophobicity, can affect the activation and differentiation of immune cells. Additionally, biomaterials can be engineered to release immunomodulatory factors, such as anti-inflammatory cytokines, to promote a tolerogenic immune response. In conclusion, the interaction between biomaterials and the body's immune system is an intricate procedure with potential consequences for the effectiveness of therapeutics and medical devices. A better understanding of this interplay can help to design biomaterials that promote favorable immune responses and minimize adverse reactions.

Bullous Pemphigoid in X-linked Alport Syndrome

Skin lesions in X-linked Alport syndrome (XLAS) are rarely observed. Bullous pemphigoid (BP) is caused by autoantibodies against BP180, also called α1 (XVII) chain, in the basement membrane zone (BMZ). A 48-year-old man with XLAS developed tense blisters. A skin biopsy showed a cleft between the basal cell layer and dermis, with the infiltration of neutrophils and eosinophils. α1 (XVII) staining was positive on the epidermal side of α2/5 (IV) staining. Oral prednisolone improved his symptoms gradually. Abundant tense blisters on the palms and soles might suggest an important role of the α5 (IV) chain in the integrity of BMZ.

Collagen Type IV Alpha 5 Chain in Bronchiolitis Obliterans Syndrome After Lung Transplant: The First Evidence

INTRODUCTION

Bronchiolitis obliterans syndrome (BOS) is the most common form of CLAD and is characterized by airflow limitation and an obstructive spirometry pattern without parenchymal opacities. The protein signature of BOS lesions concerns extracellular matrix organization and aberrant basement membrane composition. In this pilot study, we investigated the presence of COL4A5 in the serum of patients with BOS.

METHODS

41 patients who had undergone LTX were enrolled. Of these, 27 developed BOS and 14 (control group) were considered stable at the time of serum sampling. Of BOS patients, serum samples were analysed at the time of BOS diagnosis and before the clinical diagnosis (pre-BOS). COL4A5 levels were detected through the ELISA kit.

RESULTS

Serum concentrations of COL4A5 were higher in pre-BOS than in stable patients (40.5 ± 13.9 and 24.8 ± 11.4, respectively, p = 0.048). This protein is not influenced by comorbidities, such as acute rejection or infections, or by therapies. Survival analysis also reveals that a higher level of COL4A5 was also associated with less probability of survival. Our data showed a correlation between concentrations of COL4A5 and FEV1 at the time of diagnosis of BOS.

CONCLUSION

Serum concentrations of COL4A5 can be considered a good prognostic marker due to their association with survival and correlation with functional parameters.

Alport Syndrome and Oral Mucous Membrane Pemphigoid: An Interesting Case

Alport syndrome (AS) is a hereditary progressive glomerular disease associated with sensorineural hearing loss and ocular abnormalities. It is attributed to the altered structure and the subsequent dysfunction of the glomerular basement membrane (GBM) due to the mutated type IV collagen a3/a4/a5 chains. It may emerge either as an X-linked disease, the most common, or as an autosomal disease, both recessive and dominant. A female patient, 26 years old, came in 2023 to the Department of Oral Medicine/ Pathology, Dental School, Aristotle University of Thessaloniki, complaining about pain and a burning sensation in her right cheek. Her medical history revealed the diagnosis of Alport syndrome in 2016 and kidney transplantation in 2022 with extensive post-transplantation drug administration. The clinical examination revealed an ulcer, partially covered by a pseudomembrane, on the oral mucosa of the right cheek, surrounded by an erythematous border. A biopsy was taken, and the histopathological examination showed the oral manifestation of mucous membrane pemphigoid. After communicating with the attending nephrologist, the prescription of methylprednisolone was decided, and the lesions receded. The differential diagnosis included both AS-induced pemphigoid and drug-induced pemphigoid. The thorough medical history, detailed clinical investigation, lesion biopsy, and collaboration of different dental and medical specialties constitute necessary prerequisites for a successful treatment, even in immunosuppressed patients.

Modelling the Complexity of Human Skin In Vitro

The skin serves as an important barrier protecting the body from physical, chemical and pathogenic hazards as well as regulating the bi-directional transport of water, ions and nutrients. In order to improve the knowledge on skin structure and function as well as on skin diseases, animal experiments are often employed, but anatomical as well as physiological interspecies differences may result in poor translatability of animal-based data to the clinical situation. In vitro models, such as human reconstructed epidermis or full skin equivalents, are valuable alternatives to animal experiments. Enormous advances have been achieved in establishing skin models of increasing complexity in the past. In this review, human skin structures are described as well as the fast evolving technologies developed to reconstruct the complexity of human skin structures in vitro.

The synergistic effect of retinyl propionate and hydroxypinacolone retinoate on skin aging

BACKGROUND

Aging is responsible for the majority of skin and soft tissue remolding in humans. Retinol and its derivatives or retinoids effectively intervene skin aging process. Nevertheless, retinoids usually induce skin intolerance, especially among the Chinese, and thus, their application to prevent skin aging is yet to be well accepted. The study of optimal composition and concentration of retinoids is necessary to offer strong antiaging efficacies with minimum irritations. Therefore, a better understanding of retinol and its derivatives is acutely needed to develop strategies to combat skin aging.

OBJECTIVE

In this study, we aimed to determine the optimal ratio of two retinol derivatives-hydroxypinacolone retinoate (HPR) and retinyl propionate (RP) in terms of dermal remodeling and skin aging prevention-and to investigate their synergistic antiaging effects both in vitro and in vivo.

METHODS

An in vitro human foreskin fibroblast (HFF-1) cell model was established to evaluate the cell viability of HPR and/or RP treatment. In addition, the antiaging and retinol receptor genes expressions in HFF-1 cells cotreated with HPR and RP were quantified. The in vivo adverse reaction evaluation of skincare serums containing various levels of retinol or the optimal HPR and RP combination termed Gravi-A was performed by 24 h patch tests in 33 subjects prior to the clinical research. Last but not the least, clinical research with 42 Chinese urban women was conducted to assess the in vivo antiaging efficacy of the skincare serum containing this optimal retinoid combination.

RESULTS

The combination of HPR and RP at the weight ratio of 5:9 was shown to achieve the optimal in vitro antiaging performance. Coadministration of 5 μg/mL HPR and 9 μg/mL RP to HFF-1 cells promoted their proliferation at 24 h and synergistically enhanced the expressions of type IV collagen, CRBP-I, and RARB genes. In addition, the skincare serum containing HPR and RP combination at 5:9 weight ratio demonstrated superior in vivo anti-wrinkle and skin elasticity improvement benefits without any adverse reactions, while retinol in the same concentration exerted much higher adverse effect. Skin wrinkles, skin smoothness, TEWL, skin elasticity R2 and R5 were improved by 8.3%, 11.9%, 25.7%, 14.5%, and 22.6%, respectively, after 8-week use.

CONCLUSION

Our results indicated the advanced antiaging effect of HPR and RP combination both in vitro and in vivo. In addition, little adverse effect was observed in this study, in comparison with retinol. This combination named as Gravi-A is a potential therapeutic strategy to prevent skin aging, especially for Chinese women.

Effect of cold atmospheric microwave plasma (CAMP) on wound healing in canine keratinocytes

Cutaneous wound healing is a biological process that occurs upon skin injury and involves different mechanisms to repair tissue damage. Improper healing or prolonged curation period of wound lesions may induce unpleasant complications. Cold atmospheric microwave plasma (CAMP) is an upcoming medical therapeutic option for skin infection and wound treatment. However, the molecular mechanisms of CAMP-mediated canine wound healing are not well characterized. Wound-healing activity was examined to elucidate the biological effects and molecular mechanisms of CAMP. Canine keratinocytes (CPEKs) were treated using CAMP, and their wound-healing activities were evaluated. The molecular mechanisms of that effect were examined, based on RNA-Seq analysis data, and verified using immunoblotting and polymerase chain reaction. It was found that the CAMP-treated cells exhibited a significant increase in cell migration evaluated by scratch assay in human keratinocytes (HaCaT) and canine keratinocytes (CPEK). Additionally, CAMP-treated CPEK cells showed a significant positive effect on cell invasion. The RNA-Seq data revealed that CAMP alters different genes and pathways in CPEK cells. Gene expression involved in the cell cycle, cell proliferation, angiogenesis, cell adhesion, and wound healing was upregulated in CAMP-treated cells compared with gas-activated media used as a control. The Hippo pathway was also analyzed, and the protein and mRNA levels of YAP were significantly increased in CAMP-treated cells. CAMP-treated CPEK cells indicated the downregulation of E-cadherin and upregulation of vimentin, Snail, and Slug at transcription and translation levels, contributing to a favorable effect on cell migration. Our findings suggested that CAMP treatment provided beneficial effects on the curative wound process through the induction of genes involved in wound healing, promotion of EMT, and increase in the molecular targets in the Hippo signaling pathway.

Revisiting laminin and extracellular matrix remodeling in metastatic squamous cell carcinoma: What have we learned after more than four decades of research?

Patients with squamous cell carcinoma (SCC) have significantly lower survival upon the development of distant metastases. The extracellular matrix (ECM) is a consistent yet dynamic influence on the metastatic capacity of SCCs. The ECM encompasses a milieu of structural proteins, signaling molecules, and enzymes. Just over 40 years ago, the fibrous ECM glycoprotein laminin was identified. Roughly four decades of research have revealed a pivotal role of laminins in metastasis. However, trends in ECM alterations in some cancers have been applied broadly to all metastatic diseases, despite evidence that these characteristics vary by tumor type. We will summarize how laminins influence the SCC metastatic process exclusively. Enhanced laminin protein deposition occurs at the invasive edge of SCC tumors, which correlates with elevated levels of laminin-binding β1 integrins on SCC cells, increased MMP-3 presence, worse prognosis, and lymphatic dissemination. Although these findings are significant, gaps in knowledge of the formation of a premetastatic niche, the processes of intra- and extravasation, and the contributions of the ECM to SCC metastatic cell dormancy persist. Bridging these gaps requires novel in vitro systems and animal models that reproduce tumor-stromal interactions and spontaneous metastasis seen in the clinic. These advances will allow accurate assessment of laminins to predict responders to transforming growth factor-β inhibitors and immunotherapy, as well as potential combinatorial therapies with the standard of care. Such clinical interventions may drastically improve quality of life and patient survival by explicitly targeting SCC metastasis.

TNF-α‒Mediated Keratinocyte Expression and Release of Matrix Metalloproteinase 9: Putative Mechanism of Pathogenesis in Stevens‒Johnson Syndrome/Toxic Epidermal Necrolysis

Stevens‒Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are severe cutaneous adverse drug reactions characterized by widespread keratinocyte cell death and epidermal detachment. At present, there is little understanding of how the detachment occurs or how it is abrogated by the TNF-α inhibitor etanercept, an effective SJS/TEN treatment. RNA sequencing was used to identify upregulated transcripts in formalin-fixed paraffin-embedded SJS/TEN skin biopsies. Epidermal matrix metalloproteinase 9 (MMP9) expression was assessed by immunohistochemistry in skin biopsies and cultured human skin explants exposed to serum from patients with cutaneous adverse drug reactions. TNF-α‒induced MMP9 expression and activity and its abrogation by etanercept were determined using the HaCaT immortalized keratinocyte cell line. Epidermal MMP9 expression was significantly higher in SJS/TEN skin (70.6%) than in healthy control skin (0%) (P = 0.0098) and nonbullous skin reactions (10.7%) (P = 0.0002). SJS/TEN serum induced significant MMP9 expression and collagenase activity in healthy skin explants, which was reduced by etanercept. Etanercept was also able to negate the TNF-α‒induced MMP9 expression in the HaCaT cell line. Data suggest that elevated epidermal MMP9 expression and collagenase activity are a putative pathogenic mechanism in SJS/TEN, which is limited by etanercept. Modulation of MMP9 expression and activity represents, to our knowledge, a previously unreported therapeutic target for the treatment of SJS/TEN.

The extracellular matrix fibulin 7 maintains epidermal stem cell heterogeneity during skin aging

Tissue stem cells (SCs) divide infrequently as a protective mechanism against internal and external stresses associated with aging. Here, we demonstrate that slow- and fast-cycling SCs in the mouse skin epidermis undergo distinct aging processes. Two years of lineage tracing reveals that Dlx1+ slow-cycling clones expand into the fast-cycling SC territory, while the number of Slc1a3+ fast-cycling clones gradually declines. Transcriptome analysis further indicate that the molecular properties of each SC population are altered with age. Mice lacking fibulin 7, an extracellular matrix (ECM) protein, show early impairments resembling epidermal SC aging, such as the loss of fast-cycling clones, delayed wound healing, and increased expression of inflammation- and differentiation-related genes. Fibulin 7 interacts with structural ECM and matricellular proteins, and the overexpression of fibulin 7 in primary keratinocytes results in slower proliferation and suppresses differentiation. These results suggest that fibulin 7 plays a crucial role in maintaining tissue resilience and epidermal SC heterogeneity during skin aging.

The basement membrane in epidermal polarity, stemness, and regeneration

The epidermis is a specialized epithelium that constitutes the outermost layer of the skin, and it provides a protective barrier against environmental assaults. Primarily consisting of multilayered keratinocytes, the epidermis is continuously renewed by proliferation of stem cells and the differentiation of their progeny, which undergo terminal differentiation as they leave the basal layer and move upward toward the surface, where they die and slough off. Basal keratinocytes rest on a basement membrane at the dermal-epidermal junction that is composed of specific extracellular matrix proteins organized into interactive and mechanically supportive networks. Firm attachment of basal keratinocytes, and their dynamic regulation via focal adhesions and hemidesmosomes, is essential for maintaining major skin processes, such as self-renewal, barrier function, and resistance to physical and chemical stresses. The adhesive integrin receptors expressed by epidermal cells serve structural, signaling, and mechanosensory roles that are critical for epidermal cell anchorage and tissue homeostasis. More specifically, the basement membrane components play key roles in preserving the stem cell pool, and establishing cell polarity cues enabling asymmetric cell divisions, which result in the transition from a proliferative basal cell layer to suprabasal cells committed to terminal differentiation. Finally, through a well-regulated sequence of synthesis and remodeling, the components of the dermal-epidermal junction play an essential role in regeneration of the epidermis during skin healing. Here too, they provide biological and mechanical signals that are essential to the restoration of barrier function.

Chemical Composition of Impatiens textori Miq. Flower Absolute and Its Potential Wound Repair and Anti-Melanogenesis-Promoting Activities in Skin Cells

Impatiens textori Miq. (ITM; family Balsaminaceae) is a traditional medicinal plant with many biological activities, which include anti-allergic, anti-inflammatory, and anti-pruritic properties. However, it remains to be determined whether ITM affects biological activities in the skin. Thus, we investigated the effects of ITM flower absolute (ITMFAb) extract on the biological activities of skin, especially those related to skin wound repair and whitening. ITMFAb was extracted with hexane, and its composition was determined through GC/MS. The biological activities of ITMFAb on HaCaT keratinocytes and B16BL6 melanoma cells were analyzed using a water-soluble tetrazolium salt, 5-bromo-2'-deoxyuridine incorporation, a Boyden chamber, an ELISA, a sprouting assay, and by immunoblotting. These analyses were performed in a range of ITMFAb concentrations that did not inhibit the viability of the cells (HaCaT, ≤400 µg/mL; B16BL6, ≤200 µg/m). Forty components were identified in ITMFAb. ITMFAb stimulated proliferation, migration, sprout outgrowth, and type I and IV collagen synthesis and upregulated the activations of ERK1/2, JNK, p38 MAPK, and AKT in HaCaT cells. In addition, ITMFAb attenuated the serum-induced proliferation of B16BL6 cells. ITMFAb inhibited melanin synthesis, tyrosinase activity, and expressions of MITF and tyrosinase in α-MSH-exposed B16BL6 cells. These findings indicate that ITMFAb has beneficial effects on wound repairing and whitening-linked responses in the skin and suggest the potential use of ITMFAb as a natural material for the development of skin wound repair and whitening agents.

Molecular Dynamics Investigation on the Effects of Protonation and Lysyl Hydroxylation on Sulfilimine Cross-links in Collagen IV

Collagen IV networks are an essential component of basement membranes that are important for their structural integrity and thus that of an organism's tissues. Improper functioning of these networks has been associated with several diseases. Cross-links, such as sulfilimine bonds interconnecting NC1 domains, are critical for forming and mechanically stabilizing these collagen IV networks. More specifically, the sulfilimine cross-links form between methionine (Met93) and lysine/hydroxylsine (Lys211/Hyl211) residues of NC1 domains. Therefore, the dynamic nature of the sulfilimine bond in collagen IV is crucial for network formation. To understand the dynamic nature of a neutral and protonated sulfilimine bond in collagen IV, we performed molecular dynamics (MD) simulations on four sulfilimine cross-linked systems (i.e., _Met93S-N_Lys211, _Met93S-NH_Lys211 ⁺, _Met93S-N_Hyl211, and _Met93S-NH_Hyl211 ⁺) of collagen IV. The MD results showed that the neutral _Met93S-N_Lys211 system has the smallest protein backbone and showed the cross-linked residues' RMSD value. The conformational change analyses showed that the conformations of the sulfilimine cross-linked residues take on a U-shape for the _Met93S-N_Hyl211 and _Met93S-HN_Hyl211 ⁺ systems, whereas the conformations of the sulfilimine cross-linked residues are more open for the _Met93S-N_Lys211, and _Met93S-NH_Lys211 ⁺ systems. Protonation is a crucial biochemical process to stabilize the protein structure or the biological cross-links. Furthermore, the protonation of the sulfilimine bond could potentially influence hydrogen bond interaction with near amino acid residues, and according to water distribution analyses, the sulfilimine bond can potentially exist in one or more protonation states.

Advancements in Extracellular Matrix-Based Biomaterials and Biofabrication of 3D Organotypic Skin Models

Over the last decades, three-dimensional (3D) organotypic skin models have received enormous attention as alternative models to in vivo animal models and in vitro two-dimensional assays. To date, most organotypic skin models have an epidermal layer of keratinocytes and a dermal layer of fibroblasts embedded in an extracellular matrix (ECM)-based biomaterial. The ECM provides mechanical support and biochemical signals to the cells. Without advancements in ECM-based biomaterials and biofabrication technologies, it would have been impossible to create organotypic skin models that mimic native human skin. In this review, the use of ECM-based biomaterials in the reconstruction of skin models, as well as the study of complete ECM-based biomaterials, such as fibroblasts-derived ECM and decellularized ECM as a better biomaterial, will be highlighted. We also discuss the benefits and drawbacks of several biofabrication processes used in the fabrication of ECM-based biomaterials, such as conventional static culture, electrospinning, 3D bioprinting, and skin-on-a-chip. Advancements and future possibilities in modifying ECM-based biomaterials to recreate disease-like skin models will also be highlighted, given the importance of organotypic skin models in disease modeling. Overall, this review provides an overview of the present variety of ECM-based biomaterials and biofabrication technologies available. An enhanced organotypic skin model is expected to be produced in the near future by combining knowledge from previous experiences and current research.

Investigation of the synergistic effect of platelet-rich plasma and polychromatic light on human dermal fibroblasts seeded chitosan/gelatin scaffolds for wound healing

Conventional wound healing treatments are insufficient for chronic wounds caused by factors such as senescence of fibroblasts, reduced growth factor synthesis, and poor angiogenesis. Recently, tissue engineering approaches have been investigated to develop effective therapies. In this study, a biochemical/biophysical stimulant-based 3D system was developed for the healing of chronic wounds. In this direction, genipin crosslinked chitosan (CHT)/gelatin (GEL) scaffolds were fabricated by freeze-drying and loaded with platelet-rich plasma (PRP). The scaffolds were seeded with human dermal fibroblasts and then, polychromatic light in near infrared region (NIR) was applied to the scaffolds for activating the platelets and stimulating the fibroblasts (photoactivation, PAC). Thus, fibroblasts were stimulated both chemically and physically by PRP and light, respectively. Cell migration, proliferation, morphology, gene expressions and reactive oxygen species (ROS) activity were evaluated in-vitro. Laminin and collagen 4 expressions that are important for extracellular matrix (ECM) formation, and PDGF (Platelet-derived growth factor) and VEGF (Vascular endothelial growth factor) expressions that are important for vascularization significantly increased in the presence of both PRP and light. Besides, PRP and light improved cell migration in 3D core-and shell model synergistically. Hydrogen peroxide content decreased in both PRP and light, indicating inhibition of ROS production. It was concluded that the stimulation of platelets with light in the NIR has a great potential to use for both platelets activation and stimulation of fibroblasts. As a result, an effective therapy can be developed for chronic wounds by using scaffold-based 3D systems together with PRP and photostimulation.

Remodeling of the Dermal Extracellular Matrix in a Tissue-Engineered Psoriatic Skin Model by n-3 Polyunsaturated Fatty Acids

Psoriasis is an inflammatory skin disease mainly associated with an epidermal disorder. However, the involvement of the dermal extracellular matrix (ECM) composition in psoriasis is still poorly understood. This study aimed to investigate the expression of ECM components in psoriatic skin substitutes (PS⁻) compared with healthy skin substitutes (HS⁻), as well as the effect of an n-3 polyunsaturated fatty acid, namely α-linolenic acid (ALA), on the psoriatic dermal compartment (PS^ALA+). Liquid chromatography tandem mass spectrometry analyses revealed that the lipidome of PS⁻ contained higher amounts of n-6 derived prostaglandins (PGE₂) and lipoxygenase products (9-HODE and 15-HETE). ALA supplementation increased the levels of PGE₃, 13-HOTrE, 15-HEPE, and 18-HEPE, and decreased the levels of PGE₂, 15-HETE, and 9-HOPE compared with PS⁻, indicating that ALA modulates the dermal lipidome of psoriatic skin substitutes. Gene expression profiling showed that several genes encoding for different ECM proteins were overexpressed in PS⁻ compared with HS⁻, namely COL1A1 (4.2-fold), COL1A2 (3-fold), COL3A1 (4.4-fold), COL4A1 (2.3-fold), COL4A2 (6.3-fold), COL5A1 (3.3-fold), COL5A2 (5.2-fold), and COL5A3 (4.6-fold). Moreover, the expression of collagen IV (Col IV), collagen VII (Col VII), and laminin was found to be increased in PS⁻ compared with HS⁻, and to be restored with ALA (PS^ALA+) according to immunofluorescence staining, while only the collagen I to collagen III ratio was altered according to dot blot analyses. Linear regression analysis revealed several positive correlations, including Col III with 14-HDHA levels, fibronectin with 12-HETE and 15-HETE levels, the dermo-epidermal junction Col IV with PGF_2α, 9-HODE, and 13-HODE levels, and laminin with levels of PGF_2α, 9-HODE, 13-HODE, 5-HETE, 12-HETE, and 15-HETE. These results suggest that the ECM plays an underestimated role in the pathogenesis of psoriasis and that ALA supplementation can regulate the ECM composition.

Autologous hematopoietic stem cell transplantation promotes connective tissue remodeling in systemic sclerosis patients

BACKGROUND

Autologous hematopoietic stem cell transplantation (AHSCT) treats patients with severe and progressive systemic sclerosis (SSc). However, basic mechanisms associated with the therapeutic efficacy of the procedure are not entirely understood. We aimed to evaluate how AHSCT affects skin fibrosis in SSc patients.

METHODS

Clinical data, serum, and skin samples from 39 SSc patients who underwent AHSCT were retrospectively evaluated. Skin biopsies were analyzed by immunohistochemistry with anti-MMP-1, -MMP-2, -MMP-3, -MMP-9, -TIMP-1, -α-SMA, -TGF-β, and -NF-κB p65 antibodies, and stained with hematoxylin and eosin and picrosirius red to assess skin thickness and collagen density, respectively. Serum samples were evaluated by Multiplex Assay for COL1A1, COL4A1, FGF-1, MMP-1, MMP-3, MMP-12, MMP-13, PDGF-AA, PDGF-BB, S100A9, and TIMP-1 levels and compared to healthy controls.

RESULTS

After AHSCT, SSc patients showed clinical improvement in skin involvement, assessed by modified Rodnan's skin score (mRSS). Histologically, collagen density and skin thickness decreased after AHSCT. Immunohistochemical analyses showed increased expression of MMP-2, MMP-3, MMP-9, and TIMP-1 after AHSCT, whereas expression of NF-κB p65 decreased. At baseline, serum levels of COL4A1 and S100A9 were higher than in healthy controls. Serum levels of S100A9 normalized after AHCST in SSc patients compared to controls. Serum levels of PDGF-AA, PDGF-BB, TIMP-1, and MMP-1 decreased, while COL1A1 increased after AHSCT in SSc patients. No changes were detected in MMP-3, MMP-12, MMP-13, and FGF-1 serum levels after AHSCT.

CONCLUSIONS

Our results suggest that the therapeutic effects of AHSCT on skin fibrosis are related to changes in molecules associated with connective tissue maintenance and inflammation in SSc.

Multiscale Characterization of Type I Collagen Fibril Stress–Strain Behavior under Tensile Load: Analytical vs. MD Approaches

Type I collagen is one of the most important proteins in the human body because of its role in providing structural support to the extracellular matrix of the connective tissues. Understanding its mechanical properties was widely investigated using experimental testing as well as molecular and finite element simulations. In this work, we present a new approach for defining the properties of the type I collagen fibrils by analytically formulating its response when subjected to a tensile load and investigating the effects of enzymatic crosslinks on the behavioral response. We reveal some of the shortcomings of the molecular dynamics (MD) method and how they affect the obtained stress–strain behavior of the fibril, and we prove that not only does MD underestimate the Young’s modulus and the ultimate tensile strength of the collagen fibrils, but also fails to detect the mechanics of some stretching phases of the fibril. We prove that non-crosslinked fibrils have three tension phases: (i) an initial elastic deformation corresponding to the collagen molecule uncoiling, (ii) a linear regime related to the stretching of the backbone of the tropocollagen molecules, and (iii) a plastic regime dominated by molecular sliding. We also show that for crosslinked fibrils, the second regime can be subdivided into three sub-regimes, and we define the properties of each regime. We also prove, analytically, the alleged MD quadratic relation between the ultimate tensile strength of the fibril and the concentration of enzymatic crosslinks (β).

Identification and In Silico Characterization of a Novel COLGALT2 Gene Variant in a Child with Mucosal Rectal Prolapse

Rectal prolapse is influenced by many factors including connective tissue dysfunction. Currently, there is no data about genetic contribution in the etiology of this disorder. In this study, we performed trio whole-exome sequencing in an 11-year-old girl with mucosal rectal prolapse and her parents and sibling. Genetic testing revealed a novel heterozygous missense variant c.1406G>T; p.G469V in exon 11 of the COLGALT2 gene encoding the GLT25 D2 enzyme. Sanger sequencing confirmed this variant only in the patient while the mother, father and sister showed a wild-type sequence. The pathogenicity of the novel variant was predicted using 10 different in silico tools that classified it as pathogenic. Further, in silico prediction, according to Phyre2, Project HOPE, I-Mutant3.0 and MutPred2 showed that the missense variant can decrease protein stability and cause alterations in the physical properties of amino acids resulting in structural and functional changes of the GLT25D2 protein. In conclusion, the present study identifies a previously unknown missense mutation in the COLGALT2 gene that encodes the enzyme involved in collagen glycosylation. The clinical features observed in the patient and the results of in silico analysis suggest that the new genetic variant can be pathogenic.

CelLock TM: an innovative standardized cell-block preparation procedure

The CelLock™ procedure kit is used to collect and prepare cellular specimens such as fine needle aspirates (FNA), cytology specimens, cultured cells, small tissue biopsies, and samples with scant tissue fragments or cells into a paraffin cell-block. This cell-block can be used for subsequent microtomy and staining using hematoxylin and eosin (H&E), special stains, immunohistochemistry (IHC), and applicable molecular techniques such as in situ hybridization (ISH). CelLock is a standardized method that provides optimal receipt, preservation, preparation, and processing of cell-blocks which, contain virtually all of the submitted specimens and are able to be embedded and sectioned in a reproducible fashion. The specimen contained within the cell-block is preserved such that all the cellular protein and genetic information is available for histological and ancillary testing.

Coaxial structured drug loaded dressing combined with induced stem cell differentiation for enhanced wound healing

Controllable drug-loaded dressings combined with induced stem cell differentiation have received considerable interest. In this study, a directional core-shell drug-loaded magnetocaloric response PCL/Gelatin-Antibiotics/Fe₃O₄ multifunctional dressing was developed. Due to the magnetothermal heating effect of magnetic nanoparticles and the contraction of elastic electrospun fibers, the fibers release antibiotics as needed to prevent drug-resistant infection. IV collagenase catalyzes the degradation of gelatin by achieving an optimum reaction temperature, the purpose of which is also to reduce the viscosity of liquid gelatin and promote the release of drugs. With the sacrifice of gelatin, the directional structure of scaffold and the internal steric hindrance promoted stem cell differentiation and wound healing. The expression of Vimentin, VEGF, bFGF, TGF-β, and THY1 was confirmed by fluorescence immunostaining and RT-PCR. Western blot was used to detect expression of Vimentin, collagen, CD34, and CD31 in the (5/5, v/v) PCL/gelatin scaffold incubated with mouse wound. Therefore, the functional fibers can significantly accelerate the healing process.

Potential of Biofermentative Unsulfated Chondroitin and Hyaluronic Acid in Dermal Repair

Chondroitin obtained through biotechnological processes (BC) shares similarities with both chondroitin sulfate (CS), due to the dimeric repetitive unit, and hyaluronic acid (HA), as it is unsulfated. In the framework of this experimental research, formulations containing BC with an average molecular size of about 35 KDa and high molecular weight HA (HHA) were characterized with respect to their rheological behavior, stability to enzymatic hydrolysis and they were evaluated in different skin damage models. The rheological characterization of the HHA/BC formulation revealed a G’ of 92 ± 3 Pa and a G″ of 116 ± 5 Pa and supported an easy injectability even at a concentration of 40 mg/mL. HA/BC preserved the HHA fraction better than HHA alone. BTH was active on BC alone only at high concentration. Assays on scratched keratinocytes (HaCaT) monolayers showed that all the glycosaminoglycan formulations accelerated cell migration, with HA/BC fastening healing 2-fold compared to the control. In addition, in 2D HaCaT cultures, as well as in a 3D skin tissue model HHA/BC efficiently modulated mRNA and protein levels of different types of collagens and elastin remarking a functional tissue physiology. Finally, immortalized human fibroblasts were challenged with TNF-α to obtain an in vitro model of inflammation. Upon HHA/BC addition, secreted IL-6 level was lower and efficient ECM biosynthesis was re-established. Finally, co-cultures of HaCaT and melanocytes were established, showing the ability of HHA/BC to modulate melanin release, suggesting a possible effect of this specific formulation on the reduction of stretch marks. Overall, besides demonstrating the safety of BC, the present study highlights the potential beneficial effect of HHA/BC formulation in different damage dermal models.

Multiscale modelling of the extracellular matrix

The extracellular matrix is a complex three-dimensional network of molecules that provides cells with a complex microenvironment. The major constituents of the extracellular matrix such as collagen, elastin and associated proteins form supramolecular assemblies contributing to its physicochemical properties and organization. The structure of proteins and their supramolecular assemblies such as fibrils have been studied at the atomic level (e.g., by X-ray crystallography, Nuclear Magnetic Resonance and cryo-Electron Microscopy) or at the microscopic scale. However, many protein complexes are too large to be studied at the atomic level and too small to be studied by microscopy. Most extracellular matrix components fall into this intermediate scale, so-called the mesoscopic scale, preventing their detailed characterization. Simulation and modelling are some of the few powerful and promising approaches that can deepen our understanding of mesoscale systems. We have developed a set of modelling tools to study the self-organization of the extracellular matrix and large motion of macromolecules at the mesoscale level by taking advantage of the dynamics of articulated rigid bodies as a mean to study a larger range of motions at the cost of atomic resolution.

Computational insights into the formation and nature of the sulfilimine bond in collagen-IV

Collagen IV is essential component of basement membrane in the tissues. It provides proper cellular structure by the formation of sulfilimine bond (S Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> N) between methionine and lysine or hydroxylysine (cross-links) residues which can be formed with or without post-translational modification. The sulfilimine bond has critical roles in tissue development and human diseases. Peroxidasin, a basement membrane peroxidase, generates reactive halogen species including hypobromous (HOBr) acid and hypochlorous (HOCl) acid which help to form halosulfonium or haloamine. The sulfilamine bond can be formed either by the formation of halosulfonium or by the formation of halomine. The aim of the study is the investigation of the formation of sulfilimine bond and its nature in collagen IV using multi-scale approach that included MD, QM-cluster, systematic series of small models, and NBO analysis. These results suggest that sulfilimine bond can be formed either via brominated/chlorinated halosulfonium or haloamine pathway. The results of systematic series of small model indicate that the formation of sulfilimine complex from halosulfonium happens through the formation of positively charged halosulfonated sulfilimine complex. It also suggests that the formation of sulfilimine complex from haloamine occurs through the formation of positively charged sulfilimine complex where the S and N bond forms and halogen goes off at the same time. Furthermore, the NBO analysis suggest the S and N bond is strongly polarized toward nitrogen in both single protonated and neutral system, N^δ− ← S^δ+ and also indicate the existence of a coordinate covalent (i.e. dative) bond.

The proposed mechanisms for formation of the sulfilimine bond in collagen IV, and effects of protonation on the nature and properties of the bond have been computationally examined.

Screening of Self-Assembling of Collagen IV Fragments into Stable Structures Potentially Useful in Regenerative Medicine

The aim of the research was to check whether it is possible to use fragments of type IV collagen to obtain, as a result of self-assembling, stable spatial structures that could be used to prepare new materials useful in regenerative medicine. Collagen IV fragments were obtained by using DMT/NMM/TosO- as a coupling reagent. The ability to self-organize and form stable spatial structures was tested by the CD method and microscopic techniques. Biological studies covered: resazurin assay (cytotoxicity assessment) on BJ, BJ-5TA and C2C12 cell lines; an alkaline version of the comet assay (genotoxicity), Biolegend Legendplex human inflammation panel 1 assay (SC cell lines, assessment of the inflammation activity) and MTT test to determine the cytotoxicity of the porous materials based on collagen IV fragments. It was found that out of the pool of 37 fragments (peptides 1-33 and 2.1-2.4) reconstructing the outer sphere of collagen IV, nine fragments (peptides: 2, 4, 5, 6, 14, 15, 25, 26 and 30), as a result of self-assembling, form structures mimicking the structure of the triple helix of native collagens. The stability of spatial structures formed as a result of self-organization at temperatures of 4 °C, 20 °C, and 40 °C was found. The application of the MST method allowed us to determine the Kd of binding of selected fragments of collagen IV to ITGα1β1. The stability of the spatial structures of selected peptides made it possible to obtain porous materials based on their equimolar mixture. The formation of the porous materials was found for cross-linked structures and the material stabilized only by weak interactions. All tested peptides are non-cytotoxic against all tested cell lines. Selected peptides also showed no genotoxicity and no induction of immune system responses. Research on the use of porous materials based on fragments of type IV collagen, able to form stable spatial structures as scaffolds useful in regenerative medicine, will be continued.

Olive leaf-derived PPAR agonist complex induces collagen IV synthesis in human skin models

INTRODUCTION

Peroxisome proliferator-activated receptor (PPAR) agonists are known to modulate the synthesis of dermal lipids and proteins including collagens. Olive (Olea europaea) leaves have been reported to contain PPAR-binding ligands. Collagen IV, a major dermal-epidermal junction (DEJ) protein, degrades with both age and disease. Here, we report the formulation of a novel multi-ligand complex, Linefade, and its effects on collagen IV synthesis.

METHODS

Linefade prepared from the leaves of Olea europaea contains 2% w/w plant extract solids dissolved in a mixture of glyceryl monoricinoleate and dimethyl isosorbide. In silico docking was performed with PPAR-α (PDB ID: 2P54). Linefade was evaluated for PPAR-α-dependent transcription in a luciferase reporter assay system. Cell viability and collagen IV levels in human dermal fibroblast cultures were measured using the MTT method and ELISA assay, respectively. Transcriptome analysis was conducted on a full-thickness reconstituted human skin (EpiDermFT) model. Ex vivo cell viability and collagen IV immunostaining were performed on human skin explants.

RESULTS

In silico docking model of the major constituents (oleanolic acid and glyceryl monoricinoleate) produced a co-binding affinity of -6.7 Kcal/mole. Linefade significantly increased PPAR-α transcriptional activity in CHO cells and collagen IV synthesis in adult human dermal fibroblasts. Transcriptome analysis revealed that 1% Linefade modulated the expression of 280 genes with some related to epidermal differentiation, DEJ, PPAR, Nrf2 and retinoid pathways. An ex vivo human explant study showed that 1% Linefade, delivered via a triglycerides excipient, increased collagen IV levels along the dermal-epidermal junction by 52%.

CONCLUSION

In silico modelling and in vitro and ex vivo analyses confirmed Linefade-mediated activation of PPAR-α and stimulation of collagen IV synthesis.

Suppression of collagen IV alpha-2 subunit by prolyl hydroxylase domain inhibition via hypoxia-inducible factor-1 in chronic kidney disease

Elevation of hypoxia-inducible factor 1 protein has been shown to be protective in acute kidney injury and HIF1α enhancing drug therapies are currently in clinical trials for the treatment of anemia of chronic kidney disease. Despite its benefits, long-term HIF1 elevation seems to be associated with additional effects in the kidneys such as tubulointerstitial fibrosis. To better understand the effects of prolonged HIF1 exposure, assessment of baseline and post-therapy levels of HIF1α and other related biomarkers is essential. In this study, we assessed the effect of HIF1α enhancement using prolyl hydroxylase inhibitor (PHD-I) DMOG, on a key profibrotic marker of kidney disease. In specific, we examined the change in expression of Collagen 4 subunit A2 in cultured urinary cells of CKD patients pre and post 24-hour exposure to 1mM DMOG. Our results show that besides HIF1α enhancement, COL4A2 protein is suppressed in presence of DMOG. To determine if this effect is mediated by HIF1, we used HIF1α gene silencing in HEK293 cells and examined the effect of DMOG on protein and gene expression of COL4A2 post 24-hour exposure. We showed that silencing HIF1α reverses and amplifies the expression of COL4A2 in HEK293 cells. Our data suggest that HIF1 directly regulates the expression of COL4A2 in kidney cells and that HIF1α enhancing therapy has suppressive effects on COL4A2 that may be clinically relevant and must be considered in determining the safety and efficacy of these drugs in the treatment of anemia.

A combined physicochemical approach towards human tenocyte phenotype maintenance

During in vitro culture, bereft of their optimal tissue context, tenocytes lose their phenotype and function. Considering that tenocytes in their native tissue milieu are exposed simultaneously to manifold signals, combination approaches (e.g. growth factor supplementation and mechanical stimulation) are continuously gaining pace to control cell fate during in vitro expansion, albeit with limited success due to the literally infinite number of possible permutations. In this work, we assessed the potential of scalable and potent physicochemical approaches that control cell fate (substrate stiffness, anisotropic surface topography, collagen type I coating) and enhance extracellular matrix deposition (macromolecular crowding) in maintaining human tenocyte phenotype in culture. Cell morphology was primarily responsive to surface topography. The tissue culture plastic induced the largest nuclei area, the lowest aspect ratio, and the highest focal adhesion kinase. Collagen type I coating increased cell number and metabolic activity. Cell viability was not affected by any of the variables assessed. Macromolecular crowding intensely enhanced and accelerated native extracellular matrix deposition, albeit not in an aligned fashion, even on the grooved substrates. Gene analysis at day 14 revealed that the 130 kPa grooved substrate without collagen type I coating and under macromolecular crowding conditions positively regulated human tenocyte phenotype. Collectively, this work illustrates the beneficial effects of combined physicochemical approaches in controlling cell fate during in vitro expansion.

Involvement of COL5A2 and TGF-β1 in pathological scarring

Dysregulation in the cutaneous wound-healing process is a consequence of alterations in the efficiency and activity of the various components involved in the healing process. This dysregulation may result in various clinical appearances of a lesion, such as skin ulcers, keloids, hypertrophic and atrophic scars. The collagen type V alpha 2 (COL5A2) gene provides a template for a component of type V collagen, found primarily within the skin basement membrane. Transforming growth factor (TGF)-β is involved in inflammation, angiogenesis, proliferation of fibroblasts, collagen synthesis and extracellular matrix remodeling. Hypertrophic scar fibroblasts possess a disrupted expression pattern of the TGF-β signaling compared to normal healing, while an increased TGF-β signaling reduces the epidermal proliferation rate, triggering atrophic scarring. In the present study, 71 female patients who had undergone planned Caesarean section, without postoperative complications, were examined. These patients were clinically and molecularly evaluated after developing scars in order to determine the role of TGF-β1 (rs201700967 and rs200230083) and COL5A2 (rs369072636) in pathological scarring. Clinical scar evaluation was carried out using SCAR and POSAS scales and genotyping was performed by RT-PCR. No statistical differences were found between the subgroups regarding the genotype and the pathological scarring, since all the patients included were wild-type allele carriers. Further investigations and a more representative study group may highlight the involvement of COL5A2 and TGF-β1 single nucleotide variants in pathological scarring.

Single Dose of N-Acetylcysteine in Local Anesthesia Increases Expression of HIF1α, MAPK1, TGFβ1 and Growth Factors in Rat Wound Healing

In this study, we aimed to investigate the influence of N-acetylcysteine (NAC) on the gene expression profile, neoangiogenesis, neutrophils and macrophages in a rat model of incisional wounds. Before creating wounds on the backs of 24 Sprague-Dawley rats, intradermal injections were made. Lidocaine-epinephrin solutions were supplemented with 0.015%, 0.03% or 0.045% solutions of NAC, or nothing (control group). Scars were harvested on the 3rd, 7th, 14th and 60th day post-surgery. We performed immunohistochemical staining in order to visualize macrophages (anti-CD68), neutrophils (anti-MPO) and newly formed blood vessels (anti-CD31). Additionally, RT-qPCR was used to measure the relative expression of 88 genes involved in the wound healing process. On the 14th day, the number of cells stained with anti-CD68 and anti-CD31 antibodies was significantly larger in the tissues treated with 0.03% NAC compared with the control. Among the selected genes, 52 were upregulated and six were downregulated at different time points. Interestingly, NAC exerted a significant effect on the expression of 45 genes 60 days after its administration. In summation, a 0.03% NAC addition to the pre-incisional anesthetic solution improves neovasculature and increases the macrophages' concentration at the wound site on the 14th day, as well as altering the expression of numerous genes that are responsible for the regenerative processes.

Regenerative Effects of Hypoxia Primed Flowable Placental Formulation in Muscle and Dermal Injury

The placental tissue, due to its angiogenic, anti-inflammatory, antioxidative, antimicrobial, and anti-fibrotic properties, has become a compelling source towards a solution for several indications in regenerative medicine. However, methods to enhance and capture the therapeutic properties with formulations that can further the applications of viable placental tissue have not been explored. In this study, we investigated the regenerative effects of a hypoxia primed flowable placental formulation (FPF), composed of amnion/chorion and umbilical tissue, in two in vivo injury models. Laser Doppler data from rodent ischemia hindlimbs treated with FPF revealed significant tissue perfusion improvements compared to control ischemic hindlimbs. To further corroborate FPF's effects, we used a rodent ischemic bipedicle skin flap wound model. FPF treatment significantly increased the rate of wound closure and the quality of wound healing. FPF-treated wounds displayed reduced inflammation and an increase in angiogenesis. Furthermore, quantitative PCR and next-generation sequencing analysis confirmed these changes in the FPF-treated group at both the gene and transcriptional level. The observed modulation in miRNAs was associated with angiogenesis, regulation of inflammatory microenvironment, cell migration and apoptosis, reactive oxygen species generation, and restoring epithelial barrier function, all processes involved in impaired tissue healing. Taken together, these data validate the tissue regenerative properties of the flowable placental formulation configuration tested.

Identification of potential hub genes associated with skin wound healing based on time course bioinformatic analyses

Background

The skin is the largest organ of the body and has multiple functions. Wounds remain a significant healthcare problem due to the large number of traumatic and pathophysiological conditions patients suffer.

Methods

Gene expression profiles of 37 biopsies collected from patients undergoing split-thickness skin grafts at five different time points were downloaded from two datasets (GSE28914 and GSE50425) in the Gene Expression Omnibus (GEO) database. Principal component analysis (PCA) was applied to classify samples into different phases. Subsequently, differentially expressed genes (DEGs) analysis, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway functional enrichment analyses were performed, and protein–protein interaction (PPI) networks created for each phase. Furthermore, based on the results of the PPI, hub genes in each phase were identified by molecular complex detection combined with the ClueGO algorithm.

Results

Using principal component analysis, the collected samples were divided into four phases, namely intact phase, acute wound phase, inflammatory and proliferation phase, and remodeling phase. Intact samples were used as control group. In the acute wound phase, a total of 1 upregulated and 100 downregulated DEGs were identified. Tyrosinase (TYR), tyrosinase Related Protein 1 (TYRP1) and dopachrome tautomerase (DCT) were considered as hub genes and enriched in tyrosine metabolism which dominate the process of melanogenesis. In the inflammatory and proliferation phase, a total of 85 upregulated and 164 downregulated DEGs were identified. CHEK1, CCNB1 and CDK1 were considered as hub genes and enriched in cell cycle and P53 signaling pathway. In the remodeling phase, a total of 121 upregulated and 49 downregulated DEGs were identified. COL4A1, COL4A2, and COL6A1 were considered as hub genes and enriched in protein digestion and absorption, and ECM-receptor interaction.

Conclusion

This comprehensive bioinformatic re-analysis of GEO data provides new insights into the molecular pathogenesis of wound healing and the potential identification of therapeutic targets for the treatment of wounds.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12893-021-01298-w.

Hyaluronic Acid as Macromolecular Crowder in Equine Adipose-Derived Stem Cell Cultures

The use of macromolecular crowding in the development of extracellular matrix-rich cell-assembled tissue equivalents is continuously gaining pace in regenerative engineering. Despite the significant advancements in the field, the optimal macromolecular crowder still remains elusive. Herein, the physicochemical properties of different concentrations of different molecular weights hyaluronic acid (HA) and their influence on equine adipose-derived stem cell cultures were assessed. Within the different concentrations and molecular weight HAs, the 10 mg/mL 100 kDa and 500 kDa HAs exhibited the highest negative charge and hydrodynamic radius, and the 10 mg/mL 100 kDa HA exhibited the lowest polydispersity index and the highest % fraction volume occupancy. Although HA had the potential to act as a macromolecular crowding agent, it did not outperform carrageenan and Ficoll®, the most widely used macromolecular crowding molecules, in enhanced and accelerated collagen I, collagen III and collagen IV deposition.