Collagens--structure, function, and biosynthesis

Preparation and characterization of a novel humanized collagen III with repeated fragments of Gly300-Asp329

Recombinant human collagens have attracted intensive interest in the past two decades, demonstrating considerable potential in medicine, tissue engineering, and cosmetics. Several humanized recombinant collagens have been produced, exhibiting similar characteristics as the native species. To get insight into the structural and bioactive properties of different parts of collagen, in this study, the segment of Gly300-Asp329 of type III collagen was first adopted and repeated 18 times to prepare a novel recombinant collagen (named rhCLA). RhCLA was successfully expressed in E. coli, and a convenient separation procedure was established through reasonably combining alkaline precipitation and acid precipitation, yielding crude rhCLA with a purity exceeding 90%. Additionally, a polishing purification step utilizing cation exchange chromatography was developed, achieving rhCLA purity surpassing 98% and an overall recovery of approximately 120 mg/L culture. Simultaneously, the contents of endotoxin, nucleic acids, and host proteins were reduced to extremely low levels. This fragmented type III collagen displayed a triple-helical structure and gel-forming capability at low temperatures. Distinct fibrous morphology was also observed through TEM analysis. In cell experiments, rhCLA exhibited excellent biocompatibility and cell adhesion properties. These results provide valuable insights for functional studies of type III collagen and a reference approach for the large-scale production of recombinant collagens.

A comprehensive guide to western blotting for tendon research

Tendons are classified as dense fibrous connective tissue. This fibrous composition poses challenges in protein extraction, particularly hindering the application of Western blotting techniques. Because of these challenges, it becomes necessary to implement additional steps and specific solutions to attain success in this methodology with the tissue in question. The objective of this article is to provide a detailed protocol, elucidating each step, and making it easily replicable for researchers. The study focused on the Achilles tendons of Sprague-Dawley rats, emphasizing the need for a tailored approach in working with this tissue. By addressing the nuances of protein extraction from the dense and fibrous tendons, our protocol aims to facilitate the reproducibility of Western blotting experiments, contributing to a better understanding of this tissue.

[Efficacy and safety of undenatured type II collagen in patients with knee osteoarthritis: a multicenter, prospective, double-blind, placebo-controlled, randomized trial]

BACKGROUND

Non-pharmacological treatments based on collagen as a dietary supplement are emerging as a new area of interest to support preventive or therapeutic effects in patients with osteoarthritis (OA).

AIM

In a multicenter, prospective, double-blind, placebo-controlled, randomized study, to evaluate the effectiveness and safety of the use of the Artneo complex containing undenatured chicken collagen type II in patients with OA of the knee joints.

MATERIALS AND METHODS

The study enrolled 212 outpatients from 12 centers in the Russian Federation with knee OA, stages II and III according to the Kellgren-Lawrence classification. The participants included 171 women (80.7%) and 41 men (19.3%), with an average age of 60.2±9.0 years (range: 40 to 75 years). The study population was randomly allocated in equal proportions into two groups using an interactive web response system (IWRS). Group 1 (Artneo) consisted of 106 patients who took one capsule of the drug once daily for 180 days. Group 2 (Placebo) also had 106 patients, with the dosage form and regimen identical to Group 1. During the treatment period, the following outcomes were assessed: WOMAC index, KOOS, pain according to VAS, quality of life using the EQ-5D questionnaire, and the need for NSAIDs. All patients underwent a clinical blood test, general urine analysis, biochemical blood test, and ultrasound examination of the affected knee joint.

RESULTS

In a prospective, double-blind, placebo-controlled, randomized study, it was demonstrated that the Artneo combination, containing undenatured chicken collagen type II, has a positive effect on all clinical manifestations of OA: it effectively reduces pain, stiffness, and improves the functional state of joints and quality of life. It has a good safety profile and is superior to placebo in all parameters studied.

CONCLUSION

The results of the study confirm the good effectiveness and safety of the Artneo combination in patients with OA of the knee joints.

Simultaneous fingerprinting of multiplex collagen biomarkers in connective tissues by multicolor quantum dots-based peptide probes

The accurate detection of multiplex collagen biomarkers is vital for diagnosing and treating various critical diseases such as tumors and fibrosis. Despite the attractive optical properties of quantum dots (QDs), it remains technically challenging to create stable and specific QDs-based probes for multiplex biological imaging. We report for the first time the construction of multi-color QDs-based peptide probes for the simultaneous fingerprinting of multiplex collagen biomarkers in connective tissues. A bipeptide system composed of a glutathione (GSH) host peptide and a collagen-targeting guest peptide (CTP) has been developed, yielding CTP-QDs probes that exhibit exceptional luminescence stability when exposed to ultraviolet irradiation and mildly acidic conditions. The versatile bipeptide system allows for facile one-pot synthesis of high-quality multicolor CTP-QDs probes, exhibiting superior selectivity in targeting critical collagen biomarkers including denatured collagen, type I collagen, type II collagen, and type IV collagen. The multicolor CTP-QDs probes have demonstrated remarkable efficacy in simultaneously fingerprinting multiple collagen types in diverse connective tissues, irrespective of their status, whether affected by injury, diseases, or undergoing remodeling processes. The innovative multicolor CTP-QDs probes offer a robust toolkit for the multiplex fingerprinting of the collagen suprafamily, demonstrating significant potential in the diagnosis and treatment of collagen-related diseases.

Research progress of photo-crosslink hydrogels in ophthalmology: A comprehensive review focus on the applications

Hydrogel presents a three-dimensional polymer network with high water content. Over the past decade, hydrogel has developed from static material to intelligent material with controllable response. Various stimuli are involved in the formation of hydrogel network, among which photo-stimulation has attracted wide attention due to the advantages of controllable conditions, which has a good application prospect in the treatment of ophthalmic diseases. This paper reviews the application of photo-crosslink hydrogels in ophthalmology, focusing on the types of photo-crosslink hydrogels and their applications in ophthalmology, including drug delivery, tissue engineering and 3D printing. In addition, the limitations and future prospects of photo-crosslink hydrogels are also provided.

Catalytically Active Carbon for Oxygen Reduction Reaction in Energy Conversion: Recent Advances and Future Perspectives

The shortage and unevenness of fossil energy sources are affecting the development and progress of human civilization. The technology of efficiently converting material resources into energy for utilization and storage is attracting the attention of researchers. Environmentally friendly biomass materials are a treasure to drive the development of new-generation energy sources. Electrochemical theory is used to efficiently convert the chemical energy of chemical substances into electrical energy. In recent years, significant progress has been made in the development of green and economical electrocatalysts for oxygen reduction reaction (ORR). Although many reviews have been reported around the application of biomass-derived catalytically active carbon (CAC) catalysts in ORR, these reviews have only selected a single/partial topic (including synthesis and preparation of catalysts from different sources, structural optimization, or performance enhancement methods based on CAC catalysts, and application of biomass-derived CACs) for discussion. There is no review that systematically addresses the latest progress in the synthesis, performance enhancement, and applications related to biomass-derived CAC-based oxygen reduction electrocatalysts synchronously. This review fills the gap by providing a timely and comprehensive review and summary from the following sections: the exposition of the basic catalytic principles of ORR, the summary of the chemical composition and structural properties of various types of biomass, the analysis of traditional and the latest popular biomass-derived CAC synthesis methods and optimization strategies, and the summary of the practical applications of biomass-derived CAC-based oxidative reduction electrocatalysts. This review provides a comprehensive summary of the latest advances to provide research directions and design ideas for the development of catalyst synthesis/optimization and contributes to the industrialization of biomass-derived CAC electrocatalysis and electric energy storage.

Histological and molecular difference in albumen quality between post-adolescent hens and aged hens

The decline in albumen quality resulting from aging hens poses a threat to the financial benefits of the egg industry. Exploring the underlying mechanisms from the perspective of cell molecules of albumen formation is significant for the efficient regulation of albumen quality. Two individual groups of Hy-Line Brown layers with ages of 40 (W40) and 100 (W100) wk old were used in the present study. Each group contained over 2,000 birds. This study assessed the egg quality, biochemical indicators and physiological status of hens between W40 and W100. Subsequently, a quantitative proteomic analysis was conducted to identify differences in protein abundance in magnum tissues between W40 and W100. In the W40 group, significant increases (P < 0.05) were notable for albumen quality (thick albumen solid content, albumen height, Haugh unit), serum indices (calcium, estrogen, and progesterone levels), magnum histomorphology (myosin light-chain kinase content, secretory capacity, mucosal fold, goblet cell count and proportion) as well as the total antioxidant capacity of the liver. However, the luminal diameter of the magnum, albumen gel properties and random coil of the albumen were increased (P < 0.05) in the W100 group. The activity of glutathione, superoxidase dismutase, and malondialdehyde in the liver, magnum, and serum did not vary (P > 0.05) among the groups. Proteomic analysis revealed the identification of 118 differentially expressed proteins between the groups, which comprised proteins associated with protein secretion, DNA damage and repair, cell proliferation, growth, antioxidants, and apoptosis. Furthermore, Kyoto Encyclopedia of Genes pathway analysis revealed that BRCA2 and FBN1 were significantly downregulated in Fanconi anemia (FA) and TGF-β signaling pathways in W100, validated through quantitative real-time PCR (qRT-PCR). In conclusion, significant age-related variations in albumen quality, and magnum morphology are regulated by proteins involved in antioxidant capacity.

The action of microbial collagenases in dentinal matrix degradation in root caries and potential strategies for its management: a comprehensive state-of-the-art review

Conventional views associate microbial biofilm with demineralization in root caries (RC) onset, while research on their collagenases role in the breakdown of collagen matrix has been sporadically developed, primarily in vitro. Recent discoveries, however, reveal proteolytic bacteria enrichment, specially Porphyromonas and other periodontitis-associated bacteria in subgingivally extended lesions, suggesting a potential role in RC by the catabolism of dentin organic matrix. Moreover, genes encoding proteases and bacterial collagenases, including the U32 family collagenases, were found to be overexpressed in both coronal and root dentinal caries. Despite these advancements, to prove microbial collagenolytic proteases' definitive role in RC remains a significant challenge. A more thorough investigation is warranted to explore the potential of anti-collagenolytic agents in modulating biofilm metabolic processes or inhibiting/reducing the size of RC lesions. Prospective treatments targeting collagenases and promoting biomodification through collagen fibril cross-linking show promise for RC prevention and management. However, these studies are currently in the in vitro phase, necessitating additional research to translate findings into clinical applications. This is a comprehensive state-of-the-art review aimed to explore contributing factors to the formation of RC lesions, particularly focusing on collagen degradation in root tissues by microbial collagenases.

Endotrophin, a Key Marker and Driver for Fibroinflammatory Disease

Our overview covers several key areas related to recent results obtained for collagen type VI and endotrophin (ETP). (1) An introduction to the history of ETP, including how it was identified, how it is released, and its function and potential receptors. (2) An introduction to the collagen family, with a focus on what differentiates collagen type VI from an evolutionary standpoint. (3) An overview of collagen type VI, the 6 individual chains (COL6A1, A2, A3, A4, A5, and A6), their differences and similarities, as well as their expression profiles and function. (4) A detailed analysis of COL6A3, including the cleaved product endotrophin, and what separates it from the other 5 collagen 6 molecules, including its suggested function based on insights gained from knockout and gain of function mouse models. (5) The pathology of ETP. What leads to its presence and release and what are the consequences thereof? (6) Functional implications of circulating ETP. Here we review the data with the functional roles of ETP in mind. (7) We propose that ETP is a mediator for fibrotic (or fibroinflammatory) disorders. Based on what we know about ETP, we have to consider it as a target for the treatment of fibrotic (or fibroinflammatory) disorders. What segment(s) of the patient population would most dramatically respond to an ETP-targeted intervention? How can we find the population that would profit most from an intervention? We aim to present a broad overview over the ETP field at large, providing an assessment of where the future research efforts need to be placed to tap into the vast potential of ETP, both as a marker and as a target in different diseases.

Engineering Cell Instructive Microenvironments for In Vitro Replication of Functional Barrier Organs

Multicellular organisms exhibit synergistic effects among their components, giving rise to emergent properties crucial for their genesis and overall functionality and survival. Morphogenesis involves and relies upon intricate and biunivocal interactions among cells and their environment, that is, the extracellular matrix (ECM). Cells secrete their own ECM, which in turn, regulates their morphogenetic program by controlling time and space presentation of matricellular signals. The ECM, once considered passive, is now recognized as an informative space where both biochemical and biophysical signals are tightly orchestrated. Replicating this sophisticated and highly interconnected informative media in a synthetic scaffold for tissue engineering is unattainable with current technology and this limits the capability to engineer functional human organs in vitro and in vivo. This review explores current limitations to in vitro organ morphogenesis, emphasizing the interplay of gene regulatory networks, mechanical factors, and tissue microenvironment cues. In vitro efforts to replicate biological processes for barrier organs such as the lung and intestine, are examined. The importance of maintaining cells within their native microenvironmental context is highlighted to accurately replicate organ-specific properties. The review underscores the necessity for microphysiological systems that faithfully reproduce cell-native interactions, for advancing the understanding of developmental disorders and disease progression.

Unveiling Collagen's Role in Breast Cancer: Insights into Expression Patterns, Functions and Clinical Implications

Collagen, the predominant protein constituent of the mammalian extracellular matrix (ECM), comprises a diverse family of 28 members (I-XXVIII). Beyond its structural significance, collagen is implicated in various diseases or cancers, notably breast cancer, where it influences crucial cellular processes including proliferation, metastasis, apoptosis, and drug resistance, intricately shaping cancer progression and prognosis. In breast cancer, distinct collagens exhibit differential expression profiles, with some showing heightened or diminished levels in cancerous tissues or cells compared to normal counterparts, suggesting specific and pivotal biological functions. In this review, we meticulously analyze the expression of individual collagen members in breast cancer, utilizing Transcripts Per Million (TPM) data sourced from the GEPIA2 database. Through this analysis, we identify collagens that deviate from normal expression patterns in breast cancer, providing a comprehensive overview of their expression dynamics, functional roles, and underlying mechanisms. Our findings shed light on recent advancements in understanding the intricate interplay between these aberrantly expressed collagens and breast cancer. This exploration aims to offer valuable insights for the identification of potential biomarkers and therapeutic targets, thereby advancing the prospects of more effective interventions in breast cancer treatment.

Prognostic and therapeutic potential of senescent stromal fibroblasts in prostate cancer

The stromal component of the tumour microenvironment in primary and metastatic prostate cancer can influence and promote disease progression. Within the prostatic stroma, fibroblasts are one of the most prevalent cell types associated with precancerous and cancerous lesions; they have a vital role in the structural composition, organization and integrity of the extracellular matrix. Fibroblasts within the tumour microenvironment can undergo cellular senescence, which is a stable arrest of cell growth and a phenomenon that is emerging as a recognized hallmark of cancer. Supporting the idea that cellular senescence has a pro-tumorigenic role, a subset of senescent cells exhibits a senescence-associated secretory phenotype (SASP), which, along with increased inflammation, can promote prostate cancer cell growth and survival. These cellular characteristics make targeting senescent cells and/or modulating SASP attractive as a potential preventive or therapeutic option for prostate cancer.

Collagen/chitosan/genipin hydrogel loaded with phycocyanin nanoparticles and ND-336 for diabetic wound healing

Diabetic wound healing remains a healthcare challenge due to the overexpression of matrix metalloproteinase-9 (MMP-9) and the imbalance between angiogenic factors and vascular inhibitory factors. In this study, we developed a nanocomposite injectable collagen/chitosan hydrogel for the treatment of delayed diabetic wound healing, which can promote cell migration to the wound site (through the addition of phycocyanin) and reduce the expression of MMP-9 (through the use of ND-336) to improve the therapeutic effect of diabetic wound healing. Furthermore, different weight ratios of collagen and chitosan hydrogels were prepared to select the hydrogel with proper mechanical properties. In vitro experiments confirmed that all hydrogels have favorable biocompatibility and hemocompatibility. Notably, Gel 2, with a weight ratio of collagen and chitosan at 25:75, was found to have an excellent capability to facilitate cell migration and in vivo studies further proved that Gel 2 nanocomposite hydrogel had the best ability to improve diabetic wound healing by promoting cell migration and decreasing MMP-9 expression. The collagen/chitosan/genipin hydrogel loaded phycocyanin and ND-336 can be harnessed for non-toxic and efficient treatment of wound healing management of diabetes.

Establishment and validation of an efficient method for the 3D culture of osteoclasts in vitro

INTRODUCTION

Osteoclasts (OCs) play a crucial role in maintaining bone health. Changes in OC activity are linked to different bone diseases, making them an intriguing focus for research. However, most studies on OCs have relied on 2D cultures, limiting our understanding of their behavior. Yet, there's a lack of knowledge regarding platforms that effectively support osteoclast formation in 3D cultures.

METHODS

In our investigation, we explored the capacity of collagen and GelMA hydrogels to facilitate osteoclast development in 3D culture settings. We assessed the osteoclast development by using different hydrogels and cell seeding strategies and optimizing cell seeding density and cytokine concentration. The osteoclast development in 3D cultures was further validated by biochemical assays and immunochemical staining.

RESULTS

Our findings revealed that 0.3 % (w/v) collagen was conducive to osteoclast formation in both 2D and 3D cultures, demonstrated by increased multinucleation and higher TRAP activity compared to 0.6 % collagen and 5 % to 10 % (w/v) GelMA hydrogels. Additionally, we devised a "sandwich" technique using collagen substrates and augmented the initial macrophage seeding density and doubling cytokine concentrations, significantly enhancing the efficiency of OC culture in 3D conditions. Notably, we validated osteoclasts derived from macrophages in our 3D cultures express key osteoclast markers like cathepsin K and TRAP.

CONCLUSIONS

To conclude, our study contributes to establishing an effective method for cultivating osteoclasts in 3D environments in vitro. This innovative approach not only promises a more physiologically relevant platform to study osteoclast behavior during bone remodeling but also holds potential for applications in bone tissue engineering.

CLINICAL SIGNIFICANCE

This study introduces an efficient method for cultivating osteoclasts in 3D environments in vitro. It offers a more physiologically relevant platform to investigate osteoclast behavior and holds promise to advance research in bone biology and regenerative dentistry.

Sex differences in COL1A1 Expression and Collagen Content in Skeletal Muscle of Mature and Juvenile Shamo Chickens

Collagen content is an important parameter affecting meat consistency. Sex differences in collagen were therefore studied in mature and juvenile Shamo chickens. The pectoral (PT), lateral iliotibial (ITL), medial part of puboischiofemoral (PIF), and lateral part of gastrocnemius (GCL) muscles were weighed, and their COL1A1 expression levels and total collagen content were analyzed. Body and muscle weights were significantly higher in males than in females of all ages. Muscle/body weight ratios were also higher in mature males than in females, but this difference was not observed in juveniles. In mature chickens, COL1A1 expression was higher in the PIF and GCL muscles; this was not the case in juvenile chicken muscles. Sex differences in collagen content were observed only in the ITLs of mature chickens. A positive correlation between muscle weight and intramuscular collagen content was found for PT and GCL, but not for ITL and PIF, muscles. These results suggest that the sex difference in intramuscular collagen content only occurs in specific muscles and that COL1A1 expression is not necessarily related to collagen content in mature chickens. Factors that determine the intramuscular collagen content likely differ by muscle type.

Aucubin produces anti-osteoporotic effects under mechanical stretch stress and orthodontic tooth movement

Aucubin (AU), an iridoid glycoside extracted from Eucommia ulmoides, exerts anti-osteoporotic effects by promoting osteogenesis, as reported in previous studies. Here, we investigated the effects of AU under mechanical stretch stress. MC3T3-E1 cells were treated with dexamethasone (DEX) in vitro and subjected to mechanical stretch stress to establish an osteoporotic orthodontic force cell model. AU treatment increased the mRNA and protein expressions of BMP2, OPN, RUNX2, COL-1 and other osteogenic differentiation factors in MC3T3-E1 cells. Furthermore, we established an in vivo orthodontic tooth movement (OTM) model of osteoporosis. Serum parameter detection of ALP concentration, radiography of the femur, hematoxylin-eosin (HE) staining, and micro-CT of the maxilla confirmed that AU could partially reverse the damage induced by DEX. Immunohistochemical (IHC) analysis showed that AU increased the expression of COL-1, OCN, and OPN on the tension side of the periodontium. In conclusion, AU treatment promotes osteogenic differentiation under mechanical stretch stress and positively affects bone remodeling during OTM in DEX-induced osteoporosis.

Understanding the matrix: collagen modifications in tumors and their implications for immunotherapy

Tumors are highly complex and heterogenous ecosystems where malignant cells interact with healthy cells and the surrounding extracellular matrix (ECM). Solid tumors contain large ECM deposits that can constitute up to 60% of the tumor mass. This supports the survival and growth of cancerous cells and plays a critical role in the response to immune therapy. There is untapped potential in targeting the ECM and cell-ECM interactions to improve existing immune therapy and explore novel therapeutic strategies. The most abundant proteins in the ECM are the collagen family. There are 28 different collagen subtypes that can undergo several post-translational modifications (PTMs), which alter both their structure and functionality. Here, we review current knowledge on tumor collagen composition and the consequences of collagen PTMs affecting receptor binding, cell migration and tumor stiffness. Furthermore, we discuss how these alterations impact tumor immune responses and how collagen could be targeted to treat cancer.

A conserved strategy to attack collagen: The activator domain in bacterial collagenases unwinds triple-helical collagen

Bacterial collagenases are important virulence factors, secreted by several pathogenic Clostridium, Bacillus, Spirochaetes, and Vibrio species. Yet, the mechanism by which these enzymes cleave collagen is not well understood. Based on biochemical and mutational studies we reveal that collagenase G (ColG) from Hathewaya histolytica recognizes and processes collagen substrates differently depending on their nature (fibrillar vs. soluble collagen); distinct dynamic interactions between the activator and peptidase domain are required based on the substrate type. Using biochemical and circular dichroism studies, we identify the presumed noncatalytic activator domain as the single-domain triple helicase that unwinds collagen locally, transiently, and reversibly.

Collagen-polyurethane-dextran hydrogels enhance wound healing by inhibiting inflammation and promoting collagen fibrillogenesis

Diabetic foot ulcers are a serious complication of uncontrolled diabetes, emphasizing the need to develop wound healing strategies that are not only effective but also biocompatible, biodegradable, and safe. We aimed to create biomatrices composed of semi-interpenetrated polymer networks of collagen, polyurethane, and dextran, to enhance the wound healing process. The hydrogels were extensively characterized by various analytical techniques, including analysis of their structure, crystallinity, thermal properties, gelation process, reticulation, degradation, cell proliferation, and healing properties, among others. Semi-interpenetrated hydrogels containing dextran at levels of 10%, 20%, and 30% exhibited porous interconnections between collagen fibers and entrapped dextran granules, with a remarkable crosslinking index of up to 94% promoted by hydrogen bonds. These hydrogels showed significant improvements in mechanical properties, swelling, and resistance to proteolytic and hydrolytic degradation. After 24 h, there was a significant increase in the viability of several cell types, including RAW 264.7 cells, human peripheral blood mononuclear cells, and dermal fibroblasts. In addition, these hydrogels demonstrated an increased release of interleukin-10 and transforming growth factor-beta1 while inhibiting the release of monocyte chemotactic protein-1 and tumor necrosis factor-alpha after 72 h. Furthermore, these hydrogels accelerated the wound healing process in diabetic rats after topical application. Notably, the biomaterial with 20% dextran (D20) facilitated wound closure in only 21 days. These results highlight the potential of the D20 hydrogel, which exhibits physicochemical and biological properties that enhance wound healing by inhibiting inflammation and fibrillogenesis while remaining safe for application to the skin.

Chromatographic separation by RPLC-ESI-MS of all hydroxyproline isomers for the characterization of collagens from different sources

During collagen biosynthesis, proline is post-translationally converted to hydroxyproline by specific enzymes. This amino acid, unique to collagen, plays a crucial role in stabilizing the collagen triple helix structure and could serve as an important biomarker for collagen content and quality analysis. Hydroxyproline has four isomers, depending on whether proline is hydroxylated at position 4 or 3 and on whether the cis- or trans- conformation is formed. Moreover, as extensive hydrolysis of collagen is required for its amino acid analysis, epimerization may also occur, although to a lesser extent, giving a total of eight possible isomers. The aim of the present study was to develop a reversed-phase high-performance liquid chromatography-UV-mass spectrometry (RPLC-UV-MS) method for the separation and quantification of all eight hydroxyproline isomers. After the chiral derivatization of the hydroxyproline isomers with Nα-(2,4-dinitro-5-fluorophenyl)-L-valinamide (L-FDVA), to enable their UV detection, the derivatized diastereoisomers were separated by testing different C18 column technologies and morphologies and optimizing operative conditions such as the mobile phase composition (solvent, additives), elution mode, flow rate and temperature. Baseline resolution of all eight isomers was achieved on a HALO® ES-C18 reversed-phase column (150×1.5 mm, 2.7 μm, 160 Å) using isocratic elution and MS-compatible mobile phase. The optimized method was validated for the quantification of hydroxyproline isomers and then applied to different collagen hydrolysates to gain insight and a deeper understanding of hydroxyproline abundances in different species (human, chicken) and sources (native, recombinant).

Gelatin Methacryloyl (GelMA)-Based Biomaterial Inks: Process Science for 3D/4D Printing and Current Status

Tissue engineering for injured tissue replacement and regeneration has been a subject of investigation over the last 30 years, and there has been considerable interest in using additive manufacturing to achieve these goals. Despite such efforts, many key questions remain unanswered, particularly in the area of biomaterial selection for these applications as well as quantitative understanding of the process science. The strategic utilization of biological macromolecules provides a versatile approach to meet diverse requirements in 3D printing, such as printability, buildability, and biocompatibility. These molecules play a pivotal role in both physical and chemical cross-linking processes throughout the biofabrication, contributing significantly to the overall success of the 3D printing process. Among the several bioprintable materials, gelatin methacryloyl (GelMA) has been widely utilized for diverse tissue engineering applications, with some degree of success. In this context, this review will discuss the key bioengineering approaches to identify the gelation and cross-linking strategies that are appropriate to control the rheology, printability, and buildability of biomaterial inks. This review will focus on the GelMA as the structural (scaffold) biomaterial for different tissues and as a potential carrier vehicle for the transport of living cells as well as their maintenance and viability in the physiological system. Recognizing the importance of printability toward shape fidelity and biophysical properties, a major focus in this review has been to discuss the qualitative and quantitative impact of the key factors, including microrheological, viscoelastic, gelation, shear thinning properties of biomaterial inks, and printing parameters, in particular, reference to 3D extrusion printing of GelMA-based biomaterial inks. Specifically, we emphasize the different possibilities to regulate mechanical, swelling, biodegradation, and cellular functionalities of GelMA-based bio(material) inks, by hybridization techniques, including different synthetic and natural biopolymers, inorganic nanofillers, and microcarriers. At the close, the potential possibility of the integration of experimental data sets and artificial intelligence/machine learning approaches is emphasized to predict the printability, shape fidelity, or biophysical properties of GelMA bio(material) inks for clinically relevant tissues.

Pseudodiproline (Pro-Cyp) Oligomers Fold into Helical Polyproline Type secondary structures

The synthesis and conformational properties of oligo-proline mimetics composed of dimeric and tetrameric Pro-Cyp constructs linked by a hydroxymethylene unit are reported. Oligomers were studied both in the solid state and in solution, unveiling right-handed helical conformation depending on the configuration of the vicinally substituted trans-cyclopentane carboxylic acid unit (Cyp). Unlike polyproline oligomers, the alternating synthetic Pro-Cyp counterparts are not stabilized by n-π* interactions but rely instead on the steric demands of the extended backbone conformation within the hydroxymethylene-linked Pro-Cyp repeating units.

Sea Urchin Food Waste into Bioactives: Collagen and Polyhydroxynaphtoquinones from P. lividus and S. granularis

Approximately 75,000 tons of different sea urchin species are globally harvested for their edible gonads. Applying a circular economy approach, we have recently demonstrated that non-edible parts of the Mediterranean Sea urchin Paracentrotus lividus can be fully valorized into high-value products: antioxidant pigments (polyhydroxynaphthoquinones-PHNQs) and fibrillar collagen can be extracted to produce innovative biomaterials for biomedical applications. Can waste from other edible sea urchin species (e.g., Sphaerechinus granularis) be similarly valorised? A comparative study on PHNQs and collagen extraction was conducted. PHNQ extraction yields were compared, pigments were quantified and identified, and antioxidant activities were assessed (by ABTS assay) and correlated to specific PHNQ presence (i.e., spinochrome E). Similarly, collagen extraction yields were evaluated, and the resulting collagen-based biomaterials were compared in terms of their ultrastructure, degradation kinetics, and resistance to compression. Results showed a partially similar PHNQ profile in both species, with significantly higher yield in P. lividus, while S. granularis exhibited better antioxidant activity. P. lividus samples showed higher collagen extraction yield, but S. granularis scaffolds showed higher stability. In conclusion, waste from different species can be successfully valorised through PHNQ and collagen extraction, offering diverse applications in the biomedical field, according to specific technical requirements.

Multifunctional Injectable Hydrogel Microparticles Loaded with miR-29a Abundant BMSCs Derived Exosomes Enhanced Bone Regeneration by Regulating Osteogenesis and Angiogenesis

The study investigated whether both the osteogenic and angiogenic potential of Exos (Exosomes) can be enhanced by overexpression of exosomal miRNA (microRNA) and to confirm whether Exos loaded in HMPs (Hydrogel microparticles) exert long-term effects during new bone formation. BMSCs and Exos are successfully obtained. In vitro and in vivo experiments confirmed that HDAC4 (Histone deacetylase 4) is inhibited by miR-29a overexpression accompanied by the upregulation of RUNX2 (Runt-related transcription factor 2) and VEGF (Vascular Endothelial Growth Factor), thereby enhancing osteogenic and angiogenic capabilities. The HMP@Exo system is synthesized from HB-PEGDA (Hyperbranched Poly Ethylene Glycol Diacrylate)- and SH-HA (Sulfhydryl-Modified Hyaluronic Acid)-containing Exos using a microfluidic technique. The HMP surface is modified with RGD (Arg-Gly-Asp) peptides to enhance cell adhesion. The system demonstrated good injectability, remarkable compatibility, outstanding cell adhesion properties, and slow degradation capacity, and the sustained release of Agomir-29a-Exos (Exosomes derived from Agomir-29a transfected BMSCs) from HMPs enhanced the proliferation and migration of BMSCs and HUVECs (Human Umbilical Vein Endothelial Cells) while promoting osteogenesis and angiogenesis. Overall, the findings demonstrate that the HMP@Exo system can effectively maintain the activity and half-life of Exos, accompanied by overexpression of miR-29a (microRNA-29a). The injectable system provides an innovative approach for accelerating fracture healing by coupling osteogenesis and angiogenesis.

Morphofunctional and histological patterns of blood vessels in the superficial cervicofacial musculoaponeurotic system in midlateral face regions

OBJECTIVE

The superficial cervicofacial musculoaponeurotic system (SMAS) is a complex network formed by mimic muscles and conjunctive tissue of the superficial fascia of the face.This study aimed to introduce new anatomofunctional data on the importance of the trans-SMAS distribution pattern of the skin microperfusion of the face and to underline the role of SMAS in maintaining the homeostasis of the vascular network that crosses it. Considering the fibrous and muscular matrix of the SMAS, using COLIII and MyoH2 antibodies, together with endothelial immunohistochemistry(IHC)intercellular adhesion molecule 2 marker, we determined the correlation of these structures and their interaction.

METHODS

This study included 33donors of SMAS tissues, which have been stained withregular hematoxylin and eosin (HE), and three different IHC markers have been used (collagen III, muscular tissue, and blood vessels). The samples were collected from parotid, masseteric, jugal, and zygomatic regions. Magnetic resonance angiography was used to identify the main vascular sources of the midlateral regions of the face of another 47 patients.

RESULTS

Significant differences in topographic arrangement, density, and relations of the microsopic vasculature were observed between each of the four regions. Major differences were identified between the role of SMAS in each of these regions, from the parotid capsule to masseteric fascia, transition mobile part, and attaching manners in the zygomatic subunit.

CONCLUSIONS

Blood vessel topography must be related with the surrounding conjunctive and muscular tissue, especially regarding facial SMAS. Intrinsic relations between these three components of the SMAS and nervous fibers can provide us important hints on the functionality of the whole system.

Open-system force-elongation relationship of collagen in chemo-mechanical equilibrium with water

A significant deformation mechanism of collagen at low loads is molecular uncoiling and rearrangement. Although the effect of hydration and cross-linking has been investigated at larger loads when collagen undergoes molecular sliding, their effects on collagen molecular reorganization remain unclear. Here we develop two thermodynamic models that use the notion of open-system elasticity to elucidate the effect of swelling due to water uptake during deformation of collagen networks under low and high cross-linking conditions. With low crosslinking, entropic contributions dominate resulting in rejection of solvent from the polymer network leading to reduced collagen stiffness with increased loads. Contrarily, high cross-linking inhibits initial coiling and structural kinking and the mechanical behavior is dominated by elastic energy. In this configuration, the solvent content depends on the sign of the applied load resulting in a non-linear open-system stress-strain relationship. The models provide insight on the parameters that impact the stress-strain relationships of hydrated collagen and can inform the way collagenous matrices are treated both in medical and laboratory settings.

Unlocking the Therapeutic Potential of Marine Collagen: A Scientific Exploration for Delaying Skin Aging

Aging is closely associated with collagen degradation, impacting the structure and strength of the muscles, joints, bones, and skin. The continuous aging of the skin is a natural process that is influenced by extrinsic factors such as UV exposure, dietary patterns, smoking habits, and cosmetic supplements. Supplements that contain collagen can act as remedies that help restore vitality and youth to the skin, helping combat aging. Notably, collagen supplements enriched with essential amino acids such as proline and glycine, along with marine fish collagen, have become popular for their safety and effectiveness in mitigating the aging process. To compile the relevant literature on the anti-aging applications of marine collagen, a search and analysis of peer-reviewed papers was conducted using PubMed, Cochrane Library, Web of Science, and Embase, covering publications from 1991 to 2024. From in vitro to in vivo experiments, the reviewed studies elucidate the anti-aging benefits of marine collagen, emphasizing its role in combating skin aging by minimizing oxidative stress, photodamage, and the appearance of wrinkles. Various bioactive marine peptides exhibit diverse anti-aging properties, including free radical scavenging, apoptosis inhibition, lifespan extension in various organisms, and protective effects in aging humans. Furthermore, the topical application of hyaluronic acid is discussed as a mechanism to increase collagen production and skin moisture, contributing to the anti-aging effects of collagen supplementation. The integration of bio-tissue engineering in marine collagen applications is also explored, highlighting its proven utility in skin healing and bone regeneration applications. However, limitations to the scope of its application exist. Thus, by delving into these nuanced considerations, this review contributes to a comprehensive understanding of the potential and challenges associated with marine collagen in the realm of anti-aging applications.

Protein Hydrolysis as a Way to Valorise Squid-Processing Byproducts: Obtaining and Identification of ACE, DPP-IV and PEP Inhibitory Peptides

The industrial processing of Argentine shortfin squid to obtain rings generates a significant amount of protein-rich waste, including the skin, which is rich in collagen and attached myofibrillar proteins. This waste is generally discarded. In this study, skin was used as a source of proteins that were hydrolysed using Trypsin, Esperase® or Alcalase®, which released peptides with antioxidant potential and, in particular, antihypertensive (ACE inhibition), hypoglycemic (DPP-IV inhibition) and/or nootropic (PEP inhibition) potential. Among the three enzymes tested, Esperase® and Alcalase produced hydrolysates with potent ACE-, DPP-IV- and PEP-inhibiting properties. These hydrolysates underwent chromatography fractionation, and the composition of the most bioactive fractions was analysed using HPLC-MS-MS. The fractions with the highest bioactivity exhibited very low IC50 values (16 and 66 µg/mL for ACE inhibition, 97 µg/mL for DPP-IV inhibition and 55 µg/mL for PEP inhibition) and were mainly derived from the hydrolysate obtained using Esperase®. The presence of Leu at the C-terminal appeared to be crucial for the ACE inhibitory activity of these fractions. The DPP-IV inhibitory activity of peptides seemed to be determined by the presence of Pro or Ala in the second position from the N-terminus, and Gly and/or Pro in the last C-terminal positions. Similarly, the presence of Pro in the peptides present in the best PEP inhibitory fraction seemed to be important in the inhibitory effect. These results demonstrate that the skin of the Argentine shortfin squid is a valuable source of bioactive peptides, suitable for incorporation into human nutrition as nutraceuticals and food supplements.

Identification of Key Genes Associated with Tumor Microenvironment Infiltration and Survival in Gastric Adenocarcinoma via Bioinformatics Analysis

OBJECTIVE

Gastric carcinoma (GC) is the fifth most commonly diagnosed cancer and the third leading cause of cancer-related deaths globally. The tumor microenvironment plays a significant role in the pathogenesis, prognosis, and response to immunotherapy. However, the immune-related molecular mechanisms underlying GC remain elusive. Bioinformatics analysis of the gene expression of GC and paracancerous healthy tissues from the same patient was performed to identify the key genes and signaling pathways, as well as their correlation to the infiltration of the tumor microenvironment (TME) by various immune cells related to GC development.

METHODS

We employed GSE19826, a gene expression profile from the Gene Expression Omnibus (GEO), for our analysis. Functional enrichment analysis of Differentially Expressed Genes (DEGs) was conducted using the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes database.

RESULTS

Cytoscape software facilitated the identification of nine hub DEGs, namely, FN1, COL1A1, COL1A2, THBS2, COL3A1, COL5A1, APOE, SPP1, and BGN. Various network analysis algorithms were applied to determine their high connectivity. Among these hub genes, FN1, COL1A2, THBS2, COL3A1, COL5A1, and BGN were found to be associated with a poor prognosis for GC patients. Subsequent analysis using the TIMER database revealed the infiltration status of the TME concerning the overexpression of these six genes. Specifically, the abovementioned genes demonstrated direct correlations with cancer-associated fibroblasts, M1 and M2 macrophages, myeloid-derived suppressor cells, and activated dendritic cells.

CONCLUSION

Our findings suggest that the identified hub genes, particularly BGN, FN1, COL1A2, THBS2, COL3A1, and COL5A1, play crucial roles in GC prognosis and TME cell infiltration. This comprehensive analysis enhances our understanding of the molecular mechanisms underlying GC development and may contribute to the identification of potential therapeutic targets and prognostic markers for GC patients.

Glycosylation Modulates the Structure and Functions of Collagen: A Review

Collagens are fundamental constituents of the extracellular matrix and are the most abundant proteins in mammals. Collagens belong to the family of fibrous or fiber-forming proteins that self-assemble into fibrils that define their mechanical properties and biological functions. Up to now, 28 members of the collagen superfamily have been recognized. Collagen biosynthesis occurs in the endoplasmic reticulum, where specific post-translational modification-glycosylation-is also carried out. The glycosylation of collagens is very specific and adds β-d-galactopyranose and β-d-Glcp-(1→2)-d-Galp disaccharide through β-O-linkage to hydroxylysine. Several glycosyltransferases, namely COLGALT1, COLGALT2, LH3, and PGGHG glucosidase, were associated the with glycosylation of collagens, and recently, the crystal structure of LH3 has been solved. Although not fully understood, it is clear that the glycosylation of collagens influences collagen secretion and the alignment of collagen fibrils. A growing body of evidence also associates the glycosylation of collagen with its functions and various human diseases. Recent progress in understanding collagen glycosylation allows for the exploitation of its therapeutic potential and the discovery of new agents. This review will discuss the relevant contributions to understanding the glycosylation of collagens. Then, glycosyltransferases involved in collagen glycosylation, their structure, and catalytic mechanism will be surveyed. Furthermore, the involvement of glycosylation in collagen functions and collagen glycosylation-related diseases will be discussed.

HTRA1-driven detachment of type I collagen from endoplasmic reticulum contributes to myocardial fibrosis in dilated cardiomyopathy

BACKGROUND

The aberrant secretion and excessive deposition of type I collagen (Col1) are important factors in the pathogenesis of myocardial fibrosis in dilated cardiomyopathy (DCM). However, the precise molecular mechanisms underlying the synthesis and secretion of Col1 remain unclear.

METHODS AND RESULTS

RNA-sequencing analysis revealed an increased HtrA serine peptidase 1 (HTRA1) expression in patients with DCM, which is strongly correlated with myocardial fibrosis. Consistent findings were observed in both human and mouse tissues by immunoblotting, quantitative reverse transcription polymerase chain reaction (qRT-PCR), immunohistochemistry, and immunofluorescence analyses. Pearson's analysis showed a markedly positive correlation between HTRA1 level and myocardial fibrosis indicators, including extracellular volume fraction (ECV), native T1, and late gadolinium enhancement (LGE), in patients with DCM. In vitro experiments showed that the suppression of HTRA1 inhibited the conversion of cardiac fibroblasts into myofibroblasts and decreased Col1 secretion. Further investigations identified the role of HTRA1 in promoting the formation of endoplasmic reticulum (ER) exit sites, which facilitated the transportation of Col1 from the ER to the Golgi apparatus, thereby increasing its secretion. Conversely, HTRA1 knockdown impeded the retention of Col1 in the ER, triggering ER stress and subsequent induction of ER autophagy to degrade misfolded Col1 and maintain ER homeostasis. In vivo experiments using adeno-associated virus-serotype 9-shHTRA1-green fluorescent protein (AAV9-shHTRA1-GFP) showed that HTRA1 knockdown effectively suppressed myocardial fibrosis and improved left ventricular function in mice with DCM.

CONCLUSIONS

The findings of this study provide valuable insights regarding the treatment of DCM-associated myocardial fibrosis and highlight the therapeutic potential of targeting HTRA1-mediated collagen secretion.

Age-dependent changes in collagen crosslinks reduce the mechanical toughness of human meniscus

The mechanical resilience of the knee meniscus is provided by a group of structural proteins in the extracellular matrix. Aging can alter the quantity and molecular structure of these proteins making the meniscus more susceptible to debilitating tears. In this study, we determined the effect of aging on the quantity of structural proteins and collagen crosslinks in human lateral meniscus, and examined whether the quantity of these molecules was predictive of tensile toughness (area under the stress-strain curve). Two age groups were tested: a young group under 40 and an older group over 65 years old. Using mass spectrometry, we quantified the abundance of proteins and collagen crosslinks in meniscal tissue that was adjacent to the dumbbell-shaped specimens used to measure uniaxial tensile toughness parallel or perpendicular to the circumferential fiber orientation. We found that the enzymatic collagen crosslink deoxypyridinoline had a significant positive correlation with toughness, and reductions in the quantity of this crosslink with aging were associated with a loss of toughness in the ground substance and fibers. The non-enzymatic collagen crosslink carboxymethyl-lysine increased in quantity with aging, and these increases corresponded to reductions in ground substance toughness. For the collagenous (Types I, II, IV, VI, VIII) and non-collagenous structural proteins (elastin, decorin, biglycan, prolargin) analyzed in this study, only the quantity of collagen VIII was predictive of toughness. This study provides valuable insights on the structure-function relationships of the human meniscus, and how aging causes structural adaptations that weaken the tissue's mechanical integrity.

Assessing type I collagen expression and quality in cellular models of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a group of genetic disorders of bone formation characterized by soft and shorter brittle bones in affected individuals. OI is generally considered a collagenopathy resulting from abnormal expression of type I collagen. As assay system to detect the cellular level and quality of type I collagen would help in rapid and correct detection of OI from the diagnostic perspectives. Here, we report an immunofluorescence assay for detection of type I collagen in fibroblast models of OI and represented them into two broad categories based on the expression level and aggregation characteristics of pro-α1(I). Cell phenotypic assays of pro-α1(I) in OI-related gene knocked down fibroblasts revealed aggregates of pro-α1(I) in conditions with knockdown of SERPINF1, CRTAP, P3H1, PPIB, SERPINH1, FKBP10, TMEM38B, MESD, and KDELR2, whereas pro-α1(I) expression was very low in fibroblasts which had knockdown of IFITM5, SP7, BMP1, WNT1, CREB3L1, MBTPS2, and CCDC134. The expression of pro-α1(I) showed abundant and non-aggregated distribution in the fibroblasts with knockdown of non-OI skeletal disorder-related genes (RAB33B and IFT52). The in vitro assay accurately detected abnormally expressed pro-α1(I) levels in cellular models of various types of OI. Thus, this procedure represents a promising point-of-detection assay for potential diagnosis and therapeutic decisions in OI.

A physicochemical evaluation of ossein-hydroxyapatite within the bovine bone matrix revealed demineralization and making type I collagen available as a result of processing and solubilization by acids

Bovine bone is an animal-origin matrix rich in type I collagen (COL I) and it necessitates prior demineralization and makes COL I available. This study investigated the ossein-hydroxyapatite physicochemical properties evaluation as a result of processing and solubilization by acids and revealed the bone matrix demineralization and making COL I available. The tibia residue from bovine sources was processed, ground, and transformed into bone matrix powder. The bone matrix was solubilized in acetic acid followed by lactic acid. The bone matrix was evaluated as a result of processing and solubilization by acids: ossein and hydroxyapatite percentages by nitrogen and ash content, mineral content, particle size distribution, Fourier-transformation infrared spectroscopy, x-ray diffraction, and scanning electron microscope. For the obtained residual extracts, pH and mineral content were evaluated. The solubilization by acids affected the ossein-hydroxyapatite physicochemical properties, and the bone matrix solubilized by acetic and lactic acid showed the preservation of the ossein alongside the loss of hydroxyapatite. The processing and the solubilization by acids were revealed to be a  alternative to bone matrix demineralization and enabling the accessibility of bone COL I. PRACTICAL APPLICATION: Bovine bone is an abundant type I collagen source, but processing maneuvers and demineralization effect present limitations due to the rigidity of the structural components. Exploring methodologies to process and demineralize will allow type I collagen to be obtained from the bone source, and direct and amplify the potentialities in the chemical and food industries. The research focused on bone sources and collagen availability holds paramount significance, and promotes repurposing agribusiness residues and development of protein-base products.

Progesterone signaling in uterine leiomyoma biology: Implications for potential targeted therapy

Uterine leiomyomas (ULs) are the most common benign smooth muscle cell steroid-dependent tumors that occur in women of reproductive age. Progesterone (P4) is a major hormone that promotes the ULs development and growth. P4 action in ULs is mediated mainly by its nuclear progesterone receptors (PGRs), although rapid non-genomic responses have also been observed. Data on the membrane progesterone receptors (mPRs) regulated signaling pathways in ULs in the available literature is still very limited. One of the essential characteristics of ULs is the excessive production of extracellular matrix (ECM). P4 has been shown to stimulate ECM production and collagen synthesis in ULs. Recent research demonstrated that, despite their benign nature, ULs may present with abnormal vasculature. P4 has been shown to regulate angiogenesis in ULs through the upregulation of vascular endothelial growth factor (VEGF) and by controlling the secretion of permeability factors. This review summarizes the key findings regarding the role of PGRs and mPRs in ULs, especially highlighting the potential ECM and angiogenesis modulation by P4. An increased understanding of this mechanistic role of nuclear and specifically mPRs in the biology of P4-modulated ECM and angiogenesis in the growth of ULs could turn out to be fundamental for developing effective targeted therapies for ULs.

The Future of Microsurgery: Vascularized Composite Allotransplantation and Engineering Vascularized Tissue

Background

Microsurgical techniques have revolutionized the field of reconstructive surgery and are the mainstay for complex soft tissue reconstruction. However, their limitations have promoted the development of viable alternatives. This article seeks to explore technologies that have the potential of revolutionizing microsurgical reconstruction as it is currently known, reflect on current and future vascularized composite allotransplantation (VCA) practices, as well as describe the basic science within emerging technologies and their potential translational applications.

Methods

A literature review was performed of the technologies that may represent the future of microsurgery: vascularized tissue engineering (VCA) and flap-specific tissue engineering.

Results

VCA has shown great promise and has already been employed in the clinical setting (especially in face and limb transplantation). Immunosuppression, logistics, cost, and regulatory pathways remain barriers to overcome to make it freely available. Vascularized and flap-specific tissue engineering remain a laboratory reality but have the potential to supersede VCA. The capability of creating an off-the-shelf free flap matching the required tissue, size, and shape is a significant advantage. However, these technologies are still at the early stage and require significant advancement before they can be translated into the clinical setting.

Conclusion

VCA, vascularized tissue engineering, and flap-specific bioengineering represent possible avenues for the evolution of current microsurgical techniques. The next decade will elucidate which of these three strategies will evolve into a tangible translational option and hopefully bring a paradigm shift of reconstructive surgery.

Recent research advances on polysaccharide-, peptide-, and protein-based hemostatic materials: A review

Hemorrhage is a potentially life-threatening emergency that can occur at any time or place. Whether traumatic, congenital, surgical, disease-related, or drug-induced, bleeding can lead to severe complications or death. Therefore, the development of efficient hemostatic materials is critical. However, the results and prognosis demonstrated by clinical means of hemostasis do not reach expectations. With the development of technology, novel hemostatic materials have been developed from polysaccharides (chitosan, hyaluronic acid, alginate, cellulose, cyclodextrins, starch, dextran, and carrageenan), peptides (self-assembling peptides), and proteins (silk fibroin, collagen, gelatin, keratin, and thrombin). These new materials exhibit high hemostatic efficacy due to the enhancement or interaction of various hemostatic mechanisms. The main forms include adhesives, sealants, bandages, hemostatic powders, and hemostatic sponges. This article introduces the clotting process and principles of hemostatic methods and reviews the research on polysaccharide-, peptide-, and protein-based hemostatic materials in the last five years. The design ideas and hemostatic principles of polysaccharide-, peptide-, and protein-based hemostatic materials are mainly introduced. Finally, we summarize material designs, advantages, disadvantages, and challenges regarding hemostatic materials.

Type 1 collagen: Synthesis, structure and key functions in bone mineralization

Collagen is a highly abundant protein in the extracellular matrix of humans and mammals, and it plays a critical role in maintaining the body's structural integrity. Type I collagen is the most prevalent collagen type and is essential for the structural integrity of various tissues. It is present in nearly all connective tissues and is the main constituent of the interstitial matrix. Mutations that affect collagen fiber formation, structure, and function can result in various bone pathologies, underscoring the significance of collagen in sustaining healthy bone tissue. Studies on type 1 collagen have revealed that mutations in its encoding gene can lead to diverse bone diseases, such as osteogenesis imperfecta, a disorder characterized by fragile bones that are susceptible to fractures. Knowledge of collagen's molecular structure, synthesis, assembly, and breakdown is vital for comprehending embryonic and foetal development and several aspects of human physiology. In this review, we summarize the structure, molecular biology of type 1 collagen, its biomineralization and pathologies affecting bone.

Single-cell RNA sequencing reveals the impact of mechanical loading on knee tibial cartilage in osteoarthritis

Articular cartilage degeneration is one of the major pathogenic alterations observed in knee osteoarthritis (KOA). Mechanical stress has been verified to contribute to KOA development. To gain insight into the pathogenic mechanism of KOA development, we investigated chondrocyte subsets under different mechanical loading conditions via single-cell RNA sequencing (scRNA-seq). Articular cartilage tissues from both high mechanical loading (named the OATL group) and low mechanical loading (named the OATN group) surfaces were obtained from the proximal tibia of KOA patients, and scRNA-seq was conducted. Chondrocyte subtypes, including a new subset, HTC-C (hypertrophic chondrocytes-C), and their functions, development and interactions among cell subsets were identified. Immunohistochemical staining was also conducted to verify the existence and location of each chondrocyte subset. Furthermore, differentially expressed genes (DEGs) and their functions between regions with high and low mechanical loading were identified. Based on Gene Ontology terms for the DEGs in each cell type, the characteristic of cartilage degeneration in the OATL region was clarified. Mitochondrial dysfunction may be involved in the KOA process in the OATN region.

Anti-photoaging effects of canola meal extract on human dermal fibroblasts against UVB-induced oxidative stress

Canola meal, a by-product of canola oil processing, is a source of bioactive compounds that show antioxidant and skin anti-aging effects through upcycling (i.e., creative reuse). Here we describe the antioxidant and skin anti-aging effects of canola meal extract (CME) obtained by upcycling canola meal. The antioxidant capacity of CME is due in part to its antioxidative phenolics. Seven phenolics, including sinapine and sinapic acid, in CME were identified using ultra-high-performance liquid chromatography-Orbitrap mass spectrometry. Addition of CME (1000 μg/mL) to human dermal fibroblast neonatal cells  significantly (p < 0.05) reduced matrix metalloproteinase-12 production and increased pro-collagen Ι alpha 1 content in response to ultraviolet B-induced oxidative stress compared with cells without CME. These results suggest that CME can serve as a functional food ingredient with antioxidant capacity and anti-aging effects on the skin.

Selenium Compounds Affect Differently the Cytoplasmic Thiol/Disulfide State in Dermic Fibroblasts and Improve Cell Migration by Interacting with the Extracellular Matrix

Deficient wound healing is frequently observed in patients diagnosed with diabetes, a clinical complication that compromises mobility and leads to limb amputation, decreasing patient autonomy and family lifestyle. Fibroblasts are crucial for secreting the extracellular matrix (ECM) to pave the wound site for endothelial and keratinocyte regeneration. The biosynthetic pathways involved in collagen production and crosslinking are intimately related to fibroblast redox homeostasis. In this study, two sets of human dermic fibroblasts were cultured in normal (5 mM) and high (25 mM)-glucose conditions in the presence of 1 µM selenium, as sodium selenite (inorganic) and the two selenium amino acids (organic), Se-cysteine and Se-methionine, for ten days. We investigated the ultrastructural changes in the secreted ECM induced by these conditions using scanning electron microscopy (SEM). In addition, we evaluated the redox impact of these three compounds by measuring the basal state and real-time responses of the thiol-based HyPer biosensor expressed in the cytoplasm of these fibroblasts. Our results indicate that selenium compound supplementation pushed the redox equilibrium towards a more oxidative tone in both sets of fibroblasts, and this effect was independent of the type of selenium. The kinetic analysis of biosensor responses allowed us to identify Se-cysteine as the only compound that simultaneously improved the sensitivity to oxidative stimuli and augmented the disulfide bond reduction rate in high-glucose-cultured fibroblasts. The redox response profiles showed no clear association with the ultrastructural changes observed in matrix fibers secreted by selenium-treated fibroblasts. However, we found that selenium supplementation improved the ECM secreted by high-glucose-cultured fibroblasts according to endothelial migration assessed with a wound healing assay. Direct application of sodium selenite and Se-cysteine on purified collagen fibers subjected to glycation also improved cellular migration, suggesting that these selenium compounds avoid the undesired effect of glycation.

Longitudinal plasma proteomics reveals biomarkers of alveolar-capillary barrier disruption in critically ill COVID-19 patients

The pathobiology of respiratory failure in COVID-19 consists of a complex interplay between viral cytopathic effects and a dysregulated host immune response. In critically ill patients, imatinib treatment demonstrated potential for reducing invasive ventilation duration and mortality. Here, we perform longitudinal profiling of 6385 plasma proteins in 318 hospitalised patients to investigate the biological processes involved in critical COVID-19, and assess the effects of imatinib treatment. Nine proteins measured at hospital admission accurately predict critical illness development. Next to dysregulation of inflammation, critical illness is characterised by pathways involving cellular adhesion, extracellular matrix turnover and tissue remodelling. Imatinib treatment attenuates protein perturbations associated with inflammation and extracellular matrix turnover. These proteomic alterations are contextualised using external pulmonary RNA-sequencing data of deceased COVID-19 patients and imatinib-treated Syrian hamsters. Together, we show that alveolar capillary barrier disruption in critical COVID-19 is reflected in the plasma proteome, and is attenuated with imatinib treatment. This study comprises a secondary analysis of both clinical data and plasma samples derived from a clinical trial that was registered with the EU Clinical Trials Register (EudraCT 2020-001236-10, https://www.clinicaltrialsregister.eu/ctr-search/trial/2020-001236-10/NL ) and Netherlands Trial Register (NL8491, https://www.trialregister.nl/trial/8491 ).

The Characterization and Cytotoxic Evaluation of Chondrosia reniformis Collagen Isolated from Different Body Parts (Ectosome and Choanosome) Envisaging the Development of Biomaterials

Chondrosia reniformis is a collagen-rich marine sponge that is considered a sustainable and viable option for producing an alternative to mammalian-origin collagens. However, there is a lack of knowledge regarding the properties of collagen isolated from different sponge parts, namely the outer region, or cortex, (ectosome) and the inner region (choanosome), and how it affects the development of biomaterials. In this study, a brief histological analysis focusing on C. reniformis collagen spatial distribution and a comprehensive comparative analysis between collagen isolated from ectosome and choanosome are presented. The isolated collagen characterization was based on isolation yield, Fourier-transformed infrared spectroscopy (FTIR), circular dichroism (CD), SDS-PAGE, dot blot, and amino acid composition, as well as their cytocompatibility envisaging the development of future biomedical applications. An isolation yield of approximately 20% was similar for both sponge parts, as well as the FTIR, CD, and SDS-PAGE profiles, which demonstrated that both isolated collagens presented a high purity degree and preserved their triple helix and fibrillar conformation. Ectosome collagen had a higher OHpro content and possessed collagen type I and IV, while the choanosome was predominately constituted by collagen type IV. In vitro cytotoxicity assays using the L929 fibroblast cell line displayed a significant cytotoxic effect of choanosome collagen at 2 mg/mL, while ectosome collagen enhanced cell metabolism and proliferation, thus indicating the latter as being more suitable for the development of biomaterials. This research represents a unique comparative study of C. reniformis body parts, serving as a support for further establishing this marine sponge as a promising alternative collagen source for the future development of biomedical applications.

Insights into How Plant-Derived Extracts and Compounds Can Help in the Prevention and Treatment of Keloid Disease: Established and Emerging Therapeutic Targets

Keloid is a disease in which fibroblasts abnormally proliferate and synthesize excessive amounts of extracellular matrix, including collagen and fibronectin, during the healing process of skin wounds, causing larger scars that exceed the boundaries of the original wound. Currently, surgical excision, cryotherapy, radiation, laser treatment, photodynamic therapy, pressure therapy, silicone gel sheeting, and pharmacotherapy are used alone or in combinations to treat this disease, but the outcomes are usually unsatisfactory. The purpose of this review is to examine whether natural products can help treat keloid disease. I introduce well-established therapeutic targets for this disease and various other emerging therapeutic targets that have been proposed based on the phenotypic difference between keloid-derived fibroblasts (KFs) and normal epidermal fibroblasts (NFs). We then present recent studies on the biological effects of various plant-derived extracts and compounds on KFs and NFs. Associated ex vivo, in vivo, and clinical studies are also presented. Finally, we discuss the mechanisms of action of the plant-derived extracts and compounds, the pros and cons, and the future tasks for natural product-based therapy for keloid disease, as compared with existing other therapies. Extracts of Astragalus membranaceus, Salvia miltiorrhiza, Aneilema keisak, Galla Chinensis, Lycium chinense, Physalis angulate, Allium sepa, and Camellia sinensis appear to modulate cell proliferation, migration, and/or extracellular matrix (ECM) production in KFs, supporting their therapeutic potential. Various phenolic compounds, terpenoids, alkaloids, and other plant-derived compounds could modulate different cell signaling pathways associated with the pathogenesis of keloids. For now, many studies are limited to in vitro experiments; additional research and development are needed to proceed to clinical trials. Many emerging therapeutic targets could accelerate the discovery of plant-derived substances for the prevention and treatment of keloid disease. I hope that this review will bridge past, present, and future research on this subject and provide insight into new therapeutic targets and pharmaceuticals, aiming for effective keloid treatment.

Surface Modification Progress for PLGA-Based Cell Scaffolds

Poly(lactic-glycolic acid) (PLGA) is a biocompatible bio-scaffold material, but its own hydrophobic and electrically neutral surface limits its application as a cell scaffold. Polymer materials, mimics ECM materials, and organic material have often been used as coating materials for PLGA cell scaffolds to improve the poor cell adhesion of PLGA and enhance tissue adaptation. These coating materials can be modified on the PLGA surface via simple physical or chemical methods, and coating multiple materials can simultaneously confer different functions to the PLGA scaffold; not only does this ensure stronger cell adhesion but it also modulates cell behavior and function. This approach to coating could facilitate the production of more PLGA-based cell scaffolds. This review focuses on the PLGA surface-modified materials, methods, and applications, and will provide guidance for PLGA surface modification.

From biochemical markers to molecular endotypes of osteoarthritis: a review on validated biomarkers

INTRODUCTION

Osteoarthritis (OA) affects over 500 million people worldwide. OA patients are symptomatically treated, and current therapies exhibit marginal efficacy and frequently carry safety-risks associated with chronic use. No disease-modifying therapies have been approved to date leaving surgical joint replacement as a last resort. To enable effective patient care and successful drug development there is an urgent need to uncover the pathobiological drivers of OA and how these translate into disease endotypes. Endotypes provide a more precise and mechanistic definition of disease subgroups than observable phenotypes, and a panel of tissue- and pathology-specific biochemical markers may uncover treatable endotypes of OA.

AREAS COVERED

We have searched PubMed for full-text articles written in English to provide an in-depth narrative review of a panel of validated biochemical markers utilized for endotyping of OA and their association to key OA pathologies.

EXPERT OPINION

As utilized in IMI-APPROACH and validated in OAI-FNIH, a panel of biochemical markers may uncover disease subgroups and facilitate the enrichment of treatable molecular endotypes for recruitment in therapeutic clinical trials. Understanding the link between biochemical markers and patient-reported outcomes and treatable endotypes that may respond to given therapies will pave the way for new drug development in OA.

Dendrobium officinale Kinura et Migo glycoprotein promotes skin wound healing by regulating extracellular matrix secretion and fibroblast proliferation on the proliferation phase

Dendrobium officinale Kinura et Migo (DOKM) has a variety of medicinal applications; however, its ability to promote wound healing has not been previously reported. The purpose of this study is to investigate the proliferative phase of the wound-healing effect of DOKM glycoprotein (DOKMG) in rats and to elucidate its mechanism of action in vitro. In the present study, the ointment mixture containing DOKMG was applied to the dorsal skin wounds of the full-thickness skin excision rat model, and the results showed that the wound healing speed was faster in the proliferative phase than vaseline. Histological analysis demonstrates that DOKMG promoted the re-epithelialization of wound skin. Immunofluorescence staining and quantitative polymerase chain reaction assays revealed that DOKMG promotes the secretion of Fibronectin and inhibits the secretion of Collagen IV during the granulation tissue formation period, indicating that DOKMG could accelerate the formation of granulation tissue by precisely regulating extracellular matrix (ECM) secretion. In addition, we demonstrated that DOKMG enhanced the migration and proliferation of fibroblast (3T6 cell) in two-dimensional trauma by regulating the secretion of ECM, via a mechanism that may implicate the AKT and JAK/STAT pathways under the control of epidermal growth factor receptor (EGFR) signalling. In summary, we have demonstrated that DOKMG promotes wound healing during the proliferative phase. Therefore, we suggest that DOKMG may have a potential therapeutic application for the treatment and management of cutaneous wounds.

Synthetic Collagen Hydrogels through Symmetric Self-Assembly of Small Peptides

Animal-sourced hydrogels, such as collagen, are widely used as extracellular-matrix (ECM) mimics in tissue engineering but are plagued with problems of reproducibility, immunogenicity, and contamination. Synthetic, chemically defined hydrogels can avoid such issues. Despite the abundance of collagen in the ECM, synthetic collagen hydrogels are extremely rare due to design challenges brought on by the triple-helical structure of collagen. Sticky-ended symmetric self-assembly (SESSA) overcomes these challenges by maximizing interactions between the strands of the triple helix, allowing the assembly of collagen-mimetic peptides (CMPs) into robust synthetic collagen nanofibers. This optimization, however, also minimizes interfiber contacts. In this work, symmetric association states for the SESSA of short CMPs to probe their increased propensity for interfiber association are modelled. It is found that 33-residue CMPs not only self-assemble through sticky ends, but also form hydrogels. These self-assemblies behave with remarkable consistency across multiple scales and present a clear link between their triple-helical architecture and the properties of their hydrogels. The results show that SESSA is an effective and robust design methodology that enables the rational design of synthetic collagen hydrogels.

Iron role paradox in nerve degeneration and regeneration

Iron accumulates in the neural tissue during peripheral nerve degeneration. Some studies have already been suggested that iron facilitates Wallerian degeneration (WD) events such as Schwann cell de-differentiation. On the other hand, intracellular iron levels remain elevated during nerve regeneration and gradually decrease. Iron enhances Schwann cell differentiation and axonal outgrowth. Therefore, there seems to be a paradox in the role of iron during nerve degeneration and regeneration. We explain this contradiction by suggesting that the increase in intracellular iron concentration during peripheral nerve degeneration is likely to prepare neural cells for the initiation of regeneration. Changes in iron levels are the result of changes in the expression of iron homeostasis proteins. In this review, we will first discuss the changes in the iron/iron homeostasis protein levels during peripheral nerve degeneration and regeneration and then explain how iron is related to nerve regeneration. This data may help better understand the mechanisms of peripheral nerve repair and find a solution to prevent or slow the progression of peripheral neuropathies.

Laryngeal Applications of Platelet Rich Plasma and Platelet Poor Plasma: A Systematic Review

BACKGROUND

Platelet rich plasma (PRP) and platelet poor plasma (PPP) are regenerative therapies that offer the potential for improving care for disorders of the larynx. The laryngeal applications of these substances have been examined in both animals and humans. The goal of this systematic review is to examine the various applications of PRP and PPP in laryngology, assess the protocols for preparation and application of these substances and evaluate the outcomes and complications in both humans and animals.

METHODS

A search of PUBMED was conducted in April 2021 using combinations of keywords of "platelet rich plasma" and "platelet poor plasma" with keywords such as "larynx," "vocal folds," "laryngology," and others. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRIMSA) guidelines were followed. Articles were reviewed by two independent coauthors and included based on selection criteria pertinent to the goals of this study. The risk of bias in the included studies was assessed by two independent co-authors using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Randomized Controlled Trials and JBI Critical Appraisal Checklist for Quasi-Experimental Studies. Data regarding the pathologies treated using PRP and PPP, PRP, and PPP preparation protocols, application protocols, human voice outcomes, histopathological animal outcomes, and complications were extracted from each of the studies and presented in tables.

RESULTS

Seven studies were included based on the selection criteria. PRP or PPP were used for vocal fold scar, sulcus, atrophy and palsy; acute vocal fold injury; glottic insufficiency, and graft healing. PRP or PPP were derived from autologous blood in a one- or two-step centrifugation process and administered via injection, soaking of cartilage grafts or topical application. Mean and median voice handicap index-10 (VHI-10) and voice handicap index (VHI) scores decreased following PRP or PPP injections in two human studies and one human study showed a similar VHI-10 score before and after PRP treatment. Videostroboscopy showed the absence of injection site reactions and at least temporary improvement in glottic gap or vibratory function following treatment in some patients. Other objective measures of voice outcomes in human studies showed improved phonatory function in the one-to-four-month period following PRP or PPP injections, with some patients experiencing a subjective decrease or return to baseline in phonatory function following the initial improvement period. Animal studies found elevated levels of growth factors, organized collagen deposition, decreased granulation tissue, increased vascularization, and increased cartilage proliferation in PRP treated laryngeal tissue.

DISCUSSION

PRP and PPP might have the potential to be safely used in the larynx and at least temporarily influence wound healing and vocal function. Further study using comparable outcome measurement tools is required to assess their role and efficacy in treating acute vocal fold injury, chronic vocal fold pathologies, graft healing, and other laryngeal applications.