Collagenase unwinds triple-helical collagen prior to peptide bond hydrolysis

Bioprinting of transparent and adhesive corneal patches: Integrating photo-crosslinkable dopamine-conjugated silk fibroin and decellularized cornea matrix for sutureless tissue integration and regeneration

Corneal injuries, a leading cause of visual impairment, are traditionally addressed through tissue transplantation. However, challenges such as donor shortages, graft rejection, and complications from suturing often limit their effectiveness. Current corneal adhesives frequently fall short in both adhesion strength and biocompatibility. We present an innovative solution: a photocurable hydrogel that integrates dopamine-conjugated methacrylated silk fibroin (d-MSF) with a decellularized corneal matrix (DCM). This hydrogel combines advanced materials to create a bioadhesive system that offers superior adhesion inspired by mussel adhesion and mimics the native tissue environment. FTIR and NMR analyses confirm that our conjugation process prevents unwanted beta-sheet aggregation, ensuring both stability and transparency. The hydrogel demonstrates excellent rheological properties, including enhanced shear-thinning and impressive shear and creep recovery, making it highly suitable for extrusion-based bioprinting. We successfully bioprinted a bilayer corneal patch, featuring a concentric ring of d-MSF as the first layer, overlaid with a second layer of DCM. The implants exhibit strong tissue adhesion, with an adhesion strength of 85 ± 5.6 KPa, and Young's modulus of 0.48 ± 0.064 MPa, ensuring excellent structural integrity. This results in a highly transparent (>80 %) and functional adhesive corneal patch. This advancement offers a promising, biocompatible alternative to traditional keratoprostheses, advancing corneal repair technology.

Enhancing caries-affected dentin bonding with a mussel-inspired primer

Introduction

Dental caries is the most common oral disease. In caries-affected dentin (CAD), excessive mineral loss, extensive collagen exposure and collapse, increased enzyme activity, and bacterial residues result in significantly lower resin bonding strength and durability compared to sound dentin (SD). Currently, there are no effective clinical strategies to enhance CAD bonding. Inspired by the excellent wet adhesion capability and collagen affinity of marine mussels, this study aimed to evaluate a mussel-inspired polymerizable monomer (catechol-Lys-methacrylate [CLM]) as a primer to improve CAD bonding performance.

Methods

The interactions between CLM and collagen were analyzed via Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). Microtensile bond strength, nanoleakage, in-situ zymography, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were used to assess the bond strength and interface stability. Furthermore, the antibacterial properties of CLM were evaluated using colony-forming units counts, live/dead bacterial staining, and bacterial morphology observation.

Results

FTIR and NMR results showed that CLM was successfully grafted onto CAD collagen through its catechol groups, facilitating subsequent chemical bonding with resin. CLM increased the immediate CAD bond strength by approximately 30% and reduced immediate nanoleakage by approximately 24%, maintaining effectiveness after aging. Moreover, collagen chemical modification by CLM promoted collagen crosslinking, inhibited endogenous enzymatic activity, and conferred antibacterial properties, further enhancing bonding interface stability.

Discussion

In summary, this study reports the application of a mussel-inspired monomer, CLM, in CAD bonding. During the wet bonding process, CLM not only improves collagen stability but also serves as a molecular bridge between inorganic resin and organic collagen, thereby enhancing both immediate and aged bonding performance. These findings showing promising clinical application potential.

Collagen turnover during cervical remodeling involves both intracellular and extracellular collagen degradation pathways†

Reproductive success requires accurately timed remodeling of the cervix to orchestrate the maintenance of pregnancy, the process of labor, and birth. Prior work in mice established that a combination of continuous turnover of fibrillar collagen and reduced formation of collagen cross-links allows for the gradual increase in tissue compliance and delivery of the fetus during labor. However, the mechanism for continuous collagen degradation to ensure turnover during cervical remodeling is still unknown. This study demonstrates the functional role of extracellular and intracellular collagen degradative pathways in two different settings of cervical remodeling: physiological term remodeling and inflammation-mediated premature remodeling. Extracellular collagen degradation is achieved by the activity of fibroblast-derived matrix metalloproteases MMP14, MMP2, and fibroblast activation protein (FAP). In parallel, we demonstrate the function of an intracellular collagen degradative pathway in fibroblast cells mediated by the collagen endocytic mannose receptor type-2 (MRC2). These pathways appear to be functionally redundant as loss of MRC2 does not obstruct collagen turnover or cervical function in pregnancy. While both extracellular and intracellular pathways are also utilized in inflammation-mediated premature cervical remodeling, the extracellular collagen degradation pathway uniquely employs fibroblast and immune-cell-derived proteases. In sum, these findings identify the dual utilization of two distinct degradative pathways as a failsafe mechanism to achieve continuous collagen turnover in the cervix, thereby allowing dynamic shifts in cervical tissue mechanics and function.

Decoding the MMP14 integrin link: Key player in the secretome landscape

Rapid progress has been made in the exciting field of secretome research in health and disease. The tumor secretome, which is a significant proportion of the tumor proteome, is secreted into the extracellular space to promote intercellular communication and thus tumor progression. Among the many molecules of the secretome, integrins and matrix metalloproteinase 14 (MMP14) stand out as the interplay of adhesion and proteolysis drives invasion. Integrins serve as mechanosensors that mediate the contact of cells with the scaffold of the extracellular matrix and are significantly involved in the precise positioning and activity control of the membrane-bound collagenase MMP14. As a secretome proteinase, MMP14 influences and modifies the secretome itself. While integrins and MT-MMPs are membrane bound, but can be released and are therefore border crossers between the cell surface and the secretome, the extracellular matrix is not constitutively cell-bound, but its binding to integrins and other cell receptors is a stringently regulated process. To understand the mutual interactions in detail, we first summarize the structure and function of MMP14 and how it is regulated at the enzymatic and cellular level. In particular, the mutual interactions between integrins and MMP14 include the proteolytic cleavage of integrins themselves by MMP14. We then review the biochemical, cell biological and physiological effects of MMP14 on the composition and associated functions in the tumor secretome when either bound to the cell membrane, or located on extracellular microvesicles, or as a proteolytically shed non-membrane-bound ectodomain. Novel methods of proteomics, including the analysis of extravesicular vesicles, and new methods for the quantification of MMP14 will provide new research and diagnostic tools. The proteolytic modification of the tumor secretome, especially by MMP14, may bring an additional aspect to tumor secretome studies and will have an impact on the diagnosis and most likely also on the therapy of cancer patients.

Focal adhesion in the tumour metastasis: from molecular mechanisms to therapeutic targets

The tumour microenvironment is the "hotbed" of tumour cells, providing abundant extracellular support for growth and metastasis. However, the tumour microenvironment is not static and is constantly remodelled by a variety of cellular components, including tumour cells, through mechanical, biological and chemical means to promote metastasis. Focal adhesion plays an important role in cell-extracellular matrix adhesion. An in-depth exploration of the role of focal adhesion in tumour metastasis, especially their contribution at the biomechanical level, is an important direction of current research. In this review, we first summarize the assembly of focal adhesions and explore their kinetics in tumour cells. Then, we describe in detail the role of focal adhesion in various stages of tumour metastasis, especially its key functions in cell migration, invasion, and matrix remodelling. Finally, we describe the anti-tumour strategies targeting focal adhesion and the current progress in the development of some inhibitors against focal adhesion proteins. In this paper, we summarize for the first time that focal adhesion play a positive feedback role in pro-tumour metastatic matrix remodelling by summarizing the five processes of focal adhesion assembly in a multidimensional way. It is beneficial for researchers to have a deeper understanding of the role of focal adhesion in the biological behaviour of tumour metastasis and the potential of focal adhesion as a therapeutic target, providing new ideas for the prevention and treatment of metastases.

Degradomics defines proteolysis information flow from human knee osteoarthritis cartilage to matched synovial fluid and the contributions of secreted proteases ADAMTS5, MMP13 and CMA1 to articular cartilage breakdown

OBJECTIVES

Proteolytic cartilage extracellular matrix breakdown is a major mechanism of articular cartilage loss in osteoarthritis (OA) pathogenesis. We sought to determine the overlap of proteolytic peptides in matched knee OA cartilage and synovial fluid on a proteome-wide scale to increase the prospective biomarker repertoire and to attribute proteolytic cleavages to specific secreted proteases.

DESIGN

Matched human knee OA cartilage and synovial fluid (n = 5) were analyzed by N-terminomics using Terminal Amine Isotopic Labeling of Substrates (TAILS), comprising labeling and enrichment of protein N-termini, high-resolution mass spectrometry and positional peptide mapping. Donor non-OA articular cartilage was digested with CMA1, MMP13 or ADAMTS5, and TAILS was used to identify cleavage sites, which were matched against cartilage and synovial fluid degradomes.

RESULTS

Of over 20,000 cleaved peptides in the combined OA cartilage and synovial fluid degradomes, 677 peptides, originating from 153 proteins, were present in all cartilage and synovial fluid samples. CMA1, MMP13 and ADAMTS5 digestion of cartilage identified numerous cleavage sites for each protease and distinct cleavage site preferences. Peptides resulting from the activities of these proteases were detected in OA cartilage and synovial fluid.

CONCLUSIONS

Proteolytic fragments from both cartilage and circulating proteins are detectable by synovial fluid degradomics. CMA1, MMP13 and ADAMTS5 activity profiles in cartilage are distinct from each other and the previously determined HtrA1 profile. This work expands the proteolytic biomarker space for OA investigation, suggests that multiple, diverse proteases contribute to cartilage destruction, and demonstrates that their specific contributions can each be defined by multiple biomarkers.

Zymography as a Tool for Exploring Protease Activity in Dental Research

The presence and activity of matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs) in dentin significantly affect the progress of carious and erosive lesions into dentin, as well as the durability and integrity of dental restorations. Understanding the mechanisms involved on this proteolytic activity could therefore provide valuable insights into the pathogenesis of these conditions and inform the development of novel therapeutic strategies. This manuscript provides a comprehensive overview of zymographic techniques applied in dental research, with a focus on the sample's preparation and different measurements of the enzymatic activity through substrate hydrolysis. Standard zymography assays using dentin as a substrate to evaluate the gelatinolytic activity of metalloproteinases (MMPs) and cysteine cathepsins (CCs) are presented, including gel zymography, in situ zymography using fluorescent gelatin-substrate, and reverse zymography for investigating proteolytic activity in dentin.

Tailoring membrane technology with galactomannan for enhanced biocompatibility and antibacterial action

In this study, we elaborated advanced asymmetric membranes using polyvinyl alcohol (PVA) and a galactomannan (GA) derived from Delonix regia seeds, a blend known for its biocompatibility properties. These membranes, crosslinked with sulfosuccinic acid (SSA), exhibited remarkable enhancements in various crucial aspects for biomedical applications, in particular provides antibacterial properties. The incorporation of GA leads to the formation of globular regions, enhancing crosslinking and swelling properties. Increasing GA content results in membranes with enhanced biodegradation, reduced mechanical resistance, and increased elongation at break. The chemical composition of these membranes actively stimulates the metabolism of fibroblasts, osteoblasts, and to a lesser extent, monocytes, promoting cell proliferation particularly at GA contents between 10 and 20 %. Notably, the membrane containing 20 wt% GA demonstrates anti-inflammatory effects by reducing MCP-1 cytokine secretion without compromising tissue repair capacity, as TGF-ß secretion remains unaffected in human monocytes. This multifaceted approach underscores the potential of these membranes in biomedical applications, particularly in wound healing and tissue engineering.

Modeling collagen fibril degradation as a function of matrix microarchitecture

Collagenolytic degradation is a process fundamental to tissue remodeling. The microarchitecture of collagen fibril networks changes during development, aging, and disease. Such changes to microarchitecture are often accompanied by changes in matrix degradability. In a matrix, the pore size and fibril characteristics such as length, diameter, number, orientation, and curvature are the major variables that define the microarchitecture. In vitro, collagen matrices of the same concentration but different microarchitectures also vary in degradation rate. How do different microarchitectures affect matrix degradation? To answer this question, we developed a computational model of collagen degradation. We first developed a lattice model that describes collagen degradation at the scale of a single fibril. We then extended this model to investigate the role of microarchitecture using Brownian dynamics simulation of enzymes in a multi-fibril three dimensional matrix to predict its degradability. Our simulations predict that the distribution of enzymes around the fibrils is non-uniform and depends on the microarchitecture of the matrix. This non-uniformity in enzyme distribution can lead to different extents of degradability for matrices of different microarchitectures. Our simulations predict that for the same enzyme concentration and collagen concentration, a matrix with thicker fibrils degrades more than that with thinner fibrils. Our model predictions were tested using in vitro experiments with synthetic collagen gels of different microarchitectures. Experiments showed that indeed degradation of collagen depends on the matrix architecture and fibril thickness. In summary, our study shows that the microarchitecture of the collagen matrix is an important determinant of its degradability.

Unlocking the Potential of Collagenases: Structures, Functions, and Emerging Therapeutic Horizons

Collagenases, a class of enzymes that are specifically responsible for collagen degradation, have garnered substantial attention because of their pivotal roles in tissue repair, remodeling, and medical interventions. This comprehensive review investigates the diversity, structures, and mechanisms of collagenases and highlights their therapeutic potential. First, it provides an overview of the biochemical properties of collagen and highlights its importance in extracellular matrix function. Subsequently, it meticulously analyzes the sources of collagenases and their applications in tissue engineering and food processing. Notably, this review emphasizes the predominant role played by microbial collagenases in commercial settings while discussing their production and screening methods. Furthermore, this study elucidates the methodology employed for determining collagenase activity and underscores the importance of an accurate evaluation for both research purposes and clinical applications. Finally, this review highlights the future research prospects for collagenases, with a particular focus on promoting wound healing and treating scar tissue formation and fibrotic diseases.

Bioactive Properties of Enzymatic Gelatin Hydrolysates Based on In Silico, In Vitro, and In Vivo Studies

This current study aims to analyze the potential bioactivities possessed by the enzymatic hydrolysates of commercial bovine, porcine, and tilapia gelatins using bioinformatics in combination with in vitro and in vivo studies. The hydrolysate with superior inhibition of angiotensin converting enzyme (ACE) activity was used to treat the D-galactose (DG)-induced amnesic mice. In silico digestion of the gelatins led to the identification of peptide sequences with potential antioxidant, ACE-inhibitory, and anti-amnestic properties. The results of in vitro digestion revealed that the <1 kDa peptide fraction of porcine gelatin hydrolysate obtained after 1 h digestion with papain (PP) (PP1, <1 kDa) potently inhibited ACE, acetylcholinesterase, and prolyl endopeptidase activities at 87.42%, 21.24%, and 48.07%, respectively. Administering the PP1 to DG-induced amnesic mice ameliorated the spatial cognitive impairment and Morris water maze learning abilities. The dentate area morphology in the PP1-treated mice was relatively similar to the control group. In addition, PP1 enhanced the antioxidant capacity in the DG-induced amnesic mice. This study suggests that PP1 could serve as a potential treatment tool against oxidative stress, hypertension, and neurodegenerative diseases.

Engineering a microparticle-loaded rough membrane for guided bone regeneration modulating osteoblast response without inducing inflammation

Guided bone regeneration (GBR) is a widely used procedure that prevents the fast in-growth of soft tissues into bone defect. Among the different types of membranes, the use of collagen membranes is the gold standard. However, these membranes are implanted in tissue location where a severe acute inflammation will occur and can be negatively affected. The aim of this study was to develop a collagen-based membrane for GBR that incorporated alginate-hydroxyapatite microparticles. Membranes were manufactured using collagen type I and gelatin and alginate-hydroxyapatite microparticles. Membranes were assessed in terms of topography by scanning electron microscopy and confocal microscopy; stability by swelling after an overnight incubation in saline and enzymatic degradation against collagenase and mechanical properties by tensile tests. Furthermore, the biological response was assessed with SaOs-2 cells and THP-1 macrophages to determine alkaline phosphatase activity and inflammatory cytokine release. Our results showed that the incorporation of different percentages of these microparticles could induce changes in the surface topography. When the biological response was analyzed, either membranes were not cytotoxic to THP-1 macrophages or to SaOs-2 cells and they did not induce the release of pro-inflammatory cytokines. However, the different surface topographies did not induce changes in the macrophage morphology and the release of pro- and anti-inflammatory cytokines, suggesting that the effect of surface roughness on macrophage behavior could be dependent on other factors such as substrate stiffness and composition. Collagen-gelatin membranes with embedded alginate-hydroxyapatite microparticles increased ALP activity, suggesting a positive effect of them on bone regeneration, remaining unaffected the release of pro- and anti-inflammatory cytokines.

Matrix metalloproteinases targeting in prostate cancer

Prostate cancer (PCa) is one of the most common tumors affecting men all over the world. PCa has brought a huge health burden to men around the world, especially for elderly men, but its pathogenesis is unclear. In prostate cancer, epigenetic inheritance plays an important role in the development, progression, and metastasis of the disease. An important role in cancer invasion and metastasis is played by matrix metalloproteinases (MMPs), zinc-dependent proteases that break down extracellular matrix. We review two important forms of epigenetic modification and the role of matrix metalloproteinases in tumor regulation, both of which may be of significant value as novel biomarkers for early diagnosis and prognosis monitoring. The author considers that both mechanisms have promising therapeutic applications for therapeutic agent research in prostate cancer, but that efforts should be made to mitigate or eliminate the side effects of drug therapy in order to maximize quality of life of patients. The understanding of epigenetic modification, MMPs, and their inhibitors in the functional regulation of prostate cancer is gradually advancing, it will provide a new technical means for the prevention of prostate cancer, early diagnosis, androgen-independent prostate cancer treatment, and drug research.

Modeling collagen fibril degradation as a function of matrix microarchitecture

Collagenolytic degradation is a process fundamental to tissue remodeling. The microarchitecture of collagen fibril networks changes during development, aging, and disease. Such changes to microarchitecture are often accompanied by changes in matrix degradability. In vitro, collagen matrices of the same concentration but different microarchitectures also vary in degradation rate. How do different microarchitectures affect matrix degradation? To answer this question, we developed a computational model of collagen degradation. We first developed a lattice model that describes collagen degradation at the scale of a single fibril. We then extended this model to investigate the role of microarchitecture using Brownian dynamics simulation of enzymes in a multi-fibril three dimensional matrix to predict its degradability. Our simulations predict that the distribution of enzymes around the fibrils is non-uniform and depends on the microarchitecture of the matrix. This non-uniformity in enzyme distribution can lead to different extents of degradability for matrices of different microarchitectures. Our model predictions were tested using in vitro experiments with synthesized collagen gels of different microarchitectures. Experiments showed that indeed degradation of collagen depends on the matrix architecture and fibril thickness. In summary, our study shows that the microarchitecture of the collagen matrix is an important determinant of its degradability.

Novel Insights into the Catalytic Mechanism of Collagenolysis by Zn(II)-Dependent Matrix Metalloproteinase-1

Collagen hydrolysis, catalyzed by Zn(II)-dependent matrix metalloproteinases (MMPs), is a critical physiological process. Despite previous computational investigations into the catalytic mechanisms of MMP-mediated collagenolysis, a significant knowledge gap in understanding remains regarding the influence of conformational sampling and entropic contributions at physiological temperature on enzymatic collagenolysis. In our comprehensive multilevel computational study, employing quantum mechanics/molecular mechanics (QM/MM) metadynamics (MetD) simulations, we aimed to bridge this gap and provide valuable insights into the catalytic mechanism of MMP-1. Specifically, we compared the full enzyme-substrate complex in solution, clusters in solution, and gas-phase to elucidate insights into MMP-1-catalyzed collagenolysis. Our findings reveal significant differences in the catalytic mechanism when considering thermal effects and the dynamic evolution of the system, contrasting with conventional static potential energy surface QM/MM reaction path studies. Notably, we observed a significant stabilization of the critical tetrahedral intermediate, attributed to contributions from conformational flexibility and entropy. Moreover, we found that protonation of the scissile bond nitrogen occurs via proton transfer from a Zn(II)-coordinated hydroxide rather than from a solvent water molecule. Following C-N bond cleavage, the C-terminus remains coordinated to the catalytic Zn(II), while the N-terminus forms a hydrogen bond with a solvent water molecule. Subsequently, the release of the C-terminus is facilitated by the coordination of a water molecule. Our study underscores the pivotal role of protein conformational dynamics at physiological temperature in stabilizing the transition state of the rate-limiting step and key intermediates, compared to the corresponding reaction in solution. These fundamental insights into the mechanism of collagen degradation provide valuable guidance for the development of MMP-1-specific inhibitors.

Preclinical evaluation of mucogingival defect treatment using piscine membranes: An in vivo assessment of wound healing

Periodontitis is a bacteria-induced chronic inflammatory disease characterized by degradation of the supporting tissue and bone in the oral cavity. Treatment modalities seek to facilitate periodontal rehabilitation while simultaneously preventing further gingival tissue recession and potentially bone atrophy. The aim of this study was to compare two differently sourced membranes, a resorbable piscine collagen membrane and a porcine-derived collagen membrane, in the repair of soft tissue defects utilizing a preclinical canine model. This in vivo component consisted of 10 beagles which were subjected to bilateral maxillary canine mucogingival flap defects, as well as bilateral soft tissue defects (or pouches) with no periodontal ligament damage in the mandibular canines. Defects received either a piscine-derived dermal membrane, (Kerecis® Oral, Ísafjörður, Iceland) or porcine-derived dermal membrane (Geistlich Mucograft®, Wolhusen, Switzerland) in a randomized fashion (to avoid site bias) and were allowed to heal for 30, 60, or 90 days. Statistical evaluation of tissue thickness was performed using general linear mixed model analysis of variance and least significant difference (LSD) post hoc analyses with fixed factors of time and membrane. Semi-quantitative analysis employed for inflammation assessment was evaluated using a chi-squared test along with a heteroscedastic t-test and values were reported as mean and corresponding 95% confidence intervals. In both the mucogingival flap defects and soft tissue gingival pouches, no appreciable qualitative differences were observed in tissue healing between the membranes. Furthermore, no statistical differences were observed in the thickness measurements between piscine- and porcine-derived membranes in the mucogingival flap defects (1.05 mm [±0.17] and 1.29 mm [±0.17], respectively [p = .06]) or soft tissue pouches (1.36 mm [±0.14] and 1.47 mm [±0.14], respectively [p = .27]), collapsed over time. Independent of membrane source (i.e., piscine or porcine), similar inflammatory responses were observed in both the maxilla and mandible at the three time points (p = .88 and p = .79, respectively). Histologic and histomorphometric evaluation results indicated that both membranes yielded equivalent tissue responses, remodeling dynamics and healing patterns for the mucogingival flap as well as the soft tissue gingival pouch defect models.

Exploring the Fibrous Nature of Single-Stranded DNA-Collagen Complexes: Nanostructural Observations and Physicochemical Insights

Nucleic acid-collagen complexes (NACCs) are a self-assembled biomimetic fibrillary platform arising from the spontaneous complexation of single-stranded DNA (ssDNA) oligonucleotides and collagen. NACCs merge the extracellular matrix functionality of collagen with the tunable bioactivity of ssDNA as aptamers for broad biomedical applications. We hypothesize that NACCs offer a hierarchical architecture across multiple length scales that significantly varies compared to native collagen. We investigate this using atomic force microscopy and electron microscopy (transmission electron microscopy and cryogenic electron microscopy). Results demonstrate key topographical differences induced by adding ssDNA oligonucleotides to collagen type I. NACCs form a dense network of intertwined collagen fiber bundles in the microscale and nanoscale while retaining their characteristic D-band periodicities (∼67 nm). Additionally, our exploration of thermodynamic parameters governing the interaction indicates an entropically favorable NACC formation driven by ssDNA. Thermal analysis demonstrates the preservation of collagen's triple helical domains and a more stabilized polypeptide structure at higher temperatures than native collagen. These findings offer important insights into our understanding of the ssDNA-induced complexation of collagen toward the further establishment of structure-property relationships in NACCs and their future development into practical biomaterials. They also provide pathways for manipulating and enhancing collagenous matrices' properties without requiring complex chemical modifications or fabrication procedures.

Contrast enhanced photoacoustic detection of fibrillar collagen in the near infrared region-I

Fibrillar collagen accumulation emerges as a promising biomarker in several diseases, such as desmoplastic tumors and unstable atherosclerotic plaque. Gold nanorods (GNRs) hold great potential as contrast agents in high-resolution, biomedically safe, and non-invasive photoacoustic imaging (PAI). This study presents the design and characterization of a specialized imaging tool which exploits GNR assisted targeted photoacoustic imaging that is tailored for the identification of fibrillar collagen. In addition to the photoacoustic characterization of collagen in the NIR 1 and 2 regions, we demonstrate the detailed steps of conjugating a decoy to GNRs. This study serves as a proof of concept, that demonstrates that conjugated collagenase-1 (MMP-1) generates a distinct and collagen-specific photoacoustic signal, facilitating real-time visualization in the wavelength range of 700-970 nm (NIR I). As most of the reported studies utilized the endogenous contrast of collagen in the NIR II wavelength that has major limitations to perform in vivo deep tissue imaging, the approach that we are proposing is unique and it highlights the promise of MMP-1 decoy-functionalized GNRs as novel contrast agents for photoacoustic imaging of collagen in the NIR 1 region. To our knowledge this is the first time functionalized GNRs are optimized for the detection of fibrillar collagen and utilized in the field of non-invasive photoacoustic imaging that can facilitate a better prognosis of desmoplastic tumors and broken atherosclerotic plaques.

Evaluation of Monomer-containing Isocyanate Groups on Stabilizing Demineralized Dentin Matrix Against Bond Interface Degradation

PURPOSE

To evaluate the effect of urethane methacrylate precursor (UMP) on the enzymatic resistance of demineralized dentin (DD) matrices.

MATERIALS AND METHODS

Experimental treatments containing 0 (control), 1, and 5 mmol/L UMP dissolved in an acetone (Ace) solution were formulated. Dentin matrix specimens were demineralized in vitro and immersed in the experimental treatments for 1 h. The treated specimens were then stored in 0.1 mg/mL collagenase solution for 24 h, after which their dry mass loss and hydroxyproline (HYP) release were assessed. The swelling ratios of specimens in each group were also evaluated. The interaction between UMP and the dentin matrix was observed using field-emission scanning electron microscopy (FE-SEM). Endogenous enzyme activity in dentin was evaluated using confocal laser scanning microscopy (CLSM).

RESULTS

Compared with the other treatment groups, treatment with 1 mM and 5 mM UMP-Ace significantly decreased the dry mass loss, HYP release and swelling ratio of the DD matrix (p < 0.05). FE-SEM and CLSM observations showed that treatment with UMP-Ace protected the structure of the dentin matrix and decreased porosity within the dentin-collagen network.

CONCLUSION

Treatment with 1 mM and 5 mM UMP-Ace protects DD matrix against collagenase degradation and may be clinically useful for improving the durability of the hybrid layer.

Reversible immobilization of cellulase on gelatin for efficient insoluble cellulose hydrolysis

Immobilized enzymes are one of the most common tools used in enzyme engineering, as they can substantially reduce the cost of enzyme isolation and use. However, efficient catalysis of solid substrates using immobilized enzymes is challenging, hydrolysis of insoluble cellulose by immobilized cellulases is a typical example of this problem. In this study, inspired by bees and honeycombs, we prepared gelatin-modified cellulase (BEE) and gelatin hydrogels (HONEYCOMB) to achieve reversible recycling versus release of cellulase through temperature-responsive changes in the triple-stranded helix-like interactions between BEE and HONEYCOMB. At elevated temperatures, BEE was released from HONEYCOMB and participated in hydrolytic saccharification. After 24 h, the glucose yields of both the free enzyme and BEE reached the same level. When the temperature was decreased, BEE recombined with HONEYCOMB to facilitate the effective separation and recycling of BEE from the system. The enzymatic system retained >70 % activity after four reuse cycles. In addition, this system showed good biocompatibility and environmental safety. This method increases the mass transfer capacity and enables easy recovery of immobilized cellulase, thereby serving as a valuable strategy for the immobilization of other enzymes.

The fusion of physics and biology in early mammalian embryogenesis

Biomechanics in embryogenesis is a dynamic field intertwining the physical forces and biological processes that shape the first days of a mammalian embryo. From the first cell fate bifurcation during blastulation to the complex symmetry breaking and tissue remodeling in gastrulation, mechanical cues appear critical in cell fate decisions and tissue patterning. Recent strides in mouse and human embryo culture, stem cell modeling of mammalian embryos, and biomaterial design have shed light on the role of cellular forces, cell polarization, and the extracellular matrix in influencing cell differentiation and morphogenesis. This chapter highlights the essential functions of biophysical mechanisms in blastocyst formation, embryo implantation, and early gastrulation where the interplay between the cytoskeleton and extracellular matrix stiffness orchestrates the intricacies of embryogenesis and placenta specification. The advancement of in vitro models like blastoids, gastruloids, and other types of embryoids, has begun to faithfully recapitulate human development stages, offering new avenues for exploring the biophysical underpinnings of early development. The integration of synthetic biology and advanced biomaterials is enhancing the precision with which we can mimic and study these processes. Looking ahead, we emphasize the potential of CRISPR-mediated genomic perturbations coupled with live imaging to uncover new mechanosensitive pathways and the application of engineered biomaterials to fine-tune the mechanical conditions conducive to embryonic development. This synthesis not only bridges the gap between experimental models and in vivo conditions to advancing fundamental developmental biology of mammalian embryogenesis, but also sets the stage for leveraging biomechanical insights to inform regenerative medicine.

Unveiling cellular and molecular aspects of ascending thoracic aortic aneurysms and dissections

Ascending thoracic aortic aneurysm (ATAA) remains a significant medical concern, with its asymptomatic nature posing diagnostic and monitoring challenges, thereby increasing the risk of aortic wall dissection and rupture. Current management of aortic repair relies on an aortic diameter threshold. However, this approach underestimates the complexity of aortic wall disease due to important knowledge gaps in understanding its underlying pathologic mechanisms.Since traditional risk factors cannot explain the initiation and progression of ATAA leading to dissection, local vascular factors such as extracellular matrix (ECM) and vascular smooth muscle cells (VSMCs) might harbor targets for early diagnosis and intervention. Derived from diverse embryonic lineages, VSMCs exhibit varied responses to genetic abnormalities that regulate their contractility. The transition of VSMCs into different phenotypes is an adaptive response to stress stimuli such as hemodynamic changes resulting from cardiovascular disease, aging, lifestyle, and genetic predisposition. Upon longer exposure to stress stimuli, VSMC phenotypic switching can instigate pathologic remodeling that contributes to the pathogenesis of ATAA.This review aims to illuminate the current understanding of cellular and molecular characteristics associated with ATAA and dissection, emphasizing the need for a more nuanced comprehension of the impaired ECM-VSMC network.

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.

Influences of Polyphenols on the Properties of Crosslinked Acellular Fish Swim Bladders: Experiments and Molecular Dynamic Simulations

Acellular fish swim bladders (AFSBs) are a promising biomaterial in tissue engineering, however, they may suffer from rapid degradation due to enzyme invasion. In this work, natural polyphenols, including epigallocatechin gallate (EGCG), proanthocyanidin (PC), tannic acid (TA) and protocatechuic acid (PCA), were utilized to improve the properties of AFSBs through crosslinking modifications. Fourier transform infrared (FTIR) results indicate that the triple helix of the collagen in AFSBs is well preserved after crosslinking. The differential scanning calorimetry (DSC), water contact angle (WCA) and in vitro degradation tests indicate that the polyphenol-crosslinked AFSBs exhibit improved thermal stability, enzymatic stability, hydrophilicity and mechanical properties. Among them, EGCG with multiple phenolic hydroxyl groups and low potential resistance is more favorable for the improvement of the mechanical properties and enzymatic stability of AFSBs, as well as their biocompatibility and integrity with the collagen triple helix. Moreover, the crosslinking mechanism was demonstrated to be due to the hydrogen bonds between polyphenols and AFSBs, and was affected by the molecular size, molecular weight and the hydroxyl groups activity of polyphenol molecules, as clarified by molecular dynamic (MD) simulations. The approach presented in this work paves a path for improving the properties of collagen materials.

The role of inflammatory mediators and matrix metalloproteinases (MMPs) in the progression of osteoarthritis

Osteoarthritis (OA) is a chronic musculoskeletal disorder characterized by an imbalance between (synthesis) and catabolism (degradation) in altered homeostasis of articular cartilage mediated primarily by the innate immune system. OA degenerates the joints resulting in synovial hyperplasia, degradation of articular cartilage with damage of the structural and functional integrity of the cartilage extracellular matrix, subchondral sclerosis, osteophyte formation, and is characterized by chronic pain, stiffness, and loss of function. Inflammation triggered by factors like biomechanical stress is involved in the development of osteoarthritis. In OA apart from catabolic effects, anti-inflammatory anabolic processes also occur continually. There is also an underlying chronic inflammation present, not only in cartilage tissue but also within the synovium, which perpetuates tissue destruction of the OA joint. The consideration of inflammation in OA considers synovitis and/or other cellular and molecular events in the synovium during the progression of OA. In this review, we have presented the progression of joint degradation that results in OA. The critical role of inflammation in the pathogenesis of OA is discussed in detail along with the dysregulation within the cytokine networks composed of inflammatory and anti-inflammatory cytokines that drive catabolic pathways, inhibit matrix synthesis, and promote cellular apoptosis. OA pathogenesis, fluctuation of synovitis, and its clinical impact on disease progression are presented here along with the role of synovial macrophages in promoting inflammatory and destructive responses in OA. The role of interplay between different cytokines, structure, and function of their receptors in the inter-cellular signaling pathway is further explored. The effect of cytokines in the increased synthesis and release of matrix-decomposing proteolytic enzymes, such as matrix metalloproteinase (MMPs) and a disintegrin-like and metalloproteinase with thrombospondin motif (ADAMTS), is elaborated emphasizing the potential impact of MMPs on the chondrocytes, synovial cells, articular and periarticular tissues, and other immune system cells migrating to the site of inflammation. We also shed light on the pathogenesis of OA via oxidative damage particularly due to nitric oxide (NO) via its angiogenic response to inflammation. We concluded by presenting the current knowledge about the tissue inhibitors of metalloproteinases (TIMPs). Synthetic MMP inhibitors include zinc binding group (ZBG), non-ZBG, and mechanism-based inhibitors, all of which have the potential to be therapeutically beneficial in the treatment of osteoarthritis. Improving our understanding of the signaling pathways and molecular mechanisms that regulate the MMP gene expression, may open up new avenues for the creation of therapies that can stop the joint damage associated with OA.

Inhibitory effects of Acanthopanax sessiliflorus Harms extract on the etiology of rheumatoid arthritis in a collagen-induced arthritis mouse model

BACKGROUND

The biological function of Acanthopanax sessiliflorus Harm (ASH) has been investigated on various diseases; however, the effects of ASH on arthritis have not been investigated so far. This study investigates the effects of ASH on rheumatoid arthritis (RA).

METHODS

Supercritical carbon dioxide (CO2) was used for ASH extract preparation, and its primary components, pimaric and kaurenoic acids, were identified using gas chromatography-mass spectrometer (GC-MS). Collagenase-induced arthritis (CIA) was used as the RA model, and primary cultures of articular chondrocytes were used to examine the inhibitory effects of ASH extract on arthritis in three synovial joints: ankle, sole, and knee.

RESULTS

Pimaric and kaurenoic acids attenuated pro-inflammatory cytokine-mediated increase in the catabolic factors and retrieved pro-inflammatory cytokine-mediated decrease in related anabolic factors in vitro; however, they did not affect pro-inflammatory cytokine (IL-1β, TNF-α, and IL-6)-mediated cytotoxicity. ASH effectively inhibited cartilage degradation in the knee, ankle, and toe in the CIA model and decreased pannus development in the knee. Immunohistochemistry demonstrated that ASH mostly inhibited the IL-6-mediated matrix metalloproteinase. Gene Ontology and pathway studies bridge major gaps in the literature and provide insights into the pathophysiology and in-depth mechanisms of RA-like joint degeneration.

CONCLUSIONS

To the best of our knowledge, this is the first study to conduct extensive research on the efficacy of ASH extract in inhibiting the pathogenesis of RA. However, additional animal models and clinical studies are required to validate this hypothesis.

Mapping the Binding Sites of MMPs on Types II and III Collagens Using Triple-Helical Peptide Toolkits

Libraries of triple-helical collagen-like peptides (Collagen Toolkits) have helped to define collagens II and III binding specificities of numerous collagen-binding proteins. Here I describe a simple solid-phase binding assay utilizing a biotin-streptavidin system to screen the Collagen Toolkits for binding of two distinct matrix metalloproteinases (MMPs) implicated in cancer: the collagenolytic MMP1 (collagenase 1) and the non-collagenolytic MMP3 (stromelysin 1). The screening revealed markedly disparate binding footprints of these MMPs on collagens II and III, in line with their distinct biological activities. Analogous screening of other potentially collagen-binding proteases may shed light on their inherent tissue retention capabilities and their pro- or anti-metastatic potential.

NDGA enhances the physicochemical and anti-biodegradation performance of dentin collagen

OBJECTIVES

Collagen fibrils from carious dentin matrix are prone to enzymatic degradation. This study investigates the feasibility and mechanism of nordihydroguaiaretic acid (NDGA), as a collagen crosslinker, to bio-modify the demineralized dentin matrix.

METHODS

The physicochemical properties of the crosslinked dentin matrix were characterized by swelling ratio, ninhydrin assay, Fourier Transform Infrared spectroscopy, and atomic force microscopy. The collagenase degradation resistance was evaluated by measuring loss of dry mass, hydroproline release, loss of elasticity, and micro-nano structure integrity. The cytotoxicity of NDGA-crosslinked dentin collagen was evaluated by flow cytometry.

RESULTS

NDGA crosslinked dentin matrix without destroying the integrity of collagen. Mechanistically, NDGA formed bisquinone bond between two adjacent o-quinone groups, resulting in NDGA polymeric matrix in which collagen fibrils were embedded. NDGA modification could significantly enhance the stiffness of dentin matrix at macro-nano scale. The NDGA-crosslinked dentin matrix exhibited remarkably low collagen degradation and sustained bulk elasticity after collagenase challenge, which were attributed to decreased water content, physical masking of collagenase bind sites on collagen, and improved stiffness of collagen fibrils. Notably, NDGA-crosslinked dentin matrix exhibited excellent biocompatibility.

CONCLUSION

NDGA, as a biocompatible collagen crosslinker, improves the mechanical properties and biodegradation resistance of demineralized dentin matrix.

Pathogenesis and therapeutic implications of matrix metalloproteinases in intervertebral disc degeneration: A comprehensive review

Intervertebral disc (IVD) degeneration (IDD) is a common disorder that affects the spine and is a major cause of lower back pain (LBP). The extracellular matrix (ECM) is the structural foundation of the biomechanical properties of IVD, and its degradation is the main pathological characteristic of IDD. Matrix metalloproteinases (MMPs) are a group of endopeptidases that play an important role in the degradation and remodeling of the ECM. Several recent studies have shown that the expression and activity of many MMP subgroups are significantly upregulated in degenerated IVD tissue. This upregulation of MMPs results in an imbalance of ECM anabolism and catabolism, leading to the degradation of the ECM and the development of IDD. Therefore, the regulation of MMP expression is a potential therapeutic target for the treatment of IDD. Recent research has focused on identifying the mechanisms by which MMPs cause ECM degradation and promote IDD, as well as on developing therapies that target MMPs. In summary, MMP dysregulation is a crucial factor in the development of IDD, and a deeper understanding of the mechanisms involved is needed to develop effective biological therapies that target MMPs to treat IDD.

Pan-tissue scaling of stiffness versus fibrillar collagen reflects contractility-driven strain that inhibits fibril degradation

Polymer network properties such as stiffness often exhibit characteristic power laws in polymer density and other parameters. However, it remains unclear whether diverse animal tissues, composed of many distinct polymers, exhibit such scaling. Here, we examined many diverse tissues from adult mouse and embryonic chick to determine if stiffness ( E tissue ) follows a power law in relation to the most abundant animal protein, Collagen-I, even with molecular perturbations. We quantified fibrillar collagen in intact tissue by second harmonic generation (SHG) imaging and from tissue extracts by mass spectrometry (MS), and collagenase-mediated decreases were also tracked. Pan-tissue power laws for tissue stiffness versus Collagen-I levels measured by SHG or MS exhibit sub-linear scaling that aligns with results from cellularized gels of Collagen-I but not acellular gels. Inhibition of cellular myosin-II based contraction fits the scaling, and combination with inhibitors of matrix metalloproteinases (MMPs) show collagenase activity is strain - not stress- suppressed in tissues, consistent with past studies of gels and fibrils. Beating embryonic hearts and tendons, which differ in both collagen levels and stiffness by >1000-fold, similarly suppressed collagenases at physiological strains of ∼5%, with fiber-orientation regulating degradation. Scaling of E tissue based on 'use-it-or-lose-it' kinetics provides insight into scaling of organ size, microgravity effects, and regeneration processes while suggesting contractility-driven therapeutics.

Collagen architecture and signaling orchestrate cancer development

The tumor microenvironment (TME) controls tumor progression and maintenance. Accordingly, tumor-centric cancer treatment must adjust to being more holistic and TME-centric. Collagens are the most abundant TME proteins, and their dynamic remodeling profoundly affects both TME architecture and tumor development. Recent evidence shows that in addition to being structural elements, collagens are an important source of nutrients and decisive growth controlling and immunoregulatory signals. This review focuses on macropinocytosis-dependent collagen support of cancer cell metabolism and the role of collagen fiber remodeling and trimer heterogeneity in control of tumor bioenergetics, growth, progression, and response to therapy. If properly translated, these basic advances may alter the future of cancer treatment.

Cell mediated ECM-degradation as an emerging tool for anti-fibrotic strategy

Investigation into the role of cells with respect to extracellular matrix (ECM) remodeling is still in its infancy. Particularly, ECM degradation is an indispensable process during the recovery from fibrosis. Cells with ECM degradation ability due to the secretion of various matrix metalloproteinases (MMPs) have emerged as novel contributors to the treatment of fibrotic diseases. In this review, we focus on the ECM degradation ability of cells associated with the repertoire of MMPs that facilitate the attenuation of fibrosis through the inhibition of ECM deposition. Besides, innovative approaches to engineering and characterizing cells with degradation ability, as well as elucidating the mechanism of the ECM degradation, are also illustrated. Studies conducted to date on the use of cell-based degradation for therapeutic purposes to combat fibrosis are summarized. Finally, we discuss the therapeutic potential of cells with high degradation ability, hoping to bridge the gap between benchside research and bedside applications in treating fibrotic diseases.

Development of Matrix Metalloproteinases-Mediated Extracellular Matrix Remodeling in Regenerative Medicine: A Mini Review

Extracellular matrix (ECM) components confer biomechanical properties, maintain cell phenotype and mediate tissue homeostasis. ECM remodeling is complex and plays a key role in both physiological and pathological processes. Matrix metalloproteinases (MMPs) are a group of enzymes responsible for ECM degradation and have been accepted as a key regulator in ECM remodeling. In this mini-review, we summarize MMPs categories, functions and the targeted substrates. We then discuss current understanding of the role of MMPs-mediated events, including inflammation reaction, angiogenesis, cellular activities, etc., in ECM remodeling in the context of regenerative medicine.

The Chemistry and Biology of Collagen Hybridization

Collagen provides mechanical and biological support for virtually all human tissues in the extracellular matrix (ECM). Its defining molecular structure, the triple-helix, could be damaged and denatured in disease and injuries. To probe collagen damage, the concept of collagen hybridization has been proposed, revised, and validated through a series of investigations reported as early as 1973: a collagen-mimicking peptide strand may form a hybrid triple-helix with the denatured chains of natural collagen but not the intact triple-helical collagen proteins, enabling assessment of proteolytic degradation or mechanical disruption to collagen within a tissue-of-interest. Here we describe the concept and development of collagen hybridization, summarize the decades of chemical investigations on rules underlying the collagen triple-helix folding, and discuss the growing biomedical evidence on collagen denaturation as a previously overlooked ECM signature for an array of conditions involving pathological tissue remodeling and mechanical injuries. Finally, we propose a series of emerging questions regarding the chemical and biological nature of collagen denaturation and highlight the diagnostic and therapeutic opportunities from its targeting.

Crosslinking Improve Demineralized Dentin Performance and Synergistically Promote Biomimetic Mineralization by CaP_PILP

OBJECTIVE

to explore the effects of optimal crosslinking (chemical treatment) on demineralized dentin matrix and the possible synergism with calcium phosphate polymer-induced liquid precursor (CaP-PILP) bionic remineralization (physical treatment), and offer benefit to the clinic of resin-dentin bonding and dentin hypersensitivity.

METHODS

demineralized dentin was treated with glutaraldehyde (GA), carbodiimide (EDC), and procyanidin (PA) for crosslinking, followed by CaP-PILP biomimetic remineralization. The morphology, surface mechanical and physio-chemical properties, and enzymatic resistance were evaluated regardless of the modification.

RESULTS

the collagen fibers appeared morphologically complete with higher surface microhardness and characteristic peaks of amide I-III bands were visible after GA, PA, and EDC crosslinking. Collagen collapse and dissolution were seen in untreated demineralized dentin with enzyme attack, while the collagen fiber structure remained intact in GA- and PA-treated specimens. The lamellar mineral phase was visible at 2 days and the dentin tubules were almost completely enclosed at 4-6 days after PA crosslinking and mineralization. However, demineralized collagen fibers and open tubules were still visible between the dentinal tubules on day 8 in the control group.

CONCLUSION

the structure integrity, enzyme resistance, and mechanical properties of the collagen fiber network could be significantly preserved by GA and PA crosslinking than EDC and no treatment. While, strongest synergistic effects were observed in PA on bionic remineralization by CaP-PILP, and further significantly improve the quality and shorten the duration of mineralization. These findings would be beneficial for dental clinical practice of resin-dentin bonding and dentin hypersensitivity.

Effects of Riboflavin Collagen Crosslinker on Dentin Adhesive Bonding Efficiency: A Systematic Review and Meta-Analysis

The aim of this study was to evaluate published data regarding riboflavin (RF) as a cross-linker for improved adhesive bond strength to dentin and to analyze previous studies for optimal concentration of riboflavin range suitable for dentin bond. Saliva and distilled water were used as storage media and aging time was 24 h and 6 months. Results of meta-analysis were synthesized using a statistical method of inverse variance in random effects with a 95% Confidence Interval (CI). Cochrane review manager 5.4.1 was used to determine results of the meta-analysis. In total, 3172 articles were found from search databases "PubMed", "Scopus", and "Google Scholar". Six of the fifteen studies were eligible for meta-analysis. Micro tensile strength shows significant improvement with the addition of riboflavin (p < 0.05) compared to without the addition of riboflavin from with 95% CI. A significant difference has been found in micro tensile bond strength between use of the riboflavin cross-linker and without use of the riboflavin crosslinker in the dentin adhesive system. With a 95% confidence interval (CI), the I² for micro tensile strength was 89% with strong heterogeneity, Chi² = 44.76, df = 5 (p < 0.00001), and overall effect size is Z = 2.22 (p = 0.03) after immediate aging. Chiang et al. 2013 shows maximum mean differences which is 38.50 [17.93-59.07]. After 6 months of aging in distilled water or artificial saliva micro tensile bond strength has been increased with the addition of riboflavin (p < 0.05). It can be clearly seen that pooled effect and 95% CI did not cross the line of no effect. With a 95% confidence interval (CI), the I² for micro tensile strength was 96% with strong heterogeneity, Chi² = 117.56, df = 5 (p < 0.00001), and overall effect size is Z = 2.30 (p = 0.02). Subgroup analysis proved a similar effect of distilled water and artificial saliva as storage media on micro tensile bond strength after incorporating riboflavin as a collagen crosslinker. An artificial saliva aged forest plot also showed considerable heterogeneity with I² = 96%; Tau² = 257.32; Chi² = 94.37; df = 2 (p < 0.00001); test for overall effect, Z = 1.06 (p = 0.29). Riboflavin prior to or with bonding is recommended to improve the bonding of different adhesive systems.

First Characterization of the Transcriptome of Lung Fibroblasts of SSc Patients and Healthy Donors of African Ancestry

Systemic sclerosis (SSc) is a connective tissue disorder that results in fibrosis of the skin and visceral organs. SSc-associated pulmonary fibrosis (SSc-PF) is the leading cause of death amongst SSc patients. Racial disparity is noted in SSc as African Americans (AA) have a higher frequency and severity of disease than European Americans (EA). Using RNAseq, we determined differentially expressed genes (DEGs; q < 0.1, log2FC > |0.6|) in primary pulmonary fibroblasts from SSc lungs (SScL) and normal lungs (NL) of AA and EA patients to characterize the unique transcriptomic signatures of AA-NL and AA-SScL fibroblasts using systems-level analysis. We identified 69 DEGs in "AA-NL vs. EA-NL" and 384 DEGs in "AA-SScL vs. EA-SScL" analyses, and a comparison of disease mechanisms revealed that only 7.5% of DEGs were commonly deregulated in AA and EA patients. Surprisingly, we also identified an SSc-like signature in AA-NL fibroblasts. Our data highlight differences in disease mechanisms between AA and EA SScL fibroblasts and suggest that AA-NL fibroblasts are in a "pre-fibrosis" state, poised to respond to potential fibrotic triggers. The DEGs and pathways identified in our study provide a wealth of novel targets to better understand disease mechanisms leading to racial disparity in SSc-PF and develop more effective and personalized therapies.

Involvement of MMP-9 in collagen degradation of sea bass (Lateolabrax japonicus): Cloning, expression, and characterization

Disintegration of intramuscular connective tissue is responsible for postmortem tenderization of fish muscles during chilled storage. Matrix metalloproteinase-9 (MMP-9) was reported to be involved in this process, whereas the mechanism has not been revealed. In the present study, purified type I and V collagens from the connective tissues of sea bass (Lateolabrax japonicus) muscles were first prepared. These two kinds of collagens comprise three polypeptide chains (α), forming a typical triple-helical domain as determined by circular dichroism. The complete coding region of MMP-9 containing an open reading frame of 2070 bp encoding 689 amino acid residues was then cloned. The recombinant MMP-9 catalytic domain (rcMMP-9) was expressed in Escherichia coli and exhibited high hydrolyzing activity toward gelatin. Besides, rcMMP-9 was effective in degrading type V collagen rather than type I collagen at 4°C. The enzymatic activity of rcMMP-9 was highly pH-dependent, and its enzymatic activity under neutral and basic conditions was higher than that under acidic conditions. Metal ion Ca²⁺ was necessary for the maintenance of rcMMP-9 activity, whereas Zn²⁺ inhibited its activity. Our present study indicated that MMP-9 is responsible for the disintegration of intramuscular connective tissues by cleaving type V collagen during postmortem tenderization of fish muscle. PRACTICAL APPLICATION: Elucidation the involvement of MMP-9 in collagen degradation will deliver a reference for the prevention of muscular protein decomposition during chilled storage of fish fillets.

Mechanism of the Early Catalytic Events in the Collagenolysis by Matrix Metalloproteinase-1

Metalloproteinase-1 (MMP-1) catalyzed collagen degradation is essential for a wide variety of normal physiological processes, while at the same time contributing to several diseases in humans. Therefore, a comprehensive understanding of this process is of great importance. Although crystallographic and spectroscopic studies provided fundamental information about the structure and function of MMP-1, the precise mechanism of collagen degradation especially considering the complex and flexible structure of the substrate, remains poorly understood. In addition, how the protein environment dynamically reorganizes at the atomic scale into a catalytically active state capable of collagen hydrolysis remains unknown. In this study, we applied experimentally-guided multiscale molecular modeling methods including classical molecular dynamics (MD), well-tempered (WT) classical metadynamics (MetD), combined quantum mechanics/molecular mechanics (QM/MM) MD and QM/MM MetD simulations to explore and characterize the early catalytic events of MMP-1 collagenolysis. Importantly the study provided a complete atomic and dynamic description of the transition from the open to the closed form of the MMP-1•THP complex. Notably, the formation of catalytically active Michaelis complex competent for collagen cleavage was characterized. The study identified the changes in the coordination state of the catalytic zinc(II) associated with the conformational transformation and the formation of catalytically productive ES complex. Our results confirm the essential role of the MMP-1 catalytic domain's α-helices (hA, hB and hC) and the linker region in the transition to the catalytically competent ES complex. Overall, the results provide unique mechanistic insight into the conformational transformations and associated changes in the coordination state of the catalytic zinc(II) that would be important for the design of effective MMP-1 inhibitors.

The Role of Membrane-Type 1 Matrix Metalloproteinase-Substrate Interactions in Pathogenesis

A protease is an enzyme with a proteolytic activity that facilitates the digestion of its substrates. Membrane-type I matrix metalloproteinase (MT1-MMP), a member of the broader matrix metalloproteinases (MMP) family, is involved in the regulation of diverse cellular activities. MT1-MMP is a very well-known enzyme as an activator of pro-MMP-2 and two collagenases, MMP-8 and MMP-13, all of which are essential for cell migration. As an anchored membrane enzyme, MT1-MMP has the ability to interact with a diverse group of molecules, including proteins that are not part of the extracellular matrix (ECM). Therefore, MT1-MMP can regulate various cellular activities not only by changing the extra-cellular environment but also by regulating cell signaling. The presence of both intracellular and extra-cellular portions of MT1-MMP can allow it to interact with proteins on both sides of the cell membrane. Here, we reviewed the MT1-MMP substrates involved in disease pathogenesis.

Species-Based Differences in Mechanical Properties, Cytocompatibility, and Printability of Methacrylated Collagen Hydrogels

Collagen methacrylation is a promising approach to generate photo-cross-linkable cell-laden hydrogels with improved mechanical properties. However, the impact of species-based variations in amino acid composition and collagen isolation method on methacrylation degree (MD) and its subsequent effects on the physical properties of methacrylated collagen (CMA) hydrogels and cell response are unknown. Herein, we compared the effects of three collagen species (bovine, human, and rat), two collagen extraction methods (pepsin digestion and acid extraction), and two photoinitiators (lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) and Irgacure-2959 (I-2959)) on the physical properties of CMA hydrogels, printability and mesenchymal stem cell (MSC) response. Human collagen showed the highest MD. LAP was more cytocompatible than I-2959. The compressive modulus and cell viability of rat CMA were significantly higher (p < 0.05) than bovine CMA. Human CMA yielded constructs with superior print fidelity. Together, these results suggest that careful selection of collagen source and cross-linking conditions is essential for biomimetic design of CMA hydrogels for tissue engineering applications.

Relationships of Matrix Metalloproteinase 1 and a Tissue Inhibitor of Metalloproteinase to Collagen Metabolism in Haliotis discus hannai

In response to physical, chemical, and/or biological stimuli, considerable tissue self-degradation occurs in abalone, causing severe post-harvest quality loss. During this process, the extracellular matrix (ECM) is greatly degraded by endogenous proteases. The main component of the ECM is collagen, primarily type I collagen. Although the activity of matrix metalloproteinases (MMPs), which can specifically degrade collagen, is precisely regulated by tissue inhibitors of MPs (TIMPs), indicating that MMPs and TIMPs play crucial roles in the regulation of tissue self-degradation, few studies have reported the interaction between MMPs and TIMPs. In this study, we reveal collagenases to participate in postmortem tissue self-degradation of Haliotis discus hannai by degrading type I collagen. The recombinant MMP-1 catalytic domain (rMMP1c) of abalone with high purity and enzyme activity is expressed using a prokaryotic expression system. The optimum temperature and pH for rMMP1c are 37 °C and 7.0, respectively. The thermal denaturation temperature of rMMP1c is 67.0 ± 0.9 °C. Ethylenediamine tetraacetic acid (EDTA) and 1,10-phenanthroline can completely inhibit rMMP1c activity, while Ba²⁺, Ca²⁺, and Mg²⁺ can significantly elevate it. TIMP is also expressed using HEK 293F cells. Recombinant TIMP (rTIMP) shows good inhibitory activity toward rMMP1c. Inhibition kinetics analyses reveal rTIMP to be a competitive inhibitor of rMMP1c. Biolayer interferometry reveals that rTIMP can effectively bind with rMMP1c, with an equilibrium dissociation constant value of 263 nM. rMMP1c effectively degrades type I collagen γ-β-α chains in turn, and rTIMP can significantly inhibit rMMP1c degradation activity. These results provide a theoretical basis for the study of MMP and TIMP interaction and elucidate the possible mechanism for abalone tissue self-degradation.

Biophysical and in vitro wound healing assessment of collagen peptides processed from fish skin waste

The present study was conducted to examine the bioactive and wound healing properties of collagen hydrolysate derived from Piaractus brachypomus (pacu) fish skin waste. Collagen type I (P coll.) yielding 72.25% was isolated from skin waste by following acid-soluble collagen extraction method. Further, collagen was fragmented using bacterial collagenase and the processed collagen hydrolysate (peptides) was in the range of 10–15 kDa that was further purified using ion-exchange chromatography. The FTIR spectra of both P coll. and collagen hydrolysate (PSCH) were nearly similar showing that PSCH retained the structural and chemical composition similar to its parent molecule (P coll.). Solubility analysis revealed that PSCH has slightly better solubility compared to P coll. Similarly, scanning electron micrographs also exhibited more uniform and porous microstructure of PSCH compared to P coll. Further, PSCH was found to be efficient in peroxide quenching (64.5%) and radical scavenging activities (85.74%). MTT studies confirmed PSCH to be non-toxic displaying 84.68% cell viability at the highest concentration (3 mg/ml) and hemocompatibility test revealed PSCH to be non-hemolytic with minimal lysis of only 2.1% of human RBCs. In addition, PSCH also displayed a remarkable wound closure ability of more than 80% at 12 h and 100% within 24 h. Hence, these findings suggest that recycled PSCH has potent wound healing ability and can be produced economically on a large scale for possible biological applications in regenerative medicine.

The application of collagen in the repair of peripheral nerve defect

Collagen is a natural polymer expressed in the extracellular matrix of the peripheral nervous system. It has become increasingly crucial in peripheral nerve reconstruction as it was involved in regulating Schwann cell behaviors, maintaining peripheral nerve functions during peripheral nerve development, and being strongly upregulated after nerve injury to promote peripheral nerve regeneration. Moreover, its biological properties, such as low immunogenicity, excellent biocompatibility, and biodegradability make it a suitable biomaterial for peripheral nerve repair. Collagen provides a suitable microenvironment to support Schwann cells’ growth, proliferation, and migration, thereby improving the regeneration and functional recovery of peripheral nerves. This review aims to summarize the characteristics of collagen as a biomaterial, analyze its role in peripheral nerve regeneration, and provide a detailed overview of the recent advances concerning the optimization of collagen nerve conduits in terms of physical properties and structure, as well as the application of the combination with the bioactive component in peripheral nerve regeneration.

Identification and Characterization of Fibronectin-Binding Peptides in Gelatin

Collagen and fibronectin (FN) are important components in the extracellular matrix (ECM). Collagen-FN binding belongs to protein-protein interaction and plays a key role in regulating cell behaviors. In this study, FN-binding peptides were isolated from gelatin (degraded collagen) using affinity chromatography, and the amino acid sequences were determined using HPLC-MS. The results indicated that all FN-binding peptides contained GPAG or GPPG. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and dual-polarization interferometry (DPI) were used to analyze the effects of hydroxylation polypeptide on FN binding activity. DPI analysis indicated that peptides with molecular weight (MW) between 2 kDa and 30 kDa showed higher FN-binding activity, indicating MW range played an important role in the interaction between FN and peptides. Finally, two peptides with similar sequences except for hydroxylation of prolines were synthesized. The FN-binding properties of the synthesized peptides were determined by MALDI-TOF MS. For peptide, GAPGADGP*AGAPGTP*GPQGIAGQR, hydroxylation of P8 and P15 is necessary for FN-binding. For peptide, GPPGPMGPPGLAGPPGESGR, the FN-binding process is independent of proline hydroxylation. Thus, FN-binding properties are proline-hydroxylation dependent.

Effects of the Combined Application of Trimethylated Chitosan and Carbodiimide on the Biostability and Antibacterial Activity of Dentin Collagen Matrix

The structural integrity of a dentin matrix that has been demineralized by the clinical use of etchants or calcium-depleting endodontic irrigants, such as endodontic ethylenediaminetetraacetic acid (EDTA), is often deteriorated due to the collagenolytic activities of reactivated endogenous enzymes as well as the infiltration of extrinsic bacteria. Therefore, the biomodification of dentin collagen with improved stability and antibacterial activity holds great promise in conservative dentistry. The purpose of this study was to evaluate the effects of the combined application of trimethylated chitosan (TMC) and 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC) on the biostability and antibacterial activity of the demineralized dentin collagen matrix. The morphological changes in the collagen matrix were observed by scanning electron microscopy (SEM), the amount of TMC adsorbed on the collagen surface was detected by X-ray photoelectron spectroscopy, and the elastic modulus was measured by a three-point bending device. Dry weight loss and amino acid release were detected to evaluate its anti-collagenase degradation performance. The antibacterial performance was detected by confocal microscopy. The TMC-treated group had less collagen space and a more compact collagen arrangement, while the untreated group had a looser collagen arrangement. The combined application of TMC and EDC can increase the elastic modulus, reduce the loss of elastic modulus, and result in good antibacterial performance. The current study proved that a dentin collagen matrix biomodified by TMC and EDC showed improved biodegradation resistance and antibacterial activities.

Multi-pin contact drawing enables production of anisotropic collagen fiber substrates for alignment of fibroblasts and monocytes

Type I collagen is the most abundant protein in the human body and is known to play important roles in numerous biological processes including tissue morphogenesis and wound healing. As such, it is one of the most frequently used substrates for cell culture, and there have been considerable efforts to develop collagen-based cell culture substrates that mimic the structural organization of collagen as it is found in native tissues, i.e., collagen fibers. However, producing collagen fibers from extracted collagen has been notoriously difficult, with existing methods providing only low throughput production of collagen fibers. In this study, we prepared collagen fibers using a highly efficient, bio-friendly, and cost-effective approach termed contact drawing, which uses an entangled polymer fluid to aid in fiber formation. Contact drawing technology has been demonstrated previously for collagen using highly concentrated dextran solutions with low concentrations of collagen. Here, we show that by replacing dextran with polyethylene oxide (PEO), high collagen content fibers may be readily formed from mixtures of soluble collagen and PEO, a polymer that readily forms fibers by contact drawing at concentrations as low as 0.5%wt. The presence of collagen and the formation of well-ordered collagen structures in the resulting fibers were characterized by attenuated total reflectance Fourier-transform infrared spectromicroscopy, Raman spectromicroscopy, and fluorescence microscopy. Corresponding to well-ordered collagen, the mechanical properties of the PEO-collagen fibers approximated those observed for native collagen fibers. Growth of cells on aligned PEO-collagen fibers attached to a polydimethyl siloxane support was examined for human dermal fibroblast (WS1) and human peripheral leukemia blood monocyte (THP-1) cell lines. WS1 and THP-1 cells readily attached, displayed alignment through migration and spreading, and proliferated on the collagen fiber substrate over the course of several days. We also demonstrated the retrieval of viable cells from the PEO-collagen fiber substrates through enzymatic digestion of the collagen substrate with collagenase IV.

Matrix Metalloproteinases: From Molecular Mechanisms to Physiology, Pathophysiology, and Pharmacology

The first matrix metalloproteinase (MMP) was discovered in 1962 from the tail of a tadpole by its ability to degrade collagen. As their name suggests, matrix metalloproteinases are proteases capable of remodeling the extracellular matrix. More recently, MMPs have been demonstrated to play numerous additional biologic roles in cell signaling, immune regulation, and transcriptional control, all of which are unrelated to the degradation of the extracellular matrix. In this review, we will present milestones and major discoveries of MMP research, including various clinical trials for the use of MMP inhibitors. We will discuss the reasons behind the failures of most MMP inhibitors for the treatment of cancer and inflammatory diseases. There are still misconceptions about the pathophysiological roles of MMPs and the best strategies to inhibit their detrimental functions. This review aims to discuss MMPs in preclinical models and human pathologies. We will discuss new biochemical tools to track their proteolytic activity in vivo and ex vivo, in addition to future pharmacological alternatives to inhibit their detrimental functions in diseases. SIGNIFICANCE STATEMENT: Matrix metalloproteinases (MMPs) have been implicated in most inflammatory, autoimmune, cancers, and pathogen-mediated diseases. Initially overlooked, MMP contributions can be both beneficial and detrimental in disease progression and resolution. Thousands of MMP substrates have been suggested, and a few hundred have been validated. After more than 60 years of MMP research, there remain intriguing enigmas to solve regarding their biological functions in diseases.

Another Wrinkle with Age: Aged Collagen and Intra-peritoneal Metastasis of Ovarian Cancer

Background

Age is the most significant risk factor for ovarian cancer (OvCa), the deadliest gynecologic malignancy. Metastasizing OvCa cells adhere to the omentum, a peritoneal structure rich in collagen, adipocytes, and immune cells. Ultrastructural changes in the omentum and the omental collagen matrix with aging have not been evaluated.

Aim

The aim of this study was to test the hypothesis that age-related changes in collagen in the ovarian tumor microenvironment promote OvCa metastatic success in the aged host.

Methods/Results

Young (3-6 months) and aged mice (20-23 months) were used to study the role of aging in metastatic success. Intra-peritoneal (IP) injection of ID8Trp53 ^-/- ovarian cancer cells showed enhanced IP dissemination in aged vs young mice. In vitro assays using purified collagen demonstrated reduced collagenolysis of aged fibers, as visualized using scanning electron microscopy (SEM) and quantified with a hydroxyproline release assay. Omental tumors in young and aged mice showed similar collagen deposition; however enhanced intra-tumoral collagen remodeling was seen in aged mice probed with a biotinylated collagen hybridizing peptide (CHP). In contrast, second harmonic generation (SHG) microscopy showed significant differences in collagen fiber structure and organization in omental tissue and SEM demonstrated enhanced omental fenestration in aged omenta. Combined SHG and Alexa Fluor-CHP microscopy in vivo demonstrated that peri-tumoral collagen was remodeled more extensively in young mice. This collagen population represents truly aged host collagen, in contrast to intra-tumoral collagen that is newly synthesized, likely by cancer associated fibroblasts (CAFs).

Conclusions

Our results demonstrate that tumors in an aged host can grow with minimal collagen remodeling, while tumors in the young host must remodel peri-tumoral collagen to enable effective proliferation, providing a mechanism whereby age-induced ultrastructural changes in collagen and collagen-rich omenta establish a permissive pre-metastatic niche contributing to enhanced OvCa metastatic success in the aged host.

Marine origin biomaterials using a compressive and absorption methodology as cell-laden hydrogel envisaging cartilage tissue engineering

In the recent decade, marine origin products have been growingly studied as building blocks complying with the constant demand of the biomedical sector regarding the development of new devices for Tissue Engineering and Regenerative Medicine (TERM). In this work, several combinations of marine collagen-chitosan-fucoidan hydrogel were formed using a newly developed eco-friendly compressive and absorption methodology to produce hydrogels (CAMPH), which consists of compacting the biopolymers solution while removing the excess of water. The hydrogel formulations were prepared by blending solutions of 5% collagen from jellyfish and/or 3% collagen from blue shark skin, with solutions of 3% chitosan from squid pens and solutions of 10% fucoidan from brown algae, at different ratios. The biopolymer physico-chemical characterization comprised Amino Acid analysis, ATR-FTIR, CD, SDS-PAGE, ICP, XRD, and the results suggested the shark/jellyfish collagen(s) conserved the triple helical structure and had similarities with type I and type II collagen, respectively. The studied collagens also contain a denaturation temperature of around 30-32 °C and a molecular weight between 120 and 125 kDa. Additionally, the hydrogel properties were determined by rheology, water uptake ability, degradation rate, and SEM, and the results showed that all formulations had interesting mechanical (strong viscoelastic character) and structural stability properties, with a significant positive highlight in the formulation of H₃ (blending all biopolymers, i.e., 5% collagen from jellyfish, 3% collagen from skin shark, 3% chitosan and 10% of fucoidan) in the degradation test, that shows a mass loss around 18% over the 30 days, while the H₁ and H₂, present a mass loss of around 35% and 44%, respectively. Additionally, the in vitro cellular assessments using chondrocyte cells (ATDC5) in encapsulated state revealed, for all hydrogel formulations, a non-cytotoxic behavior. Furthermore, Live/Dead assay and Phalloidin/DAPI staining, to assess the cytoskeletal organization, proved that the hydrogels can provide a suitable microenvironment for cell adhesion, viability, and proliferation, after being encapsulated. Overall, the results show that all marine collagen (jellyfish/shark)-chitosan-fucoidan hydrogel formulations provide a good structural architecture and microenvironment, highlighting the H₃ biomaterial due to containing more polymers in their composition, making it suitable for biomedical articular cartilage therapies.