Physical network regimes of 3D fibrillar collagen networks trigger invasive phenotypes of breast cancer cells

The mechanical characteristics of the extracellular environment are known to significantly influence cancer cell behavior in vivo and in vitro. The structural complexity and viscoelastic dynamics of the extracellular matrix (ECM) pose significant challenges in understanding its impact on cancer cells. Herein, we report distinct regulatory signatures in the invasion of different breast cancer cell lines into three-dimensional (3D) fibrillar collagen networks, caused by systematic modifications of the physical network properties. By reconstituting collagen networks of thin fibrils, we demonstrate that such networks can display network strand flexibility akin to that of synthetic polymer networks, known to exhibit entropic rubber elasticity. This finding contrasts with the predominant description of the mechanics of fibrillar collagen networks by an enthalpic bending elasticity of rod-like fibrils. Mean-squared displacement analysis of free-standing fibrils confirmed a flexible fiber regime in networks of thin fibrils. Furthermore, collagen fibrils in both networks were softened by the adsorption of highly negatively charged sulfonated polymers and colloidal probe force measurements of network elastic modulus again proofed the occurrence of the two different physical network regimes. Our cell assays revealed that the cellular behavior (morphology, clustering, invasiveness, matrix metalloproteinase (MMP) activity) of the 'weakly invasive' MCF-7 and 'highly invasive' MDA-MB-231 breast cancer cell lines is distinctively affected by the physical (enthalpic/entropic) network regime, and cannot be explained by changes of the network elastic modulus, alone. These results highlight an essential pathway, albeit frequently overlooked, how the physical characteristics of fibrillar ECMs affect cellular behavior. Considering the coexistence of diverse physical network regimes of the ECM in vivo, our findings underscore their critical role of ECM's physical network regimes in tumor progression and other cell functions, and moreover emphasize the significance of 3D in vitro collagen network models for quantifying cell responses in both healthy and pathological states.

The Influence of Sulfation Degree of Glycosaminoglycan-Functionalized 3D Collagen I Networks on Cytokine Profiles of In Vitro Macrophage-Fibroblast Cocultures

Cell-cell interactions between fibroblasts and immune cells, like macrophages, are influenced by interaction with the surrounding extracellular matrix during wound healing. In vitro hydrogel models that mimic and modulate these interactions, especially of soluble mediators like cytokines, may allow for a more detailed investigation of immunomodulatory processes. In the present study, a biomimetic extracellular matrix model based on fibrillar 3D collagen I networks with a functionalization with heparin or 6-ON-desulfated heparin, as mimics of naturally occurring heparan sulfate, was developed to modulate cytokine binding effects with the hydrogel matrix. The constitution and microstructure of the collagen I network were found to be stable throughout the 7-day culture period. A coculture study of primary human fibroblasts/myofibroblasts and M-CSF-stimulated macrophages was used to show its applicability to simulate processes of progressed wound healing. The quantification of secreted cytokines (IL-8, IL-10, IL-6, FGF-2) in the cell culture supernatant demonstrated the differential impact of glycosaminoglycan functionalization of the collagen I network. Most prominently, IL-6 and FGF-2 were shown to be regulated by the cell culture condition and network constitution, indicating changes in paracrine and autocrine cell-cell communication of the fibroblast-macrophage coculture. From this perspective, we consider our newly established in vitro hydrogel model suitable for mechanistic coculture analyses of primary human cells to unravel the role of extracellular matrix factors in key events of tissue regeneration and beyond.

Four-Arm Polymer-Guided Formation of Curcumin-Loaded Flower-Like Porous Microspheres as Injectable Cell Carriers for Diabetic Wound Healing

Stem cell injection is an effective approach for treating diabetic wounds; however, shear stress during injections can negatively affect their stemness and cell growth. Cell-laden porous microspheres can provide shelter for bone mesenchymal stem cells (BMSC). Herein, curcumin-loaded flower-like porous microspheres (CFPM) are designed by combining phase inversion emulsification with thermally induced phase separation-guided four-arm poly (l-lactic acid) (B-PLLA). Notably, the CFPM shows a well-defined surface topography and inner structure, ensuring a high surface area to enable the incorporation and delivery of a large amount of -BMSC and curcumin. The BMSC-carrying CFPM (BMSC@CFPM) maintains the proliferation, retention, and stemness of -BMSCs, which, in combination with their sustainable curcumin release, facilitates the endogenous production of growth/proangiogenic factors and offers a local anti-inflammatory function. An in vivo bioluminescence assay demonstrates that BMSC@CFPM can significantly increase the retention and survival of BMSC in wound sites. Accordingly, BMSC@CFPM, with no significant systemic toxicity, could significantly accelerate diabetic wound healing by promoting angiogenesis, collagen reconstruction, and M2 macrophage polarization. RNA sequencing further unveils the mechanisms by which BMSC@CFPM promotes diabetic wound healing by increasing -growth factors and enhancing angiogenesis through the JAK/STAT pathway. Overall, BMSC@CFPM represents a potential therapeutic tool for diabetic wound healing.

Mechanical Signal-Tailored Hydrogel Microspheres Recruit and Train Stem Cells for Precise Differentiation

The aberrant mechanical microenvironment in degenerated tissues induces misdirection of cell fate, making it challenging to achieve efficient endogenous regeneration. Herein, a hydrogel microsphere-based synthetic niche with integrated cell recruitment and targeted cell differentiation properties via mechanotransduction is constructed . Through the incorporation of microfluidics and photo-polymerization strategies, fibronectin (Fn) modified methacrylated gelatin (GelMA) microspheres are prepared with the independently tunable elastic modulus (1-10Kpa) and ligand density (2 and 10 µg mL-1 ), allowing a wide range of cytoskeleton modulation to trigger the corresponding mechanobiological signaling. The combination of the soft matrix (2Kpa) and low ligand density (2 µg mL-1 ) can support the nucleus pulposus (NP)-like differentiation of intervertebral disc (IVD) progenitor/stem cells by translocating Yes-associated protein (YAP), without the addition of inducible biochemical factors. Meanwhile, platelet-derived growth factor-BB (PDGF-BB) is loaded onto Fn-GelMA microspheres (PDGF@Fn-GelMA) via the heparin-binding domain of Fn to initiate endogenous cell recruitment. In in vivo experiments, hydrogel microsphere-niche maintained the IVD structure and stimulated matrix synthesis. Overall, this synthetic niche with cell recruiting and mechanical training capabilities offered a promising strategy for endogenous tissue regeneration.

Collagen Fibril Orientation Instructs Fibroblast Differentiation Via Cell Contractility

Collagen alignment is one of the key microarchitectural signatures of many pathological conditions, including scarring and fibrosis. Investigating how collagen alignment modulates cellular functions will pave the way for understanding tissue scarring and regeneration and new therapeutic strategies. However, current approaches for the fabrication of three-dimensional (3D) aligned collagen matrices are low-throughput and require special devices. To overcome these limitations, a simple approach to reconstitute homogeneous 3D collagen matrices with adjustable degree of fibril alignment using 3D printed inclined surfaces is developed. By characterizing the mechanical properties of reconstituted matrices, it is found that the elastic modulus of collagen matrices is enhanced with an increase in the alignment degree. The reconstituted matrices are used to study fibroblast behavior to reveal the progression of scar formation where a gradual enhancement of collagen alignment can be observed. It is found that matrices with aligned fibrils trigger fibroblast differentiation into myofibroblasts via cell contractility, while collagen stiffening through a crosslinker does not. The results suggest the impact of collagen fibril organization on the regulation of fibroblast differentiation. Overall, this approach to reconstitute 3D collagen matrices with fibril alignment opens opportunities for biomimetic pathological-relevant tissue in vitro, which can be applied for other biomedical research.

Tenascin-C Activation of Lung Fibroblasts in a 3D Synthetic Lung Extracellular Matrix Mimic

The lung extracellular matrix (ECM) maintains the structural integrity of the tissue and regulates the phenotype and functions of resident fibroblasts. Lung-metastatic breast cancer alters these cell-ECM interactions, promoting fibroblast activation. There is a need for bio-instructive ECM models that match the ECM composition and biomechanics of the lung to study these cell-matrix interactions in vitro. Here, a synthetic, bioactive hydrogel is synthesized that mimics the native lung modulus and includes a representative distribution of the most abundant ECM peptide motifs responsible for integrin-binding and matrix metalloproteinase (MMP)-mediated degradation in the lung, which enables quiescent culture of human lung fibroblasts (HLFs). Stimulation with transforming growth factor β1 (TGF-β1), metastatic breast cancer conditioned media (CM), or tenascin-C-derived integrin-binding peptide activated hydrogel-encapsulated HLFs demonstrates multiple environmental methods to activate HLFs in a lung ECM-mimicking hydrogel. This lung hydrogel platform is a tunable, synthetic approach to studying the independent and combinatorial effects of ECM in regulating fibroblast quiescence and activation.

Interactions of Fibroblast Subtypes Influence Osteoclastogenesis and Alveolar Bone Destruction in Periodontitis

Background

To analyze the fibroblasts subtypes in the gingival tissues of healthy controls, gingivitis and periodontitis patients, as well as the effects of interaction between subtypes on alveolar bone destruction.

Methods

Gingival tissues were divided into three groups according to clinical and radiographic examination, and the immunostaining of EDA+FN was assessed. Fibroblasts from gingiva developed colony formation units (CFUs) and induced Trap+MNCs. The expression of osteoclastogenesis-related genes was assessed by real-time PCR. Variances in the gene profiles of CFUs were identified by principal component analysis, and cluster analysis divided CFUs into subtypes. The induction of Trap+MNCs and gene expression were compared among individual or cocultured subtypes. The fibroblast subtypes exerted critical effect on Trap+MNCs formation were selected and edited by CRISPR/Cas to investigate the influence on osteoclastogenesis in the periodontitis in mice.

Results

Most periodontitis samples exhibited intensive EDA+FN staining (P < 0.05), and these fibroblasts also induced most Trap+MNCs among three groups; consistently, fibroblasts from periodontitis highly expressed genes facilitating osteoclastogenesis. According to gene profiles and osteoclastogenic induction, four clusters of CFUs were identified. The proportion of clusters was significantly different (P < 0.05) among three groups, and their interaction influenced osteoclastogenic induction. Although Cluster 4 induced less osteoclasts, it enhanced the effects of Clusters 1 and 3 on Trap+MNCs formation (P < 0.05). EDA knockout in Cluster 4 abrogated this promotion (P < 0.05), and decreased osteoclasts and alveolar bone destruction in experimental periodontitis (P < 0.05).

Conclusion

Heterogeneous fibroblast subtypes affect the switch or development of periodontitis. A subtype (Cluster 4) played important role during alveolar bone destruction, by regulating other subtypes via EDA+FN paracrine.

Design of medical tympanostomy conduits with selective fluid transport properties

Implantable tubes, shunts, and other medical conduits are crucial for treating a wide range of conditions from ears and eyes to brain and liver but often impose serious risks of device infection, obstruction, migration, unreliable function, and tissue damage. Efforts to alleviate these complications remain at an impasse because of fundamentally conflicting design requirements: Millimeter-scale size is required to minimize invasiveness but exacerbates occlusion and malfunction. Here, we present a rational design strategy that reconciles these trade-offs in an implantable tube that is even smaller than the current standard of care. Using tympanostomy tubes (ear tubes) as an exemplary case, we developed an iterative screening algorithm and show how unique curved lumen geometries of the liquid-infused conduit can be designed to co-optimize drug delivery, effusion drainage, water resistance, and biocontamination/ingrowth prevention in a single subcapillary-length-scale device. Through extensive in vitro studies, we demonstrate that the engineered tubes enabled selective uni- and bidirectional fluid transport; nearly eliminated adhesion and growth of common pathogenic bacteria, blood, and cells; and prevented tissue ingrowth. The engineered tubes also enabled complete eardrum healing and hearing preservation and exhibited more efficient and rapid antibiotic delivery to the middle ear in healthy chinchillas compared with current tympanostomy tubes, without resulting in ototoxicity at up to 24 weeks. The design principle and optimization algorithm presented here may enable tubes to be customized for a wide range of patient needs.

Tenascin-C activation of lung fibroblasts in a 3D synthetic lung extracellular matrix mimic

The lung extracellular matrix (ECM) maintains the structural integrity of the tissue and regulates the phenotype and functions of resident fibroblasts. Lung-metastatic breast cancer alters these cell-ECM interactions, promoting fibroblast activation. There is a need for bio-instructive ECM models that contain the ECM composition and biomechanics of the lung to study these cell-matrix interactions in vitro . Here, we developed a synthetic, bioactive hydrogel that mimics the native lung modulus, and includes a representative distribution of the most abundant ECM peptide motifs responsible for integrin binding and matrix metalloproteinase (MMP)-mediated degradation in the lung, which promotes quiescence of human lung fibroblasts (HLFs). Stimulation with transforming growth factor β1 (TGF-β1), metastatic breast cancer conditioned media (CM), or tenascin-C activated these hydrogel-encapsulated HLFs in a manner reflective of their native in vivo responses. We propose this lung hydrogel platform as a tunable, synthetic approach to study the independent and combinatorial effects of ECM in regulating fibroblast quiescence and activation.

Role of fibroblast plasticity and heterogeneity in modulating angiogenesis and healing in the diabetic foot ulcer

Chronic diabetic foot ulcers (DFUs) are an important clinical issue faced by clinicians despite the advanced treatment strategies consisting of wound debridement, off-loading, medication, wound dressings, and keeping the ulcer clean. Non-healing DFUs are associated with the risk of amputation, increased morbidity and mortality, and economic stress. Neo-angiogenesis and granulation tissue formation are necessary for physiological DFU healing and acute inflammation play a key role in healing. However, chronic inflammation in association with diabetic complications holds the ulcer in the inflammatory phase without progressing to the resolution phase contributing to non-healing. Fibroblasts acquiring myofibroblasts phenotype contribute to granulation tissue formation and angiogenesis. However, recent studies suggest the presence of five subtypes of fibroblast population and of changing density in non-healing DFUs. Further, the association of fibroblast plasticity and heterogeneity with wound healing suggests that the switch in fibroblast phenotype may affect wound healing. The fibroblast phenotype shift and altered function may be due to the presence of chronic inflammation or a diabetic wound microenvironment. This review focuses on the role of fibroblast plasticity and heterogeneity, the effect of hyperglycemia and inflammatory cytokines on fibroblasts, and the interaction of fibroblasts with other cells in diabetic wound microenvironment in the perspective of DFU healing. Next, we summarize secretory, angiogenic, and angiostatic phenotypes of fibroblast which have been discussed in other organ systems but not in relation to DFUs followed by the perspective on the role of their phenotypes in promoting angiogenesis in DFUs.

Fasudil Ameliorates Osteoporosis Following Myocardial Infarction by Regulating Cardiac Calcitonin Secretion

We hypothesis that Rho kinase inhibitor fasudil ameliorates osteoporosis following myocardial infarction (MI) by regulating cardiac calcitonin secretion. A mice model of MI and cultured neonatal cardiomyocytes exposed to hypoxia and serum deprivation (H/SD), and fibroblasts exposed to TGF-β were used, respectively. Cardiac function in vivo was assessed with echocardiography. Osteoporosis in vivo was assessed with X-ray and micro-CT. In vivo and in vitro studies used histological and immunohistochemical techniques, along with western blots. In mice post-MI, fasudil ameliorates the microstructure and bone metabolism of the lumbar, improved cardiac function, and attenuated myocardial fibrosis. In vitro, fasudil or αCGRP could effectively inhibit the proliferation of primary fibroblasts treated with TGF-β. Moreover, fasudil ameliorates the cardiac calcitonin secretion induced by MI in vivo or by H/SD in vitro. Our findings suggest that fasudil improved MI-induced osteoporosis by promoting cardiac secreting calcitonin.

Pemafibrate attenuates pulmonary fibrosis by inhibiting myofibroblast differentiation

BACKGROUND AND OBJECTIVE

Idiopathic pulmonary fibrosis is a chronic progressive disease associated with substantial morbidity and mortality despite advances in medical therapy. Increasing evidence suggests that peroxisome proliferator-activated receptors (PPARs) play important roles in the fibrosis-related diseases and their agonists may become effective therapeutic targets. Pemafibrate is a selective PPARα agonist, but the efficacy against pulmonary fibrosis and mechanisms involved have not been systematically evaluated. Thus, the aims of this study were to explore the role of PPARα in the pulmonary fibrosis and to assess the effect of pemafibrate in vivo and in vitro.

METHODS

The effects of pemafibrate were evaluated in bleomycin-challenged murine pulmonary fibrosis model and transforming growth factor-beta 1 (TGF-β1) stimulated lung fibroblasts.

RESULTS

Bleomycin instillation induced body weight loss, declined lung function, pulmonary fibrosis, and extensive collagen deposition in the mice, accompanied with decreased pulmonary expression of PPARα, all of which were partially improved by pemafibrate at a dose of 2 mg/kg. Besides, pemafibrate effectively inhibits TGF-β1-induced myofibroblast differentiation and extracellular matrix (ECM) production in vivo and in vitro. Furthermore, we showed that pemafibrate not only inhibited pulmonary expression of NLRP3 and cleaved caspase-1 in bleomycin-inhaled mice, but also repressed activation of NLRP3/caspase-1 axis in TGF-β1 stimulated lung fibroblasts.

CONCLUSION

Our data suggest that pemafibrate exerts a marked protection against from the development of pulmonary fibrosis, which could constitute a novel candidate for the treatment for pulmonary fibrosis.

3D in vitro M2 macrophage model to mimic modulation of tissue repair

Distinct anti-inflammatory macrophage (M2) subtypes, namely M2a and M2c, are reported to modulate the tissue repair process tightly and chronologically by modulating fibroblast differentiation state and functions. To establish a well-defined three-dimensional (3D) cell culture model to mimic the tissue repair process, we utilized THP-1 human monocytic cells and a 3D collagen matrix as a biomimetic tissue model. THP-1 cells were differentiated into macrophages, and activated using IL-4/IL-13 (M_IL-4/IL-13) and IL-10 (M_IL-10). Both activated macrophages were characterized by both their cell surface marker expression and cytokine secretion profile. Our cell characterization suggested that M_IL-4/IL-13 and M_IL-10 demonstrate M2a- and M2c-like subtypes, respectively. To mimic the initial and resolution phases during the tissue repair, both activated macrophages were co-cultured with fibroblasts and myofibroblasts. We showed that M_IL-4/IL-13 were able to promote matrix synthesis and remodeling by induction of myofibroblast differentiation via transforming growth factor beta-1 (TGF-β1). On the contrary, M_IL-10 demonstrated the ability to resolve the tissue repair process by dedifferentiation of myofibroblast via IL-10 secretion. Overall, our study demonstrated the importance and the exact roles of M2a and M2c-like macrophage subtypes in coordinating tissue repair in a biomimetic model. The established model can be applied for high-throughput platforms for improving tissue healing and anti-fibrotic drugs testing, as well as other biomedical studies.

Fibroblast Differentiation and Matrix Remodeling Impaired under Simulated Microgravity in 3D Cell Culture Model

Exposure to microgravity affects astronauts' health in adverse ways. However, less is known about the extent to which fibroblast differentiation during the wound healing process is affected by the lack of gravity. One of the key steps of this process is the differentiation of fibroblasts into myofibroblasts, which contribute functionally through extracellular matrix production and remodeling. In this work, we utilized collagen-based three-dimensional (3D) matrices to mimic interstitial tissue and studied fibroblast differentiation under simulated microgravity (sµG). Our results demonstrated that alpha-smooth muscle actin (αSMA) expression and translocation of Smad2/3 into the cell nucleus were reduced upon exposure to sµG compared to the 1g control, which suggests the impairment of fibroblast differentiation under sµG. Moreover, matrix remodeling and production were decreased under sµG, which is in line with the impaired fibroblast differentiation. We further investigated changes on a transcriptomic level using RNA sequencing. The results demonstrated that sµG has less effect on fibroblast transcriptomes, while sµG triggers changes in the transcriptome of myofibroblasts. Several genes and biological pathways found through transcriptome analysis have previously been reported to impair fibroblast differentiation. Overall, our data indicated that fibroblast differentiation, as well as matrix production and remodeling, are impaired in 3D culture under sµG conditions.

Manipulating electrostatic field to control the distribution of bioactive proteins or polymeric microparticles on planar surfaces for guiding cell migration

We report a general strategy to generate linear and circular gradients of active proteins or polymeric microparticles on planar surfaces by controlling the distribution of electrostatic field during electrohydrodynamic jet printing or electrospray process. Taking fibronectin as an example, we generated a circular gradient of fibronectin and investigated its effect on accelerating the migration of fibroblasts to suit for use in wound closure. In another demonstration, we created linear gradients of laminin in unidirectional and bidirectional patterns, respectively. We showed that such gradations significantly promoted the migration of human neuroblastoma cells with the increase of laminin content. When we changed fibronectin/laminin to electrosprayed poly(lactic-co-glycolic acid) (PLGA) microparticles, we found similar results in terms of guiding cell migration, except that the guidance cues varied from biological signal to topographic structure. Taken together, this method for generating linear/circular gradients of fibronectin/laminin and PLGA microparticles can be readily extended to different types of bioactive proteins and polymeric microparticles to suit wound closure, nerve repair, and related applications involving cell migration.

Anlotinib Inhibits PFKFB3-Driven Glycolysis in Myofibroblasts to Reverse Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal disease in which the normal alveolar network is gradually replaced by fibrotic scars. Current evidence suggests that metabolic alterations correlate with myofibroblast activation in IPF. Anlotinib has been proposed to have antifibrotic effects, but the efficacy and mechanisms of anlotinib against lung fibrosis have not been systematically evaluated. The antifibrotic effects of anlotinib were evaluated in bleomycin-induced mouse models and transforming growth factor-beta 1 (TGF-β1)-stimulated lung fibroblasts. We measured lactate levels, 2-NBDG glucose uptake and the extracellular acidification rate (ECAR) to assess glycolysis in fibroblasts. RNA-protein coimmunoprecipitation (RIP) and polysome analyses were performed to investigate novel mechanisms of glycolytic reprogramming in pulmonary fibrosis. We found that anlotinib diminished myofibroblast activation and inhibited the augmentation of glycolysis. Moreover, we show that PCBP3 posttranscriptionally increases PFKFB3 expression by promoting its translation during myofibroblast activation, thus promoting glycolysis in myofibroblasts. Regarding mechanism, anlotinib exerts potent antifibrotic effects by downregulating PCBP3, reducing PFKFB3 translation and inhibiting glycolysis in myofibroblasts. Furthermore, we observed that anlotinib had preventative and therapeutic antifibrotic effects on bleomycin-induced pulmonary fibrosis. Therefore, we identify PCBP3 as a protein involved in the regulation of glycolysis reprogramming and lung fibrogenesis and propose it as a therapeutic target for pulmonary fibrosis. Our data suggest that anlotinib has antifibrotic effects on the lungs, and we provide a novel mechanism for this effect. Anlotinib may constitute a novel and potent candidate for the treatment of pulmonary fibrosis.

Fibrillar biopolymer-based scaffolds to study macrophage-fibroblast crosstalk in wound repair

Controlled wound healing requires a temporal and spatial coordination of cellular activities within the surrounding extracellular matrix (ECM). Disruption of cell-cell and cell-matrix communication results in defective repair, like chronic or fibrotic wounds. Activities of macrophages and fibroblasts crucially contribute to the fate of closing wounds. To investigate the influence of the ECM as an active part controlling cellular behavior, coculture models based on fibrillar 3D biopolymers such as collagen have already been successfully used. With well-defined biochemical and biophysical properties such 3D scaffolds enable in vitro studies on cellular processes including infiltration and differentiation in an in vivo like microenvironment. Further, paracrine and autocrine signaling as well as modulation of soluble mediator transport inside the ECM can be modeled using fibrillar 3D scaffolds. Herein, we review the usage of these scaffolds in in vitro coculture models allowing in-depth studies on the crosstalk between macrophages and fibroblasts during different stages of cutaneous wound healing. A more accurate mimicry of the various processes of cellular crosstalk at the different stages of wound healing will contribute to a better understanding of the impact of biochemical and biophysical environmental parameters and help to develop further strategies against diseases such as fibrosis.

Myofibroblasts: Function, Formation, and Scope of Molecular Therapies for Skin Fibrosis

Myofibroblasts are contractile, α-smooth muscle actin-positive cells with multiple roles in pathophysiological processes. Myofibroblasts mediate wound contractions, but their persistent presence in tissues is central to driving fibrosis, making them attractive cell targets for the development of therapeutic treatments. However, due to shared cellular markers with several other phenotypes, the specific targeting of myofibroblasts has long presented a scientific and clinical challenge. In recent years, myofibroblasts have drawn much attention among scientific research communities from multiple disciplines and specialisations. As further research uncovers the characterisations of myofibroblast formation, function, and regulation, the realisation of novel interventional routes for myofibroblasts within pathologies has emerged. The research community is approaching the means to finally target these cells, to prevent fibrosis, accelerate scarless wound healing, and attenuate associated disease-processes in clinical settings. This comprehensive review article describes the myofibroblast cell phenotype, their origins, and their diverse physiological and pathological functionality. Special attention has been given to mechanisms and molecular pathways governing myofibroblast differentiation, and updates in molecular interventions.

Functional label-free assessment of fibroblast differentiation in 3D collagen-I-matrices using particle image velocimetry

Fibroblasts are a diverse population of connective tissue cells that are a key component in physiological wound healing. Myofibroblasts are differentiated fibroblasts occurring in various physiological and pathological conditions, like in the healing of wounds or in the tumour microenvironment. They exhibit important functions compared to fibroblasts in terms of proliferation, protein secretion, and contractility. The gold standard to distinguish myofibroblasts is alpha-smooth muscle actin (αSMA) expression and its incorporation in stress fibres, which is only revealed by gene expression analysis and immunostaining. Here, we introduce an approach to functionally determine the myofibroblast status of live fibroblasts directly in in vitro cell culture by analysing their ability to contract the extracellular matrix around them without the need for labelling. It is based on particle image velocimetry algorithms applied to dynamic deformations of the extracellular matrix network structure imaged by phase contrast microscopy. Advanced image analysis allows us to distinguish between various differentiation stages of fibroblasts including the dynamic change over several days. We further apply machine learning classification to automatically evaluate different cell culture conditions. With this new method, we provide a versatile tool to functionally evaluate the dynamic process of fibroblast differentiation. It can be applied for in vitro screening studies in biomimetic 3D cell cultures with options to extend it to other cell systems with contractile phenotypes.

Curcumin Loading on Alginate Nano-Micelle for Anti-Infection and Colonic Wound Healing

Despite the antibacterial, and anti-inflammatory properties of curcumin (C), its effect on wound healing, especially in the colorectal, is ambiguous. Moreover, due to the hydrophobic properties of C, its use is limited. Therefore, to reduce the bioavailability challenge and improve the transfer to colon area, we designed a C-alginate-based nano-micelle (C-A-NM). After fabrication of C-A-NM (55.5 nm) and physicochemical studies with the TEM, DLS and XRD, the C release rate based on gastrointestinal state was evaluated. Furthermore, the effects of C-A-NM on the survival of HCT-8 cells at 24 and 48 hours by MTT method and its antibacterial effects were also evaluated. To explain the effects of wound healing in rats, in addition to colonoscopy on the 14th-day, the repaired tissue on the 7th and 14th days were examined by Hematoxylin and Eosin method. Also, for evaluating wound healing in the colon, the protein/collagen concentration, and TGFβ1/NFκB gene expression were determined. The results of C cumulative release showed that the NM allows the drug to be loaded in the colon in a favourable manner. Also, the toxicity outputs revealed that C-A-NM at a concentration of 7.5 mg had no negative effects on cell viability. While the activity of Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, bacteria decreased based on the minimum inhibitory concentration value with 153, 245 and 319 (μg/mL). The use of C-A-NM not only increases protein and collagen in damaged sites, but also increases TGFβ1 expression in contrast to NFκB. Based on these results, and the results of histopathology and colonoscopy, it was found that C-A-NM accelerates the healing of damaged areas. Overall, the results show that the use of C-A-NM can significantly accelerate the healing of wounds in the gastrointestinal tract based on collagen induction and reduced bacterial activity.

Asthmatic Eosinophils Promote Contractility and Migration of Airway Smooth Muscle Cells and Pulmonary Fibroblasts In Vitro

Enhanced contractility and migration of airway smooth muscle cells (ASMC) and pulmonary fibroblasts (PF) are part of airway remodeling in asthma. Eosinophils are the central inflammatory cells that participate in airway inflammation. However, the role of asthmatic eosinophils in ASMC and PF contractility, migration, and differentiation to contractile phenotype has not yet been precisely described. A total of 38 individuals were included in this study: 13 steroid-free non-severe allergic asthma (AA) patients, 11 severe non-allergic eosinophilic asthma (SNEA) patients, and 14 healthy subjects (HS). For AA patients and HS groups, a bronchial allergen challenge with D. pteronyssinus was performed. Individual combined cell cultures were prepared from isolated peripheral blood eosinophils and immortalized ASMC or commercial PF cell lines separately. The migration of ASMC and PF was evaluated using wound healing assay and contractility using collagen gel assay. Gene expression of contractile apparatus proteins, COL1A1, COL5A1, and FN, in ASMC and PF was evaluated using qRT-PCR. We found that contractility and migration of ASMC and PF significantly increased after incubation with asthmatic eosinophils compared to HS eosinophils, p < 0.05, and SNEA eosinophils demonstrated the highest effect on contractility of ASMC and migration of both cell lines, p < 0.05. AA and SNEA eosinophils significantly increased gene expression of contractile apparatus proteins, COL1A1 and FN, in both cell lines, p < 0.05. Furthermore, the allergen-activated AA eosinophils significantly increased the contractility of ASMC, and migration and gene expression in ASMC and PF, p < 0.05. Thus, asthmatic eosinophils change ASMC and PF behavior by increasing their contractility and migration, contributing to airway remodeling.

Dendritic cell immune potency on 2D and in 3D collagen matrices

Dendritic cells (DCs) are antigen-presenting cells capable of either activating the immune response or inducing and maintaining immune tolerance. Understanding how biophysical properties affect DC behaviors will provide insight into the biology of a DC and its applications. In this work, we studied how cell culture dimensionality (two-dimensional (2D) and three-dimensional (3D)), and matrix density of 3D collagen matrices modulate differentiation and functions of DCs. Besides, we aimed to point out the different conceptual perspectives in modern immunological research, namely tissue-centric and cell-centric perspectives. The tissue-centric perspective intends to reveal how specific microenvironments dictate DC differentiation and in turn modulate DC functionalities, while the cell-centric perspective aims to demonstrate how pre-differentiated DCs behave in specific microenvironments. DC plasticity was characterized in terms of cell surface markers and cytokine secretion profiles. Subsequently, antigen internalization and T cell activation were quantified to demonstrate the cellular functions of immature DCs (iDCs) and mature DCs (mDCs), respectively. In the tissue-centric perspective, we found that expressed surface markers and secreted cytokines of both iDCs and mDCs are generally higher in 2D culture, while they are regulated by matrix density in 3D culture. In contrast, in the cell-centric perspective, we found enhanced expression of cell surface markers as well as distinct cytokine secretion profiles in both iDCs and mDCs. By analyzing cellular functions of cells in the tissue-centric perspective, we found matrix density dependence in antigen uptake by iDCs, as well as on mDC-mediated T cell proliferation in 3D cell culture. On the other hand, in the cell-centric perspective, both iDCs and mDCs appeared to lose their functional potentials to internalization antigen and T cell stimulation. Additionally, mDCs from tissue- and cell-centric perspectives modulated T cell differentiation by their distinct cytokine secretion profiles towards Th1 and Th17, respectively. In sum, our work emphasizes the importance of dimensionality, as well as collagen fibrillar density in the regulation of the immune response of DCs. Besides this, we demonstrated that the conceptual perspective of the experimental design could be an essential key point in research in immune cell-material interactions and biomaterial-based disease models of immunity.

Fibronectin-loaded Collagen/Gelatin Hydrogel Is a Potent Signaling Biomaterial for Dental Pulp Regeneration

INTRODUCTION

Guided tissue regeneration has been considered a promising biological strategy to replace conventional endodontic therapies of teeth with incomplete root formation. Therefore, in the present study, a collagen/gelatin hydrogel either containing dosages of fibronectin (FN), or not, was developed and assessed concerning their bioactive and chemotactic potential on human apical papilla cells (hAPCs).

METHODS

Hydrogels were prepared by varying the ratio of collagen and gelatin (Col/Gel; v/v), and used to establish the following groups: Collagen (positive control); Col/Gel 4:6; Col/Gel 6:4; Col/Gel 8:2. The viability, adhesion, and spreading of cells seeded on the hydrogels were evaluated. Different concentrations of FN (0, 5, or 10 μg/mL) were incorporated into the best formulation of the collagen/gelatin hydrogel selected. Then, the hAPCs seeded on the biomaterials were assessed concerning the cell migration, viability, adhesion and spreading, and gene expression of ITGA5, ITGAV, COL1A1, and COL3A1.

RESULTS

The Col/Gel 8:2 group exhibited better cell viability, adhesion and spreading in comparison with Control. Higher values of hAPC migration, viability, adhesion, spreading and gene expression of pulp regeneration markers were found, the higher the concentration was of FN incorporated into the collagen/gelatin hydrogel.

CONCLUSION

Collagen/gelatin hydrogel with 10 μg/mL of FN had potent bioactive and chemotactic effects on cultured hAPCs.

Fibronectin-functionalization of 3D collagen networks supports immune tolerance and inflammation suppression in human monocyte-derived macrophages

The extracellular matrix (ECM) is dynamically reorganized during wound healing. Concomitantly, recruited monocytes differentiate into macrophages. However, the role of the wound's ECM during this transition remain to be fully understood. Fibronectin is a multifunctional glycoprotein present in early wound ECM with a potential immunomodulatory role during monocyte-to-macrophage differentiation. Hence, to investigate the impact of fibronectin during this differentiation step, 3D fibrillar collagen type I networks with or without fibronectin-functionalization were engineered with defined topology (fibril and pore diameter: 0.8 μm; 7 μm) and amount of adsorbed fibronectin (0.15 μg per μg collagen). Primary, human monocytes were then differentiated into macrophages inside these networks. The immunological imprinting of the resulting macrophages was monitored by means of the expression of FABP4, CLEC4E, SLC2A6, and SOD2 which discriminate naïve and tolerized macrophages, as well pro-inflammatory (M1) and anti-inflammatory (M2) macrophage polarization. The analyses indicate that fibronectin-functionalization of collagen I networks induces macrophage tolerance rather than M1 or M2 macrophage phenotypes. This finding was confirmed by release profiles of pro- and anti-inflammatory cytokines such as IL6, IL8, CXCL10, and IL10. Nevertheless, upon LPS challenge, immune suppression by fibronectin was overridden since these macrophages could then deploy an efficient immune response. Our results therefore provide new perspectives in biomaterial science of wound healing scaffolds and the design of instructive materials for human monocyte-derived cells.

Construction of a 3D brain extracellular matrix model to study the interaction between microglia and T cells in co-culture

Neurodegenerative disorders are characterised by the activation of brain-resident microglia cells and by the infiltration of peripheral T cells. However, their interplay in disease has not been clarified yet. It is difficult to investigate complex cellular dynamics in living animals, and simple two-dimensional (2D) cell culture models do not resemble the soft 3D structure of brain tissue. Therefore, we developed a biomimetic 3D in vitro culture system for co-cultivation of microglia and T cells. As the activation and/or migration of immune cells in the brain might be affected by components of the extracellular matrix, defined 3D fibrillar collagen I-based matrices were constructed and modified with hyaluronan and/or chondroitin sulphate, resembling aspects of brain extracellular matrix. Murine microglia and spleen-derived T cells were cultured alone or in co-culture on the constructed matrices. Microglia exhibited in vivo-like morphology and T cells showed enhanced survival when co-cultured with microglia or to a minor degree in the presence of glia-conditioned medium. The open and porous fibrillar structure of the matrix allowed for cell invasion and direct cell-cell interaction, with stronger invasion of T cells. Both cell types showed no dependence on the matrix modifications. Microglia could be activated on the matrices by lipopolysaccharide resulting in interleukin-6 and tumour necrosis factor-α secretion. The findings herein indicate that biomimetic 3D matrices allow for co-cultivation and activation of primary microglia and T cells and provide useful tools to study their interaction in vitro.

Matrix Remodeling and Hyaluronan Production by Myofibroblasts and Cancer-Associated Fibroblasts in 3D Collagen Matrices

The tumor microenvironment is a key modulator in cancer progression and has become a novel target in cancer therapy. An increase in hyaluronan (HA) accumulation and metabolism can be found in advancing tumor progression and are often associated with aggressive malignancy, drug resistance and poor prognosis. Wound-healing related myofibroblasts or activated cancer-associated fibroblasts (CAF) are assumed to be the major sources of HA. Both cell types are capable to synthesize new matrix components as well as reorganize the extracellular matrix. However, to which extent myofibroblasts and CAF perform these actions are still unclear. In this work, we investigated the matrix remodeling and HA production potential in normal human dermal fibroblasts (NHFB) and CAF in the absence and presence of transforming growth factor beta -1 (TGF-β1), with TGF-β1 being a major factor of regulating fibroblast differentiation. Three-dimensional (3D) collagen matrix was utilized to mimic the extracellular matrix of the tumor microenvironment. We found that CAF appeared to response insensitively towards TGF-β1 in terms of cell proliferation and matrix remodeling when compared to NHFB. In regards of HA production, we found that both cell types were capable to produce matrix bound HA, rather than a soluble counterpart, in response to TGF-β1. However, activated CAF demonstrated higher HA production when compared to myofibroblasts. The average molecular weight of produced HA was found in the range of 480 kDa for both cells. By analyzing gene expression of HA metabolizing enzymes, namely hyaluronan synthase (HAS1-3) and hyaluronidase (HYAL1-3) isoforms, we found expression of specific isoforms in dependence of TGF-β1 present in both cells. In addition, HAS2 and HYAL1 are highly expressed in CAF, which might contribute to a higher production and degradation of HA in CAF matrix. Overall, our results suggested a distinct behavior of NHFB and CAF in 3D collagen matrices in the presence of TGF-β1 in terms of matrix remodeling and HA production pointing to a specific impact on tumor modulation.

In Vitro Generation of Novel Functionalized Biomaterials for Use in Oral and Dental Regenerative Medicine Applications. Running Title: Fibrin-Agarose Functionalized Scaffolds

Recent advances in tissue engineering offer innovative clinical alternatives in dentistry and regenerative medicine. Tissue engineering combines human cells with compatible biomaterials to induce tissue regeneration. Shortening the fabrication time of biomaterials used in tissue engineering will contribute to treatment improvement, and biomaterial functionalization can be exploited to enhance scaffold properties. In this work, we have tested an alternative biofabrication method by directly including human oral mucosa tissue explants within the biomaterial for the generation of human bioengineered mouth and dental tissues for use in tissue engineering. To achieve this, acellular fibrin-agarose scaffolds (AFAS), non-functionalized fibrin-agarose oral mucosa stroma substitutes (n-FAOM), and novel functionalized fibrin-agarose oral mucosa stroma substitutes (F-FAOM) were developed and analyzed after 1, 2, and 3 weeks of in vitro development to determine extracellular matrix components as compared to native oral mucosa controls by using histochemistry and immunohistochemistry. Results demonstrate that functionalization speeds up the biofabrication method and contributes to improve the biomimetic characteristics of the scaffold in terms of extracellular matrix components and reduce the time required for in vitro tissue development.

Collagen Fibril Density Modulates Macrophage Activation and Cellular Functions during Tissue Repair

Monocytes circulate in the bloodstream, extravasate into the tissue and differentiate into specific macrophage phenotypes to fulfill the immunological needs of tissues. During the tissue repair process, tissue density transits from loose to dense tissue. However, little is known on how changes in tissue density affects macrophage activation and their cellular functions. In this work, monocytic cell line THP-1 cells were embedded in three-dimensional (3D) collagen matrices with different fibril density and were then differentiated into uncommitted macrophages (MPMA) using phorbol-12-myristate-13-acetate (PMA). MPMA macrophages were subsequently activated into pro-inflammatory macrophages (MLPS/IFNγ) and anti-inflammatory macrophages (MIL-4/IL-13) using lipopolysaccharide and interferon-gamma (IFNγ), and interleukin 4 (IL-4) and IL-13, respectively. Although analysis of cell surface markers, on both gene and protein levels, was inconclusive, cytokine secretion profiles, however, demonstrated differences in macrophage phenotype. In the presence of differentiation activators, MLPS/IFNγ secreted high amounts of IL-1β and tumor necrosis factor alpha (TNFα), while M0PMA secreted similar cytokines to MIL-4/IL-13, but low IL-8. After removing the activators and further culture for 3 days in fresh cell culture media, the secretion of IL-6 was found in high concentrations by MIL-4/IL-13, followed by MLPS/IFNγ and MPMA. Interestingly, the secretion of cytokines is enhanced with an increase of fibril density. Through the investigation of macrophage-associated functions during tissue repair, we demonstrated that M1LPS/IFNγ has the potential to enhance monocyte infiltration into tissue, while MIL-4/IL-13 supported fibroblast differentiation into myofibroblasts via transforming growth factor beta 1 (TGF-β1) in dependence of fibril density, suggesting a M2a-like phenotype. Overall, our results suggest that collagen fibril density can modulate macrophage response to favor tissue functions. Understanding of immune response in such complex 3D microenvironments will contribute to the novel therapeutic strategies for improving tissue repair, as well as guidance of the design of immune-modulated materials.

3D Scaffold-Based Macrophage Fibroblast Coculture Model Reveals IL-10 Dependence of Wound Resolution Phase

Persistent inflammation and impaired repair in dermal wound healing are frequently associated with cell-cell and cell-matrix miscommunication. A direct coculture model of primary human myofibroblasts (MyoFB) and M-CSF-differentiated macrophages (M-Mɸ) in fibrillar three-dimensional Collagen I (Coll I) matrices is developed to study intercellular interactions. The coculture experiments reveal the number of M-Mɸ regulated MyoFB dedifferentiation in a dose-dependent manner. The amount of MyoFB decreases in dependence of the number of cocultured M-Mɸ, even in the presence of MyoFB-inducing transforming growth factor β₁ (TGF-β₁ ). Gene expression analysis of matrix proteins (collagen I, collagen III, ED-A-fibronectin) confirms the results of an altered MyoFB phenotype. Additionally, M-Mɸ is shown to be the main source of secreted cytokine interleukin-10 (IL-10), which is suggested to affect MyoFB dedifferentiation. These findings indicate a paracrine impact of IL-10 secretion by M-Mɸ on the MyoFB differentiation status counteracting the TGF-β₁ -driven MyoFB activation. Hence, the in vitro coculture model simulates physiological situations during wound resolution and underlines the importance of paracrine IL-10 signals by M-Mɸ. In sum, the 3D Coll I-based matrices with a MyoFB-M-Mɸ coculture form a highly relevant biomimetic model of late stages of wound healing.

Recombinant FNIII9-10-derived extracellular signaling effects on the physiology of dermal fibroblasts during in vitro culture

Previous reports showed that fibronectin (FN) was effective in stimulating the recovery of damaged dermis. However, native FN has multifunctional domains transmitting beneficial as well as unbeneficial signals to dermal tissue cells through the mediation of integrin heterodimers. The use of a functional domain [FN type III9-10 fragments (FNIII9-10)] providing beneficial effects on the physiology of dermal tissue cells would enhance an in vitro culture system for dermal fibroblasts (DFs). We therefore investigated the FNIII9-10-derived extracellular signaling effect on the physiology of DFs during in vitro culture. Recombinant FNIII9-10 proteins were constructed and their functionality was determined by observing the adhesion of adult human DFs (aHDFs) to recombinant FNIII9-10 and of low adhesion integrin α₅β₁- and α_vβ₃-blocked aHDFs to recombinant FNIII9-10. Cellular proliferation, morphology, and senescence were measured and compared in the aHDFs cultured on native FN and recombinant FNIII9-10 for short or long periods. The results show that recombinant FNIII9-10-derived extracellular signaling stimulated increased proliferation of aHDF (both in short- and long-term cultures) and inhibited the generation of morphological abnormalities (in short- and long-term cultures) and cellular senescence (long-term culture) when compared with native FN-derived extracellular signaling. Our results suggest that, instead of native FN, recombinant FNIII9-10 better enhanced the in vitro culture of aHDFs while diminishing the adverse effects associated with the use of human-derived materials.

Impact of Fibronectin Knockout on Proliferation and Differentiation of Human Infrapatellar Fat Pad-Derived Stem Cells

Fibronectin plays an essential role in tissue development and regeneration. However, the effects of fibronectin knockout (FN1-KO) on stem cells' proliferation and differentiation remain unknown. In this study, CRISPR/Cas9 generated FN1-KO in human infrapatellar fat pad-derived stem cells (IPFSCs) was evaluated for proliferation ability including cell cycle and surface markers as well as stemness gene expression and for differentiation capacity including chondrogenic and adipogenic differentiation. High passage IPFSCs were also evaluated for proliferation and differentiation capacity after expansion on decellularized ECM (dECM) deposited by FN1-KO cells. Successful FN1-KO in IPFSCs was confirmed by Sanger sequencing and Inference of CRISPR Edits analysis (ICE) as well as immunostaining for fibronectin expression. Compared to the GFP control, FN1-KO cells showed an increase in cell growth, percentage of cells in the S and G2 phases, and CD105 and CD146 expression but a decrease in expression of stemness markers CD73, CD90, SSEA4, and mesenchymal condensation marker CDH2 gene. FN1-KO decreased both chondrogenic and adipogenic differentiation capacity. Interestingly, IPFSCs grown on dECMs deposited by FN1-KO cells exhibited a decrease in cell proliferation along with a decline in CDH2 expression. After induction, IPFSCs plated on dECMs deposited by FN1-KO cells also displayed decreased expression of both chondrogenic and adipogenic capacity. We concluded that FN1-KO increased human IPFSCs' proliferation capacity; however, this capacity was reversed after expansion on dECM deposited by FN1-KO cells. Significance of fibronectin in chondrogenic and adipogenic differentiation was demonstrated in both FN1-KO IPFSCs and FN(-) matrix microenvironment.

Augmenting endogenous repair of soft tissues with nanofibre scaffolds

As our ability to engineer nanoscale materials has developed we can now influence endogenous cellular processes with increasing precision. Consequently, the use of biomaterials to induce and guide the repair and regeneration of tissues is a rapidly developing area. This review focuses on soft tissue engineering, it will discuss the types of biomaterial scaffolds available before exploring physical, chemical and biological modifications to synthetic scaffolds. We will consider how these properties, in combination, can provide a precise design process, with the potential to meet the requirements of the injured and diseased soft tissue niche. Finally, we frame our discussions within clinical trial design and the regulatory framework, the consideration of which is fundamental to the successful translation of new biomaterials.

The Non-Fibrillar Side of Fibrosis: Contribution of the Basement Membrane, Proteoglycans, and Glycoproteins to Myocardial Fibrosis

The extracellular matrix (ECM) provides structural support and a microenvironmentfor soluble extracellular molecules. ECM is comprised of numerous proteins which can be broadly classified as fibrillar (collagen types I and III) and non-fibrillar (basement membrane, proteoglycans, and glycoproteins). The basement membrane provides an interface between the cardiomyocytes and the fibrillar ECM, while proteoglycans sequester soluble growth factors and cytokines. Myocardial fibrosis was originally only linked to accumulation of fibrillar collagens, but is now recognized as the expansion of the ECM including the non-fibrillar ECM proteins. Myocardial fibrosis can be reparative to replace the lost myocardium (e.g., ischemic injury or myocardial infarction), or can be reactive resulting from pathological activity of fibroblasts (e.g., dilated or hypertrophic cardiomyopathy). Contribution of fibrillar collagens to fibrosis is well studied, but the role of the non-fibrillar ECM proteins has remained less explored. In this article, we provide an overview of the contribution of the non-fibrillar components of the extracellular space of the heart to highlight the potential significance of these molecules in fibrosis, with direct evidence for some, although not all of these molecules in their direct contribution to fibrosis.

Fibronectin precoating wound bed enhances the therapeutic effects of autologous epidermal basal cell suspension for full-thickness wounds by improving epidermal stem cells' utilization

Background

Autologous epidermal basal cell suspension therapy has been proven to be one of the most effective treatments for full-thickness wounds. However, we found there remain obvious defects that significantly confined the utilization and function of the epidermal basal cells (EBCs), especially the epidermal stem cells (ESCs) in it. This study investigated whether precoating fibronectin (FN) on the wound bed before spraying EBCs could overcome these defects and further explored its possible mechanisms.

Methods

In the in vitro study, EBCs were isolated from the donor skin of patients who needed skin grafting. Different concentrations of FN were used to precoat culture dishes before cell culture; the adherent efficiency, proliferation and migration ability of ESCs were analyzed and compared with traditional collagen IV precoating.

In the in vivo study, Sprague–Dawley (SD) rats with full-thickness skin wounds were selected as full-thickness wounds’ model. For the experiment groups, 20 μg/ml FN was precoated on the wound bed 10 min before EBC spray. The quality of wound healing was estimated by the residual wound area rate, wound healing time, and hematoxylin and eosin (H&E) staining. Expression of ESC markers, neovascular markers, inflammation markers, and collagen formation and degradation markers was elucidated by immunohistochemistry (IHC), immunofluorescence (IF), western blot (WB), and RT-qPCR analysis.

Results

The in vitro study showed that the dishes precoated with 20 μg/ml FN had a similar adherent efficiency and colony formation rate with collagen IV, but it could improve the proliferation and migration of ESCs significantly. Similarly, in the in vivo study, precoating FN on wound bed before EBC spray also significantly promote wound healing by improving ESCs’ utilization efficiency, promoting angiogenesis, decreasing inflammations, and regulating collagen formation and degradation.

Conclusion

FN precoating wound bed before EBC spray could significantly promote full-thickness wound healing by improving the utilization and function of the ESCs and further by promoting angiogenesis, decreasing inflammations, and regulating collagen formation and degradation.

Graphical abstract

Role of ALDH1A1 and HTRA2 expression in CCL2/CCR2-mediated breast cancer cell growth and invasion

Chemokines mediate immune cell trafficking during tissue development, wound healing and infection. The chemokine CCL2 is best known to regulate macrophage recruitment during wound healing, infection and inflammatory diseases. While the importance of CCL2/CCR2 signaling in macrophages during cancer progression is well documented, we recently showed that CCL2-mediated breast cancer progression depends on CCR2 expression in carcinoma cells. Using 3D Matrigel: Collagen cultures of SUM225 and DCIS.com breast cancer cells, this study characterized the mechanisms of CCL2/CCR2 signaling in cell growth and invasion. SUM225 cells, which expressed lower levels of CCR2 than DCIS.com cells, formed symmetrical spheroids in Matrigel: Collagen, and were not responsive to CCL2 treatment. DCIS.com cells formed asymmetric cell clusters in Matrigel: Collagen. CCL2 treatment increased growth, decreased expression of E-cadherin and increased TWIST1 expression. CCR2 overexpression in SUM225 cells increased responsiveness to CCL2 treatment, enhancing growth and invasion. These phenotypes corresponded to increased expression of Aldehyde Dehydrogenase 1A1 (ALDH1A1) and decreased expression of the mitochondrial serine protease HTRA2. CCR2 deficiency in DCIS.com cells inhibited CCL2-mediated growth and invasion, corresponding to decreased ALDH1A1 expression and increased HTRA2 expression. ALDH1A1 and HTRA2 expression were modulated in CCR2-deficient and CCR2-overexpressing cell lines. We found that ALDH1A1 and HTRA2 regulates CCR2-mediated breast cancer cell growth and cellular invasion in a CCL2/CCR2 context-dependent manner. These data provide novel insight on the mechanisms of chemokine signaling in breast cancer cell growth and invasion, with important implications on targeted therapeutics for anti-cancer treatment.

This article has an associated First Person interview with the first author of the paper.

Summary: Chemokines are known to regulate immune cell recruitment during inflammation. This report characterizes novel molecular mechanisms through which CCL2/CCR2 chemokine signaling in breast cancer cells regulates growth and invasion.

Deconstructing Immune Microenvironments of Lymphoid Tissues for Reverse Engineering

The immune microenvironment presents a diverse panel of cues that impacts immune cell migration, organization, differentiation, and the immune response. Uniquely, both the liquid and solid phases of every specific immune niche within the body play an important role in defining cellular functions in immunity at that particular location. The in vivo immune microenvironment consists of biomechanical and biochemical signals including their gradients, surface topography, dimensionality, modes of ligand presentation, and cell-cell interactions, and the ability to recreate these immune biointerfaces in vitro can provide valuable insights into the immune system. This manuscript reviews the critical roles played by different immune cells and surveys the current progress of model systems for reverse engineering of immune microenvironments with a focus on lymphoid tissues.

Fibroblast fate regulation by time dependent TGF-β1 and IL-10 stimulation in biomimetic 3D matrices

The presentation of TGF-β1 during the early stage of wound healing is a prerequisite for extracellular matrix (ECM) synthesis and remodeling by activated fibroblasts, called myofibroblasts. At later stages, clearance of myofibroblasts is needed to avoid overshooting ECM production. Apoptosis of myofibroblasts and the macrophage-released anti-inflammatory cytokine IL-10 are controversially discussed as regulating cues in this context. To reveal the regulating cues, defined biomaterial scaffolds are needed to conduct in-depth in vitro studies in a physiologically relevant context. In this work, we used an in vitro biomimetic wound healing model. It consists of a 3D fibrillar matrix from collagen I and fibronectin and different temporal stimuli by TGF-β1 and IL-10. Human dermal fibroblast behavior was investigated in terms of myofibroblast differentiation (αSMA expression), matrix remodeling, proliferation and migration in the permanent or sequential presence of TGF-β1 and IL-10 over 4 days. We could show that removal of TGF-β1 after initial stimulation resulted in an increase of apoptosis of myofibroblasts. In contrast, TGF-β1 stimulation followed by IL-10 treatment did not result in increased cell apoptosis but instead led to a significant increase of cell motility and reduction of myofibroblasts. The findings suggest that myofibroblasts are a transiently "activated" fibroblastic phenotype and can be de-differentiated to fibroblasts in the presence of IL-10. Overall, our 3D ECM model allows mimicking the early and late stages of wound healing and highlights the temporal sequence of TGF-β1 and IL-10 as an important cue for completion of tissue formation and maintenance of tissue homeostasis.

A three-dimensional in vitro dynamic micro-tissue model of cardiac scar formation

In vitro cardiac models able to mimic the fibrotic process are paramount to develop an effective anti-fibrosis therapy that can regulate fibroblast behaviour upon myocardial injury. In previously developed in vitro models, typical fibrosis features were induced by using scar-like stiffness substrates and/or potent morphogen supplementation in monolayer cultures. In our model, we aimed to mimic in vitro a fibrosis-like environment by applying cyclic stretching of cardiac fibroblasts embedded in three-dimensional fibrin-hydrogels alone. Using a microfluidic device capable of delivering controlled cyclic mechanical stretching (10% strain at 1 Hz), some of the main fibrosis hallmarks were successfully reproduced in 7 days. Cyclic strain indeed increased cell proliferation, extracellular matrix (ECM) deposition (e.g. type-I-collagen, fibronectin) and its stiffness, forming a scar-like tissue with superior quality compared to the supplementation of TGFβ1 alone. Taken together, the observed findings resemble some of the key steps in the formation of a scar: (i) early fibroblast proliferation, (ii) later phenotype switch into myofibroblasts, (iii) ECM deposition and (iv) stiffening. This in vitro scar-on-a-chip model represents a big step forward to investigate the early mechanisms possibly leading later to fibrosis without any possible confounding supplementation of exogenous potent morphogens.

Biomimetic tumor microenvironments based on collagen matrices

This review provides an overview of the current approaches to engineer defined 3D matrices for the investigation of tumor cell behaviorin vitro, with a focus on collagen-based fibrillar systems.

Effects and Mechanisms of Total Flavonoids from Blumea balsamifera (L.) DC. on Skin Wound in Rats

Chinese herbal medicine (CHM) evolved through thousands of years of practice and was popular not only among the Chinese population, but also most countries in the world. Blumea balsamifera (L.) DC. as a traditional treatment for wound healing in Li Nationality Medicine has a long history of nearly 2000 years. This study was to evaluate the effects of total flavonoids from Blumea balsamifera (L.) DC. on skin excisional wound on the back of Sprague-Dawley rats, reveal its chemical constitution, and postulate its action mechanism. The rats were divided into five groups and the model groups were treated with 30% glycerol, the positive control groups with Jing Wan Hong (JWH) ointment, and three treatment groups with high dose (2.52 g·kg⁻¹), medium dose (1.26 g·kg⁻¹), and low dose (0.63 g·kg⁻¹) of total flavonoids from B. balsamifera. During 10 consecutive days of treatment, the therapeutic effects of rates were evaluated. On day 1, day 3, day 5, day 7, and day 10 after treatment, skin samples were taken from all the rats for further study. Significant increases of granulation tissue, fibroblast, and capillary vessel proliferation were observed at day 7 in the high dose and positive control groups, compared with the model group, with the method of 4% paraformaldehyde for histopathological examination and immunofluorescence staining. To reveal the action mechanisms of total flavonoids on wound healing, the levels of CD68, vascular endothelial growth factor (VEGF), transforming growth factor-β₁ (TGF-β₁), and hydroxyproline were measured at different days. Results showed that total flavonoids had significant effects on rat skin excisional wound healing compared with controls, especially high dose ones (p < 0.05). Furthermore, the total flavonoid extract was investigated phytochemically, and twenty-seven compounds were identified from the total flavonoid sample by ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry/diode array detector (UPLC-Q-TOF-MS/DAD), including 16 flavonoid aglucons, five flavonoid glycosides (main peaks in chromatogram), five chlorogenic acid analogs, and 1 coumarin. Reports show that flavonoid glycoside possesses therapeutic effects of curing wounds by inducing neovascularization, and chlorogenic acid also has anti-inflammatory and wound healing activities; we postulated that all the ingredients in total flavonoids sample maybe exert a synergetic effect on wound curing. Accompanied with detection of four growth factors, the upregulation of these key growth factors may be the mechanism of therapeutic activities of total flavonoids. The present study confirmed undoubtedly that flavonoids were the main active constituents that contribute to excisional wound healing, and suggested its action mechanism of improving expression levels of growth factors at different healing phases.

Quantitative label-free single cell tracking in 3D biomimetic matrices

Live cell imaging enables an observation of cell behavior over a period of time and is a growing field in modern cell biology. Quantitative analysis of the spatio-temporal dynamics of heterogeneous cell populations in three-dimensional (3D) microenvironments contributes a better understanding of cell-cell and cell-matrix interactions for many biomedical questions of physiological and pathological processes. However, current live cell imaging and analysis techniques are frequently limited by non-physiological 2D settings. Furthermore, they often rely on cell labelling by fluorescent dyes or expression of fluorescent proteins to enhance contrast of cells, which frequently affects cell viability and behavior of cells. In this work, we present a quantitative, label-free 3D single cell tracking technique using standard bright-field microscopy and affordable computational resources for data analysis. We demonstrate the efficacy of the automated method by studying migratory behavior of a large number of primary human macrophages over long time periods of several days in a biomimetic 3D microenvironment. The new technology provides a highly affordable platform for long-term studies of single cell behavior in 3D settings with minimal cell manipulation and can be implemented for various studies regarding cell-matrix interactions, cell-cell interactions as well as drug screening platform for primary and heterogeneous cell populations.

Mimicking Paracrine TGFβ1 Signals during Myofibroblast Differentiation in 3D Collagen Networks

TGFβ1 is a key regulator for induction of tissue remodeling after dermal wounding. We present a model of paracrine delivery of TGFβ1 for differentiation of dermal fibroblasts based on a fibrillar 3D collagen matrix and embedded TGFβ1 releasing microparticles. We found differentiation into myofibroblasts was achieved in a TGFβ1 dependent manner at much lower doses than systemic delivery. This effect is accounted to the slow and sustained TGFβ1 release mimicking paracrine cell signals.

Vascular disease-causing mutation, smooth muscle α-actin R258C, dominantly suppresses functions of α-actin in human patient fibroblasts

The most common genetic alterations for familial thoracic aortic aneurysms and dissections (TAAD) are missense mutations in vascular smooth muscle (SM) α-actin encoded by ACTA2 We focus here on ACTA2-R258C, a recurrent mutation associated with early onset of TAAD and occlusive moyamoya-like cerebrovascular disease. Recent biochemical results with SM α-actin-R258C predicted that this variant will compromise multiple actin-dependent functions in intact cells and tissues, but a model system to measure R258C-induced effects was lacking. We describe the development of an approach to interrogate functional consequences of actin mutations in affected patient-derived cells. Primary dermal fibroblasts from R258C patients exhibited increased proliferative capacity compared with controls, consistent with inhibition of growth suppression attributed to SM α-actin. Telomerase-immortalized lines of control and R258C human dermal fibroblasts were established and SM α-actin expression induced with adenovirus encoding myocardin-related transcription factor A, a potent coactivator of ACTA2 Two-dimensional Western blotting confirmed induction of both wild-type and mutant SM α-actin in heterozygous ACTA2-R258C cells. Expression of mutant SM α-actin in heterozygous ACTA2-R258C fibroblasts abrogated the significant effects of SM α-actin induction on formation of stress fibers and focal adhesions, filamentous to soluble actin ratio, matrix contraction, and cell migration. These results demonstrate that R258C dominantly disrupts cytoskeletal functions attributed to SM α-actin in fibroblasts and are consistent with deficiencies in multiple cytoskeletal functions. Thus, cellular defects due to this ACTA2 mutation in both aortic smooth muscle cells and adventitial fibroblasts may contribute to development of TAAD and proliferative occlusive vascular disease.

Molecular weight specific impact of soluble and immobilized hyaluronan on CD44 expressing melanoma cells in 3D collagen matrices

Hyaluronan (HA) and its principal receptor CD44 are known to be involved in regulating tumor cell dissemination and metastasis. The direct correlation of CD44-HA interaction on proliferation and invasion of tumor cells in dependence on the molecular weight and the presentation form of HA is not fully understood because of lack of appropriate matrix models. To address this issue, we reconstituted 3D collagen (Coll I) matrices and functionalized them with HA of molecular weight of 30-50kDa (low molecular weight; LMW-HA) and 500-750kDa (high molecular weight; HMW-HA). A post-modification strategy was applied to covalently immobilize HA to reconstituted fibrillar Coll I matrices, resulting in a non-altered Coll I network microstructure and stable immobilization over days. Functionalized Coll I matrices were characterized regarding topological and mechanical characteristics as well as HA amount using confocal laser scanning microscopy, colloidal probe force spectroscopy and quantitative Alcian blue assay, respectively. To elucidate HA dependent tumor cell behavior, BRO melanoma cell lines with and without CD44 receptor expression were used for in vitro cell experiments. We demonstrated that only soluble LMW-HA promoted cell proliferation in a CD44 dependent manner, while HMW-HA and immobilized LMW-HA did not. Furthermore, an enhanced cell invasion was found only for immobilized LMW-HA. Both findings correlated with a very strong and specific adhesive interaction of LMW-HA and CD44+ cells quantified in single cell adhesion measurements using soft colloidal force spectroscopy. Overall, our results introduce an in vitro biomaterials model allowing to test presentation mode and molecular weight specificity of HA in a 3D fibrillar matrix thus mimicking important in vivo features of tumor microenvironments.

STATEMENT OF SIGNIFICANCE

Molecular weight and presentation form (bound vs. soluble) of hyaluronan (HA) are intensively discussed as key regulators in tumor progression and inflammation. We introduce 3D fibrillar collagen matrices with defined microstructure and stiffness allowing the presentation of specific molecular weight forms of HA in soluble and bound manner. Mimicking in that way important in vivo features of tumor microenvironments, we found that only low molecular weight HA (LMW-HA) in soluble form promoted proliferation of a melanoma cell line (BRO), while it enhanced cell invasion in bound form. The molecular weight specificity of LMW-HA was verified to be CD44 receptor dependent and was correlated to adhesive ligand-receptor interactions in quantitative colloidal force spectroscopy at single cell level.

Breast cancer-derived extracellular vesicles stimulate myofibroblast differentiation and pro-angiogenic behavior of adipose stem cells

Adipose-derived stem cells (ASCs) are abundantly present in the mammary microenvironment and can promote breast cancer malignancy by differentiating into myofibroblasts. However, it remains largely unclear which role tumor-derived extracellular vesicles (TEVs) play in this process. Here, we used microfabricated, type I collagen-based 3-D tissue culture platforms to investigate the effect of breast cancer cell-derived TEVs on ASCs myofibroblast differentiation and consequential changes in extracellular matrix remodeling and vascular sprouting. TEVs collected from MDA MB-231 human metastatic breast cancer cells (MDAs) promoted ASC myofibroblast differentiation in both 2-D and 3-D cultures as indicated by increased alpha smooth muscle actin (α-SMA) and fibronectin (Fn) levels. Correspondingly, TEV-treated ASCs were more contractile, secreted more vascular endothelial growth factor (VEGF), and promoted angiogenic sprouting of human umbilical vein endothelial cells (HUVECs). These changes were dependent on transforming growth factor beta (TGF-β)-related signaling and tumor cell glutaminase activity as their inhibition decreased TEV-related myofibroblastic differentiation of ASCs and related functional consequences. In summary, our data suggest that TEVs are important signaling factors that contribute to ASC desmoplastic reprogramming in the tumor microenvironment, and suggest that tumor cell glutamine metabolism may be used as a therapeutic target to interfere with this process.

Involvement of eIF6 in external mechanical stretch-mediated murine dermal fibroblast function via TGF-β1 pathway

External mechanical loading on a wound commonly increases fibrosis. Transforming growth factor-β1 (TGF-β1) has been implicated in fibrosis in various models, including the mechanical force model. However, the underlying mechanism is unclear. Our previous experiments suggested that eukaryotic initiation factor 6 (eIF6) acted as a regulator of TGF-β1 expression, and negatively impact on collagen synthesis. Our current results showed that external mechanical stretching significantly increased COL1A1, TGF-β1 and eIF6 expression as well as dermal fibroblasts proliferation, both in vitro and in vivo. eIF6 –deficient (eIF6^+/−) cells exhibited significantly higher levels of COL1A1, and these levels increased further with external mechanical stretching, suggesting that mechanical stretching plays a synergistic role in promoting COL1A1 expression in eIF6^+/− cells. Inhibition of TGFβR I/II by LY2109761 decreased COL1A1 protein expression in eIF6^+/− dermal fibroblasts in a cell stretching model, and attenuated granulation tissue formation in partial thickness wounds of eIF6^+/− mice. These data suggest that mechanical stretching has a synergistic role in the expression of COL1A1 in eIF6^+/− cells, and is mediated by activation of TGFβRI/II. Taken together, our results indicate that eIF6 may be involved in external mechanical force-mediated murine dermal fibroblast function at least partly through the TGF-β1 pathway.