The development of new multi-target combination treatment strategies to tackle ischemic stroke (IS) remains to be challenging. Herein, a proof-of-concept demonstration of an advanced nanomedicine formulation composed of macrophage membrane (MM)-camouflaged phosphorous dendrimer (termed as AK137)/fibronectin (FN) nanocomplexes (NCs) loaded with antioxidant edaravone (EDV) to modulate both microglia and neurons for effective IS therapy is showcased. The created MM@AK137-FN/EDV (M@A-F/E) NCs with a mean size of 260 nm possess good colloidal stability, sustained EDV release kinetics, and desired cytocompatibility. By virtue of MM decoration, the M@A-F/E NCs can cross blood-brain barrier, act on microglia to exert the anti-inflammatory (AK137 and FN) and antioxidative (FN and EDV) effects in vitro for oxidative stress alleviation, microglia M2 polarization, and reduction of pro-inflammatory cytokine secretion, and act on neuron cells to be anti-apoptotic. In a transient middle cerebral artery occlusion rat model, the developed M@A-F/E NCs can exert enhanced antioxidant/anti-inflammatory/anti-apoptotic therapeutic effects to comprehensively regulate the brain microenvironment and promote vascular regeneration to collaboratively restore the blood flow after ischemia-reperfusion. The designed MM-coated NCs composed of all-active ingredients of phosphorous dendrimers, FN, and EDV that can fully regulate the brain inflammatory microenvironment may expand their application scope in other neurodegenerative diseases.

The extracellular matrix (ECM) is a critical component of tissue where it provides structural and signaling support to cells. Its dysregulation and accumulation lead to fibrosis, a major clinical challenge underlying many diseases that currently has little effective treatment. An understanding of the key molecular initiators of fibrosis would be both diagnostically useful and provide potential targets for therapeutics. The ECM protein fibronectin (FN) is upregulated in fibrotic conditions and other ECM proteins depend on assembly of a FN foundational ECM for their matrix incorporation. We used cell culture and in vivo models to investigate the role of FN in the progression of lung fibrosis. We confirmed that normal human lung fibroblasts (NHLFs) treated with transforming growth factor-beta (TGF-β) to stimulate fibrotic gene expression significantly increased both FN expression and its assembly into a matrix. We found that levels of alternatively spliced EDA and EDB exons were proportional to the increase in total FN RNA and protein showing that inclusion of these exons is not enhanced by TGF-β stimulation. RNA-sequencing identified 43 core matrisome genes that were significantly up- or down-regulated by TGF-β treatment and a Luminex immunoassay demonstrated increased levels of ECM proteins in conditioned medium of TGF-β-treated NHLFs. Interestingly, among the regulated core matrisome genes, 16 encode known FN-binding proteins and, of these, insulin-like growth factor binding protein 3 (IGFBP3) was most highly up-regulated. To link the NHLF results with in vivo disease, we analyzed lung tissue and bronchoalveolar lavage fluid from bleomycin-treated mice and found dramatically higher levels of FN and the FN-binding proteins IGFBP3, tenascin-C, and type I collagen in fibrotic conditions compared to controls. Altogether, our data identify a set of FN-binding proteins whose upregulation is characteristic of IPF and suggest that FN provides the foundational matrix for deposition of these proteins as fibrosis develops.

UNASSIGNED: The acetylation of histone H3 proteins keeps local chromatin regions open and accessible, thereby facilitating transcriptional events. We recently reported integrative epigenomic and transcriptome analyses of differentiating dental pulp stem cells (DPSCs). A significant increase in the number of super-enhancers, which are local genomic locations marked by condensed open chromatin peaks that facilitate transcriptional events, in differentiating DPSCs were observed. However, it is still unclear whether histone deacetylase (HDACs) inhibitors (HDACis) have beneficial effects on the odontogenic differentiation of DPSCs and on the matrix mineralization-inducing ability of DPSCs.
UNASSIGNED: DPSCs were cultured in an odontogenic induction medium for a prolonged period in the presence of HDACis, MS-275 and Trichostatin A (TSA). ATAC-seq and RNA-seq samples were collected from differentiating DPSCs to explore the epigenomic and transcriptomic alterations induced by HDACis and identify key target proteins that mediate HDACis-induced phenotypic changes.
UNASSIGNED: MS-275 and TSA did not change whole-genome open chromatin accessibility or increase odontogenic differentiation, as assessed by alkaline phosphate activity. However, the matrix mineralization-inducing ability assessed by calcified nodule formation was significantly increased by MS-275 but not by TSA. FN1, which encodes fibronectin, was identified as upregulated by MS-275. The knockdown of fibronectin evidently suppressed MS-275-induced calcified nodule formation.
UNASSIGNED: MS-275 induced calcified nodule formation by the mechanistic upregulation of FN1, independent of epigenomic alterations. Hence, the application of MS-275 as direct capping materials has therapeutic potential for promoting reparative dentin formation by constructing a fibronectin-organizing physiological extracellular matrix environment that is adequate for matrix mineralization.

BACKGROUND: Replacing damaged organs or tissues and repairing damage by tissue engineering are attracting great interest today. A potentially effective method for bone remodeling involves combining nanofiber scaffolds with extracellular matrix (ECM), and growth factors. Today, electrospun PCL-based scaffolds are widely used for tissue engineering applications.
METHODS: In this study, we used an electrospun polycaprolactone (PCL) scaffold coated with fibronectin (Fn), a ubiquitous ECM glycoprotein, to investigate the induction potential of this scaffold in osteogenesis with adipose-derived mesenchymal stem cells (AD-MSCs).
RESULTS: Scanning electron microscopy (SEM) analysis showed that fibronectin, by binding to the membrane receptors of mesenchymal stem cells (MSCs), leads to their attachment and proliferation on the PCL scaffold and provides a suitable environment for osteogenesis. In addition, biochemical tests showed that fibronectin leads to increased calcium deposition. The results also showed that alkaline phosphatase activity was significantly higher in the PCL scaffold coated with fibronectin than in the control groups (PCL scaffold group and tissue culture polystyrene (TCPS) group) (P<0.05). Also, the analysis of quantitative reverse transcription PCR (qRT-PCR) data showed that the relative expression of bone marker genes such as osteonectin (ON), osteocalcin (OC), RUNX family transcription factor 2 (RUNX2), and collagen type I alpha 1 (COL1) was much higher in the cells seeded on the PCL/Fn scaffold than in the other groups (P<0.05).
CONCLUSIONS: The results show that fibronectin has an increasing effect in accelerating bone formation and promising potential for use in bone tissue engineering.

This study assessed the biocompatibility of two types of nanogold composites: fibronectin-gold (FN-Au) and collagen-gold (Col-Au). It consisted of three main parts: surface characterization, in vitro biocompatibility assessments, and animal models. To determine the structural and functional differences between the materials used in this study, atomic force microscopy, Fourier-transform infrared spectroscopy, and ultraviolet-visible spectrophotometry were used to investigate their surface topography and functional groups. The F-actin staining, proliferation, migration, reactive oxygen species generation, platelet activation, and monocyte activation of mesenchymal stem cells (MSCs) cultured on the FN-Au and Col-Au nanocomposites were investigated to determine their biological and cellular behaviors. Additionally, animal biocompatibility experiments measured capsule formation and collagen deposition in female Sprague-Dawley rats. The results showed that MSCs responded better on the FN-Au and Col-AU nanocomposites than on the control (tissue culture polystyrene) or pure substances, attributed to their incorporation of an optimal Au concentration (12.2 ppm), which induced significant surface morphological changes, nano topography cues, and better biocompatibility. Moreover, neuronal, endothelial, bone, and adipose tissues demonstrated better differentiation ability on the FN-Au and Col-Au nanocomposites. Nanocomposites have a crucial role in tissue engineering and even vascular grafts. Finally, MSCs were demonstrated to effectively enhance the stability of the endothelial structure, indicating that they can be applied as promising alternatives to clinics in the future.

The placenta experiences a low-oxygen stage during early pregnancy. Aspirin is an effective preventative treatment for preeclampsia if applied early in pregnancy. Elevation of fibronectin (FN) level has been reported to be associated with preeclampsia; however, the role of FN in the physiological hypoxic phase and whether aspirin exerts its effect on FN at this hypoxic stage remain unknown. We determined pregnancy outcomes by injecting saline or recombinant FN protein into C57BL/6 pregnant mice and one group of FN-injected mice was fed aspirin. The effects of FN, the underlying pathways on trophoblast biology, and cilia formation under hypoxia were investigated in FN-pretreated or FN-knockdown HTR-8/SVneo cells in a hypoxic chamber (0.1 % O2). Preeclampsia-like phenotypes, including blood pressure elevation and proteinuria, developed in FN-injected pregnant mice. The fetal weight of FN-injected mice was significantly lower than that of non-FN-injected mice (p < 0.005). Trophoblast FN expression was upregulated under hypoxia, which could be suppressed by aspirin treatment. FN inhibited trophoblast invasion and migration under hypoxia, and this inhibitory effect occurred through downregulating ZEB1/2, MMP 9 and the Akt and MAPK signaling pathways. Ciliogenesis of trophoblasts was stimulated under hypoxia but was inhibited by FN treatment. Aspirin was shown to reverse the FN-mediated inhibitory effect on trophoblast invasion/migration and ciliogenesis. In conclusion, FN overexpression induces preeclampsia-like symptoms and impairs fetal growth in mice. Aspirin may exert its suppressive effect on FN upregulation and FN-mediated cell function in the hypoxic stage of pregnancy and therefore provides a preventative effect on preeclampsia development.

Primary open angle glaucoma (POAG) is a progressive and chronic disease exhibiting many of the features of fibrosis. The extracellular matrix (ECM) in the trabecular meshwork (TM) undergoes extensive remodeling and enhanced rigidity, resembling fibrotic changes. In addition, there are changes associated with myofibroblast activation and cell contractility that further drives tissue fibrosis and stiffening. This review discusses what is known about the integrins in the TM and their involvement in fibrotic processes.

A large number of bacterial pathogens bind to host extracellular matrix (ECM) components. For example, many Gram-negative and Gram-positive pathogens express binding proteins for fibronectin (FN) on their cell surface. Mutagenesis studies of bacterial FN-binding proteins have demonstrated their importance in pathogenesis in preclinical animal models. However, means to draw on these findings to design therapeutic approaches that specifically target FN-bacteria interactions have not been successful because bacterial pathogens can elaborate several FN-binding proteins and also because FN is an essential protein and likely a nondruggable target. Here we report that select heparan compounds potently inhibit Streptococcus pneumoniae infection of injured corneas in mice. Using intact heparan sulfate (HS) and heparin (HP), heparinase-digested fragments of HS, HP oligosaccharides, and chemically or chemoenzymatically modified heparan compounds, we found that inhibition of S. pneumoniae corneal infection by heparan compounds is not mediated by simple charge effects but by a selective sulfate group. Removal of 2-O-sulfates significantly inhibited the ability of HP to inhibit S. pneumoniae corneal infection, whereas the addition of 2-O-sulfates to heparosan (H) significantly increased H\'s ability to inhibit bacterial corneal infection. Proximity ligation assays indicated that S. pneumoniae attaches directly to FN fibrils in the corneal epithelial ECM and that HS and HP specifically inhibit this binding interaction in a 2-O-sulfate-dependent manner. These data suggest that heparan compounds containing 2-O-sulfate groups protect against S. pneumoniae corneal infection by inhibiting bacterial attachment to FN fibrils in the subepithelial ECM of injured corneas. Moreover, 2-O-sulfated heparan compounds significantly inhibited corneal infection in immunocompromised hosts, by a clinical keratitis isolate of S. pneumoniae, and also when topically administered in a therapeutic manner. These findings suggest that the administration of nonanticoagulant 2-O-sulfated heparan compounds may represent a plausible approach to the treatment of S. pneumoniae keratitis.

In an attempt to repair injured central nervous system (CNS) nerves/tracts, immune cells are recruited into the injury site, but endogenous response in adult mammals is insufficient for promoting regeneration of severed axons. Here, we found that a portion of retinal ganglion cell (RGC) CNS projection neurons that survive after optic nerve crush (ONC) injury are enriched for and upregulate fibronectin (Fn)-interacting integrins Itga5 and ItgaV, and that Fn promotes long-term survival and long-distance axon regeneration of a portion of axotomized adult RGCs in culture. We then show that, Fn is developmentally downregulated in the axonal tracts of optic nerve and spinal cord, but injury-activated macrophages/microglia upregulate Fn while axon regeneration-promoting zymosan augments their recruitment (and thereby increases Fn levels) in the injured optic nerve. Finally, we found that Fn\'s RGD motif, established to interact with Itga5 and ItgaV, promotes long-term survival and long-distance axon regeneration of adult RGCs after ONC in vivo, with some axons reaching the optic chiasm when co-treated with Rpl7a gene therapy. Thus, experimentally augmenting Fn levels in the injured CNS is a promising approach for therapeutic neuroprotection and axon regeneration of at least a portion of neurons.

The role extracellular matrix (ECM) in multiple events of morphogenesis has been well described, little is known about its specific role in early eye development. One of the first morphogenic events in lens development is placodal thickening, which converts the presumptive lens ectoderm from cuboidal to pseudostratified epithelium. This process occurs in the anterior pre-placodal ectoderm when the optic vesicle approaches the cephalic ectoderm and is regulated by transcription factor Pax6 and secreted BMP4. Since cells and ECM have a dynamic relationship of interdependence and modulation, we hypothesized that the ECM evolves with cell shape changes during lens placode formation. This study investigates changes in optic ECM including both protein distribution deposition, extracellular gelatinase activity and gene expression patterns during early optic development using chicken and mouse models. In particular, the expression of Timp2, a metalloprotease inhibitor, corresponds with a decrease in gelatinase activity within the optic ECM. Furthermore, we demonstrate that optic ECM remodeling depends on BMP signaling in the placode. Together, our findings suggest that the lens placode plays an active role in remodeling the optic ECM during early eye development.