Differential ß3 Integrin Expression Regulates the Response of Human Lung and Cardiac Fibroblasts to Extracellular Matrix and Its Components.

Extracellular matrix (ECM) derived from whole organ decellularization has been successfully used in a variety of tissue engineering applications. ECM contains a complex mixture of functional and structural molecules that are ideally suited for the tissue from which the ECM is harvested. However, decellularization disrupts the structural properties and protein composition of the ECM, which may impact function when cells such as the fibroblast are reintroduced during recellularization. We hypothesized that the ECM structure and composition, fibroblast source, and integrin expression would influence the fibroblast phenotype. Human cardiac fibroblasts (HCFs) and normal human lung fibroblasts (NHLFs) were cultured on intact cardiac ECM, collagen gels, and coatings composed of cardiac ECM, lung ECM, and individual ECM components (collagen and fibronectin [FN]) for 48 h. COL1A expression of HCFs and NHLFs cultured on ECM and FN coatings decreased to <50% of that of untreated cells; COL1A expression for HCFs cultured on ECM coatings was one- to twofold higher than HCFs cultured on intact ECM. NHLFs cultured on ECM and FN coatings expressed 12- to 31-fold more alpha-smooth muscle actin (αSMA) than HCFs; the αSMA expression for HCFs and NHLFs cultured on ECM coatings was ∼2- to 5-fold higher than HCFs and NHLFs cultured on intact ECM. HCFs expressed significantly higher levels of ß3 and ß4 integrins when compared to NHLFs. Inhibition of the ß3 integrin, but not ß4, resulted in a 16- to 26-fold increase in αSMA expression in HCFs cultured on ECM coatings and FN. Our results demonstrate that ß3 integrin expression depends on the source of the fibroblast and that its expression inhibits αSMA expression (and thus the myofibroblast phenotype). We conclude that the fibroblast source and integrin expression play important roles in regulating the fibroblast phenotype.

Safety and efficacy of an injectable extracellular matrix hydrogel for treating myocardial infarction.

New therapies are needed to prevent heart failure after myocardial infarction (MI). As experimental treatment strategies for MI approach translation, safety and efficacy must be established in relevant animal models that mimic the clinical situation. We have developed an injectable hydrogel derived from porcine myocardial extracellular matrix as a scaffold for cardiac repair after MI. We establish the safety and efficacy of this injectable biomaterial in large- and small-animal studies that simulate the clinical setting. Infarcted pigs were treated with percutaneous transendocardial injections of the myocardial matrix hydrogel 2 weeks after MI and evaluated after 3 months. Echocardiography indicated improvement in cardiac function, ventricular volumes, and global wall motion scores. Furthermore, a significantly larger zone of cardiac muscle was found at the endocardium in matrix-injected pigs compared to controls. In rats, we establish the safety of this biomaterial and explore the host response via direct injection into the left ventricular lumen and in an inflammation study, both of which support the biocompatibility of this material. Hemocompatibility studies with human blood indicate that exposure to the material at relevant concentrations does not affect clotting times or platelet activation. This work therefore provides a strong platform to move forward in clinical studies with this cardiac-specific biomaterial that can be delivered by catheter.

Hexosamine template. A platform for modulating gene expression and for sugar-based drug discovery.

This study investigates the breadth of cellular responses engendered by short chain fatty acid (SCFA)-hexosamine hybrid molecules, a class of compounds long used in "metabolic glycoengineering" that are now emerging as drug candidates. First, a "mix and match" strategy showed that different SCFA (n-butyrate and acetate) appended to the same core sugar altered biological activity, complementing previous results [Campbell et al. J. Med. Chem. 2008, 51, 8135-8147] where a single type of SCFA elicited distinct responses. Microarray profiling then compared transcriptional responses engendered by regioisomerically modified ManNAc, GlcNAc, and GalNAc analogues in MDA-MB-231 cells. These data, which were validated by qRT-PCR or Western analysis for ID1, TP53, HPSE, NQO1, EGR1, and VEGFA, showed a two-pronged response where a core set of genes was coordinately regulated by all analogues while each analogue simultaneously uniquely regulated a larger number of genes. Finally, AutoDock modeling supported a mechanism where the analogues directly interact with elements of the NF-kappaB pathway. Together, these results establish the SCFA-hexosamine template as a versatile platform for modulating biological activity and developing new therapeutics.

MRSI and DTI: a multimodal approach for improved detection of white matter abnormalities in alcohol and nicotine dependence.

Our previous proton magnetic resonance spectroscopic imaging ((1)H MRSI) studies showed that the frontal lobe white matter (WM) in smoking recovering alcoholics (sRA) had lower concentrations of N-acetylaspartate (NAA), a marker for neuron viability, compared to both nonsmoking recovering alcoholics (nsRA) and a control group of nonsmoking light drinkers (nsLD). Using diffusion tensor imaging (DTI) in a similar population, we found lower fractional anistropy (FA), a microstructural measure of WM fiber integrity, in regions of specific fiber bundles within frontal WM of recovering alcoholics compared to light drinkers. In this study, we hypothesized that in these regions of lower FA, NAA concentrations in the alcoholic groups are lower than in non-alcoholic controls. We hypothesized further that sRA have lower regional NAA concentrations than nsRA. We retrospectively analyzed existing (1)H MRSI data by quantitating metabolite concentrations from voxels that corresponded to previously identified WM regions of lower FA, and from a control region of normal FA in alcoholics. We found significant NAA concentration differences between groups in regions of abnormal FA. In particular, sRA had significantly lower NAA concentration than nsLD, but in no region was NAA significantly lower in nsRA than nsLD. Furthermore, no NAA group differences were detected in a frontal WM region of normal FA. These results indicate regionally localized NAA loss within the frontal WM, and specifically NAA loss in regions of low FA. Compared to our previous lobar analyses, DTI-guided MRSI analysis allows the selective evaluation of small WM regions with microstructural injury, thereby increasing statistical power to detect relevant pathology and group differences. DTI-guided MRSI analyses promise to contribute to a better understanding of brain injury in alcohol and nicotine dependence and, by extension, perhaps in other neurodegenerative diseases as well.

Targeting pro-invasive oncogenes with short chain fatty acid-hexosamine analogues inhibits the mobility of metastatic MDA-MB-231 breast cancer cells.

Per-butanoylated N-acetyl-D-mannosamine (Bu(4)ManNAc), a SCFA-hexosamine cancer drug candidate with activity manifest through intact n-butyrate-carbohydrate linkages, reduced the invasion of metastatic MDA-MB-231 breast cancer cells unlike per-butanoylated-D-mannose (Bu(5)Man), a clinically tested compound that did not alter cell mobility. To gain molecular-level insight, therapeutic targets implicated in metastasis were investigated. The active compound Bu(4)ManNAc reduced both MUC1 expression and MMP-9 activity (via down-regulation of CXCR4 transcription), whereas "inactive" Bu(5)Man had counterbalancing effects on these oncogenes. This divergent impact on transcription was linked to interplay between HDACi activity (held by both Bu(4)ManNAc and Bu(5)Man) and NF-kappaB activity, which was selectively down-regulated by Bu(4)ManNAc. Overall, these results establish a new therapeutic end point (control of invasion) for SCFA-hexosamine hybrid molecules, define relative contributions of molecular players involved in cell mobility and demonstrate that Bu(4)ManNAc breaks the confounding link between beneficial HDACi activity and the simultaneous deleterious activation of NF-kappaB often found in epigenetic drug candidates.