Inhibition of Bone Morphogenetic Protein Signal Transduction Prevents the Medial Vascular Calcification Associated with Matrix Gla Protein Deficiency

Objective: Matrix Gla protein (MGP) is reported to inhibit bone morphogenetic protein (BMP) signal transduction. MGP deficiency is associated with medial calcification of the arterial wall, in a process that involves both osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs) and mesenchymal transition of endothelial cells (EndMT). In this study, we investigated the contribution of BMP signal transduction to the medial calcification that develops in MGP-deficient mice. Approach and Results MGP-deficient mice (MGP-/-) were treated with one of two BMP signaling inhibitors, LDN-193189 or ALK3-Fc, beginning one day after birth. Aortic calcification was assessed in 28-day-old mice by measuring the uptake of a fluorescent bisphosphonate probe and by staining tissue sections with Alizarin red. Aortic calcification was 80% less in MGP-/- mice treated with LDN-193189 or ALK3-Fc compared with vehicle-treated control animals (P<0.001 for both). LDN-193189-treated MGP-/- mice survived longer than vehicle-treated MGP-/- mice. Levels of phosphorylated Smad1/5 and Id1 mRNA (markers of BMP signaling) did not differ in the aortas from MGP-/- and wild-type mice. Markers of EndMT and osteogenesis were increased in MGP-/- aortas, an effect that was prevented by LDN-193189. Calcification of isolated VSMCs was also inhibited by LDN-193189. Conclusions: Inhibition of BMP signaling leads to reduced vascular calcification and improved survival in MGP-/- mice. The EndMT and osteogenic transdifferentiation associated with MGP deficiency is dependent upon BMP signaling. These results suggest that BMP signal transduction has critical roles in the development of vascular calcification in MGP-deficient mice

In vivo endothelialization and neointimal hyperplasia assessment after angioplasty of sheep carotid artery with a novel polycarbonate polyurethane patch

The aim of this study was to compare two variants of a novel polycarbonate polyurethane prosthesis with polyethylene terephthalate (Dacron) prosthesis in an established sheep model of carotid patch angioplasty. Two variants of the polycarbonate polyurethane prosthesis were used: (1) Polycarbonate polyurethane equal (PCU-e) prosthesis consisted of a multilayered porous structure with equal internal and external layers; (2) Polycarbonate polyurethane with more porous inner layers (PCU-mp) prosthesis had more porous inner layers than external layers. Carotid patch angioplasty was performed in 12 sheep: in six sheep, the PCU-e variant and in the other six sheep, the PCU-mp variant was implanted. Dacron patches were implanted in the contralateral carotid artery of all sheep as a control. Half of the animals with each polycarbonate polyurethane variant were euthanized after two weeks and the other half after eight weeks. Cellular infiltration, endothelialization, and neointimal hyperplasia were examined. All grafts were patent, and no thrombus was seen in any of the harvested arteries. The pores of all the three patch materials allowed infiltration of inflammatory cells, capillaries, and connective tissue. After eight weeks, a nearly complete endothelialization was visible in all patch groups without an obvious difference between the three patch materials. The neointima was thinner in the PCU patches (PCU-e: 56 +/- 13 mu m, PCU-mp: 119 +/- 60 mu m) when compared to Dacron patches (156 +/- 64 mu m) after two weeks. After 8 weeks, a further neointimal growth was detectable, without any significant difference of neointimal thickness between the three patch materials (Dacron: 274 +/- 82 mu m, PCU-e: 324 +/- 98 mu m, PCU-mp: 235 +/- 59 mu m). With the novel polycarbonate polyurethane patch materials, we achieved promising functional and morphological results with 100% patency and nearly complete endothelialization. Our findings showed at least a non-inferiority of the novel polycarbonate polyurethane patch material compared to Dacron. There were no significant differences detected between the two polycarbonate polyurethane patch variants

Desmoplakin Maintains Transcellular Keratin Scaffolding and Protects From Intestinal Injury

BACKGROUND & AIMS: Desmosomes are intercellular junctions connecting keratin intermediate filaments of neighboring cells. The cadherins desmoglein 2 (Dsg2) and desmocollin 2 mediate cell–cell adhesion, whereas desmoplakin (Dsp) provides the attachment of desmosomes to keratins. Although the importance of the desmosome–keratin network is well established in mechanically challenged tissues, we aimed to assess the currently understudied function of desmosomal proteins in intestinal epithelia. METHODS: We analyzed the intestine-specific villin-Cre DSP (DSP(ΔIEC)) and the combined intestine-specific DSG2/DSP(ΔIEC) (ΔDsg2/Dsp) knockout mice. Cross-breeding with keratin 8–yellow fluorescent protein knock-in mice and generation of organoids was performed to visualize the keratin network. A Dsp-deficient colorectal carcinoma HT29-derived cell line was generated and the role of Dsp in adhesion and mechanical stress was studied in dispase assays, after exposure to uniaxial cell stretching and during scratch assay. RESULTS: The intestine of DSP(ΔIEC) mice was histopathologically inconspicuous. Intestinal epithelial cells, however, showed an accelerated migration along the crypt and an enhanced shedding into the lumen. Increased intestinal permeability and altered levels of desmosomal proteins were detected. An inconspicuous phenotype also was seen in ΔDsg2/Dsp mice. After dextran sodium sulfate treatment, DSP(ΔIEC) mice developed more pronounced colitis. A retracted keratin network was seen in the intestinal epithelium of DSP(ΔIEC)/keratin 8–yellow fluorescent protein mice and organoids derived from these mice presented a collapsed keratin network. The level, phosphorylation status, and solubility of keratins were not affected. Dsp-deficient HT29 cells had an impaired cell adhesion and suffered from increased cellular damage after stretch. CONCLUSIONS: Our results show that Dsp is required for proper keratin network architecture in intestinal epithelia, mechanical resilience, and adhesion, thereby protecting from injury

Mapping the cardiac vascular niche in heart failure

The cardiac vascular and perivascular niche are of major importance in homeostasis and during disease, but we lack a complete understanding of its cellular heterogeneity and alteration in response to injury as a major driver of heart failure. Using combined genetic fate tracing with confocal imaging and single-cell RNA sequencing of this niche in homeostasis and during heart failure, we unravel cell type specific transcriptomic changes in fibroblast, endothelial, pericyte and vascular smooth muscle cell subtypes. We characterize a specific fibroblast subpopulation that exists during homeostasis, acquires Thbs4 expression and expands after injury driving cardiac fibrosis, and identify the transcription factor TEAD1 as a regulator of fibroblast activation. Endothelial cells display a proliferative response after injury, which is not sustained in later remodeling, together with transcriptional changes related to hypoxia, angiogenesis, and migration. Collectively, our data provides an extensive resource of transcriptomic changes in the vascular niche in hypertrophic cardiac remodeling