High Glucose Induced Changes in Human VEC Phenotype in a 3D Hydrogel Derived From Cell-Free Native Aortic Root

VCAM-1 targeted nanocarriers of shRNA-Smad3 mitigate endothelial-to-mesenchymal transition triggered by high glucose concentrations and osteogenic factors in valvular endothelial cells

Endothelial to mesenchymal transition (EndMT) of valvular endothelial cells (VEC) is a key process in the development and progression of calcific aortic valve disease (CAVD). High expression of the Smad3 transcription factor is crucial in the transition process. We hypothesize that silencing Smad3 could hinder EndMT and provide a novel treatment for CAVD. We aimed at developing nanoparticles encapsulating short-hairpin (sh)RNA sequences specific for Smad3 targeted to the aortic valve. We synthesized VCAM-1-targeted lipopolyplexes encapsulating shRNA-Smad3 plasmid (V-LPP/shSmad3) and investigated their potential to reduce the EndMT of human VEC. VEC incubation in a medium containing high glucose concentrations and osteogenic factors (HGOM) triggers EndMT and increased expression of Smad3. Exposed to lipopolyplexes, VEC took up efficiently the V-LPP/shSmad3. The latter reduced the EndMT process in VEC exposed to HGOM by downregulating the expression of αSMA and S100A4 mesenchymal markers and increasing the expression of the CD31 endothelial marker. In vivo, V-LPP/shSmad3 accumulated in the aortic root and aorta of a murine model of atherosclerosis complicated with diabetes, without affecting the liver and kidney function. The results suggest that targeting activated VEC with lipopolyplexes to silence Smad3 could be an effective, novel treatment for CAVD mediated by the EndMT process.

Beyond VICs: Shedding light on the overlooked VECs in calcific aortic valve disease

Calcific aortic valve disease (CAVD) is prevalent in developed nations and has emerged as a pressing global public health concern due to population aging. The precise etiology of this disease remains uncertain, and recent research has primarily focused on examining the role of valvular interstitial cells (VICs) in the development of CAVD. The predominant treatment options currently available involve open surgery and minimally invasive interventional surgery, with no efficacious pharmacological treatment. This article seeks to provide a comprehensive understanding of valvular endothelial cells (VECs) from the aspects of valvular endothelium-derived nitric oxide (NO), valvular endothelial mechanotransduction, valvular endothelial injury, valvular endothelial-mesenchymal transition (EndMT), and valvular neovascularization, which have received less attention, and aims to establish their role and interaction with VICs in CAVD. The ultimate goal is to provide new perspectives for the investigation of non-invasive treatment options for this disease.

Hyperglycemia-simulating environment attenuated experimentally induced calcification in cultured human aortic valve interstitial cells

Objectives: The role of diabetes mellitus as a risk factor for the development of calcific aortic valve disease has not been fully clarified. Aortic valve interstitial cells (VICs) have been suggested to be crucial for calcification of the valve. Induced calcification in cultured VICs is a good in vitro model for aortic valve calcification. The purpose of this study was to investigate whether increased glucose levels increase experimentally induced calcification in cultured human VICs. Design: VICs were isolated from explanted calcified aortic valves after valve replacement. Osteogenic medium induced calcification of cultured VICs at different glucose levels (5, 15, and 25 mM). Calcium deposits were visualized using Alizarin Red staining and measured spectrophotometrically. Results: The higher the glucose concentration, the lower the level of calcification. High glucose (25 mM) reduced calcification by 52% compared with calcification at a physiological (5 mM) glucose concentration (correlation and regression analysis: r = -0.55, p = .025 with increased concentration of glucose). Conclusions: In vitro hyperglycemia-like conditions attenuated calcification in VICs. High glucose levels may trigger a series of events that secondarily stimulate calcification of VICs in vivo.

Major Facilitator Superfamily Domain Containing 5 Inhibition Reduces Lipoprotein(a) Uptake and Calcification in Valvular Heart Disease

BACKGROUND

High circulating levels of Lp(a) (lipoprotein[a]) increase the risk of atherosclerosis and calcific aortic valve disease, affecting millions of patients worldwide. Although atherosclerosis is commonly treated with low-density lipoprotein-targeting therapies, these do not reduce Lp(a) or risk of calcific aortic valve disease, which has no available drug therapies. Targeting Lp(a) production and catabolism may provide therapeutic benefit, but little is known about Lp(a) cellular uptake.

METHODS

Here, unbiased ligand-receptor capture mass spectrometry was used to identify MFSD5 (major facilitator superfamily domain containing 5) as a novel receptor/cofactor involved in Lp(a) uptake.

RESULTS

Reducing MFSD5 expression by a computationally identified small molecule or small interfering RNA suppressed Lp(a) uptake and calcification in primary human valvular endothelial and interstitial cells. MFSD5 variants were associated with aortic stenosis (P=0.027 after multiple hypothesis testing) with evidence suggestive of an interaction with plasma Lp(a) levels.

CONCLUSIONS

MFSD5 knockdown suppressing human valvular cell Lp(a) uptake and calcification, along with meta-analysis of MFSD5 variants associating with aortic stenosis, supports further preclinical assessment of MFSD5 in cardiovascular diseases, the leading cause of death worldwide.

Experimental Models to Study Endothelial to Mesenchymal Transition in Myocardial Fibrosis and Cardiovascular Diseases

Fibrosis is a common feature of cardiovascular diseases and targets multiple organs, such as the heart and vessels. Endothelial to mesenchymal transition is a complex, vital process that occurs during embryonic formation and plays a crucial role in cardiac development. It is also a fundamental process implicated in cardiac fibrosis and repair, but also in other organs. Indeed, in numerous cardiovascular diseases, the endothelial-to-mesenchymal transition has been shown to be involved in the generation of fibroblasts that are able to produce extracellular matrix proteins such as type I collagen. This massive deposition results in tissue stiffening and organ dysfunction. To advance our understanding of this process for the development of new specific diagnostic and therapeutic strategies, it is essential to develop relevant cellular and animal models of this process. In this review, our aim was to gain an in-depth insight into existing in vitro and in vivo models of endothelial to mesenchymal transition in cardiovascular diseases with a focus on cardiac fibrosis. We discuss important parameters impacting endothelial to mesenchymal transition, and we give perspectives for the development of relevant models to decipher the underlying mechanisms and ultimately find new treatments specific to fibrosis happening in cardiovascular diseases.

Embedding and Backscattered Scanning Electron Microscopy (EM-BSEM) Is Preferential over Immunophenotyping in Relation to Bioprosthetic Heart Valves

Hitherto, calcified aortic valves (AVs) and failing bioprosthetic heart valves (BHVs) have been investigated by similar approaches, mostly limited to various immunostaining techniques. Having employed multiple immunostaining combinations, we demonstrated that AVs retain a well-defined cellular hierarchy even at severe stenosis, whilst BHVs were notable for the stochastic degradation of the extracellular matrix (ECM) and aggressive infiltration by ECM-digesting macrophages. Leukocytes (CD45+) comprised ≤10% cells in the AVs but were the predominant cell lineage in BHVs (≥80% cells). Albeit cells with uncertain immunophenotype were rarely encountered in the AVs (≤5% cells), they were commonly found in BHVs (≥80% cells). Whilst cell conversions in the AVs were limited to the endothelial-to-mesenchymal transition (represented by CD31+α-SMA+ cells) and the formation of endothelial-like (CD31+CD68+) cells at the AV surface, BHVs harboured numerous macrophages with a transitional phenotype, mostly CD45+CD31+, CD45+α-SMA+, and CD68+α-SMA+. In contrast to immunostaining, which was unable to predict cell function in the BHVs, our whole-specimen, nondestructive electron microscopy approach (EM-BSEM) was able to distinguish between quiescent and matrix-degrading macrophages, foam cells, and multinucleated giant cells to conduct the ultrastructural analysis of organelles and the ECM, and to preserve tissue integrity. Hence, we suggest EM-BSEM as a technique of choice for studying the cellular landscape of BHVs.

Identification of TNFα-mediated inflammation as potential pathological marker and therapeutic target for calcification progress of congenital bicuspid aortic valve

BACKGROUD

Congenital bicuspid aortic valve (cBAV) develops calcification and stenotic obstruction early compared with degenerative tricuspid aortic valve (dTAV), which requires surgical intervention. Here we report a comparative study of patients with cBAV or dTAV to identify risk factors associated with the rapid development of calcified bicuspid valves.

METHODS

A total of 69 aortic valves (24 dTAV and 45 cBAV) were collected at the time of surgical aortic valve replacement for comparative clinical characteristics. Ten samples were randomly selected from each group for histology, pathology, and inflammatory factors expression and comparison analyses. OM-induced calcification in porcine aortic valve interstitial cell cultures were prepared for illustrating the underlying molecular mechanisms about calcification progress of cBAV and dTAV.

RESULTS

We found that cBAV patients have increased cases of aortic valve stenosis compared with dTAV patients. Histopathological examinations revealed increased collagens deposition, neovascularization and infiltrations by inflammatory cells, especially T-lymphocytes and macrophages. We identified that tumor necrosis factor α (TNFα) and its regulated inflammatory cytokines are upregulated in cBAV. Further in vitro study indicated that TNFα-NFκB and TNFα-GSK3β pathway accelerate aortic valve interstitial cells calcification, while inhibition of TNFα significantly delays this process.

CONCLUSION

The finding of intensified TNFα-mediated inflammation in the pathological cBAV advocates the inhibition of TNFα as a potential treatment for patients with cBAV by alleviating the progress of inflammation-induced valve damage and calcification.

Nanocarriers of shRNA-Runx2 directed to collagen IV as a nanotherapeutic system to target calcific aortic valve disease

Runx2 is a key transcription factor involved in valvular interstitial cells (VIC) osteodifferentiation, a process actively entwined with the calcific aortic valve disease (CAVD). We hypothesize that a strategy intended to silence Runx2 could be a valuable novel therapeutic option for CAVD. To this intent, we aimed at (i) developing targeted nanoparticles for efficient delivery of short hairpin (sh)RNA sequences specific for Runx2 to the aortic valve employing a relevant mouse model for CAVD and (ii) investigate their therapeutic potential in osteoblast-differentiated VIC (oVIC) cultivated into a 3D scaffold. Since collagen IV was used as a target, a peptide that binds specifically to collagen IV (Cp) was conjugated to the surface of lipopolyplexes encapsulating shRNA-Runx2 (Cp-LPP/shRunx2). The results showed that Cp-LPP/shRunx2 were (i) cytocompatible; (ii) efficiently taken up by 3D-cultured oVIC; (iii) diminished the osteodifferentiation of human VIC (cultured in a 3D hydrogel-derived from native aortic root) by reducing osteogenic molecules expression, alkaline phosphatase activity, and calcium concentration; and (iv) were recruited in aortic valve leaflets in a murine model of atherosclerosis. Taken together, these data recommend Cp-LPP/shRunx2 as a novel targeted nanotherapy to block the progression of CAVD, with a good perspective to be introduced in practical use.

Glycosaminoglycans affect endothelial to mesenchymal transformation, proliferation, and calcification in a 3D model of aortic valve disease

Calcific nodules form in the fibrosa layer of the aortic valve in calcific aortic valve disease (CAVD). Glycosaminoglycans (GAGs), which are normally found in the valve spongiosa, are located local to calcific nodules. Previous work suggests that GAGs induce endothelial to mesenchymal transformation (EndMT), a phenomenon described by endothelial cells’ loss of the endothelial markers, gaining of migratory properties, and expression of mesenchymal markers such as alpha smooth muscle actin (α-SMA). EndMT is known to play roles in valvulogenesis and may provide a source of activated fibroblast with a potential role in CAVD progression. In this study, a 3D collagen hydrogel co-culture model of the aortic valve fibrosa was created to study the role of EndMT-derived activated valvular interstitial cell behavior in CAVD progression. Porcine aortic valve interstitial cells (PAVIC) and porcine aortic valve endothelial cells (PAVEC) were cultured within collagen I hydrogels containing the GAGs chondroitin sulfate (CS) or hyaluronic acid (HA). The model was used to study alkaline phosphatase (ALP) enzyme activity, cellular proliferation and matrix invasion, protein expression, and calcific nodule formation of the resident cell populations. CS and HA were found to alter ALP activity and increase cell proliferation. CS increased the formation of calcified nodules without the addition of osteogenic culture medium. This model has applications in the improvement of bioprosthetic valves by making replacements more micro-compositionally dynamic, as well as providing a platform for testing new pharmaceutical treatments of CAVD.