Human Aortic Valvular Interstitial Cells Research Articles

Loss of ceramide synthase 5 inhibits the development of experimentally induced aortic valve stenosis.

Inflammation and calcification are hallmarks in the development of aortic valve stenosis (AVS). Ceramides mediate inflammation and calcification in the vascular tissue. The highly abundant d18:1,16:0 ceramide (C16) has been linked to increased cardiovascular mortality and obesity. In this study, we investigate the role of ceramide synthase 5 (CerS5), a critical enzyme for C16 ceramide synthesis, in the development of AVS, particularly in conjunction with a high-fat/high-cholesterol diet (Western diet, WD). We used wild-type (WT) and CerS5-/- mice on WD or normal chow in a wire injury model. We measured the peak velocity to determine AVS development and performed histological analysis of the aortic valve area, immune cell infiltration (CD68 staining), and calcification (von Kossa). Invitro experiments involved measuring the calcification of human aortic valvular interstitial cells (VICs) and evaluating cytokine release from THP-1 cells, a human leukemia monocytic-like cell line, following CerS5 knockdown. CerS5-/- mice showed a reduced peak velocity compared to WT only in the experiment with WD. Likewise, we observed reduced immune cell infiltration and calcification in the aortic valve of CerS5-/- mice, but only on WD. Invitro, calcification was reduced after knockdown of CerS5 in VICs, while THP-1 cells exhibited a decreased inflammatory response following CerS5 knockdown. We conclude that CerS5 is an important mediator for the development of AVS in mice on WD and regulates critical pathophysiological hallmarks of AVS formation. CerS5 is therefore an interesting target for pharmacological therapy and merits further investigation.

Aortic valve calcification is promoted by interleukin-8 and restricted through antagonizing CXCR2.

Inflammatory cytokines play a critical role in the progression of calcific aortic valve disease (CAVD), for which there is currently no pharmacological treatment. The aim of this study was to test the hypothesis that interleukin-8 (IL-8), known to be involved in arterial calcification, also promotes aortic valve calcification (AVC) and to evaluate whether pharmacologically blocking the IL-8 receptor, CXC motif chemokine receptor 2 (CXCR2), could be effective in preventing AVC progression. A cohort of 195 patients (median age 73, 74% men) diagnosed with aortic valve stenosis (severe in 16.9% of cases) were prospectively followed by CT for a median time of 2.6 years. A Cox proportional hazards regression analysis indicated that baseline IL-8 serum concentrations were associated with rapid progression of AVC, defined as an annualized change in the calcification score by CT ≥ 110 AU/year, after adjustment for age, gender, bicuspid anatomy and baseline disease severity. In vitro, exposure of primary human aortic valvular interstitial cells (hVICs) to 15 pg/ml IL-8 induced a two-fold increase in inorganic phosphate (Pi)-induced calcification. IL-8 promoted NFκB pathway activation, MMP-12 expression, and elastin degradation in hVICs exposed to Pi. These effects were prevented by SCH527123, an antagonist of CXCR2. The expression of CXCR2 was confirmed in hVICs and samples of aortic valves isolated from patients with CAVD, in which the receptor was mainly found in calcified areas, along with MMP-12 and a degraded form of elastin. Finally, in a rat model of chronic kidney disease-associated CAVD, SCH527123 treatment (1 mg/kg/day given orally for 11 weeks) limited the decrease in aortic cusp separation, the increase in maximal velocity of the transaortic jet, and the increase in aortic mean pressure gradient measured by echocardiography, effects that were associated with a reduction in hydroxyapatite deposition and MMP-12 expression in the aortic valves. Overall, these results highlight, for the first time, a significant role for IL-8 in the progression of CAVD by promoting calcification via a CXCR2-- and MMP-12-dependent mechanism that leads to elastin degradation, and identify CXCR2 as a promising therapeutic target for the treatment of CAVD.

Multiomics of Tissue Extracellular Vesicles Identifies Unique Modulators of Atherosclerosis and Calcific Aortic Valve Stenosis.

Fewer than 50% of patients who develop aortic valve calcification have concomitant atherosclerosis, implying differential pathogenesis. Although circulating extracellular vesicles (EVs) act as biomarkers of cardiovascular diseases, tissue-entrapped EVs are associated with early mineralization, but their cargoes, functions, and contributions to disease remain unknown. Disease stage-specific proteomics was performed on human carotid endarterectomy specimens (n=16) and stenotic aortic valves (n=18). Tissue EVs were isolated from human carotid arteries (normal, n=6; diseased, n=4) and aortic valves (normal, n=6; diseased, n=4) by enzymatic digestion, (ultra)centrifugation, and a 15-fraction density gradient validated by proteomics, CD63-immunogold electron microscopy, and nanoparticle tracking analysis. Vesiculomics, comprising vesicular proteomics and small RNA-sequencing, was conducted on tissue EVs. TargetScan identified microRNA targets. Pathway network analyses prioritized genes for validation in primary human carotid artery smooth muscle cells and aortic valvular interstitial cells. Disease progression drove significant convergence (P<0.0001) of carotid artery plaque and calcified aortic valve proteomes (2318 proteins). Each tissue also retained a unique subset of differentially enriched proteins (381 in plaques; 226 in valves; q<0.05). Vesicular gene ontology terms increased 2.9-fold (P<0.0001) among proteins modulated by disease in both tissues. Proteomics identified 22 EV markers in tissue digest fractions. Networks of proteins and microRNA targets changed by disease progression in both artery and valve EVs revealed shared involvement in intracellular signaling and cell cycle regulation. Vesiculomics identified 773 proteins and 80 microRNAs differentially enriched by disease exclusively in artery or valve EVs (q<0.05); multiomics integration found tissue-specific EV cargoes associated with procalcific Notch and Wnt signaling in carotid arteries and aortic valves, respectively. Knockdown of tissue-specific EV-derived molecules FGFR2, PPP2CA, and ADAM17 in human carotid artery smooth muscle cells and WNT5A, APP, and APC in human aortic valvular interstitial cells significantly modulated calcification. The first comparative proteomics study of human carotid artery plaques and calcified aortic valves identifies unique drivers of atherosclerosis versus aortic valve stenosis and implicates EVs in advanced cardiovascular calcification. We delineate a vesiculomics strategy to isolate, purify, and study protein and RNA cargoes from EVs entrapped in fibrocalcific tissues. Integration of vesicular proteomics and transcriptomics by network approaches revealed novel roles for tissue EVs in modulating cardiovascular disease.

Overexpression of microRNA-93-5p and microRNA-374a-5p Suppresses the Osteogenic Differentiation and Mineralization of Human Aortic Valvular Interstitial Cells Through the BMP2/Smad1/5/RUNX2 Signaling Pathway.

Aortic valve calcification commonly occurs in patients with chronic kidney disease (CKD). However, the regulatory functions of microRNAs (miRNAs/miRs) in the osteogenic differentiation of human aortic valvular interstitial cells (hAVICs) in patients with CKD remain largely unknown. This study aimed to explore the functional role and underlying mechanisms of miR-93-5p and miR-374a-5p in the osteogenic differentiation of hAVICs. For this purpose, hAVICs calcification was induced with high-calcium/high-phosphate medium and the expression levels of miR-93-5p and miR-374a-5p were determined using bioinformatics assay. Alizarin red staining, intracellular calcium content, and alkaline phosphatase activity were used to evaluate calcification. The expression levels of bone morphogenetic protein-2 (BMP2), runt-related transcription factor 2 (Runx2), and phosphorylated (p)-Smad1/5 were detected by luciferase reporter assay, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and western blot analysis. The results revealed that the expression levels of miR-93-5p and miR-374a-5p were significantly decreased in hAVICs in response to high-calcium/high-phosphate medium. The overexpression of miR-93-5p and miR-374a-5p effectively suppressed the high-calcium/high-phosphate-induced calcification and osteogenic differentiation makers. Mechanistically, the overexpression of miR-93-5p and miR-374a-5p inhibits osteogenic differentiation by regulating the BMP2/Smad1/5/Runx2 signaling pathway. Taken together, this study indicates that miR-93-5p and miR-374a-5p suppress the osteogenic differentiation of hAVICs associated with calcium-phosphate metabolic dyshomeostasis through the inhibition of the BMP2/Smad1/5/Runx2 signaling pathway.

Increased Circulating Levels of MicroRNA-93-5p and MicroRNA-374a-5p Suppress the Osteogenic Differentiation and Mineralization of Human Aortic Valvular Interstitial Cells Via Targeting BMP2

Increased Circulating Levels of MicroRNA-93-5p and MicroRNA-374a-5p Suppress the Osteogenic Differentiation and Mineralization of Human Aortic Valvular Interstitial Cells Via Targeting BMP2

Tri-Layered and Gel-Like Nanofibrous Scaffolds with Anisotropic Features for Engineering Heart Valve Leaflets.

3D heterogeneous and anisotropic scaffolds that approximate native heart valve tissues are indispensable for the successful construction of tissue engineered heart valves (TEHVs). In this study, novel tri-layered and gel-like nanofibrous scaffolds, consisting of poly(lactic-co-glycolic) acid (PLGA) and poly(aspartic acid) (PASP), are fabricated by a combination of positive/negative conjugate electrospinning and bioactive hydrogel post-processing. The nanofibrous PLGA-PASP scaffolds present tri-layered structures, resulting in anisotropic mechanical properties that are comparable with native heart valve leaflets. Biological tests show that nanofibrous PLGA-PASP scaffolds with high PASP ratios significantly promote the proliferation and collagen and glycosaminoglycans (GAGs) secretions of human aortic valvular interstitial cells (HAVICs), compared to PLGA scaffolds. Importantly, the nanofibrous PLGA-PASP scaffolds are found to effectively inhibit the osteogenic differentiation of HAVICs. Two types of porcine VICs, from young and adult age groups, are further seeded onto the PLGA-PASP scaffolds. The adult VICs secrete higher amounts of collagens and GAGs and undergo a significantly higher level of osteogenic differentiation than young VICs. RNA sequencing analysis indicates that age has a pivotal effect on the VIC behaviors. This study provides important guidance and a reference for the design and development of 3D tri-layered, gel-like nanofibrous PLGA-PASP scaffolds for TEHV applications.

Abstract 12316: Carnitine O-octanoyltransferase Inhibition Attenuates Human Aortic Valve Interstitial Cell Calcification by Correcting Energetic Mitochondrial State

Background: Cardiovascular calcification is a critical pathology associated with increased cardiovascular risk, but there are no FDA-approved anti-calcification therapies. Through an unbiased screening approach, we previously identified carnitine O-octanoyltransferase (CROT) as a novel contributing factor to vascular calcification, but whether it can inhibit calcification in cardiac valves remains unknown. Here we investigated CROT-associated mechanisms of calcification in human valvular interstitial cells (VICs). Methods and Results: Human VICs were isolated from aortic valve leaflets of patients undergoing valve replacement surgeries at Brigham and Women’s Hospital, and cultured in osteogenic medium (OM) to induce calcification. OM increased CROT mRNA expression (1.83±0.41 fold-change; p&lt;0.05). Tissue-nonspecific alkaline phosphatase activity, a key regulator of calcification, was also increased by OM (8.80±3.81 fold-change; p&lt;0.001) and reduced by CROT siRNA treatment (0.48±0.19 fold-change; p&lt;0.01). CROT siRNA decreased calcium deposition (Alizarin red staining; &gt;99.9%; p&lt;0.001). We previously showed that mitochondria dysfunction contributes to vascular calcification. We therefore, assessed mitochondrial function in VICs by measuring oxygen consumption rate and extracellular acidification rate. Basal and maximal respiration, spare respiratory capacity and ATP production increased in VICs after OM stimulation (1.73±0.48, p&lt;0.01; 1.75±0.34, p&lt;0.01; 2.11±0.63, p&lt;0.05; 1.75±0.38, p&lt;0.05; respectively), indicating mitochondrial dysfunction. These parameters were corrected to normal state followed by CROT siRNA treatment. The combined data of oxygen consumption and extracellular acidification rates indicated that osteogenic condition induced mitochondria energetic state that was corrected to quiescent state by CROT siRNA treatment. Conclusions: CROT promotes calcification of human aortic VICs. CROT inhibition attenuates the calcification of VICs via correcting mitochondrial dysfunction induced by osteogenic environment. CROT inhibition is an attractive approach as a therapy for aortic valve calcification, a major unmet medical need.

Inhibition of PP2A enhances the osteogenic differentiation of human aortic valvular interstitial cells via ERK and p38 MAPK pathways

AimsTo investigate the role of PP2A in calcified aortic valve disease (CAVD). Materials and methodsThe expressions of PP2A subunits were detected by real-time polymerase chain reaction (RT-PCR) and western blot in aortic valves from patients with CAVD and normal controls, the activities of PP2A were analyzed by commercial assay kit at the same time. Aortic valve calcification of mice was evaluated through histological and echocardiographic analysis. ApoE−/− mice and ApoE−/− mice injected intraperitoneally with PP2A inhibitor LB100 were fed a high-cholesterol diet for 24 weeks. Immunofluorescent staining was used to locate the cell-type in which PP2A activity was decreased, the PP2A activity of valvular interstitial cells (VICs) treated with osteogenic induction medium was assessed by western blot and commercial assay kit. After changing the activity of VICs through pharmacologic and genetic intervention, the osteoblast differentiation and mineralization were assessed by western blot and Alizarin Red staining. Finally, the mechanism was clarified by using several specific inhibitors. Key findingsPP2A activity was decreased both in calcified aortic valves and human VICs under osteogenic induction. The PP2A inhibitor LB100 aggravated the aortic valve calcification of mice. Furthermore, PPP2CA overexpression inhibited osteogenic differentiation of VICs, whereas PPP2CA knockdown promoted the process. Further study revealed that the ERK/p38 MAPKs signaling pathways mediated the osteogenic differentiation of VICs induced by PP2A inactivation. SignificanceThis study demonstrated that PP2A plays an important role in CAVD pathophysiology, PP2A activation may provide a novel strategy for the pharmacological treatment of CAVD.

Caffeic Acid Phenethyl Ester Ameliorates Calcification by Inhibiting Activation of the AKT/NF-κB/NLRP3 Inflammasome Pathway in Human Aortic Valve Interstitial Cells.

Calcific aortic valve disease (CAVD) occurs via a pathophysiological process that includes inflammation-induced osteoblastic differentiation of aortic valvular interstitial cells (AVICs). Here, we investigated the role of the anti-inflammatory compound caffeic acid phenethyl ester (CAPE) in inhibiting CAVD. Human AVICs were isolated and cultured in osteogenic induction medium (OM) with or without 10 μM CAPE. Cell viability was assessed using CCK8 assays and calcified transformation of AVICs was evaluated by Alizarin Red staining and osteogenic gene/protein expression. RNA-sequencing was conducted to identify differentially expressed genes (DEGs) and enrichment in associated pathways, as potential molecular targets through which CAPE inhibits osteogenic induction. The regulatory effects of CAPE on activation of the AKT/NF-κB and NLRP3 inflammasome were evaluated by Western blot analysis and immunofluorescent staining. CAPE slowed the growth of AVICs cultured in OM but did not show significant cytotoxicity. In addition, CAPE markedly suppressed calcified nodule formation and decreased gene/protein expression of RUNX2 and ALP in AVICs. Gene expression profiles of OM-induced AVICs cultured with or without CAPE revealed 518 common DEGs, which were highly enriched in the NOD-like receptor, PI3K-AKT, and NF-κB signaling pathways. Furthermore, CAPE inhibited phosphorylation of AKT, ERK1/2, and NF-κB, and suppressed NLRP3 inflammasome activation in AVICs cultured in OM. Thus, CAPE is implicated as a potent natural product for the prevention of CAVD by inhibiting activation of the AKT/NF-κB pathway and NLRP3 inflammasome.

Novel mechanisms for osteogenic differentiation of human aortic valve interstitial cells

ObjectiveAortic valve calcification is common in aging populations without effective pharmacologic interventions. Our previous in vitro data revealed a critical role for long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 as a positive regulator of osteogenic differentiation in aortic valve calcification pathogenesis. The current study sought to determine the mechanism by which metastasis-associated lung adenocarcinoma transcript 1 is regulated in aortic valve calcification. MethodsThe stability assay was used to examine the effect of human antigen R on metastasis-associated lung adenocarcinoma transcript 1 expression. Aortic valves from patients with aortic stenosis and normal controls were subjected to determination of RNA-binding protein human antigen R expression. Mineralized bone matrix formation was assessed by Alizarin Red staining. The interaction between metastasis-associated lung adenocarcinoma transcript 1 and miR-191-3p was confirmed via RNA pull-down, luciferase reporter, and RNA-binding protein immunoprecipitation assays. ResultsIn cultured human aortic valvular interstitial cells, we found human antigen R enhanced metastasis-associated lung adenocarcinoma transcript 1 stability and thus increased its concentration. Moreover, human antigen R was significantly upregulated in human calcific aortic valves and valvular interstitial cells after osteogenic induction. Human antigen R partly relied on metastasis-associated lung adenocarcinoma transcript 1 to positively regulate osteogenic differentiation of valvular interstitial cells. Luciferase reporter assays validated human antigen R as the direct target of miR-191-3p. Metastasis-associated lung adenocarcinoma transcript 1 positively regulated the expression of human antigen R through sponging miR-191-3p. ConclusionsThis study demonstrates the existence of a regulatory loop between metastasis-associated lung adenocarcinoma transcript 1 and human antigen R during osteogenic differentiation of valvular interstitial cells. Our findings provide novel mechanistic insights into a critical role of human antigen R in the aortic valve calcification progression and shed new light on RNA-binding protein-directed diagnostics and therapeutics in aortic valve calcification.

Treatment with XAV-939 prevents in vitro calcification of human valvular interstitial cells.

The development of a substance or inhibitor-based treatment strategy for the prevention of aortic valve stenosis is a challenge and a main focus of medical research in this area. One strategy may be to use the tankyrase inhibitor XAV-939, which leads to Axin stabilisation and subsequent destruction of the β-catenin complex and dephosphorylation of β-catenin. The dephosphorylated active form of β-catenin (non-phospho-β-catenin) then promotes nuclear transcription that leads to osteogenesis. The aims of the present study were to develop an experimental system for inducing in vitro calcification of human aortic valvular interstitial cells (VICs) to investigate the potential anti-calcific effect of XAV-939 and to analyse expression of the Wnt signalling proteins and Sox9, a chondrogenesis regulator, in this model. Calcification of human VIC cultures was induced by cultivation in an osteogenic medium and the effect of co-incubation with 1μM XAV-939 was monitored. Calcification was quantified when mineral deposits were visible in culture and was histologically verified by von Kossa or Alizarin red staining and by IR-spectroscopy. Protein expression of alkaline phosphatase, Axin, β-catenin and Sox9 were quantified by western blotting. In 58% of the VIC preparations, calcification was induced in an osteogenic culture medium and was accompanied by upregulation of alkaline phosphatase. The calcification induction was prevented by the XAV-939 co-treatment and the alkaline phosphatase upregulation was suppressed. As expected, Axin was upregulated, but the levels of active non-phospho-β-catenin were also enhanced. Sox9 was induced during XAV-939 treatment but apparently not as a result of downregulation of β-catenin signalling. XAV-939 was therefore able to prevent calcification of human VIC cultures, and XAV-939 treatment was accompanied by upregulation of active non-phospho-β-catenin. Although XAV-939 does not downregulate active β-catenin, treatment with XAV-939 results in Sox9 upregulation that may prevent the calcification process.

A Feedforward Regulatory Loop between HuR and Long Noncoding RNA MALAT1 Promotes Osteogenic Differentiation of Human Aortic Valve Interstitial Cells

Objective: Aortic valve calcification (AVC) is common in aging populations without effective pharmacological interventions. Our previous in vitro data revealed a critical role for long non-coding RNA (lncRNA) MALAT1 as a positive regulator of osteogenic differentiation in AVC pathogenesis. The current study sought to determine whether MALAT1 deficiency could prevent AVC progression in vivo and the mechanism by which MALAT1 is regulated in AVC. Approach and Results: AVC was evaluated in Apoe-/- mice (n = 10) or in mice with dual deficiencies of Apoe and MALAT1 (Apoe-/-MALAT1-/-, n = 10) fed a Western diet for 24 weeks. Genetic ablation of MALAT1 attenuated pro-calcification signaling activation, and valvular calcification in the leaflets of Apoe-/- mice. In cultured human aortic valvular interstitial cells (VICs), we found RNA-binding protein (RBP) human antigen R (HuR) enhanced the mRNA stability of MALAT1 and thus promoted MALAT1 expression. Moreover, HuR was significantly upregulated in mouse and human calcific aortic valves and VICs following osteogenic induction. HuR partly relied on MALAT1 to positively regulate osteogenic differentiation of VICs. Luciferase reporter assays validated HuR as the direct target of miR-191-3p. Importantly, MALAT1 positively regulated the expression of HuR through sponging miR-191-3p. Conclusions: This study demonstrates the existence of a regulatory loop in which the expression of MALAT1 and HuR is reciprocally regulated during osteogenic differentiation of VICs. Our findings provide novel mechanistic insights into a critical role of HuR in the AVC progression, and shed new light on RBPs-directed diagnostics and therapeutics in AVC. Funding: This work was supported by the National Natural Science Foundation of China (No. 81500300) and the National Key Research and Development Program of China (No. 2016YFA0101100). Declaration of Interest: None. Ethical Approval: All animal experimental protocols complied with the Guide for the Care and Use of Laboratory Animals published by the US National Institutes of Health (NIH Publication No. 85-23, revised 1996). All animal protocols were approved by the Institutional Animal Research Committee of Tongji Medical College. The protocol complied with the Declaration of Helsinki, was approved by the Ethic Board of Tongji Medical College of Huazhong University of Science and Technology. Written informed consents were obtained before surgeries from all patients.

Deficiency of CCAAT/enhancer‐binding protein homologous protein (CHOP) prevents diet‐induced aortic valve calcification in vivo

SummaryAortic valve (AoV) calcification is common in aged populations. Its subsequent aortic stenosis has been linked with increased morbidity, but still has no effective pharmacological intervention. Our previous data show endoplasmic reticulum (ER) stress is involved in AoV calcification. Here, we investigated whether deficiency of ER stress downstream effector CCAAT/enhancer‐binding protein homology protein (CHOP) may prevent development of AoV calcification. AoV calcification was evaluated in Apoe−/− mice (n = 10) or in mice with dual deficiencies of ApoE and CHOP (Apoe−/− CHOP −/−, n = 10) fed with Western diet for 24 weeks. Histological and echocardiographic analysis showed that genetic ablation of CHOP attenuated AoV calcification, pro‐calcification signaling activation, and apoptosis in the leaflets of Apoe−/− mice. In cultured human aortic valvular interstitial cells (VIC), we found oxidized low‐density lipoprotein (oxLDL) promoted apoptosis and osteoblastic differentiation of VIC via CHOP activation. Using conditioned media (CM) from oxLDL‐treated VIC, we further identified that oxLDL triggered osteoblastic differentiation of VIC via paracrine pathway, while depletion of apoptotic bodies (ABs) in CM suppressed the effect. CM from oxLDL‐exposed CHOP‐silenced cells prevented osteoblastic differentiation of VIC, while depletion of ABs did not further enhance this protective effect. Overall, our study indicates that CHOP deficiency protects against Western diet‐induced AoV calcification in Apoe−/− mice. CHOP deficiency prevents oxLDL‐induced VIC osteoblastic differentiation via preventing VIC‐derived ABs releasing.

183 - Human aortic valvular interstitial cells: evidence of vasculogenic potential during aortic valve stenosis

183 - Human aortic valvular interstitial cells: evidence of vasculogenic potential during aortic valve stenosis

Three-dimensional printed trileaflet valve conduits using biological hydrogels and human valve interstitial cells

Tissue engineering has great potential to provide a functional de novo living valve replacement, capable of integration with host tissue and growth. Among various valve conduit fabrication techniques, three-dimensional (3-D) bioprinting enables deposition of cells and hydrogels into 3-D constructs with anatomical geometry and heterogeneous mechanical properties. Successful translation of this approach, however, is constrained by the dearth of printable and biocompatible hydrogel materials. Furthermore, it is not known how human valve cells respond to these printed environments. In this study, 3-D printable formulations of hybrid hydrogels are developed, based on methacrylated hyaluronic acid (Me-HA) and methacrylated gelatin (Me-Gel), and used to bioprint heart valve conduits containing encapsulated human aortic valvular interstitial cells (HAVIC). Increasing Me-Gel concentration resulted in lower stiffness and higher viscosity, facilitated cell spreading, and better maintained HAVIC fibroblastic phenotype. Bioprinting accuracy was dependent upon the relative concentrations of Me-Gel and Me-HA, but when optimized enabled the fabrication of a trileaflet valve shape accurate to the original design. HAVIC encapsulated within bioprinted heart valves maintained high viability, and remodeled the initial matrix by depositing collagen and glyosaminoglycans. These findings represent the first rational design of bioprinted trileaflet valve hydrogels that regulate encapsulated human VIC behavior. The use of anatomically accurate living valve scaffolds through bioprinting may accelerate understanding of physiological valve cell interactions and progress towards de novo living valve replacements.

Primary culture and in vitro calcification model establishment of human aortic valve interstitial cells

Objective To primary culture human aortic valvular interstitial cells(hVlCs).establish their in vitro calcification model,and to induce hVICs differentiation to osteogenesis and to observe the phenotype changes.Methods hVICs were digested from native valves and used for experiments after 3-7 passages.The cells were cultured in osteogenic media or in normal media.One week later the calcified nodules were stained and measured by von Kossa.The activity of alkaline phosphatase(ALP) was examined by spectrophotometer,immunofluorescence staining was used to detect the phenotype protein of hVICs,and real-time PCR and Western blotting analysis were used to examine the osteogenesis associated factors to assess the calcification model of hVICs.Results The calcified nodules were found 7 days after osteogenic induction.The calcified nodules in the experimental group were significantly more than that in the control group(51.20±14.31/well vs 3.60±1.82/ well,P0.05).The activity of ALP was significantly increased after osteogenic induction compared with the control group (increased by about 4 folds,P0.05),with increased contractile phenotypeα-smooth muscle actin(α-SMA).Real-time PCR and Western blotting results indicated that the expressions of Run×2,osteocalcin,and osteopontin in the experiment group were significantly higher than those in the control group(P0.05),so was the expression of phosphorylated Smad1/5/8(P0.05). Conclusion We have successfully established the in vitro calcification model of hVICs,with hVICs in an activated state;and the phenotype shifts to contraction and ossification,which provide a reliable cell model for the future study.

Strain Magnitude-Dependent Calcific Marker Expression in Valvular and Vascular Cells

Aortic valve disease and atherosclerosis tend to coexist in most patients with cardiovascular disease; however, the causes and mechanisms of disease development in heart valves are still not clearly understood. To understand the contributions of the magnitude of cyclic strain (5% hypotension, 10% physiological, and 15% hypertension) in calcification, we used a model system of tissue-engineered collagen gels containing human aortic smooth muscle cells and human aortic valvular interstitial cells, both isolated from noncalcific heart transplant tissue. The compacted collagen gels were cultured in osteogenic media for 3 weeks in a custom-designed bioreactor and all assessments were performed at the end of the culture period. The major finding of this study is that bone morphogenic protein (BMP)-2 and BMP-4 and transforming growth factor-β1 mRNA expression significantly changed in response to the magnitude of applied strain in valvular cells, while the lowest expression was observed for the representative physiological strain. On the other hand, mRNA expression in vascular cells did not vary in response to the magnitude of strain. Regarding BMP-2 and BMP-4 protein expression determined by immunostaining, trends were similar to mRNA expression in vascular and valvular cells, where only valvular cells showed a varied protein expression depending on the magnitude of the strain applied. Our results suggest that cellular differences exist between vascular and valvular cells in their response to altered levels of cyclic strain during calcification.

Ox-LDL Induces Expression of PiT-1 in Human Aortic Valvular Interstitial Cells

Ox-LDL Induces Expression of PiT-1 in Human Aortic Valvular Interstitial Cells

Human aortic valvular interstitial cells apoptosis and calcification: TNF-related apoptosis-inducing ligand (TRAIL) involvement

Human aortic valvular interstitial cells apoptosis and calcification: TNF-related apoptosis-inducing ligand (TRAIL) involvement

Differences in valvular and vascular cell responses to strain in osteogenic media

Calcification is the primary cause of failure of bioprosthetic and tissue-engineered vascular and valvular grafts. We used tissue-engineered collagen gels containing human aortic smooth muscle cells (HASMC) and human aortic valvular interstitial cells (HAVIC) as a model to investigate cell-mediated differences in early markers of calcification. The HASMCs and HAVICs were isolated from non-sclerotic human tissues. After 21 days of culture in either regular or osteogenic media with or without 10% cyclic strain at 1 Hz, the collagen gels were assessed for DNA content, collagen I, matrix metalloproteinase (MMP)-2 and glycosaminoglycan (GAG) content. The collagen gels containing HASMCs contained significantly greater amounts of collagen I and GAG compared to HAVICs. Although strain increased MMP-2 activity for both cell types, this trend was significant (p ≤ 0.05) only for HAVICs. Cultured gels were also assessed for osteogenic markers calcium content, alkaline phosphatase (ALP), and Runx2 and were present at greater amounts in gels containing HASMCs than HAVICs. Calcium content, Runx2 expression, and ALP activity were also modulated by mechanical strain. The results indicate that cell-mediated differences exist between the vascular and valvular calcification processes. Further investigation is necessary for improved understanding and to detect biomarkers for early detection or prevention of these diseases.