Tissue-engineered and autologous pericardium in congenital heart surgery: comparative histopathological study of human vascular explants.

OBJECTIVES: The goal of this histological study was to assess the biocompatibility of vascular patches used in the repair of congenital heart defects. METHODS: We examined tissue-engineered bovine (n = 7) and equine (n = 7) patches and autologous human pericardium (n = 7), all explanted due to functional issues or follow-up procedures. Techniques like Movat-Verhoeff, von Kossa and immunohistochemical staining were used to analyse tissue composition, detect calcifications and identify immune cells. A semi-quantitative scoring system was implemented to evaluate the biocompatibility aspects, thrombus formation, extent of pannus, inflammation of pannus, cellular response to patch material, patch degradation, calcification and neoadventitial inflammation. RESULTS: We observed distinct material degradation patterns among types of patches. Bovine patches showed collagen disintegration and exudate accumulation, whereas equine patches displayed edematous swelling and material dissolution. Biocompatibility scores were lower in terms of cellular response, degradation and overall score for human autologous pericardial patches compared to tissue-engineered types. The extent of pannus formation was not influenced by the type of patch. Bovine patches had notable calcifications causing tissue hardening, and foreign body giant cells were more frequently seen in equine patches. Plasma cells were frequently detected in the neointimal tissue of engineered patches. CONCLUSIONS: Our results confirm the superior biocompatibility of human autologous patches and highlight discernible variations in the changes of patch material and the cellular response to patch material between bovine and equine patches. Our approach implements the semi-quantitative scoring of various aspects of biocompatibility, facilitating a comparative quantitative analysis across all types of patches, despite their inherent differences.

Bridge to recovery using an Impella 2.5 device in a 3-year-old child.

Mechanical support options for children and small adolescents with acute left ventricular failure are often limited to extracorporeal life support (ECLS) and subsequent left ventricular assist device implantation. We report a case of a 3-year-old child weighing 12 kg with acute humoral rejection after cardiac transplantation not adequately responding to medical therapy who presented in persistent low cardiac output syndrome. We successfully stabilized the patient by implanting a Impella 2.5 device via a 6-mm Hemashield prosthesis on the right axillary artery. The patient was bridged to recovery.

Mid-term performance of decellularized equine pericardium in congenital heart surgery.

OBJECTIVE: The aim was to report mid-term performance of decellularized equine pericardium used for repair of various congenital heart defects in the pediatric population. METHODS: A retrospective review of all patients undergoing patch implantation between 2016 - 2020 was performed. Patch quality, surgical handling, hemostasis and early patch-related complications were studied on all patients. Mid-term performance was observed in patients with ≥12 months follow-up and intact patch at discharge (without reoperation/stent implantation). RESULTS: A total of 201 patients with median age of 2.5 years [interquartile range (IQR): 0.6-6.5] underwent 207 procedures at 314 implant locations. The patch was used in following numbers/locations: 171 for pulmonary artery (PA) augmentation, 36 for aortic repair, 35 for septal defect closure, 22 for valvular repair and 50 at other locations. Early/30-day mortality was 6.5%. Early patch-related reoperations/stent implantations occurred in 28 locations (8.9%). No patch-related complications were noted except for bleeding from implant site in three locations (1%). Follow-up ≥ 12 months was available for 132 patients/200 locations. During a median follow-up of 29.7 months [IQR: 20.7-38.3], 53 patch-related reoperations/catheter reinterventions occurred (26.5%) with the majority in PA position (88.7%, 47/53). Overall 12- and 24-months freedom from patch-related reoperation/catheter reintervention per location was 91.5% (95% CI: 86.7%-94.6%) and 85.2% (95% CI: 78.9%-89.6%) respectively. CONCLUSION: Decellularized equine pericardium used for repair of various congenital heart defects showed acceptable mid-term performance. Reoperation/reintervention rates were in a range as observed with other xenogeneic materials previously reported articles, occurring most frequently after PA augmentation.

Rapid Inflammasome Activation Is Attenuated in Post-Myocardial Infarction Monocytes.

Inflammasomes are crucial gatekeepers of the immune response, but their maladaptive activation associates with inflammatory pathologies. Besides canonical activation, monocytes can trigger non-transcriptional or rapid inflammasome activation that has not been well defined in the context of acute myocardial infarction (AMI). Rapid transcription-independent inflammasome activation induced by simultaneous TLR priming and triggering stimulus was measured by caspase-1 (CASP1) activity and interleukin release. Both classical and intermediate monocytes from healthy donors exhibited robust CASP1 activation, but only classical monocytes produced high mature interleukin-18 (IL18) release. We also recruited a limited number of coronary artery disease (CAD, n=31) and AMI (n=29) patients to evaluate their inflammasome function and expression profiles. Surprisingly, monocyte subpopulations isolated from blood collected during percutaneous coronary intervention (PCI) from AMI patients presented diminished CASP1 activity and abrogated IL18 release despite increased NLRP3 gene expression. This unexpected attenuated rapid inflammasome activation was accompanied by a significant increase of TNFAIP3 and IRAKM expression. Moreover, TNFAIP3 protein levels of circulating monocytes showed positive correlation with high sensitive troponin T (hsTnT), implying an association between TNFAIP3 upregulation and the severity of tissue injury. We suggest this monocyte attenuation to be a protective phenotype aftermath following a very early inflammatory wave in the ischemic area. Damage-associated molecular patterns (DAMPs) or other signals trigger a transitory negative feedback loop within newly recruited circulating monocytes as a mechanism to reduce post-injury tissue damage.

Pulmonary artery augmentation using decellularized equine pericardium (Matrix Patch™): initial single-centre experience.

OBJECTIVES: The aim of this study was to report our initial experience when using Matrix Patch™ a cell-free equine-derived pericardium for the augmentation of branch pulmonary arteries (PAs) in children. METHODS: Between September 2016 and September 2019, Matrix Patch was used for the augmentation of branch PAs in 96 patients and implanted in 147 separate locations. The median age at implantation was 3.2 years (interquartile range: 0.9-8.4), and 33% of patients were infants. The patch was used mainly in redo surgeries (89.6%). Intra-procedural feasibility and reinterventions were analysed. Primary end points were death or patch-related reoperation/stent implantation. Explanted patches were stained for recellularization/calcification, or to reveal proliferation/inflammation. RESULTS: A total of 81 patients, who received patches in 119 separate locations, were followed within a median of 20 months (interquartile range: 10.2-30.2). Patients with early reoperation/stent implantation were excluded from follow-up. No patch-related death was noted. Survival at last follow-up was 88% (95% CI: 78.8-93.7%). Overall probability of freedom from reoperation/stent implantation per location, 12 and 24 months after initial surgery was 85.8% (95% CI: 76.2-91.7%) and 78.7 (95% CI: 65.9-87.2%), respectively. At 20 months, superficial proliferation with discrete macrophage activity was seen in explants; however, no signs of calcification are observed. CONCLUSIONS: The initial experience with the Matrix Patch in PAs showed comparable results to other xenogeneic patch materials. Long-term follow-up data are needed to prove the desired durability of the patch in different locations.

Increased Expression of miR-483-3p Impairs the Vascular Response to Injury in Type 2 Diabetes.

Aggravated endothelial injury and impaired endothelial repair capacity contribute to the high cardiovascular risk in patients with type 2 diabetes (T2D), but the underlying mechanisms are still incompletely understood. Here we describe the functional role of a mature form of miRNA (miR) 483-3p, which limits endothelial repair capacity in patients with T2D. Expression of human (hsa)-miR-483-3p was higher in endothelial-supportive M2-type macrophages (M2MΦs) and in the aortic wall of patients with T2D than in control subjects without diabetes. Likewise, the murine (mmu)-miR-483* was higher in T2D than in nondiabetic murine carotid samples. Overexpression of miR-483-3p increased endothelial and macrophage apoptosis and impaired reendothelialization in vitro. The inhibition of hsa-miR-483-3p in human T2D M2MΦs transplanted to athymic nude mice (NMRI-Foxn1ν/Foxn1ν ) or systemic inhibition of mmu-miR-483* in B6.BKS(D)-Leprdb /J diabetic mice rescued diabetes-associated impairment of reendothelialization in the murine carotid-injury model. We identified the endothelial transcription factor vascular endothelial zinc finger 1 (VEZF1) as a direct target of miR-483-3p. VEZF1 expression was reduced in aortae of diabetic mice and upregulated in diabetic murine aortae upon systemic inhibition of mmu-483*. The miRNA miR-483-3p is a critical regulator of endothelial integrity in patients with T2D and may represent a therapeutic target to rescue endothelial regeneration after injury in patients with T2D.

Vascular repair strategies in type 2 diabetes: novel insights.

Impaired functions of vascular cells are responsible for the majority of complications in patients with type 2 diabetes (T2D). Recently a better understanding of mechanisms contributing to development of vascular dysfunction and the role of systemic inflammatory activation and functional alterations of several secretory organs, of which adipose tissue has more recently been investigated, has been achieved. Notably, the progression of vascular disease within the context of T2D appears to be driven by a multitude of incremental signaling shifts. Hence, successful therapies need to target several mechanisms in parallel, and over a long time period. This review will summarize the latest molecular strategies and translational developments of cardiovascular therapy in patients with T2D.

Systemic VEGF inhibition accelerates experimental atherosclerosis and disrupts endothelial homeostasis--implications for cardiovascular safety.

OBJECTIVES: This study sought to examine the effects and underlying mechanisms of systemic VEGF inhibition in experimental atherosclerosis and aortic endothelial cells. BACKGROUND: Pharmacological inhibition of vascular endothelial growth factor (VEGF), a major mediator of angiogenesis, has become a widely applied treatment of certain cancers and multiple ocular diseases including age-related macular degeneration. However, recent clinical trials raise concern for systemic vascular adverse effects, prompting the Food and Drug Administration to revoke the approval of bevacizumab for metastatic breast cancer. METHODS: Eight-week old apolipoprotein E knockout mice received a high-cholesterol diet (1.25% cholesterol) for 24 weeks and were exposed to a systemic pan-VEGF receptor inhibitor (PTK787/ZK222584, 50mg/kg/d) or placebo (gavage) for the last 10 weeks. Atherosclerotic lesions were characterized in thoraco-abdominal aortae and aortic arches. Mechanistic analyses were performed in cultured human aortic endothelial cells. RESULTS: Systemic VEGF inhibition increased atherosclerotic lesions by 33% whereas features of plaque vulnerability (i.e. necrotic core size, fibrous cap thickness) remained unchanged compared with controls. Aortic eNOS expression was decreased (trend). In human endothelial cells VEGF inhibition induced a dose-dependent increase in mitochondrial superoxide generation with an uncoupling of eNOS, resulting in reduced NO availability and decreased proliferation. CONCLUSION: Systemic VEGF inhibition disrupts endothelial homeostasis and accelerates atherogenesis, suggesting that these events contribute to the clinical cardiovascular adverse events of VEGF-inhibiting therapies. Cardiovascular safety profiles of currently applied anti-angiogenic regimens should be determined to improve patient selection for therapy and allow close monitoring of patients at increased cardiovascular risk.

Abnormal high-density lipoprotein induces endothelial dysfunction via activation of Toll-like receptor-2.

Endothelial injury and dysfunction (ED) represent a link between cardiovascular risk factors promoting hypertension and atherosclerosis, the leading cause of death in Western populations. High-density lipoprotein (HDL) is considered antiatherogenic and known to prevent ED. Using HDL from children and adults with chronic kidney dysfunction (HDL(CKD)), a population with high cardiovascular risk, we have demonstrated that HDL(CKD) in contrast to HDL(Healthy) promoted endothelial superoxide production, substantially reduced nitric oxide (NO) bioavailability, and subsequently increased arterial blood pressure (ABP). We have identified symmetric dimethylarginine (SDMA) in HDL(CKD) that causes transformation from physiological HDL into an abnormal lipoprotein inducing ED. Furthermore, we report that HDL(CKD) reduced endothelial NO availability via toll-like receptor-2 (TLR-2), leading to impaired endothelial repair, increased proinflammatory activation, and ABP. These data demonstrate how SDMA can modify the HDL particle to mimic a damage-associated molecular pattern that activates TLR-2 via a TLR-1- or TLR-6-coreceptor-independent pathway, linking abnormal HDL to innate immunity, ED, and hypertension.

Novel insights into the critical role of bradykinin and the kinin B2 receptor for vascular recruitment of circulating endothelial repair-promoting mononuclear cell subsets: alterations in patients with coronary disease.

BACKGROUND: Endothelial injury is considered critical for progression of atherosclerosis and its complications in coronary artery disease (CAD). The endothelial-supportive effects of bradykinin have mainly been attributed to activation of the resident endothelium. Here we newly investigate the role of bradykinin and its B2 receptor for the recruitment and functional activation of circulating mononuclear cell subsets with endothelial-repair promoting capacity, such as CD34(+)CXCR4(+)cells, at sites of arterial injury. METHODS AND RESULTS: Bradykinin-B2-receptor (B2R) blockade by icatibant substantially impaired recruitment of circulating CD34(+)CXCR4(+) mononuclear cells (expressing high levels of B2R) to endothelial cells in vitro and to injured arterial wall in vivo, whereas recruitment of CD14(hi) monocytes (expressing low levels of B2R) was unchanged. Moreover, the capacity of genetically B2R-deficient bone marrow cells to promote endothelial repair in vivo was markedly impaired as compared with wild-type bone marrow cells. B2R expression was reduced on CD34(+)CXCR4(+)mononuclear cells and endothelial repair-promoting early outgrowth cells, but not on CD14(hi)monocytes, from CAD patients as compared with healthy subjects. B2R stimulation induced CD18 activation in early outgrowth cells of healthy subjects, but not in early outgrowth cells of CAD patients. Adenoviral B2R overexpression enhanced in vivo vascular recruitment and rescued impaired endothelial repair capacity of early outgrowth cells from CAD patients. CONCLUSIONS: We newly report that bradykinin/B2R signaling may promote endothelial repair after arterial injury by selective recruitment and functional activation of B2R-expressing circulating mononuclear cell subsets. In CAD patients, B2R downregulation on endothelial repair-promoting circulating mononuclear cells substantially impairs the bradykinin-dependent endothelial repair, representing a novel mechanism promoting endothelial injury in CAD patients.

A novel flow cytometry-based assay to study leukocyte-endothelial cell interactions in vitro.

Interactions between peripheral blood mononuclear cells (PBMC) and the endothelium critically determine vascular repair and reparative angiogenesis, but also pathological processes, such as atherosclerosis. Current methodology to study these interactions mostly regards PBMC as a homogenous population or it restricts its focus on individual cell types and therefore does not appreciate the differential behavior of individual PBMC subpopulations, which synergize or antagonize each other to obtain the overall effect. We therefore developed a flow cytometry-based in vitro assay to assess multiple parameters of interaction between several individual populations of PBMC and an endothelial monolayer. Freshly isolated, unlabelled human PBMC were left to adhere to or transmigrate through a monolayer of fluorescence-labeled human aortic endothelial cells grown to confluence on the filter membrane of sterile transwell migration inserts. Monocyte chemoattractant protein-1 (MCP-1) was applied as a chemoattractant to the lower compartment of the migration chamber. After 6 h, transmigrating PBMC were harvested from the lower compartment, while nonadherent and adhering cell populations were harvested from the upper compartment by sequential washing/detachment. All three cell fractions were then individually stained with fluorescence-labeled monoclonal antibodies and analyzed by flow cytometry. Quantification was achieved by the usage of counting beads. Endothelial cells were separated from PBMC during the analysis by a multiparametric gating strategy. Using the newly established assay, we observed distinct migration patterns for inflammatory CD14(hi) CD16(neg) and resident CD16(pos) monocytes. These cell types differed in their basal adhesion and transmigration patterns as well as their responses to the CCR2 ligand MCP-1. This assay allows for the parallel study of interactions between multiple individual leukocyte populations and an endothelial layer. Several readouts can be derived from the same experiment, like the composition of adhering and transmigrating cell fractions or the individual adhesion/migration behavior of several distinct cell types.