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Open in new tab Download slide 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Open in new tab Download slide Open in new tab Download slide 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the role of bradykinin and its B2 receptor for the vascular recruitment of and activation of circulating mononuclear cell subsets. The study employs flow cytometry, in vitro adhesion assays, and isolation of peripheral blood monuclear cells (PBMCs). Results reveal that bradykinin/B2R promotes endothelial repair after arterial injury.

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 CD14hiCD16neg and resident CD16pos 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. © 2011 International Society for Advancement of Cytometry [ABSTRACT FROM AUTHOR]