Endothelialization of Polycaprolactone Vascular Graft under the Action of Locally Applied Vascular Endothelial Growth Factor.

We have previously developed a polycaprolactone (PCL) vascular graft with incorporated vascular endothelial growth factor (VEGF). Functioning of the PCL/VEGF graft in rat circulatory system over 1, 3 and 6 months after implantation into abdominal aorta was tested. Graft patency and formation of vascular wall elements were assessed histologically and by immunofluorescence staining for von Willebrand factor, CD31, CD34, and collagens I and IV and DAPI staining. Local application of VEGF promoted endothelialization and improved patency of the graft. The wall of the PCL/VEGF graft underwent remodeling due to active cellular infiltration and the extracellular matrix deposition.

Biocompatibility and Structural Features of Biodegradable Polymer Scaffolds.

We performed a comparative analysis of physicochemical properties and biocompatibility of scaffolds of different composition on the basis of biodegradable polymers fabricated by casting and electrospinning methods. For production of polyhydroxyalkanoate-based scaffolds by electrospinning method, the optimal concentration of the polymer was 8-10%. Fiber diameter and properties of the scaffold produced by electrospinning method depended on polymer composition. Addition of polycaprolactone increased elasticity of the scaffolds. Bio- and hemocompatibility of the scaffolds largely depended on the composition formulation and method of scaffold fabrication. Polylactide introduced into the composition of polyhydroxybutyrate-oxyvalerate scaffolds accelerated degradation and increased adhesive properties of the scaffolds.

Experimental model of rat aorta angioplasty with a Paclitaxel releasing balloon catheter.

We present an original and safe experimental model of the rat aorta angioplasty with a paclitaxel-releasing balloon catheter. No toxic effects of the drug on experimental animals were detected.

[Proliferative and secretory activity of human umbilical vein endothelial cells cultured under varying degrees of hypoxia].

In this study we examined the impact of 3-day hypoxia of varying degrees on the viability, proliferative and secretory activity of endothelial cells in human umbilical vein (HUVEC). The gas mixture of the three components (%) was used: 1) 10 O2, 5 CO2, 85 Ar; 2) 5 O2, 5 CO2, 90 Ar and 3) 1 O2, 5 CO2, 94 Ar. The HUVEC, cultivated in CO2-incubator under conditions of atmospheric oxygen (21% O2) were the controls. Comprehensive assessment of the results after has shown that 3-day HUVEC cultivating in the presence of 1% O2 led to pathological activation of endotheliocytes: increased NO synthesis combined with the marked secretion of endothelin-1, IL-6, IL-8 and TNF-alpha, sVCAM-1, sE-cadherin and of sE-selectin, VEGF-A and bFGF, and slow proliferation. When HUVEC were cultivated at 10% O2 and 5% O2, the level of basal secretion of the substances listed above was the least against the background of increased proliferative activity. The results showing the changes in the secretory activity of endothelial cells when cultivated under the conditions of atmospheric oxygen levels have demonstrate HUVEC activation, because the secretion of NO, IL-6, IL-8 and von Willebrand factor after 3 days of cultivation in 21% 02 exceeded that in the case of 10 and 5% O2. Thus, a gaseous medium with reduced oxygen content of up to 5% provides more physiological conditions for HUVEC cultivation. The maximum proliferative activity of HUVEC with minimal basal secretion proved such a composition to be comfortable. Increasing the oxygen content to the atmospheric level leads to the activation of endotheliocytes with signs of endothelial dysfunction, and the critical reduction in oxygen to 1% causes the development of endothelial dysfunction and reduces the proliferative potential.

The cytokine response of human coronary artery endothelial cells treated with doxorubicin: results of an in vitro experiment.

The cytokine profile of primary coronary artery endothelial cells cultivated in the presence of doxorubicin (2 µg/ml and 6 µg/ml) was evaluated using enzyme-linked immunosorbent assay and qPCR. Cultivation of cells in the presence of these concentrations of doxorubicin for 24 h, upregulated expression of the following genes: IL6 (by 2.30 and 2.66 times, respectively), IL1B (by 1.25 and 3.44 times), and CXCL8 (by 6.47 times and 6.42 times), MIF (2.34 and 2.28 times), CCL2 (4.22 and 3.98 times). Under these conditions the following genes were downregulated: IL10, IL1R2, TNF. Cultivation of cells in the presence of doxorubicin (2 µg/ml and 6 µg/ml) for 24 h also increased the secretion of IL-6.

New Tissue-Engineered Vascular Matrix Based on Regenerated Silk Fibroin: in vitro Study.

The aim of the study was to make a vascular patch based on regenerated silk fibroin (SF) and study its physical and mechanical characteristics, biocompatibility and matrix properties in comparison with polyhydroxybutyrate/valerate/polycaprolactone with incorporated vascular endothelial growth factor (PHBV/PCL/VEGF) and commercial bovine xenopericardium (XP) flap in experiments in vitro. Materials and Methods: Tissue-engineered matrices were produced by electrospinning. The surface structure, physical and mechanical characteristics, hemocompatibility (erythrocyte hemolysis, aggregation, adhesion and activation of platelets after contact with the material) and matrix properties of vascular patches (adhesion, viability, metabolic activity of EA.hy926 cells on the material) were studied. Results: The surface of SF-based matrices and PHBV/PCL/VEGF-based tissue engineered patches had a porous and fibrous structure compared to a denser and more uniform XP flap. The physical and mechanical characteristics of SF matrices were close to those of native vessels. Along with this, tissue-engineered patches demonstrated high hemocompatible properties, which do not differ from those for commercial XP flap. Adhesion, viability, and metabolic activity of EA.hy926 endothelial cells also corresponded to the previously developed PHBV/PCL/VEGF matrix and XP flap, which indicates the nontoxicity and biocompatibility of SF matrices. Conclusion: Matrices produced from regenerated SF demonstrated satisfactory results, comparable to those for PHBV/PCL/VEGF and commercial XP flap, and in the case of platelet adhesion and activation, they outperformed these patches. In total, SF can be defined as material having sufficient biological compatibility, which makes it possible to consider a tissue-engineered matrix made from it as promising for implantation into the vascular wall.

[Postoperative dynamic changes in matrix metalloproteinase levels in patients with coronary artery bypass graft procedure complications].

The purpose of this study was to evaluate diagnostic and prognostic value of matrix metalloproteinases in postoperative complication development after on-pump coronary artery bypass grafting. 29 coronary artery disease patients who had undergone on-pump coronary artery bypass grafting were examined, 4 of those had complicated systemic inflammatory response and 5 of those had isolated renal failure. Serum matrix metalloproteinase/tissue inhibitor of matrix metalloproteinase concentrations were measured before surgery, at day 1 and day 7 after surgery. Postoperative period was found to be characterized by higher levels of serum matrix metalloproteinases (MMP-9, proMMP-1) and lower levels of matrix metalloproteinase 1 tissue inhibitor. Complicated systemic inflammatory response was associated with higher levels of MMP-9, MMP-3 and proMMP-1, on particular, at day 7.

Evaluation of the Feasibility of Endothelial Colony-Forming Cells to Develop Tissue-Engineered Vascular Grafts Based on the Gene Expression Profile Analysis.

The aim of the study was to assess the suitability of endothelial colony-forming cells in the development of tissue engineering constructs based on the study of the gene expression profile compared to mature endothelial cells. Materials and Methods: In the experiment, we used the endothelial colony-forming cells (ECFC) obtained from the peripheral blood of patients who underwent percutaneous coronary intervention. The cells were isolated on a Histopaque 1077 density gradient (Sigma-Aldrich, USA), and then cultured in EGM-2MV culture medium (Lonza, Switzerland). A commercial culture of primary human coronary artery endothelial cells (HCAEC) was used as a control. The cells were unfrozen and cultured according to the manufacturer's recommendations in MesoEndo Cell Growth Medium (Cell Applications, USA).The experiment was carried out in specialized µ-Luer plates in the perfusion system (IBIDI, Germany), which provided a continuous unidirectional flow of the culture medium with a shear stress of 5 dyn/cm2. Control plates were cultured under standard conditions for a similar period of time. Total RNA was isolated from cell samples. The expression of the genes NOTCH4, NRP2, PLAT, PLAU, NOTCH1, FLT1, COL4A2, CD34, SERPINE1, HEY2, MKI67, KLF4, LYVE1, FLT4 was assessed using a quantitative real-time polymerase chain reaction. The expression of the genes was calculated by the ΔCt method and expressed on a logarithmic (log10) scale as a fold change relating to the control samples. Results: In mature endothelial cells HCAEC when exposed to a laminar flow, only the transcription factor KLF4 and venous differentiation NRP2 marker values increased significantly. ECFC showed statistically significant growth in KLF4, NRP2, CD34, and LYVE1, as well as PLAU expression decrease. In addition, we observed the overexpression of FLT4, LYVE1, NOTCH4, and NRP2 in ECFC in relation to HCAEC and HEY2 hypoexpression. CD34 overexpression characteristic of progenitor cells was also found. An increase in COL4A2 expression associated with type IV collagen synthesis was a characteristic feature of ECFC. Conclusion: The gene expression profile of endothelial colony-forming cells is quite close to that of primary endothelial cells of the human coronary artery, and thus, the cells obtained from patients' peripheral blood can be used to develop personalized tissue-engineered constructs.

Endothelial Dysfunction in the Context of Blood-Brain Barrier Modeling.

Here, we discuss pathophysiological approaches to the defining of endothelial dysfunction criteria (i.e., endothelial activation, impaired endothelial mechanotransduction, endothelial-to-mesenchymal transition, reduced nitric oxide release, compromised endothelial integrity, and loss of anti-thrombogenic properties) in different in vitro and in vivo models. The canonical definition of endothelial dysfunction includes insufficient production of vasodilators, pro-thrombotic and pro-inflammatory activation of endothelial cells, and pathologically increased endothelial permeability. Among the clinical consequences of endothelial dysfunction are arterial hypertension, macro- and microangiopathy, and microalbuminuria. We propose to extend the definition of endothelial dysfunction by adding altered endothelial mechanotransduction and endothelial-to-mesenchymal transition to its criteria. Albeit interleukin-6, interleukin-8, and MCP-1/CCL2 dictate the pathogenic paracrine effects of dysfunctional endothelial cells and are therefore reliable endothelial dysfunction biomarkers in vitro, they are non-specific for endothelial cells and cannot be used for the diagnostics of endothelial dysfunction in vivo. Conceptual improvements in the existing methods to model endothelial dysfunction, specifically, in relation to the blood-brain barrier, include endothelial cell culturing under pulsatile flow, collagen IV coating of flow chambers, and endothelial lysate collection from the blood vessels of laboratory animals in situ for the subsequent gene and protein expression profiling. Combined with the simulation of paracrine effects by using conditioned medium from dysfunctional endothelial cells, these flow-sensitive models have a high physiological relevance, bringing the experimental conditions to the physiological scenario.