Biology subjects

Panteleev, M. A.

Publications and source records attributed to Panteleev, M. A..

4 recordsLinked to original sources

bioRxiv2024

Staying on track: collagen fibers orientation strongly affects thrombi formation at high shear

ObjectiveSubendothelial matrix exhibits a distinctive organization, with collagen fibers beneath the endothelium oriented primarily parallel to the flow and comprising mainly types III and I collagen in arteries and arterioles. However, the significance of such organization in initiating rapid thrombus formation remains unclear. Approach and ResultsTo investigate the role of collagen fibers orientation in triggering thrombus formation we utilized the in vitro microfluidic model of thrombosis. Human whole blood was perfused through a system with collagen fibers oriented either parallel or perpendicular to the flow, and the primary stages of platelet adhesion and thrombi growth were analyzed using a high-speed fluorescence microscopy. At the shear rates of 200 and 1000 s-1 no significant difference in thrombogenicity was observed between the collagen fibers orientations. However, at a high shear rate of 2000 s-1, thrombi on the parallel fibers were higher and covered a much larger area than those on the perpendicular ones. High-speed microscopy revealed that platelets were able to achieve stable adhesion only after translocating for over several seconds under all studied conditions. Analysis of single platelets dynamics revealed that platelets interacted longer and translocated farther during their interaction with parallel fibers at high shear, suggesting that flow-aligned fibers facilitate stable adhesion by enabling platelets to translocate along them and stay in contact with collagen. Importantly, only a small fraction of collagen fibers belonging to type III collagen admixture - a common component of a standard type I collagen preparation - accumulated plasma vWF and supported platelet adhesion at high shear rate. ConclusionType III, but not type I collagen fibers oriented parallel to the flow facilitate stable platelet adhesion at high shear rates. Thus, axial orientation of subendothelial collagen fibers observed in vivo may have physiological relevance for triggering rapid thrombus formation at high shear rates. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=106 SRC="FIGDIR/small/627297v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@14c1af5org.highwire.dtl.DTLVardef@17dffceorg.highwire.dtl.DTLVardef@12548d1org.highwire.dtl.DTLVardef@cfc431_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2021

Analysis of microvascular thrombus mechanobiology with a novel particle-based model

Platelet accumulation at the site of vascular injury is regulated by soluble platelet agonists, which induce various types of platelet responses, including integrin activation and granule secretion. The interplay between local biochemical cues, mechanical interactions between platelets and macroscopic thrombus dynamics is poorly understood. Here we describe a novel computational model of microvascular thrombus formation for detailed analysis of thrombus mechanics. Adopting a previously developed two-dimensional particle-based model focused on the thrombus shell formation, we revise it to introduce platelet agonists. Blood flow is simulated via computational fluid dynamics approach. In order to model soluble platelet activators, we apply Langevin dynamics to a large number of non-dimensional virtual particles. Taking advantage of the available data on platelet dense granule secretion kinetics, we model platelet degranulation as a stochastic agonist-dependent process. The new model qualitatively reproduces enhanced thrombus formation due to granule secretion in line with in vivo findings and provides a mechanism for thrombin confinement at the early stages of aggregate formation. Our calculations also predict that release of dense granules results in additional mechanical stabilization of the inner layers of the thrombus. Distribution of the inter-platelet forces throughout the aggregate reveals multiple weak spots in the outer regions of thrombus, which are expected to result in mechanical disruptions at the later stages of thrombus formation.

biophysics↗

bioRxiv2020

Ex vivo observation of granulocyte activity during thrombus formation

Infiltration of growing thrombi by leukocytes, being the key part of the thromboinflammation, is well established in vivo. The study was aimed at the development of an ex vivo simulation of this phenomenon. Thrombus formation in anticoagulated whole blood from healthy volunteers and patients was visualized by fluorescent microscopy in parallel-plate flow chambers with fibrillar collagen type I coverslips. Moving CD66b-positive cells (granulocytes) were observed in hirudinated or recalcified blood under low wall shear rate conditions (<200 s-1). These cells crawled around thrombi in a step-wise manner with an average rate of 70 nm/s. Pre-incubation of blood with leukocyte priming agents lead to a significant increase in average cell velocity. On the contrary, leukocytes from Wiskott-Aldrich syndrome patients demonstrated a 1.5-fold lower average velocity, in line with their impaired actin polymerization. Thereby, the observed features of granulocytes crawling are consistent with the neutrophil chemotaxis phenomenon. We conclude that the proposed ex vivo experimental setting allows us to observe granulocytes activity in near-physiological conditions.

immunology↗

bioRxiv2019

Diffusional and chemical control in the tyrosine kinase network of platelet CLEC-2 signalling

C-type lectin-like receptor 2 (CLEC-2) is platelet membrane glycoprotein implicated in maintenance of blood vessel integrity and development of lymphatics. Organization and regulation of tyrosine kinase signalling network associated with CLEC-2 is poorly understood. Here we aimed to investigate CLEC-2 signal transduction using computational systems biology methods in combination with experimental approaches. We developed a 3D/stochastic multicompartmental computational model of CLEC-2 signalling, which was built around membrane-associated signalosome formation. The model predicted that both Syk and Src-family kinases phosphorylate CLEC-2, and that CLEC-2 ligation induces cytosolic calcium spiking. This was experimentally confirmed using flow cytometry and TIRF microscopy, respectively. Sensitivity analysis suggested that the CLEC-2 translocation to the signalosome region is one of the rate-limiting steps in the signal transduction process. In agreement with this prediction, CLEC-2-induced platelet activation was strongly temperature-dependent (unlike that mediated by G-protein coupled receptors) and was delayed by lipid raft disruption. Our results suggest a revised picture of the CLEC-2 signal transduction network functioning that emphasizes the crucial role of lipid raft structural rearrangement followed by tyrosine kinase feedback interplay.

systems biology↗