Tag Archives: hematology

Nonlinear Biomechanical Characteristics of Deep Deformation of Native RBC Membranes in Normal State and under Modifier Action

The mechanical properties and structural organization of membranes determine the functional state of red blood cells (RBCs). Deformability is one of the key physiological and biophysical indicators of RBC. Changes of the mechanical characteristics of cell membranes can lead to a decrease in the rate of capillary blood flow and to development of stagnant phenomena in the microcirculation, and it can also reduce the amount of oxygen delivered to the tissues.*

In the article “Nonlinear Biomechanical Characteristics of Deep Deformation of Native RBC Membranes in Normal State and under Modifier Action” Elena Kozlova, Aleksandr Chernysh, Ekaterina Manchenko, Viktoria Sergunova and Viktor Moroz describe how they evaluated the ability of membranes of native human red blood cells (RBCs) to bend into the cell to a depth comparable in size with physiological deformations using the methods of atomic force microscopy ( AFM ) and atomic force spectroscopy ( AFS ).*

As a true estimation of the elastic properties of RBC membranes can be obtained only by measurement of native cell properties the aim of the experiments was to study nonlinear mechanical characteristics of deep deformation of native RBC membranes in normal state and under the action of modifiers, in vitro to make sure that the result would be the closest to the characteristics of a living biological object.*

NANOSENSORS™ rounded AFM tips of the type SD-R150-T3L450B with a typical tip radius of 150 nm from the NANOSENSORS Special Developments List were used to measure the deformation of the RBC membrane by atomic force spectroscopy ( AFS ).*


Figure 5.2. (c) from “Nonlinear Biomechanical Characteristics of Deep Deformation of Native RBC Membranes in Normal State and under Modifier Action “ by Elena Kozlova et al.:
 Bending of membranes under the action of force F for stiff (1) and soft (2) membranes; F is the force acting on the membrane from the probe, Z is the vertical displacement of the piezoscanner, h is the depth of the membrane bending into RBC, PBS is the phosphate buffer solution, and rd is the bending radius of the membrane.

*Elena Kozlova, Aleksandr Chernysh, Ekaterina Manchenko, Viktoria Sergunova, and Viktor Moroz
Nonlinear Biomechanical Characteristics of Deep Deformation of Native RBC Membranes in Normal State and under Modifier Action
Scanning, Volume 2018, Article ID 1810585, 13 pages
Doi: https://doi.org/10.1155/2018/1810585

Please follow this external link to read the full article: https://www.hindawi.com/journals/scanning/2018/1810585/

Open Access The article « Nonlinear Biomechanical Characteristics of Deep Deformation of Native RBC Membranes in Normal State and under Modifier Action ” by Elena Kozlova, Aleksandr Chernysh, Ekaterina Manchenko, Viktoria Sergunova, and Viktor Moroz is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

A fibrin biofilm covers blood clots and protects from microbial invasion

New interesting publication by Macrea et. al mentioning the use of NANOSENSORS uniqprobe qp-BioAC:

“Hemostasis requires conversion of fibrinogen to fibrin fibers that generate a characteristic network, interact with blood cells, and initiate tissue repair. The fibrin network is porous and highly permeable, but the spatial arrangement of the external clot face is unknown. Here we show that fibrin transitioned to the blood-air interface through Langmuir film formation, producing a protective film confining clots in human and mouse models. We demonstrated that only fibrin is required for formation of the film, and that it occurred in vitro and in vivo. The fibrin film connected to the underlying clot network through tethering fibers. It was digested by plasmin, and formation of the film was prevented with surfactants. Functionally, the film retained blood cells and protected against penetration by bacterial pathogens in a murine model of dermal infection. Our data show a remarkable aspect of blood clotting in which fibrin forms a protective film covering the external surface of the clot, defending the organism against microbial invasion.”*

The AFM imaging and force measurements mentioned in this article were performed using CB3 of the NANOSENSORS™ uniqprobe qp-BioAC.

Supplemental Figure. 6. From Macrea et. al “A fibrin biofilm covers blood clots and protects from microbial invasion” Mechanisms and roles of fibrin film. A, Sneddon model used to calculate Young’s Modulus, where F is the force from the force curve, E is Young’s modulus, ν is Poisson’s ratio (0.5), α is the half angle for the indenter (15 degrees for our tips), and δ is the indentation. Note that this equation is only accurate with a half angle of 15 degrees for the first 200nm of indentation. B, Strength of the fibrin film in clots produced with plasma and thrombin with or without T101 (FXIII inhibitor ) investigated using atomic force microscopy (AFM). Fibrin fibres were visible under the film surface and these areas presented with stiffer Young’s modulus than fibrin film suspended between fibres. Grey lines in the zoomed-in images represent Young’s modulus scan area represented in the line force graphs. Scale bar - 2μm. C, Young’s Modulus was calculated for the suspended film and the film supported by fibers with and without T101 by fitting a Sneddon model to all AFM force curves found over the entire area that was imaged. 20 measurements were taken for each condition. **** P<0.0001. D, Clots produced from plasma with thrombin, under a layer of oil or enclosed in a ball of petroleum jelly, to eliminate the air - liquid interface, imaged by LSCM. Solid and dotted yellow lines indicate location of air liquid interface, n=3 experiments. Scale bars - 50μm. NANOSENSORS qp-BioAC AFM probes (CB3 ) were used for the AFM imaging and force measurements.
Supplemental Figure. 6. From Macrea et. al “A fibrin biofilm covers blood clots and protects from microbial invasion Mechanisms and roles of fibrin film. A, Sneddon model used to calculate Young’s Modulus, where F is the force from the force curve, E is Young’s modulus, ν is Poisson’s ratio (0.5), α is the half angle for the indenter (15 degrees for our tips), and δ is the indentation. Note that this equation is only accurate with a half angle of 15 degrees for the first 200nm of indentation. B, Strength of the fibrin film in clots produced with plasma and thrombin with or without T101 (FXIII inhibitor ) investigated using atomic force microscopy (AFM). Fibrin fibres were visible under the film surface and these areas presented with stiffer Young’s modulus than fibrin film suspended between fibres. Grey lines in the zoomed-in images represent Young’s modulus scan area represented in the line force graphs. Scale bar – 2μm. C, Young’s Modulus was calculated for the suspended film and the film supported by fibers with and without T101 by fitting a Sneddon model to all AFM force curves found over the entire area that was imaged. 20 measurements were taken for each condition. **** P<0.0001. D, Clots produced from plasma with thrombin, under a layer of oil or enclosed in a ball of petroleum jelly, to eliminate the air – liquid interface, imaged by LSCM. Solid and dotted yellow lines indicate location of air liquid interface, n=3 experiments. Scale bars – 50μm.

*Fraser L. Macrae, Cédric Duval, Praveen Papareddy, Stephen R. Baker, Nadira Yuldasheva, Katherine J. Kearney, Helen R. McPherson, Nathan Asquith, Joke Konings, Alessandro Casini, Jay L. Degen, Simon D. Connell,  Helen Philippou, Alisa S. Wolberg, Heiko Herwald, Robert A.S. Ariëns
A fibrin biofilm covers blood clots and protects from microbial invasion
Journal of  Clinical Investigation. 2018;128(8):3356-3368
DOI: https://doi.org/10.1172/JCI98734

Please follow this external link for the full article: https://www.jci.org/articles/view/98734#sd

The article “A fibrin biofilm covers blood clots and protects from microbial invasion” by Fraser L. Macrae et. al is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/ licenses/by/4.0/.