Name: measuring the stiffness of ex vivo mouse aortas using atomic force microscopy
Uploaded: 2016-10-19T14:00:00.000+00:00
Duration: 10 min 35 s
Description: Watch this Scientific Journal Video about Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy at JoVE.com

AFM analysis was performed on instrumentation supported by the Pennsylvania Muscle Institute and the Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, the University of Pennsylvania. This work was supported by NIH grants HL62250 and AG047373. YHB was supported by post-doctoral fellowship from the American Heart Association.

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The authors have nothing to disclose.

AFM Einbuchtung kann verwendet werden, um die Steifigkeit (Elastizitätsmodul) von Zellen und Geweben zu charakterisieren. In diesem Beitrag stellen wir ausführliche Schritt- für -Schritt - Protokolle , um die absteigende Aorta und Aortenbogen in der Maus und bestimmen die Elastizitätsmoduli dieser arteriellen Regionen ex vivo zu isolieren. Wir haben jetzt zusammenfassen und die technischen Probleme und Einschränkungen des Verfahrens in diesem Papier beschrieben diskutieren. Verschiedene technische Probleme können bei der Isolierung und Analyse der Maus Aorten gegeben, ihre kleinen und dünnen Natur entstehen. Wenn die gereinigten Arterien in Längsrichtung geöffnet werden, darauf zu achten, nicht die Intima (luminalen Oberfläche), wobei der Elastizitätsmodul Daten gesammelt zu stören genommen werden. Überschüssiges PBS in der letzten Probenschale verhindert die ordnungsgemäße Verklebung der Arterien auf den Teller, und dies muss sorgfältig ein Papiertuch entfernt werden, ohne die Arterie zu berühren vor dem Kleben. Beachten Sie jedoch, dass die isolierte Arterie zur Papiergewebe WHI klebenle Versuch übermäßige PBS zu entfernen, und dies kann die Probe beschädigen. Während die Arterien in die Kulturschale Kleben, ist es äußerst wichtig, daß die Arterie nicht gestreckt wird und dass nur eine geringe Menge an Klebstoff Bit-für-Bit an jedes Ende der Arterie angelegt wird. Wenn die AFM-Vertiefung durchgeführt wird, ist es wichtig, die an den Enden der Arterie zu vermeiden Sondieren, wo der Klebstoff angewendet wurde. Schließlich, weil frisch isolierten Arterien für die Messungen des Elastizitätsmoduls verwendet werden, die verstrichene Zeit von der Ernte bis zur Messung minimiert werden. Da die kugelförmigen in dieser Studie verwendeten Spitzen einen Radius von 500 nm haben, kann eine Eindringtiefe von bis zu 500 nm genau analysiert werden, die Hertz-Modell. Diese Eindringtiefe würde mit der oberen Schicht von Endothelzellen in die Intima 21 , die sich zu korrelieren. Sonde die Mechanik der subendothelialen Schichten der arteriellen Proben, größere kolloidalen Sonden (10 - 20 &amp; mgr; m im Durchmesser) verwendet werden könnte,für Vertiefung und Änderungen in der berechneten Steifigkeit mit Eindringtiefe 22,23 ermittelt werden konnte. Auch, weil biologische Proben sind in der Regel viskoelastischen anstatt rein elastisch, Spannungsrelaxation Messungen (den Zerfall in der angewandten Kraft bei einer konstanten Eindringtiefe Überwachung) könnte verwendet werden , um die viskose Komponente der arteriellen mechanischen Eigenschaften 24,25 zu bestimmen. Eine potentielle Beschränkung der AFM-Analyse ist die Scan-Größe, die nur einen kleinen Bereich des Gewebes misst. Die meisten biologischen Proben, einschließlich Arterien und Zellen, sind nicht topographisch und biomechanisch homogen und diese Heterogenität kann in artifactually große Variationen des Elastizitätsmoduls auf Glätte der Einbuchtung Ort, Eindringtiefe und der Betrag der Kraft in Abhängigkeit potentiell führen auf die Probe angewendet Oberfläche. Um einen repräsentativen Mittelwert des Gesamtelastizitätsmodul zu erhalten, ist es wichtig, wiederholte AFM-Vertiefung eine durchzuführent mehrere zufälligen Orten durch die Arterien, wie in Abbildung 4 gezeigt. Außerdem verwenden wir eine ausreichend große kugelförmige Spitze, wie frühere Studien haben gezeigt, dass AFM-Einzug mit einem scharfen pyramidalen Spitze in höheren Schätzungen des Elastizitätsmoduls geführt und beschädigt weich biologischen Proben 26,27. Auch wenn unsere ex vivo AFM - Messungen der arteriellen Steifigkeit scheinen stimmen gut mit molekularen Markern der glatten Muskelzelle Versteifung 2, ist es wichtig zu erkennen , dass diese arteriellen Proben nicht mechanisch belastet und mechanische Belastung ist wahrscheinlich eine wichtige Rolle in der Gesamt zu spielen Arterienmechanik. Vergleiche der arteriellen Steifigkeit, bestimmt durch AFM, Myographie (ein Ex - vivo - Verfahren kompatibel mit mechanischer Belastung) 28 und Pulswellengeschwindigkeit (eine in vivo Messung der arteriellen Steifigkeit) 29 wird die umfassendste Verständnis von Arter wahrscheinlich bietenial Mechanik. Wir haben die AFM im Kontaktmodus beschrieben , die ex vivo Steifigkeit der Maus Arterien zu messen. Dieses Verfahren schätzt die durchschnittliche Steifigkeit Gewebe durch zufällig auf mehreren Bereichen der Aorta Einrücken. Um die räumliche Verteilung der Steifigkeit von größeren Regionen von Geweben untersuchen, ein aktuelles Papier hat AFM in Kraft-Volumen - Modus 30 verwendet. Dieser Ansatz erhalten gleichzeitig eine Karte von Steifigkeit Variationen und ein hochauflösendes Bild der topographischen Oberfläche des Gewebes. Zusätzlich zu der Steifigkeit von Gewebeproben zu messen, kann das AFM in kraftVolumenModus in Zellen verwendet werden , um die räumliche Verteilung der intrazellulären Steifigkeit 10,31 zu überwachen.

The biomechanical properties of arteries are a critical determinant in cardiovascular disease (CVD) and aging. Arterial stiffness, a major cholesterol independent risk factor and an indicator for the progression of CVD, increases with vascular injury, atherosclerosis, age, and diabetes1-8. Arterial wall stiffening is associated with increased dedifferentiation, migration, and proliferation of vascular smooth muscle cells9-12. In addition, increased arterial stiffness has been linked to enhanced macrophage adhesion1, endothelial permeability and leukocyte transmigration13, and vessel wall remodeling14,15. Thus, therapies that could prevent arterial stiffening in CVD or aging might complement currently available pharmacological interventions that treat CVD by reducing high blood cholesterol. 
AFM is a powerful analytical tool used for various physical and biological applications. AFM is increasingly used to obtain the high-resolution images and characterize the biomechanical properties of soft biological samples such as tissues and cells1,2,10,16,17 with a great degree of accuracy at nanoscale levels. A major advantage of AFM is the fact that it can be used with living cells.
This paper describes our method for measuring the elastic modulus of mouse arteries ex vivo using AFM. The described method shows how we 1) properly isolate mouse arteries (descending aorta and aortic arch) and 2) measure the elastic modulus of these tissues by AFM. Measurements of unloaded elastic moduli in arteries can help to elucidate changes in the extracellular matrix (ECM) that occur in response to vascular injury, CVD, and aging.

<table><tbody><tr><td>BioScope Catalyst AFM system</td><td>Bruker</td><td></td><td></td></tr><tr><td>Nikon Eclipse TE 200 inverted microscope</td><td>Nikon Instruments</td><td></td><td></td></tr><tr><td>Silicon nitride AFM probe</td><td>Novascan Technologies</td><td>PT.SI02.SN.1</td><td>0.06 N/m cantilever; 1 &amp;micro;m SiO&lt;sub&gt;2&lt;/sub&gt; particle</td></tr><tr><td>Dumont #5 forceps</td><td>Fine Science Tools</td><td>11251-10</td><td>See section 1.4</td></tr><tr><td>Dumont #5SF forceps</td><td>Fine Science Tools</td><td>11252-00</td><td>See section 1.8</td></tr><tr><td>Fine Scissors-ToughCut</td><td>Fine Science Tools</td><td>14058-11</td><td>See section 1.4 (medium sized)</td></tr><tr><td>Vannas-T&amp;uuml;bingen spring scissors</td><td>Fine Science Tools</td><td>15008-08</td><td>See section 1.6 (small sized)</td></tr><tr><td>60 mm TC-treated cell culture dish</td><td>Corning</td><td>353004</td><td></td></tr><tr><td>Dulbecco&#039;s Phosphate-Buffered Saline, 1x</td><td>Corning</td><td>21-031-CM</td><td>Without calcium and magnesium</td></tr><tr><td>Krazy Glue instant all purpose liquid</td><td>Krazy Glue</td><td>KG58548R</td><td>See section 2.2</td></tr><tr><td>Gel-loading tips, 1 - 200 &amp;micro;l</td><td>Fisher</td><td>02-707-139</td><td>See section 2.2</td></tr><tr><td>Tip Tweezers</td><td>Electron Microscopy Sciences</td><td>78092-CP</td><td>See section 3.2</td></tr><tr><td>50-mm, clear wall glass bottom dishes</td><td>TED PELLA</td><td>14027-20</td><td>See section 4.4</td></tr></tbody></table>

measuring the stiffness of ex vivo mouse aortas using atomic force microscopy

Arterielle Versteifung ist ein signifikanter Risikofaktor und Biomarker für Herz-Kreislauf-Erkrankungen und ein Markenzeichen des Alterns. Rasterkraftmikroskopie (AFM) ist ein vielseitiges Analysewerkzeug für viskoelastische mechanischen Eigenschaften für eine Vielzahl von Materialien zu charakterisieren die von harten (Kunststoff, Glas, Metall, etc.) Oberflächen auf Zellen , die auf jedem Untergrund. Es wurde in großem Umfang verwendet, um die Steifigkeit der Zellen zu messen, aber weniger häufig verwendet, um die Steifigkeit des Aorten messen. In diesem Beitrag werden wir die Verfahren für die Verwendung von AFM im Kontaktmodus beschreiben die ex vivo - Elastizitätsmodul von unbelastetem Maus Arterien zu messen. Wir beschreiben unsere Verfahren zur Isolierung von Maus Aorten und dann detaillierte Informationen für die AFM-Analyse liefern. Dazu gehören die Schritt-für-Schritt-Anleitungen für die Ausrichtung des Laserstrahls eine Kalibrierung der Federkonstante und Ablenkung Empfindlichkeit der AFM-Sonde, und den Erwerb von Kraftkurven. Wir bieten auch ein detailliertes Protokoll für die Daten Analysis der Kraftkurven.

<html> 5A zeigt ein Phasenkontrastbild des absteigenden (Thorax) Aorta aus einem 6-Monate alten, männlichen C57BL / 6 - Maus. Die AFM - Cantilever ist an Ort und Stelle direkt über dem Gewebe und bereit für den Einzug. 5B und 5C zeigen repräsentative Kraftkurven durch AFM Vertiefung im Kontaktmodus erhalten. Grüne Linien in den 5B und 5C gezeigt stellen die besten Fitkurven für eine Kugel mit dem Hertzian Modell erhalten. In 5D wurden die mittlere Steifigkeit der absteigenden Aorta und Aortenbogen aus drei einzelnen Mäuse bestimmt , wie im Text beschrieben. Beachten Sie, dass die absteigende Aorta und Aortenbogen repräsentieren Regionen laminar und gestörten Strömung sind. Trotzdem ihre (mechanisch unbelastet) Elastizitätsmoduli sind ähnlich wie durch AFM bestimmt. 0 / 54630fig5.jpg &quot;/&gt; Abbildung 5: Die ausgewerteten Kraft-Einrückungen Kurven und Steifigkeitsdaten (A) Phasenkontrastmikroskopische Aufnahme eines AFM Cantilever über eine Maus zeigt absteigend Aorta ex vivo.. Maßstabsbalken, 100 &amp; mgr; m. (BC) Ein Satz von zwei repräsentativen Kraft-Einzug Kurven erworben für (B) die absteigende Aorta und (C) den Aortenbogen. (D) Mittlere Steifigkeit der Maus absteigende Aorta und Aortenbogen wurde bestimmt , wie oben beschrieben. Die Fehlerbalken zeigen Mittelwert ± SEM; n = 3 unabhängigen biologischen Replikaten. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54630/54630fig5large.jpg" target="_blank">Bitte klicken Sie hier</a> , um <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54630/54630fig5large.jpg" target="_blank">eine größere Version dieser Figur zu sehen.</a>

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Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

We present detailed protocols for isolation of aortas from mouse and measurement of their elastic modulus using atomic force microscopy.

Messung der Steifigkeit von<em&gt; Ex Vivo</em&gt; Maus Aorten Mit Rasterkraftmikroskopie

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a ...

measuring-stiffness-ex-vivo-mouse-aortas-using-atomic-force

Universidad San Sebastian

Research

JoVE Journal

Biology

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

10.5K Aufrufe.  University of Pennsylvania. We present detailed protocols for isolation of aortas from mouse and measurement of their elastic modulus using atomic force microscopy.

Serie: Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

Targeted Expression of GFP in the Hair Follicle Using Ex Vivo Viral Transduction

There are many cell types in the hair follicle, including hair matrix cells which form the hair shaft and stem cells which can initiate the hair shaft during early anagen, the growth phase of the hair cycle, as well as pluripotent stem cells that play a role in hair follicle growth but have the potential to differentiate to non-follicle cells such as neurons. These properties of the hair follicle are discussed. The various cell types of the hair follicle are potential targets for gene therapy. Gene delivery system for the hair follicle using viral vectors or liposomes for gene targeting to the various cell types in the hair follicle and the results obtained are also discussed.

The hair follicle is a highly complex appendage of the skin containing a multiplicity of cell types. The follicle undergoes constant cycling through the life of the organism including growth and resorption with growth dependent on specific stem cells. The targeting of the follicle by genes and stem cells to change its properties, in particular, the nature of the hair shaft is, discussed. Hair follicle delivery systems are described, such as liposomes and viral vectors for gene therapy. The nature of the hair follicle stem cells is discussed, in particular, its pluripotency.

Gezielte Expression von GFP in den Haarfollikel mit Ex Vivo viralen Transduktion

There are many cell types in the hair follicle, including hair matrix cells which form the hair shaft and stem cells which can initiate the hair shaft ...

Forschung

Biologie

Measuring the Mechanical Properties of Living Cells Using Atomic Force Microscopy

Mechanical properties of cells and extracellular matrix (ECM) play important roles in many biological processes including stem cell differentiation, tumor formation, and wound healing. Changes in stiffness of cells and ECM are often signs of changes in cell physiology or diseases in tissues. Hence, cell stiffness is an index to evaluate the status of cell cultures. Among the multitude of methods applied to measure the stiffness of cells and tissues, micro-indentation using an Atomic Force Microscope (AFM) provides a way to reliably measure the stiffness of living cells. This method has been widely applied to characterize the micro-scale stiffness for a variety of materials ranging from metal surfaces to soft biological tissues and cells. The basic principle of this method is to indent a cell with an AFM tip of selected geometry and measure the applied force from the bending of the AFM cantilever. Fitting the force-indentation curve to the Hertz model for the corresponding tip geometry can give quantitative measurements of material stiffness. This paper demonstrates the procedure to characterize the stiffness of living cells using AFM. Key steps including the process of AFM calibration, force-curve acquisition, and data analysis using a MATLAB routine are demonstrated. Limitations of this method are also discussed.

This paper demonstrates a protocol to characterize the mechanical properties of living cells by means of microindentation using an Atomic Force Microscope (AFM).

Messung der mechanischen Eigenschaften von lebenden Zellen mit Atomic Force Microscopy

Mechanical  properties of cells and extracellular matrix (ECM) play important roles in many  biological processes including stem cell differentiation, ...

Biotechnik

Measuring Ascending Aortic Stiffness In Vivo in Mice Using Ultrasound

We present a protocol for measuring in vivo aortic stiffness in mice using high-resolution ultrasound imaging. Aortic diameter is measured by ultrasound and aortic blood pressure is measured invasively with a solid-state pressure catheter. Blood pressure is raised then lowered incrementally by intravenous infusion of vasoactive drugs phenylephrine and sodium nitroprusside. Aortic diameter is measured for each pressure step to characterize the pressure-diameter relationship of the ascending aorta. Stiffness indices derived from the pressure-diameter relationship can be calculated from the data collected. Calculation of arterial compliance is described in this protocol.
This technique can be used to investigate mechanisms underlying increased aortic stiffness associated with cardiovascular disease and aging. The technique produces a physiologically relevant measure of stiffness compared to ex vivo approaches because physiological influences on aortic stiffness are incorporated in the measurement. The primary limitation of this technique is the measurement error introduced from the movement of the aorta during the cardiac cycle. This motion can be compensated by adjusting the location of the probe with the aortic movement as well as making multiple measurements of the aortic pressure-diameter relationship and expanding the experimental group size.

Measuring Ascending Aortic Stiffness In Vivo in Mice Using Ultrasound

We describe a technique for measuring aortic stiffness from its pressure-diameter relationship in vivo in mice. Aortic diameter is recorded by ultrasound and aortic pressure is measured invasively with a solid-state pressure catheter. Blood pressure is changed incrementally and the resulting diameter is measured.

Mess aufsteigende Aorta Steifigkeit<em&gt; In-vivo-</em&gt; In Mäuse Mit Ultraschall

We present a protocol for measuring in vivo aortic stiffness in mice using high-resolution ultrasound imaging. Aortic diameter is measured by ultrasound ...

Medizin

Measuring the Bending Stiffness of Bacterial Cells Using an Optical Trap

We developed a protocol to measure the bending rigidity of filamentous rod-shaped bacteria. Forces are applied with an optical trap, a microscopic three-dimensional spring made of light that is formed when a high-intensity laser beam is focused to a very small spot by a microscope's objective lens. To bend a cell, we first bind live bacteria to a chemically-treated coverslip. As these cells grow, the middle of the cells remains bound to the coverslip but the growing ends are free of this restraint. By inducing filamentous growth with the drug cephalexin, we are able to identify cells in which one end of the cell was stuck to the surface while the other end remained unattached and susceptible to bending forces. A bending force is then applied with an optical trap by binding a polylysine-coated bead to the tip of a growing cell. Both the force and the displacement of the bead are recorded and the bending stiffness of the cell is the slope of this relationship.

We present a protocol for bending filamentous bacterial cells attached to a cover-slip surface with an optical trap to measure the cellular bending stiffness.

Die Messung der Biegesteifigkeit von Bakterienzellen mit einer optischen Falle

We developed a protocol to measure the bending rigidity of filamentous rod-shaped bacteria. Forces are applied with an optical trap, a microscopic ...

Live Cell Response to Mechanical Stimulation Studied by Integrated Optical and Atomic Force Microscopy

To understand the mechanism by which living cells sense mechanical forces, and how they respond and adapt to their environment, a new technology able to investigate cells behavior at sub-cellular level with high spatial and temporal resolution was developed. Thus, an atomic force microscope (AFM) was integrated with total internal reflection fluorescence (TIRF) microscopy and fast-spinning disk (FSD) confocal microscopy. The integrated system is broadly applicable across a wide range of molecular dynamic studies in any adherent live cells, allowing direct optical imaging of cell responses to mechanical stimulation in real-time. Significant rearrangement of the actin filaments and focal adhesions was shown due to local mechanical stimulation at the apical cell surface that induced changes into the cellular structure throughout the cell body. These innovative techniques will provide new information for understanding live cell restructuring and dynamics in response to mechanical force. A detailed protocol and a representative data set that show live cell response to mechanical stimulation are presented.

This paper aims to instruct the reader in the operation of an integrated atomic force-optical imaging microscope for mechanical stimulation of live cells in culture. A step-by-step protocol is presented. A representative data set that shows live cell response to mechanical stimulation is presented.

Live Cell Reaktion auf mechanische Stimulation von Integrated Optical und Atomic Force Microscopy Studium

To understand the mechanism by which living cells sense mechanical forces, and how they respond and adapt to their environment, a new technology able to ...

Micro-Mechanical Characterization of Lung Tissue Using Atomic Force Microscopy

Matrix stiffness strongly influences growth, differentiation and function of adherent cells1-3. On the macro scale the stiffness of tissues and organs within the human body span several orders of magnitude4. Much less is known about how stiffness varies spatially within tissues, and what the scope and spatial scale of stiffness changes are in disease processes that result in tissue remodeling. To better understand how changes in matrix stiffness contribute to cellular physiology in health and disease, measurements of tissue stiffness obtained at a spatial scale relevant to resident cells are needed. This is particularly true for the lung, a highly compliant and elastic tissue in which matrix remodeling is a prominent feature in diseases such as asthma, emphysema, hypertension and fibrosis. To characterize the local mechanical environment of lung parenchyma at a spatial scale relevant to resident cells, we have developed methods to directly measure the local elastic properties of fresh murine lung tissue using atomic force microscopy (AFM) microindentation. With appropriate choice of AFM indentor, cantilever, and indentation depth, these methods allow measurements of local tissue shear modulus in parallel with phase contrast and fluorescence imaging of the region of interest. Systematic sampling of tissue strips provides maps of tissue mechanical properties that reveal local spatial variations in shear modulus. Correlations between mechanical properties and underlying anatomical and pathological features illustrate how stiffness varies with matrix deposition in fibrosis. These methods can be extended to other soft tissues and disease processes to reveal how local tissue mechanical properties vary across space and disease progression.

The stiffness of the extracellular matrix strongly influences multiple behaviors of adherent cells. Matrix stiffness varies spatially throughout a tissue, and undergoes modification in various disease conditions. Here we develop methods to characterize spatial variations in stiffness in normal and fibrotic mouse lung tissue using atomic force microscopy microindentation.

Micro-Mechanische Charakterisierung von Lungengewebe mit Atomic Force Microscopy

Matrix stiffness strongly influences growth, differentiation and function of adherent cells1-3.  On the macro scale the stiffness of tissues and organs ...

Isolation, Culture, and Functional Characterization of Adult Mouse Cardiomyoctyes

The use of primary cardiomyocytes (CMs) in culture has provided a powerful complement to murine models of heart disease in advancing our understanding of heart disease. In particular, the ability to study ion homeostasis, ion channel function, cellular excitability and excitation-contraction coupling and their alterations in diseased conditions and by disease-causing mutations have led to significant insights into cardiac diseases. Furthermore, the lack of an adequate immortalized cell line to mimic adult CMs, and the limitations of neonatal CMs (which lack many of the structural and functional biomechanics characteristic of adult CMs) in culture have hampered our understanding of the complex interplay between signaling pathways, ion channels and contractile properties in the adult heart strengthening the importance of studying adult isolated cardiomyocytes. Here, we present methods for the isolation, culture, manipulation of gene expression by adenoviral-expressed proteins, and subsequent functional analysis of cardiomyocytes from the adult mouse. The use of these techniques will help to develop mechanistic insight into signaling pathways that regulate cellular excitability, Ca2+ dynamics and contractility and provide a much more physiologically relevant characterization of cardiovascular disease.

Here we describe the isolation of adult mouse cardiomyoctyes using a Langendorff perfusion system. The resulting cells are Ca2+-tolerant, electrically quiescent and can be cultured and transfected with adeno- or lentiviruses to manipulate gene expression. Their functionality can also be analyzed using the MMSYS system and patch clamp techniques.

Isolierung, Kultur, und funktionelle Charakterisierung der erwachsenen Maus Cardiomyoctyes

The use of primary cardiomyocytes (CMs) in culture has provided a powerful complement to murine models of heart disease in advancing our understanding of ...

Measurement of Liver Stiffness Using Atomic Force Microscopy Coupled with Polarization Microscopy

Matrix stiffening has been recognized as one of the key drivers of the progression of liver fibrosis. It has profound effects on various aspects of cell behavior such as cell function, differentiation, and motility. However, as these processes are not homogeneous throughout the whole organ, it has become increasingly important to understand changes in the mechanical properties of tissues on the cellular level.
To be able to monitor the stiffening of collagen-rich areas within the liver lobes, this paper presents a protocol for measuring liver tissue elastic moduli with high spatial precision by atomic force microscopy (AFM). AFM is a sensitive method with the potential to characterize local mechanical properties, calculated as Young&#39;s (also referred to as elastic) modulus. AFM coupled with polarization microscopy can be used to specifically locate the areas of fibrosis development based on the birefringence of collagen fibers in tissues. Using the presented protocol, we characterized the stiffness of collagen-rich areas from fibrotic mouse livers and corresponding areas in the livers of control mice.
A prominent increase in the stiffness of collagen-positive areas was observed with fibrosis development. The presented protocol allows for a highly reproducible method of AFM measurement, due to the use of mildly fixed liver tissue, that can be used to further the understanding of disease-initiated changes in local tissue mechanical properties and their effect on the fate of neighboring cells.

We present a protocol to measure the elastic moduli of collagen-rich areas in normal and diseased liver using atomic force microscopy. The simultaneous use of polarization microscopy provides high spatial precision for localizing collagen-rich areas in the liver sections.

Messung der Lebersteifigkeit mittels Rasterkraftmikroskopie gekoppelt mit Polarisationsmikroskopie

Matrix stiffening has been recognized as one of the key drivers of the progression of liver fibrosis. It has profound effects on various aspects of cell ...

Messung der Steifigkeit in retinalen Kapillaren und subendothelialen Matrizen der Maus

Isolation of Mouse Retinal Capillaries and Subendothelial Matrix for Stiffness Measurement Using Atomic Force Microscopy

Retinal capillary degeneration is a clinical hallmark of the early stages of diabetic retinopathy (DR). Our recent studies have revealed that diabetes-induced retinal capillary stiffening plays a crucial and previously unrecognized causal role in inflammation-mediated degeneration of retinal capillaries. The increase in retinal capillary stiffness results from the overexpression of lysyl oxidase, an enzyme that crosslinks and stiffens the subendothelial matrix. Since tackling DR at the early stage is expected to prevent or slow down DR progression and associated vision loss, subendothelial matrix, and capillary stiffness represent relevant and novel therapeutic targets for early DR management. Further, direct measurement of retinal capillary stiffness can serve as a crucial preclinical validation step for the development of new imaging techniques for non-invasive assessment of retinal capillary stiffness in animal and human subjects. With this view in mind, we here provide a detailed protocol for the isolation and stiffness measurement of mouse retinal capillaries and subendothelial matrix using atomic force microscopy.

Autor im Rampenlicht: Untersuchung von Gefäßsteifigkeit und Entzündung bei früher diabetischer Retinopathie

We recently identified retinal capillary stiffening as a new paradigm for retinal dysfunction associated with diabetes. This protocol elaborates the steps for isolation of mouse retinal capillaries and the subendothelial matrix from retinal endothelial cultures, followed by a description of the stiffness measurement technique using atomic force microscopy.

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