fluorescence micropipette aspiration assay to study live cell rbc mechanosensing

Eencellige mechanobiologie met behulp van fluorescentie-micropipetaspiratie

The unfolding discoveries in the world of cellular behaviors have accentuated the role of mechanical stimuli, such as tension, fluid shear stress, compression, and substrate stiffness, in dictating dynamic cellular activities such as adhesion, migration, and differentiation. These mechanobiological aspects are of paramount importance in elucidating how cells interact with and respond to their physiological environments, impacting various biological processes1,2.
Over the past decade, micropipette-based aspiration assays have stood out as a versatile tool in studying diverse cellular responses to mechanical stimuli. This technique offers valuable insights into the intrinsic mechanical properties of living cells at the single-cell level, including cellular elastic modulus, stiffness, and cortical&#160;tension. These assays enable the measurement of various mechanical parameters, such as cell membrane&#160;tension, pressure exerted on the cell membrane, and cortical tension (summarized in Table 1). Studying the aspirational forces has enriched our understanding of how they influence cellular functions and processes, particularly in the realm of membrane dynamics, including fragmentation, elongation, and budding3,4.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Mechanical Parameter</td>
			<td>Description</td>
			<td>Seminal Approaches</td>
		</tr>
		<tr>
			<td>Cell Stiffness</td>
			<td>Measurement of a cell&#39;s mechanical rigidity and elasticity.</td>
			<td>Aspiration of the cell membrane and analysis of deformation response to the negative pressure20,21.</td>
		</tr>
		<tr>
			<td>Adhesion Strength</td>
			<td>Evaluation of how strongly cells adhere to surfaces.</td>
			<td>Application of controlled suction to detach adhered cells from a substrate2,22.</td>
		</tr>
		<tr>
			<td>Membrane Tension</td>
			<td>Assessment of the tension or stress within cell membranes.</td>
			<td>Measurement of the membrane deformation in response to applied pressure23,24.</td>
		</tr>
		<tr>
			<td>Viscoelastic Properties</td>
			<td>Characterization of a cell&#39;s combined viscous and elastic behavior.</td>
			<td>Analysis of the time-dependent deformation response to aspiration23,25.</td>
		</tr>
		<tr>
			<td>Deformability</td>
			<td>Determination of how easily a cell can change shape.</td>
			<td>Evaluation of the extent of deformation under controlled suction20,24.</td>
		</tr>
		<tr>
			<td>Surface Tension</td>
			<td>Measurement of the tension at the cell&#39;s surface.</td>
			<td>Assessment of the pressure required to form a micropipette membrane protrusion26.</td>
		</tr>
		<tr>
			<td>Cell-Material Interaction</td>
			<td>Study of interactions between cells and materials or substrates.</td>
			<td>Aspiration of cells in contact with different materials and observation of interactions2,24.</td>
		</tr>
		<tr>
			<td>Cell-Cell Interaction</td>
			<td>Examination of interactions between neighboring cells.</td>
			<td>Aspiration of a group of cells and analysis of their intercellular forces27.</td>
		</tr>
	</tbody>
</table>
Table 1: Mechanical parameters characterized by the micropipette aspiration assay.
The micropipette-based aspiration technique has been widely used to study red blood cells (RBCs), assessing the deformability and various mechanical characteristics of RBCs, which is essential in understanding their function in the circulatory system. RBCs exhibit remarkable adaptability, preserving their mechanical versatility against deformation when navigating through the intricate capillary network and inter-endothelial clefts5,6. During this journey, RBCs must traverse through passages as narrow as 0.5-1.0 &#181;m, subjecting themselves to a multitude of mechanical forces, including tension and compression7,8,9. They also have high sensitivity to the shear stress generated by blood flow during circulation10. These processes promote the activation of regulatory mechanisms involving calcium influx, a crucial signaling event with well-established roles in cellular responses to mechanical stimuli11,12. The complex mechanisms governing the calcium-mediated mechanosensing remain compelling subjects of ongoing investigation.
In this context, the fMPA stands as an effective approach to reveal the extent of calcium mobilization under precisely controlled mechanical forces, allowing for the simultaneous application of mechanical modulation (using the micropipette aspiration system) and visualization of calcium intensity (using fluorescent indicators). It particularly mimics the physiological scenario when the RBC travels through narrowing blood vessels. It is worth noting that the fMPA system we developed can generate pressure with a resolution of 1 mmHg. The implemented high-speed camera can achieve a temporal resolution of 100 ms and a spatial resolution at the submicron-meter level. These configurations ensure the precise application of mechanical forces to live cells and simultaneously capture the resulting cellular signaling. Moreover, due to the integrative engineered nature of this setup, the micropipette aspiration assay can be readily adapted to complement other equipment or techniques, enabling further exploration of the intricacies of cell mechanics. This versatility stands as an additional advantage of this approach.

Auteur in de schijnwerpers: het bevorderen van live-cell mechanobiologie door middel van fluorescentie-microaspiratie

Fluorescentie-micropipetaspiratietest om mechanosensing van rode bloedcellen te onderzoeken

The scope of our research is directed towards lifestyle mechanobiology, specifically the behavior of cells where mechanical stress is applied. We are investigating the intracellular signaling in single cells. The proposed FMPA system utilizes fluorescence imaging combined with mechanical stimuli.That is, the aspiration pressure. There are currently further advancements that have attempted to combine more than two techniques with the microaspiration setup like microfluidics or image analysis software. Current experimental challenges lie with the fact that the setup is quite labor intensive and is operator dependent.As the system is manually operated, there are inconsistencies that arise in specific steps. For example, filament preheating. The findings of research demonstrated there was a corresponding increase in the influx of calcium ions into the RBCs when the pressure was incrementally increased between negative 10 millimeter mercury to negative 40 millimeter mercury.This suggests that RBCs poses the ability to sense changes in their mechanical environment and respond by rapid calcium-related channel activities. This study places particular emphasis on the application of FMPA as a crucial tool for unveiling the nuanced mechanosensitive responses showcased by RBCs under varying stimuli.

Fluorescentie-micropipetaspiratietest om RBC-mechanosensing met levende cellen te bestuderen

Gebruik om te beginnen een diamantpotlood om een standaard glazen afdekglaasje in drie gelijke stroken te verdelen. Gebruik vacuümvet om een stuk van de afdekstrip op de bodem van een zelfgemaakte kamerhouder te plakken. Bevestig op dezelfde manier het tweede stuk van de afdekstrip aan de bovenkant van de kamerhouder.Gebruik vervolgens een pipetpistool om 200 microliter van de gelabelde RBC-suspensie tussen de twee afdekglaasjes te injecteren. Om de micropipetaspiratie-opstelling in elkaar te zetten, monteert u de celkamer op de houdertafel op een microscoopplatform. Pas de positie van de kamer aan totdat deze zich direct onder het objectief bevindt.Laat nu de houder zakken totdat deze onder het vloeistofniveau van het aangesloten waterreservoir staat. Injecteer gedemineraliseerd water in de micropipet en gebruik vervolgens een spuit met een naald van 34 gauge om eventuele luchtbellen te verwijderen. Schroef het uiteinde van de micropipethouder halverwege los en laat het water enkele seconden uit de houder druppelen.Steek vervolgens de met suspensie gevulde micropipet in de punt van de houder en draai de schroef van de houder vast. Plaats de micropipet in de celkamer. Zoek vervolgens de pipet en rode bloedcellen onder de microscoop.Laat de pipetpunt zakken om ervoor te zorgen dat deze waterpas staat met de aanwezige rode draad. Stel de hoogte van het waterreservoir in om de hydraulische druk aan de punt op nul te zetten. Til vervolgens het waterreservoir iets op om een subtiele positieve druk te genereren.Schakel de 488 nanometer fluorescerende excitatielichtbron in. Schakel de fluorescentiecamera en de uitgezonden camera in. Voer de belichtingstijd, het interessegebied en de grootte van de binning voor beide camera's in de bijbehorende software in.Stel vervolgens het acquisitienummer in op 2000 onder het deelvenster Multidimensionale acquisitie. Kies de gewenste opslagmap. Lokaliseer vervolgens de micropipet met behulp van de micromanipulator.Schakel de pneumatische drukklem in en zorg ervoor dat de schakelkast in de externe modus staat. Draai langzaam aan de knop om eventuele offsetdruk in het systeem te compenseren. Start de software die de pneumatische klem bestuurt.Gebruik het elektrische bedieningspaneel om de druk onder controle te houden met een kwikconversiefactor van 20 millivolt per millimeter. Zet nu de druk in het systeem op nul en plaats de micropipet voorzichtig dicht bij de rode bloedcellen. Pas de positie van het waterreservoir aan om een subtiele positieve druk op de punt van de micropipet te genereren.Start acquisitie in de camerasoftware en schakel de fluorescentiesluiter in. Typ de berekende spanningsgrootte in het bedieningspaneel om de gewenste druk te bereiken en een RBC aan te zuigen. Houd de druk gedurende een vooraf ingestelde periode vast en laat deze dan los.Herhaal op dezelfde manier het experiment met de volgende RBC voordat u verder analyseert. Incrementele toename van de druk resulteerde in een verhoogde mobilisatie van calciumionen in de rode bloedcellen.

Research

JoVE Journal

Biology

Fluorescence Micropipette Aspiration Assay to Study Live Cell RBC Mechanosensing

Fluorescence Micropipette Aspiration Assay to Investigate Red Blood Cell Mechanosensing

Micropipette aspiration assays have long been a cornerstone for the investigation of live-cell mechanics, offering insights into cellular responses to ...

Fabrication of Micropipettes for Fluorescence Aspiration Assay to Study Live Cell RBC Mechanosensing

Fabricage van micropipetten voor fluorescentie-aspiratietest om de mechanosensing van levende cellen te bestuderen