Rapid analysis of cell-generated forces within a multicellular aggregate using microsphere-based traction force microscopy

Kaytanlı, Buğra; Khankhel, Aimal H.; Cohen, Noy; Valentine, Megan T.

doi:10.1039/c9sm02377a

Cited by 10 publications

(7 citation statements)

References 28 publications

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“…The ability to robustly model the deformations of compressible materials in the moderate strain regime is required for broad classes of engineering materials, including most biological and biomimetic materials, which typically have a Poisson ratio in the range of 0.2-0.5 and exhibit nonlinear elastic responses [33][34][35][36][37][38]. The ability to accurately relate observed deformations to applied stress fields is particularly important for the development of traction force microscopy methods, which allow determination of cell-generated forces to understand the fundamental mechanobiology, as well as improved disease modeling and design of soft tissue replacements [39][40][41][42][43][44][45].…”

Section: Discussionmentioning

confidence: 99%

Analysis of the compressible, isotropic, neo-Hookean hyperelastic model

2023

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The most widely-used representation of the compressible, isotropic, neo-Hookean hyperelastic model is considered in this paper. The version under investigation is that which is implemented in the commercial finite element software ABAQUS, ANSYS and COMSOL. Transverse stretch solutions are obtained for the following homogeneous deformations: uniaxial loading, equibiaxial loading in plane stress, and uniaxial loading in plane strain. The ground-state Poisson’s ratio is used to parameterize the constitutive model, and stress solutions are computed numerically for the physically permitted range of its values. Despite its broad application to a number of engineering problems, the physical limitations of the model, particularly in the small to moderate stretch regimes, are not explored. In this work, we describe and analyze results and make some critical observations, underlining the model’s advantages and limitations. For example, a snap-back feature of the transverse stretch is identified in uniaxial compression, a physically undesirable behavior unless validated by experimental data. The domain of this non-unique solution is determined in terms of the ground-state Poisson’s ratio and the state of stretch and stress. The analyses we perform are essential to enable the understanding of the characteristics of the standard, compressible, isotropic, neo-Hookean model used in ABAQUS, ANSYS and COMSOL. In addition, our results provide a framework for the parameter-fitting procedure needed to characterize this standard, compressible, isotropic neo-Hookean model in terms of experimental data.

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Section: Discussionmentioning

confidence: 99%

Analysis of the compressible, isotropic, neo-Hookean hyperelastic model

2023

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“…The direct method of determining 3D cell-generated traction stresses circumvents solving an illposed inverse continuum mechanics problem, which requires approximating the measurements with theoretical models 27,57 or computational analyses (e.g., finite element method) 42 . Also, given its mathematical simplicity, the direct method yields traction stresses within a few seconds, including the computations involved in tracking the nanobead displacements with the CPD algorithm.…”

Section: Discussionmentioning

confidence: 99%

Tunable photoinitiated hydrogel microspheres for direct quantification of cell-generated forces in complex three-dimensional environments

Garcia-Herreros

Yeh

et al. 2023

Preprint

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We present a high-throughput method using standard laboratory equipment and microfluidics to produce cellular force microscopy probes with controlled size and elastic modulus. Mechanical forces play crucial roles in cell biology but quantifying these forces in physiologically relevant systems remains challenging due to the complexity of the native cell environment. Polymerized hydrogel microspheres offer great promise for interrogating the mechanics of processes inaccessible to classic force microscopy methods. However, despite significant recent advances, their small size and large surface-to-volume ratio impede the high-yield production of probes with tunable, monodisperse distributions of size and mechanical properties. To overcome these limitations, we use a flow-focusing microfluidic device to generate large quantities of droplets with highly reproducible, adjustable radii. These droplets contain acrylamide gel precursor and the photoinitiator Lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) as a source of free radicals. LAP provides fine control over microsphere polymerization due to its high molar absorptivity at UV wavelengths and moderate water solubility. The polymerized microspheres can be functionalized with different conjugated extracellular matrix proteins and embedded with fluorescent nanobeads to promote cell attachment and track microsphere deformation. As proof of concept, we measure the mechanical forces generated by a monolayer of vascular endothelial cells engulfing functionalized microspheres. Individual nanobead motions are tracked in 3D and analyzed to determine the 3D traction forces within seconds and without the need for solving an ill-posed inverse problem. These results reveal that the cell monolayer collectively exerts strong radial compression and subtle lateral distortions on the encapsulated probe.

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“…Force resolution to the order of nN Girardo et al, 2018;Mohagheghian et al, 2018;Kaytanli et al, 2020;Vorselen et al, 2020b a clamped membrane subject to a point force (Labernadie et al, 2014). By increasing the thickness of the formvar sheet and thus the substrate stiffness sensed by cells, PFM results demonstrated that leukocyte podosomes increase their protrusive forces in response to stiffer substrates, suggesting that podosomes have a mechanosensing function (Labernadie et al, 2014).…”

Section: Figure 2hmentioning

confidence: 99%

“…However, polystyrene beads are rigid, which makes it impossible to quantify the forces that VECs exert on the beads, and the recent development of methods to quantify mechanical forces in vivo via deformable hydrogel microspheres could overcome this limitation. Inspired by the seminal use of functionalized oil droplets to measure anisotropic stresses within 3-D cell aggregates (Campas et al, 2014), emerging microfabrication methods can now produce deformable hydrogel-based spherical force sensors, with sizes ranging from a few µm up to hundreds of microns (Girardo et al, 2018;Mohagheghian et al, 2018;Kaytanli et al, 2020;Vorselen et al, 2020b; Figure 2H). These elastic microspheres can be employed to study cellular forces induced by specific ligand-receptor interactions, known as microspherebased TFM.…”

Section: Quantifying Tissue-level Cell Forcesmentioning

confidence: 99%

Elucidating the Biomechanics of Leukocyte Transendothelial Migration by Quantitative Imaging

Schwartz

Campos

Criado-Hidalgo

et al. 2021

Front. Cell Dev. Biol.

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Leukocyte transendothelial migration is crucial for innate immunity and inflammation. Upon tissue damage or infection, leukocytes exit blood vessels by adhering to and probing vascular endothelial cells (VECs), breaching endothelial cell-cell junctions, and transmigrating across the endothelium. Transendothelial migration is a critical rate-limiting step in this process. Thus, leukocytes must quickly identify the most efficient route through VEC monolayers to facilitate a prompt innate immune response. Biomechanics play a decisive role in transendothelial migration, which involves intimate physical contact and force transmission between the leukocytes and the VECs. While quantifying these forces is still challenging, recent advances in imaging, microfabrication, and computation now make it possible to study how cellular forces regulate VEC monolayer integrity, enable efficient pathfinding, and drive leukocyte transmigration. Here we review these recent advances, paying particular attention to leukocyte adhesion to the VEC monolayer, leukocyte probing of endothelial barrier gaps, and transmigration itself. To offer a practical perspective, we will discuss the current views on how biomechanics govern these processes and the force microscopy technologies that have enabled their quantitative analysis, thus contributing to an improved understanding of leukocyte migration in inflammatory diseases.

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Rapid analysis of cell-generated forces within a multicellular aggregate using microsphere-based traction force microscopy

Abstract: We measure cell-generated forces from the deformations of elastic microspheres embedded within multicellular aggregates. Using a computationally efficient analytical model, we directly obtain the full 3D mapping of surface stresses within minutes.

Cited by 10 publications

References 28 publications

Analysis of the compressible, isotropic, neo-Hookean hyperelastic model

Analysis of the compressible, isotropic, neo-Hookean hyperelastic model

Tunable photoinitiated hydrogel microspheres for direct quantification of cell-generated forces in complex three-dimensional environments

Elucidating the Biomechanics of Leukocyte Transendothelial Migration by Quantitative Imaging

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