Controlled Strain of 3D Hydrogels under Live Microscopy Imaging

Kolel, Avraham; Riba, Avishy Roitblat; Natan, Sari; Tchaicheeyan, Oren; Saias, Eilom; Lesman, Ayelet

doi:10.3791/61671-v

Cited by 4 publications

(10 citation statements)

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“…In our previous work, we demonstrated the ability to stretch soft fibrin gels (shear modulus < 1 KPa) using a silicone carrier. [ 42,43 ] This approach has proven useful with biological gels such as fibrin and collagen due to their natural adhesion to the silicone interface. Uniaxial external stretch of the silicone strip resulted in homogenous straining of the embedded circular‐shaped 3D fibrin gel from its periphery.…”

Section: Resultsmentioning

confidence: 99%

“…As described in our previous work, [ 43 ] hydrogels were prepared by placing the silicone carrier on a strip of Parafilm in a 10 cm petri dish. Depending on the volume of the cut‐out, 2.5–7.0 µL cold fibrinogen solution (10 mg mL −1 , Omrix Biopharmaceuticals) was then placed in the cut‐out, an equal amount of cold thrombin solution (2 U mL −1 , Omrix Biopharmaceuticals) was added, and the mixture was then pipetted to promote homogenous cross‐linking of the hydrogel.…”

Section: Methodsmentioning

confidence: 99%

“…To confirm gel homogeneity and adherence to the cut‐out periphery throughout the thickness of the silicone, strips were attached to the stretching device, loaded onto a confocal microscope and imaged. [ 42,43 ]…”

Section: Methodsmentioning

confidence: 99%

“…Before loading the gels into the silicone carriers, fibrinogen was labeled with Alexa Fluor 546, succinimidyl ester (Invitrogen) by mixing the fibrinogen and Alexa Fluor at a molar ratio of 7.5:1, for 1 h, at room temperature and then filtering it through a HiTrap desalting column (GE Healthcare) packed with Sephadex G-25 resin to separate the unreacted dye. [54] As described in our previous work, [43] hydrogels were prepared by placing the silicone carrier on a strip of Parafilm in a 10 cm petri dish. Depending on the volume of the cut-out, 2.5-7.0 µL cold fibrinogen solution (10 mg mL −1 , Omrix Biopharmaceuticals) was then placed in the cut-out, an equal amount of cold thrombin solution (2 U mL −1 , Omrix Biopharmaceuticals) was added, and the mixture was then pipetted to promote homogenous cross-linking of the hydrogel.…”

Section: Methodsmentioning

confidence: 99%

“…To confirm gel homogeneity and adherence to the cut-out periphery throughout the thickness of the silicone, strips were attached to the stretching device, loaded onto a confocal microscope and imaged. [42,43] Fiber Orientation Analysis: Hydrogel fiber orientation was analyzed with the OrientationJ (EPFL) [55] module of the ImageJ FIJI software (NIH) [56] using a Gaussian gradient, and a 3-pixel window. Orientation histograms were created, and NOP was calculated as follows:…”

Section: Methodsmentioning

confidence: 99%

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Strain Gradient Programming in 3D Fibrous Hydrogels to Direct Graded Cell Alignment

et al. 2022

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Biological tissues experience various stretch gradients which act as mechanical signaling from the extracellular environment to cells. These mechanical stimuli are sensed by cells, triggering essential signaling cascades regulating cell migration, differentiation, and tissue remodeling. In most previous studies, a simple, uniform stretch to 2D elastic substrates has been applied to analyze the response of living cells. However, induction of nonuniform strains in controlled gradients, particularly in biomimetic 3D hydrogels, has proven challenging. In this study, 3D fibrin hydrogels of manipulated geometry are stretched by a silicone carrier to impose programmable strain gradients along different chosen axes. The resulting strain gradients are analyzed and compared to finite element simulations. Experimentally, the programmed strain gradients result in similar gradient patterns in fiber alignment within the gels. Additionally, temporal changes in the orientation of fibroblast cells embedded in the stretched fibrin gels correlate to the strain and fiber alignment gradients. The experimental and simulation data demonstrate the ability to custom‐design mechanical gradients in 3D biological hydrogels and to control cell alignment patterns. It provides a new technology for mechanobiology and tissue engineering studies.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Strain Gradient Programming in 3D Fibrous Hydrogels to Direct Graded Cell Alignment

et al. 2022

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Probing Local Force Propagation in Tensed Fibrous Gels

Goren

Levin

Brand

et al. 2022

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Fibrous hydrogels are a key component of soft animal tissues. They support cellular functions and facilitate efficient mechanical communication between cells. Due to their nonlinear mechanical properties, fibrous materials display non‐trivial force propagation at the microscale, that is enhanced compared to that of linear‐elastic materials. In the body, tissues are constantly subjected to external loads that tense or compress them, modifying their micro‐mechanical properties into an anisotropic state. However, it is unknown how force propagation is modified by this isotropic‐to‐anisotropic transition. Here, force propagation in tensed fibrin hydrogels is directly measured. Local perturbations are induced by oscillating microspheres using optical tweezers. 1‐point and 2‐point microrheology are combined to simultaneously measure the shear modulus and force propagation. A mathematical framework to quantify anisotropic force propagation trends is suggested. Results show that force propagation becomes anisotropic in tensed gels, with, surprisingly, stronger response to perturbations perpendicular to the axis of tension. Importantly, external tension can also increase the range of force transmission. Possible implications and future directions for research are discussed. These results suggest a mechanism for favored directions of mechanical communication between cells in a tissue under external loads.

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A Collection of Biomaterials and Biomechanical Experiments and Analysis Methods

Jiang

et al. 2021

JoVE

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As an important interdisciplinary research field, biomaterials and biomechanics reveal the relationships and mechanisms between the structure, performance, and function of biomaterials through experimental research and theoretical analysis, which is connected to materials science, mechanics, bioengineering, mathematics, etc. In order to improve the experimental methods of biomaterials and biomechanics, this JoVE Methods Collection discusses the corresponding experimental methods and their respective characteristics in two categories: tissue mechanical properties and bionics mechanics. The tissue mechanics observations include a

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Controlled Strain of 3D Hydrogels under Live Microscopy Imaging

Cited by 4 publications

References 0 publications

Strain Gradient Programming in 3D Fibrous Hydrogels to Direct Graded Cell Alignment

Strain Gradient Programming in 3D Fibrous Hydrogels to Direct Graded Cell Alignment

Probing Local Force Propagation in Tensed Fibrous Gels

A Collection of Biomaterials and Biomechanical Experiments and Analysis Methods

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