Straining 3D Hydrogels with Uniform Z-Axis Strains While Enabling Live Microscopy Imaging

Riba, Avishy Roitblat; Natan, Sari; Kolel, Avraham; Rushkin, Hila; Tchaicheeyan, Oren; Lesman, Ayelet

doi:10.1007/s10439-019-02426-7

Cited by 7 publications

(6 citation statements)

References 46 publications

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“…The composition of the fibrin gel used in this study (10 mg/mL fibrinogen) was chosen to allow suitable gel conditions to embed cells in 3D and support their growth, migration, and proliferation, as shown by us [40] and others [16]. The concentration of cells was chosen in the range of 1-15 × 10 3 (50-750 cells/µL) due to the fact that using lower concentrations will increase the dispersion of the cells, which may affect their growth by impeding cell-cell communications [41,42].…”

Section: Discussionmentioning

confidence: 99%

FITC-Dextran Release from Cell-Embedded Fibrin Hydrogels

et al. 2021

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Fibrin hydrogel is a central biological material in tissue engineering and drug delivery applications. As such, fibrin is typically combined with cells and biomolecules targeted to the regenerated tissue. Previous studies have analyzed the release of different molecules from fibrin hydrogels; however, the effect of embedded cells on the release profile has yet to be quantitatively explored. This study focused on the release of Fluorescein isothiocyanate (FITC)-dextran (FD) 250 kDa from fibrin hydrogels, populated with different concentrations of fibroblast or endothelial cells, during a 48-h observation period. The addition of cells to fibrin gels decreased the overall release by a small percentage (by 7–15% for fibroblasts and 6–8% for endothelial cells) relative to acellular gels. The release profile was shown to be modulated by various cellular activities, including gel degradation and physical obstruction to diffusion. Cell-generated forces and matrix deformation (i.e., densification and fiber alignment) were not found to significantly influence the release profiles. This knowledge is expected to improve fibrin integration in tissue engineering and drug delivery applications by enabling predictions and ways to modulate the release profiles of various biomolecules.

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Section: Discussionmentioning

confidence: 99%

FITC-Dextran Release from Cell-Embedded Fibrin Hydrogels

et al. 2021

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“…Fibrin gel is prepared by mixing Fibrinogen (Evicel Biopharmaceuticals) at a final concentration of 0.25 mg/ml with Thrombin (Evicel Biopharmaceuticals) at a final concentration of 1 U/ml. The fibrinogen is fluorescently labeled with Alexa Fluor 546, succinimidyl ester (Invitrogen), as previously described [59]. For isotropic gels, the solution is mixed on top of a glass slide, and closed with another slide with 1mm spacing.…”

Section: Methodsmentioning

confidence: 99%

“…For isotropic gels, the solution is mixed on top of a glass slide, and closed with another slide with 1mm spacing. Gels that will be stretched are prepared on top of a parafilm strip, inside a circular mold cut into a silicone rubber strip of 1mm thickness, as we described previously [59, 60]. The gels polymerize over-night at 37°c.…”

Section: Methodsmentioning

confidence: 99%

“…We recorded the motion of approximately 250 particles in the field of view using a CMOS video camera (Grasshoper 3, Point Gray) at a frame rate of 30 Hz with an exposure time of 10 ms. We used data from at least 105 frames. Particle tracking was done by conventional video microscopy, using the protocol of Crocker and Grier (59). The mean square displacement and G’, G” were computed using previously described methods (47, 60).…”

Section: Methodsmentioning

confidence: 99%

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Probing Local Force Propagation in Tensed Fibrous Gels

Goren

Levin

Brand

et al. 2022

Preprint

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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 micromechanical properties into an anisotropic state. However, it is unknown how force propagation is modified by this isotropic-to-anisotropic transition. Here, we directly measure force propagation in tensed fibrin hydrogels. Local perturbations are induced by oscillating microspheres using optical tweezers. We use both 1-point and 2-point microrheology to simultaneously measure both the shear modulus and force propagation. We suggest a mathematical framework to quantify anisotropic force propagation trends. We show that force propagation becomes anisotropic in tensed gels, with, surprisingly, stronger response to perturbations perpendicular to the axis of tension. Our results suggest that under external loads, there are favoured directions of mechanical communication between cells in a tissue. Importantly, we also find that external tension increases the range of force transmission by altering the power-law exponent governing the decay of oscillations with distance from the perturbation. We end with a discussion of possible implications and future directions for research.

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“…To validate our tool, we used confocal microscope to acquire video sequence of a periodically stretched fibrin hydrogel. In order to stretch this soft gel under the microscope, we used a technique recently developed in our laboratory [63]. Briefly, the gel was polymerized within a cutout silicone strip.…”

Section: Validating Examplementioning

confidence: 99%

Motion magnification analysis of microscopy videos of biological cells

et al. 2020

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It is well recognized that isolated cardiac muscle cells beat in a periodic manner. Recently, evidence indicates that other, non-muscle cells, also perform periodic motions that are either imperceptible under conventional lab microscope lens or practically not easily amenable for analysis of oscillation amplitude, frequency, phase of movement and its direction. Here, we create a real-time video analysis tool to visually magnify and explore sub-micron rhythmic movements performed by biological cells and the induced movements in their surroundings. Using this tool, we suggest that fibroblast cells perform small fluctuating movements with a dominant frequency that is dependent on their surrounding substrate and its stiffness.

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Straining 3D Hydrogels with Uniform Z-Axis Strains While Enabling Live Microscopy Imaging

Cited by 7 publications

References 46 publications

FITC-Dextran Release from Cell-Embedded Fibrin Hydrogels

FITC-Dextran Release from Cell-Embedded Fibrin Hydrogels

Probing Local Force Propagation in Tensed Fibrous Gels

Motion magnification analysis of microscopy videos of biological cells

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