Air-puff associated quantification of non-linear biomechanical properties of the human cornea in vivo

2011 ◽

Author(s):

Jinjin Ma ◽

Ellen M. Arruda

Keyword(s):

Cruciate Ligament ◽

Viscoelastic Behavior ◽

Biomechanical Properties ◽

Acl Graft ◽

Non Linear ◽

Linear Viscoelastic Behavior ◽

Linear Viscoelastic ◽

Anterior Cruciate ◽

Acl Replacement

Patellar tendon (PT) autografts and allografts are the most common methods currently used to replace a torn anterior cruciate ligament (ACL). The PT is not only much stiffer than the ACL it replaces it also exhibits qualitatively and quantitatively different non-linear viscoelastic behavior from those of the ACL. These mis-matched biomechanics may be contributing to the high incidence of early onset osteoarthritis suffered by patients who have had ACL surgeries. Thus there is a need for an ACL graft that can reproduce normal ligament biomechanics and knee function. This talk examines the inhomogeneous, non-linear viscoelastic response of native ACL and of a tissue engineered ACL graft designed to rapidly grow and remodel in vivo to restore the proper biomechanical properties of native ligament. The results using this graft as an ACL replacement are compared against those using a PT autograft for the ACL replacement. Uniaxial loading reveals that after nine months as an ACL replacement, the tissue-engineered graft develops a strain contour pattern closely resembling that of native ACL whereas the PT graft fails to similarly remodel in vivo.

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Exploring the Biomechanical Properties of the Human Cornea In Vivo Based on Corvis ST

Frontiers in Bioengineering and Biotechnology ◽

10.3389/fbioe.2021.771763 ◽

2021 ◽

Vol 9 ◽

Author(s):

Di Zhang ◽

Haixia Zhang ◽

Lei Tian ◽

Yan Zheng ◽

Caiyun Fu ◽

...

Keyword(s):

Viscoelastic Properties ◽

Strain Energy ◽

Biomechanical Properties ◽

Human Cornea ◽

Corvis St ◽

First Order ◽

Healthy Humans ◽

Nonlinear Viscoelastic ◽

Work Done

Purpose: The aim of this study was to provide a method to determine corneal nonlinear viscoelastic properties based on the output data of corneal visualization Scheimpflug technology (Corvis ST).Methods: The Corvis ST data from 18 eyes of 12 healthy humans were collected. Based on the air-puff pressure and the corneal displacement from the Corvis ST test of normal human eyes, the work done by the air-puff attaining the whole corneal displacement was obtained. By applying a visco-hyperelastic strain energy density function of the cornea, in which the first-order Prony relaxation function and the first-order Ogden strain energy were employed, the corneal strain energy during the Corvis ST test was calculated. Then the work done by the air-puff attaining the whole corneal displacement was completely regarded as the strain energy of the cornea. The identification of the nonlinear viscoelastic parameters was carried out by optimizing the sum of difference squares of the work and the strain energy using the genetic algorithm.Results: The visco-hyperelastic model gave a good fit to the data of corneal strain energy with time during the Corvis ST test (R2 > 0.95). The determined Ogden model parameter μ ranged from 0.42 to 0.74 MPa, and α ranged from 32.76 to 55.63. The parameters A and τ in the first-order Prony function were 0.09–0.36 and 1.21–1.95 ms, respectively.Conclusion: It is feasible to determine the corneal nonlinear viscoelastic properties based on the corneal contour information and air-puff pressure of the Corvis ST test.

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Biomechanics of Neutrophil Tethers

Life ◽

10.3390/life11060515 ◽

2021 ◽

Vol 11 (6) ◽

pp. 515

Author(s):

Andrea Cugno ◽

Alex Marki ◽

Klaus Ley

Keyword(s):

Cell Activation ◽

Optical Trap ◽

Biomechanical Properties ◽

Force Microscopy ◽

Advantages And Disadvantages ◽

Atomic Force ◽

Microfluidic Flow ◽

Biomembrane Force Probe ◽

Membrane Reservoir

Leukocytes, including neutrophils, which are propelled by blood flow, can roll on inflamed endothelium using transient bonds between selectins and their ligands, and integrins and their ligands. When such receptor–ligand bonds last long enough, the leukocyte microvilli become extended and eventually form thin, 20 m long tethers. Tether formation can be observed in blood vessels in vivo and in microfluidic flow chambers. Tethers can also be extracted using micropipette aspiration, biomembrane force probe, optical trap, or atomic force microscopy approaches. Here, we review the biomechanical properties of leukocyte tethers as gleaned from such measurements and discuss the advantages and disadvantages of each approach. We also review and discuss viscoelastic models that describe the dependence of tether formation on time, force, rate of loading, and cell activation. We close by emphasizing the need to combine experimental observations with quantitative models and computer simulations to understand how tether formation is affected by membrane tension, membrane reservoir, and interactions of the membrane with the cytoskeleton.

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Histological, Biomechanical, and Biological Properties of Genipin-Crosslinked Decellularized Peripheral Nerves

International Journal of Molecular Sciences ◽

10.3390/ijms22020674 ◽

2021 ◽

Vol 22 (2) ◽

pp. 674

Author(s):

Óscar Darío García-García ◽

Marwa El Soury ◽

David González-Quevedo ◽

David Sánchez-Porras ◽

Jesús Chato-Astrain ◽

...

Keyword(s):

Ex Vivo ◽

Nerve Repair ◽

Wistar Rat ◽

Biomechanical Properties ◽

Biological Properties ◽

Suitable Alternative ◽

Promising Alternative ◽

Histological Pattern ◽

The Impact

Acellular nerve allografts (ANGs) represent a promising alternative in nerve repair. Our aim is to improve the structural and biomechanical properties of biocompatible Sondell (SD) and Roosens (RS) based ANGs using genipin (GP) as a crosslinker agent ex vivo. The impact of two concentrations of GP (0.10% and 0.25%) on Wistar rat sciatic nerve-derived ANGs was assessed at the histological, biomechanical, and biocompatibility levels. Histology confirmed the differences between SD and RS procedures, but not remarkable changes were induced by GP, which helped to preserve the nerve histological pattern. Tensile test revealed that GP enhanced the biomechanical properties of SD and RS ANGs, being the crosslinked RS ANGs more comparable to the native nerves used as control. The evaluation of the ANGs biocompatibility conducted with adipose-derived mesenchymal stem cells cultured within the ANGs confirmed a high degree of biocompatibility in all ANGs, especially in RS and RS-GP 0.10% ANGs. Finally, this study demonstrates that the use of GP could be an efficient alternative to improve the biomechanical properties of ANGs with a slight impact on the biocompatibility and histological pattern. For these reasons, we hypothesize that our novel crosslinked ANGs could be a suitable alternative for future in vivo preclinical studies.

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A composite scaffold of Wharton’s jelly and chondroitin sulphate loaded with human umbilical cord mesenchymal stem cells repairs articular cartilage defects in rat knee

Journal of Materials Science Materials in Medicine ◽

10.1007/s10856-021-06506-w ◽

2021 ◽

Vol 32 (4) ◽

Author(s):

Zhong Li ◽

Yikang Bi ◽

Qi Wu ◽

Chao Chen ◽

Lu Zhou ◽

...

Keyword(s):

Stem Cells ◽

Articular Cartilage ◽

Composite Scaffold ◽

Biomechanical Properties ◽

Cartilage Defects ◽

Human Umbilical Cord ◽

Composite Scaffolds ◽

Articular Cartilage Defects

AbstractTo evaluate the performance of a composite scaffold of Wharton’s jelly (WJ) and chondroitin sulfate (CS) and the effect of the composite scaffold loaded with human umbilical cord mesenchymal stem cells (hUCMSCs) in repairing articular cartilage defects, two experiments were carried out. The in vitro experiments involved identification of the hUCMSCs, construction of the biomimetic composite scaffolds by the physical and chemical crosslinking of WJ and CS, and testing of the biomechanical properties of both the composite scaffold and the WJ scaffold. In the in vivo experiments, composite scaffolds loaded with hUCMSCs and WJ scaffolds loaded with hUCMSCs were applied to repair articular cartilage defects in the rat knee. Moreover, their repair effects were evaluated by the unaided eye, histological observations, and the immunogenicity of scaffolds and hUCMSCs. We found that in vitro, the Young’s modulus of the composite scaffold (WJ-CS) was higher than that of the WJ scaffold. In vivo, the composite scaffold loaded with hUCMSCs repaired rat cartilage defects better than did the WJ scaffold loaded with hUCMSCs. Both the scaffold and hUCMSCs showed low immunogenicity. These results demonstrate that the in vitro construction of a human-derived WJ-CS composite scaffold enhances the biomechanical properties of WJ and that the repair of knee cartilage defects in rats is better with the composite scaffold than with the single WJ scaffold if the scaffold is loaded with hUCMSCs.

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In Vivo Multiphoton Microscopy for Investigating Biomechanical Properties of Human Skin

Cellular and Molecular Bioengineering ◽

10.1007/s12195-010-0147-6 ◽

2010 ◽

Vol 4 (2) ◽

pp. 231-238 ◽

Cited By ~ 20

Author(s):

Xing Liang ◽

Benedikt W. Graf ◽

Stephen A. Boppart

Keyword(s):

Human Skin ◽

Multiphoton Microscopy ◽

Biomechanical Properties

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In Vivo and ex Vivo Approaches to Studying the Biomechanical Properties of Healing Wounds in Rat Skin

Journal of Biomechanical Engineering ◽

10.1115/1.4025109 ◽

2013 ◽

Vol 135 (10) ◽

Cited By ~ 14

Author(s):

Clare Y. L. Chao ◽

Gabriel Y. F. Ng ◽

Kwok-Kuen Cheung ◽

Yong-Ping Zheng ◽

Li-Ke Wang ◽

...

Keyword(s):

Wound Healing ◽

Ex Vivo ◽

Normal Skin ◽

Biomechanical Properties ◽

Skin Wound ◽

Sprague Dawley ◽

Rat Skin ◽

Mechanical Stiffness ◽

Air Jet

An evaluation of wound mechanics is crucial in reflecting the wound healing status. The present study examined the biomechanical properties of healing rat skin wounds in vivo and ex vivo. Thirty male Sprague-Dawley rats, each with a 6 mm full-thickness circular punch biopsied wound at both posterior hind limbs were used. The mechanical stiffness at both the central and margins of the wound was measured repeatedly in five rats over the same wound sites to monitor the longitudinal changes over time of before wounding, and on days 0, 3, 7, 10, 14, and 21 after wounding in vivo by using an optical coherence tomography-based air-jet indentation system. Five rats were euthanized at each time point, and the biomechanical properties of the wound tissues were assessed ex vivo using a tensiometer. At the central wound bed region, the stiffness measured by the air-jet system increased significantly from day 0 (17.2%), peaked at day 7 (208.3%), and then decreased progressively until day 21 (40.2%) as compared with baseline prewounding status. The biomechanical parameters of the skin wound samples measured by the tensiometer showed a marked reduction upon wounding, then increased with time (all p < 0.05). On day 21, the ultimate tensile strength of the skin wound tissue approached 50% of the normal skin; while the stiffness of tissue recovered at a faster rate, reaching 97% of its prewounded state. Our results suggested that it took less time for healing wound tissues to recover their stiffness than their maximal strength in rat skin. The stiffness of wound tissues measured by air-jet could be an indicator for monitoring wound healing and contraction.

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