CellScale User Publication Highlight: Image-based Analysis of Uniaxial Ring Test

CellScale User Publication Highlight: Image-based Analysis of Uniaxial Ring Test

A Uniaxial ring test is conducted by stretching a ring-shaped specimen in 2 opposite directions using pins or hooks. It is a common test for a variety of materials, from industrial elastomers to soft biological tissues. However, systematic errors can occur in the simultaneous compression, bending and stretching during the test that is geometry-dependent. Dr Kurniawan and his team from Eindhoven University of Technology work to resolve that by introducing a simple image-based analysis approach, accurately estimating the sample mechanical properties for a wide range of ring geometries. The samples were tested in an uniaxial displacement controlled experiment on the CellScale BioTester, with modified rakes: the pins point upward rather than downward, and the rakes were painted black to facilitate the automated analysis of the BioTester images. As proof of concept, they tested their approach on rat vascular grafts and discover a clear temporal change in the mechanical properties of these grafts after implantation.

Read the full journal article here: https://doi.org/10.1039/C8SM02343C

Read all other publications here: https://cellscale.com/publications/

 

To read about an engineered meniscus with zone-specific biochemical composition, click here.

 

CellScale User Publication Highlight: An Engineered Meniscus with Zone-specific Biochemical Composition

CellScale User Publication Highlight: An Engineered Meniscus with Zone-specific Biochemical Composition

(Image from Saanichton Physiotherapy & Sports Clinic)

The knee meniscus is a rubbery C-shaped disc that acts as a cushion during movement. Creating an engineered meniscus is challenging because the native tissue has an interior cartilaginous zone and outer fibrous zone. Dr Hasirci and his team at the Middle East Technical University in Turkey have successfully engineered an artificial meniscus through a series of steps including 3D printing, impregnation with agarose and gelatin methacrylate, loading with porcine fibrochondrocytes and incubation. The team then performed dynamic stimulation on the construct to mimic the physiological loading on the tissue and optimize the response of the engineered tissue by comparing them to the characteristics of native tissues. The end result is a construct with potential for use as a substitute for total meniscus replacement.

The CellScale UniVert participated in this research by providing the team a reliable instrument to perform mechanical tests with, allowing them to draw direct comparisons of mechanical properties of the engineered and native tissue. 

Read the full journal article here: https://doi.org/10.1088/1758-5090/aaf707

Read all other publications here: https://cellscale.com/publications/

 

To read about the treatment of chronic wounds using “bead foams”, click here.

 

CellScale User Publication Highlight: Collagenous Bioscaffolds for the Treatment of Cutaneous Wounds

CellScale User Publication Highlight: Collagenous Bioscaffolds for the Treatment of Cutaneous Wounds

Prof. Lauren Flynn and her team at Western University, Canada, are exploring new strategies to stimulate cutaneous tissue repair for the treatment of chronic wounds. They have developed a unique three-dimensional network of porous beads which they call “bead foams”. These foams are created from either human decellularized adipose tissue (DAT) or commercially-sourced bovine tendon collagen (COL). Prof. Flynn and her team have tested the foams with human wound edge dermal fibroblasts sourced from chronic wound tissues.

In this research, the CellScale MicroTester was used in parallel plate compression mode to quantify the mechanical properties of the beads under physiological conditions. The beads were nominally 1-2mm in diameter and were compressed to 50% of their original height with a force of 100μN.The video below from the onboard MicroTester imaging system shows the parallel plate compression test while the graphs above show the force-displacement data (left) and the Young’s modulus of the DAT and COL beads (right). 

Read the full journal article here: https://doi.org/10.1016/j.actbio.2018.10.042

Read all other publications here: https://cellscale.com/publications/

 

To read about a unique anti-fatigue-fracture hydrogels research, click here.

 

CellScale User Publication Highlight: Anti-fatigue-fracture Hydrogels

CellScale User Publication Highlight: Anti-fatigue-fracture Hydrogels

Hydrogels are soft materials that have similar properties to human tissues and could be used for novel medical devices, surgical applications or tissue engineering. However, almost all hydrogels have poor fatigue properties and break upon repeated stretch-relax cycles. This is in sharp contrast to natural tissues (muscle, tendons, etc.), which can withstand millions of cycles per year without rupturing. In this study, Ph.D. candidate German Parada and his team from Zhao Lab at MIT have engineered a new hydrogel that is ten times more fatigue-resistant than existing hydrogels. They have done so by introducing crystalline regions, which are hard nanometer-sized regions made of the same material as the rest of the hydrogel. This creates a reinforced material in the same way that sand is used to reinforce concrete.

In the images above, the left is a confocal microscopy image of the vertical alignment of crystalline fibres in the hydrogel matrix. This was achieved by stretching the hydrogel with the UStretch. The right image is the dry-annealed hydrogel undergoing a single-notch test with fatigue threshold as high as 1000 J/m2.

Read the full journal article here: http://advances.sciencemag.org/content/5/1/eaau8528

Read all other publications here: https://cellscale.com/publications/

 

If you are keen to read another user publication highlight about crystallinity, click here.

 

CellScale User Publication Highlight: A Platform for Generation of Chamber-Specific Cardiac Tissues and Disease Modeling

CellScale User Publication Highlight: A Platform for Generation of Chamber-Specific Cardiac Tissues and Disease Modeling

Yimu Zhao (MASc.) and her team at the Department of Chemical Engineering and Applied Chemistry at the University of Toronto has developed a platform called the “Biowire II”. This is a scalable tissue-cultivation platform that uses electrical field conditioning to perform non-invasive drug testing.

“One key feature of our Biowire II platform is to culture human cardiac tissues and perform on-line non-invasive measurements on contractile forces over a long period of time. The cardiac tissues are formed around a pair of elastic force sensors. Thus, forces generated by tissue formation and contraction can be measured with these force sensors through the use of the calibration curves (wire deflection vs. forces).

The force required to displace the polymer wire was determined using a microscale mechanical tester, MicroTester (CellScale), with modified tungsten probes. Due to the small sizes of engineered cardiac tissues, the generated forces are very difficult to measure directly and accurately. MicroTester apparatus enabled us to calibrate our polymer force sensors and facilitate the accurate force measurements on our Biowire II platform.”

             – Yimu Zhao, Ph.D. candidate of Dr. Milica Radisic

Read the full journal article here: https://doi.org/10.1016/j.cell.2018.11.042

Read all other publications here: https://cellscale.com/publications/

 

Read about another research in cardiac tissue, in this case Investigating the regional variations in mechanical properties of heart valve leaflets here.

 

CellScale User Publication Highlight: Investigating regional variations in the biaxial mechanical properties of heart valve leaflets

CellScale User Publication Highlight: Investigating regional variations in the biaxial mechanical properties of heart valve leaflets

Heart valve disease is a debilitating disease that affects millions of people. It occurs when one or more of the four valves in the heart does not open or close properly. Mechanical characterization of heart valve leaflets is critical for improving therapeutic options for valvular disease. Many attempts at characterization focus on the mechanical properties of the central region and neglect spatial variation in the tissue’s properties. Dr Lee and his team at the University of Oklahoma have utilized the CellScale BioTester to mechanically characterize six distinct regions in heart valve leaflet tissues. Specifically, they have determined that anisotropy and peak stretch vary between regions and that these variations are important for proper leaflet health and function.

Experimenting on both porcine mitral valve and tricuspid valve anterior leaflets, it was discovered that (i) central regions of the leaflet were more anisotropic than edge regions, (ii) the mitral valve anterior leaflet extended more closer to the perimeter, and (iii) mitral valve leaflet tissue regions exhibited a greater decay than tricuspid valve regions in stress-relaxation behavior. Results plotted of the Stress against Stretch for each of the 6 regions are shown below.

 

Read the full journal article here: https://doi.org/10.1016/j.jbiomech.2018.11.015

Read all other publications here: https://cellscale.com/publications/

 

Read about another user publication highlight (3D bioprinting of human tissue with dECM) here.