scholarly journals In vitro validation of measurement of volume elastic modulus using photoplethysmography

2018 ◽  
Vol 52 ◽  
pp. 10-21
Author(s):  
Haneen Njoum ◽  
Panayiotis A Kyriacou
Keyword(s):  
Elastic Modulus ◽  
Volume Elastic Modulus

scholarly journals Fabrication of 3D-Printed Interpenetrating Hydrogel Scaffolds for Promoting Chondrogenic Differentiation

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2146
Author(s):  
Jian Guan ◽  
Fu-zhen Yuan ◽  
Zi-mu Mao ◽  
Hai-lin Zhu ◽  
Lin Lin ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Elastic Modulus ◽  
Chondrogenic Differentiation ◽  
Marker Genes ◽  
Self Healing ◽  
Polyethylene Glycol Diacrylate ◽  
3D Microenvironment ◽  
3D Printed

The limited self-healing ability of cartilage necessitates the application of alternative tissue engineering strategies for repairing the damaged tissue and restoring its normal function. Compared to conventional tissue engineering strategies, three-dimensional (3D) printing offers a greater potential for developing tissue-engineered scaffolds. Herein, we prepared a novel photocrosslinked printable cartilage ink comprising of polyethylene glycol diacrylate (PEGDA), gelatin methacryloyl (GelMA), and chondroitin sulfate methacrylate (CSMA). The PEGDA-GelMA-CSMA scaffolds possessed favorable compressive elastic modulus and degradation rate. In vitro experiments showed good adhesion, proliferation, and F-actin and chondrogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) on the scaffolds. When the CSMA concentration was increased, the compressive elastic modulus, GAG production, and expression of F-actin and cartilage-specific genes (COL2, ACAN, SOX9, PRG4) were significantly improved while the osteogenic marker genes of COL1 and ALP were decreased. The findings of the study indicate that the 3D-printed PEGDA-GelMA-CSMA scaffolds possessed not only adequate mechanical strength but also maintained a suitable 3D microenvironment for differentiation, proliferation, and extracellular matrix production of BMSCs, which suggested this customizable 3D-printed PEGDA-GelMA-CSMA scaffold may have great potential for cartilage repair and regeneration in vivo.

scholarly journals Characterization of Gelatin Hydrogels Cross-Linked with Microbial Transglutaminase as Engineered Skeletal Muscle Substrates

2021 ◽  
Vol 8 (1) ◽  
pp. 6
Author(s):  
Divya Gupta ◽  
Jeffrey W. Santoso ◽  
Megan L. McCain
Keyword(s):  
Skeletal Muscle ◽  
Elastic Modulus ◽  
Ambient Air ◽  
In Vitro Models ◽  
Microbial Transglutaminase ◽  
Conventional Culture ◽  
Muscle Tissues ◽  
Physical Features ◽  
Phosphate Buffered Saline

Engineered in vitro models of skeletal muscle are essential for efficiently screening drug safety and efficacy. However, conventional culture substrates poorly replicate physical features of native muscle and do not support long-term culture, which limits tissue maturity. Micromolded gelatin hydrogels cross-linked with microbial transglutaminase (gelatin-MTG hydrogels) have previously been shown to induce C21C2 myotube alignment and improve culture longevity. However, several properties of gelatin-MTG hydrogels have not been systematically characterized, such as changes in elastic modulus during incubation in culture-like conditions and their ability to support sarcomere maturation. In this study, various gelatin-MTG hydrogels were fabricated and incubated in ambient or culture-like conditions. Elastic modulus, mass, and transmittance were measured over a one- or two-week period. Compared to hydrogels in phosphate buffered saline (PBS) or ambient air, hydrogels in Dulbecco’s Modified Eagle Medium (DMEM) and 5% CO2 demonstrated the most stable elastic modulus. A subset of gelatin-MTG hydrogels was micromolded and seeded with C2C12 or primary chick myoblasts, which aligned and fused into multinucleated myotubes with relatively mature sarcomeres. These data are important for fabricating gelatin-MTG hydrogels with predictable and stable mechanical properties and highlight their advantages as culture substrates for engineering relatively mature and stable muscle tissues.

Effect of Substrate Elasticity on In Vitro Aging of Human Mesenchymal Stem Cells

2012 ◽  
Vol 1498 ◽  
pp. 39-45
Author(s):  
Courtney E. LeBlon ◽  
Caitlin R. Fodor ◽  
Tony Zhang ◽  
Xiaohui Zhang ◽  
Sabrina S. Jedlicka
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Elastic Modulus ◽  
Myogenic Differentiation ◽  
Human Mesenchymal Stem Cells ◽  
Immunofluorescent Staining ◽  
Differentiation Potential ◽  
Gene And Protein Expression ◽  
The Impact

ABSTRACTHuman mesenchymal stem cells (hMSCs) were routinely cultured on tissue-culture polystyrene (TCPS) to investigate the in vitro aging and cell stiffening. hMSCs were also cultured on thermoplastic polyurethane (TPU), which is a biocompatible polymer with an elastic modulus of approximately 12.9MPa, to investigate the impact of substrate elastic modulus on cell stiffening and differentiation potential. Cells were passaged over several generations on each material. At each passage, cells were subjected to osteogenic and myogenic differentiation. Local cell elastic modulus was measured at every passage using atomic force microscopy (AFM) indentation. Gene and protein expression was examined using qRT-PCR and immunofluorescent staining, respectively, for osteogenic and myogenic markers. Results show that the success of myogenic differentiation is highly reliant on the elastic modulus of the undifferentiated cells. The success of osteogenic differentiations is most likely somewhat dependent on the cell elastic modulus, as differentiations were more successful in earlier passages, when cells were softer.

IN VIVO EVALUATION OF THE HUMAN CAROTID ARTERY COMPLEX ELASTIC MODULUS

2006 ◽  
Vol 06 (02) ◽  
pp. 189-208
Author(s):  
GRAF SEBASTIÁN ◽  
ZÓCALO YANINA ◽  
PESSANA FRANCO ◽  
BIA DANIEL ◽  
GAMERO LUCAS ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Frequency Response ◽  
Arterial Wall ◽  
Complex Modulus ◽  
System Modeling ◽  
In Vivo Evaluation ◽  
Viscoelastic Parameters ◽  
Before And After

The arterial wall dynamics evaluation requires the assessment of its frequency-response. The aim was to apply an original methodology, to evaluate the arterial wall pressure-diameter frequency-response and elastic complex modulus, of human in vivo and in vitro common carotid arteries (CCA). CCA pressure, diameter and wall thickness were recorded. In vitro recordings were performed using pressure microtransducer (Konigsberg) and sonomicrometry, in 14 CCA segments (from donors). The in vivo recordings were obtained non-invasively by tonometry and mode-B echography in 10 normotensive patients, and in 10 hypertensive patients before and after 3 months of treatment with an ACE-inhibitor. A system modeling-identification approach was used to estimate the viscoelastic parameters: elastic, viscous and inertial indexes, and to perform an isofrequency analysis (up to 5Hz) of the incremental elastic modulus E inc (jω) of the arterial wall. The new approach, proposed to evaluate the frequency-dependence of arterial wall mechanics, was applied satisfactorily.

scholarly journals Electrospun polyester-urethane scaffold preserves mechanical properties and exhibits strain stiffening during in situ tissue ingrowth and degradation

2019 ◽  
Author(s):  
Hugo Krynauw ◽  
Rodaina Omar ◽  
Josepha Koehne ◽  
Georges Limbert ◽  
Neil H Davies ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Mechanical Performance ◽  
Hydrolytic Degradation ◽  
Material Strength ◽  
Fibre Direction ◽  
Tissue Ingrowth ◽  
Polyester Urethane

AbstractConsistent mechanical performance from implantation through healing and scaffold degradation is highly desired for tissue-regenerative scaffolds, e.g. when used for vascular grafts. The aim of this study was the paired in vivo mechanical assessment of biostable and fast degrading electrospun polyester-urethane scaffolds to isolate the effects of material degradation and tissue formation after implantation. Biostable and degradable polyester-urethane scaffolds with substantial fibre alignment were manufactured by electrospinning. Scaffold samples were implanted paired in subcutaneous position in rats for 7, 14 and 28 days. Morphology, mechanical properties and tissue ingrowth of the scaffolds were assessed before implantation and after retrieval. Tissue ingrowth after 28 days was 83 ± 10% in the biostable scaffold and 77 ± 4% in the degradable scaffold. For the biostable scaffold, the elastic modulus at 12% strain increased significantly between 7 and 14 days and decreased significantly thereafter in fibre but not in cross-fibre direction. The degradable scaffold exhibited a significant increase in the elastic modulus at 12% strain from 7 to 14 days after which it did not decrease but remained at the same magnitude, both in fibre and in cross-fibre direction. Considering that the degradable scaffold loses its material strength predominantly during the first 14 days of hydrolytic degradation (as observed in our previous in vitro study), the consistency of the elastic modulus of the degradable scaffold after 14 days is an indication that the regenerated tissue construct retains it mechanical properties.

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