scholarly journals Osteogenic differentiation and mineralization in fibre-reinforced tubular scaffolds: theoretical study and experimental evidences

2012 ◽  
Vol 9 (74) ◽  
pp. 2201-2212 ◽  
Author(s):  
Vincenzo Guarino ◽  
Francesco Urciuolo ◽  
Marco A. Alvarez-Perez ◽  
Benedetto Mele ◽  
Paolo A. Netti ◽  
...  
Keyword(s):  
Fluid Transport ◽  
Mechanical Response ◽  
Fluid Dynamic ◽  
Human Mesenchymal Stem Cells ◽  
Filament Winding ◽  
Long Bone ◽  
Design Strategies ◽  
Dynamic Simulations ◽  
Scale Properties

The development of composite scaffolds with well-organized architecture and multi-scale properties (i.e. porosity, degradation) represents a valid approach for achieving a tissue-engineered construct capable of reproducing the medium- and long-term in vitro behaviour of hierarchically complex tissues such as spongy bone. To date, the implementation of scaffold design strategies able to summarize optimal scaffold architecture as well as intrinsic mechanical, chemical and fluid transport properties still remains a challenging issue. In this study, poly ɛ -caprolactone/polylactid acid (PCL/PLA) tubular devices (fibres of PLA in a PCL matrix) obtained by phase inversion/salt leaching and filament winding techniques were proposed as cell instructive scaffold for bone osteogenesis. Continuous fibres embedded in the polymeric matrix drastically improved the mechanical response as confirmed by compression elastic moduli, which vary from 0.214 ± 0.065 to 1.174 ± 0.143 MPa depending on the relative fibre/matrix and polymer/solvent ratios. Moreover, computational fluid dynamic simulations demonstrated the ability of composite structure to transfer hydrodynamic forces during in vitro culture, thus indicating the optimal flow rate conditions that, case by case, enables specific cellular events—i.e. osteoblast differentiation from human mesenchymal stem cells (hMSCs), mineralization, etc. Hence, we demonstrate that the hMSC differentiation preferentially occurs in the case of higher perfusion rates—over 0.05 ml min –1 —as confirmed by the expression of alkaline phosphate and osteocalcin markers. In particular, the highest osteopontin values and a massive mineral phase precipitation of bone-like phases detected in the case of intermediate flow rates (i.e. 0.05 ml min –1 ) allows us to identify the best condition to stimulate the bone extracellular matrix in-growth, in agreement with the hydrodynamic model prediction. All these results concur to prove the succesful use of tubular composite as temporary device for long bone treatment.

Fluid Dynamic Study in a Femoral Artery Branch Casting of Man With Upstream Main Lumen Curvature for Steady Flow

1985 ◽  
Vol 107 (3) ◽  
pp. 240-248 ◽  
Author(s):  
M. R. Back ◽  
Y. I. Cho ◽  
L. H. Back
Keyword(s):  
Steady Flow ◽  
Fluid Transport ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Pressure Distributions ◽  
Flow Investigation ◽  
Measured Pressure

An in-vitro, steady flow investigation was conducted in a hollow, transparent vascular replica of the profunda femoris branch of man for a range of physiological flow conditions. The replica casting tested was obtained from a human cadaver and indicated some plaque formation along the main lumen and branch. The flow visualization observations and measured pressure distributions indicated the highly three-dimensional flow characteristics with arterial curvature and branching, and the important role of centrifugal effects in fluid transport mechanisms.

scholarly journals In situ enhancement of pulmonary surfactant function using temporary flow reversal

2012 ◽  
Vol 112 (1) ◽  
pp. 149-158 ◽  
Author(s):  
Henry W. Glindmeyer ◽  
Bradford J. Smith ◽  
Donald P. Gaver
Keyword(s):  
Fluid Dynamic ◽  
The United States ◽  
Cellular Damage ◽  
Dynamic Simulations ◽  
Airway Patency ◽  
Surfactant Replacement Therapy ◽  
Starting Point ◽  
Microscale Transport

Acute respiratory distress syndrome is a pulmonary disease with a mortality rate of ∼40% and 75,000 deaths annually in the United States. Mechanical ventilation restores airway patency and gas transport but leads to ventilator-induced lung injury. Furthermore, surfactant replacement therapy is ineffective due to surfactant delivery difficulties and deactivation by vascular proteins leaking into the airspace. Here, we demonstrated that surfactant function can be substantially improved (up to 50%) in situ in an in vitro pulmonary airway model using unconventional flows that incorporate a short-term retraction of the air-liquid interface, leading to a net decrease in cellular damage. Computational fluid dynamic simulations provided insights into this method and demonstrated the physicochemical hydrodynamic foundation for the improved surfactant microscale transport and mobility. This study may provide a starting point for developing novel ventilation waveforms to improve surfactant function in edematous airways.

scholarly journals Visco- and poroelastic contributions of the zona pellucida to the mechanical response of oocytes

2021 ◽  
Vol 20 (2) ◽  
pp. 751-765
Author(s):  
Alberto Stracuzzi ◽  
Johannes Dittmann ◽  
Markus Böl ◽  
Alexander E. Ehret
Keyword(s):  
Mechanical Properties ◽  
Zona Pellucida ◽  
Fluid Transport ◽  
Mechanical Response ◽  
Viscoelastic Model ◽  
Structural Response ◽  
Progressive Relaxation ◽  
In Vitro Fertilisation ◽  
Element Analysis

AbstractProbing mechanical properties of cells has been identified as a means to infer information on their current state, e.g. with respect to diseases or differentiation. Oocytes have gained particular interest, since mechanical parameters are considered potential indicators of the success of in vitro fertilisation procedures. Established tests provide the structural response of the oocyte resulting from the material properties of the cell’s components and their disposition. Based on dedicated experiments and numerical simulations, we here provide novel insights on the origin of this response. In particular, polarised light microscopy is used to characterise the anisotropy of the zona pellucida, the outermost layer of the oocyte composed of glycoproteins. This information is combined with data on volumetric changes and the force measured in relaxation/cyclic, compression/indentation experiments to calibrate a multi-phasic hyper-viscoelastic model through inverse finite element analysis. These simulations capture the oocyte’s overall force response, the distinct volume changes observed in the zona pellucida, and the structural alterations interpreted as a realignment of the glycoproteins with applied load. The analysis reveals the presence of two distinct timescales, roughly separated by three orders of magnitude, and associated with a rapid outflow of fluid across the external boundaries and a long-term, progressive relaxation of the glycoproteins, respectively. The new results allow breaking the overall response down into the contributions from fluid transport and the mechanical properties of the zona pellucida and ooplasm. In addition to the gain in fundamental knowledge, the outcome of this study may therefore serve an improved interpretation of the data obtained with current methods for mechanical oocyte characterisation.

In Vitro Assessment of Hydroxyapatite Coating on the Surface of Additive Manufactured Ti6Al4V Scaffolds

2016 ◽  
Vol 879 ◽  
pp. 2444-2449 ◽  
Author(s):  
Ekaterina Chudinova ◽  
Maria Surmeneva ◽  
Andrey Koptioug ◽  
Irina V. Savintseva ◽  
Irina Selezneva ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Human Mesenchymal Stem Cells ◽  
Nanocrystalline Structure ◽  
X Ray Diffraction ◽  
Ha Coating ◽  
Magnetron Sputter Deposition ◽  
In Vitro Assessment ◽  
Average Size

Custom orthopedic and dental implants may be fabricated by additive manufacturing (AM), for example using electron beam melting technology. This study is focused on the modification of the surface of Ti6Al4V alloy coin-like scaffolds fabricated via AM technology (EBM®) by radio frequency (RF) magnetron sputter deposition of hydroxyapatite (HA) coating. The scaffolds with HA coating were characterized by Scanning Electron microscopy, X-ray diffraction. HA coating showed a nanocrystalline structure with the crystallites of an average size of 32±9 nm. The ability of the surface to support adhesion and the proliferation of human mesenchymal stem cells was studied using biological short-term tests in vitro. In according to in vitro assessment, thin HA coating stimulated the attachment and proliferation of cells. Human mesenchymal stem cells cultured on the HA-coated scaffold also formed mineralized nodules.

scholarly journals 22(R)-hydroxycholesterol for dopaminergic neuronal specification of MSCs and amelioration of Parkinsonian symptoms in rats

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Manisha Singh ◽  
Manish Jain ◽  
Samrat Bose ◽  
Ashutosh Halder ◽  
Tapas Chandra Nag ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Stem Cells ◽  
Parkinson's Disease ◽  
Dental Pulp ◽  
Neuronal Cells ◽  
Human Mesenchymal Stem Cells ◽  
Wistar Rat ◽  
Human Mscs ◽  
In Vitro Differentiation

AbstractOxysterols play vital roles in the human body, ranging from cell cycle regulation and progression to dopaminergic neurogenesis. While naïve human mesenchymal stem cells (hMSCs) have been explored to have neurogenic effect, there is still a grey area to explore their regenerative potential after in vitro differentiation. Hence, in the current study, we have investigated the neurogenic effect of 22(R)-hydroxycholesterol (22-HC) on hMSCs obtained from bone marrow, adipose tissue and dental pulp. Morphological and morphometric analysis revealed physical differentiation of stem cells into neuronal cells. Detailed characterization of differentiated cells affirmed generation of neuronal cells in culture. The percentage of generation of non-DA cells in the culture confirmed selective neurogenic potential of 22-HC. We substantiated the efficacy of these cells in neuro-regeneration by transplanting them into Parkinson’s disease Wistar rat model. MSCs from dental pulp had maximal regenerative effect (with 80.20 ± 1.5% in vitro differentiation efficiency) upon transplantation, as shown by various behavioural examinations and immunohistochemical tests. Subsequential analysis revealed that 22-HC yields a higher percentage of functional DA neurons and has differential effect on various tissue-specific primary human MSCs. 22-HC may be used for treating Parkinson’s disease in future with stem cells.

scholarly journals Design Strategies for Electrochemical Aptasensors for Cancer Diagnostic Devices

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 736
Author(s):  
Kamila Malecka ◽  
Edyta Mikuła ◽  
Elena E. Ferapontova
Keyword(s):  
Cancer Diagnosis ◽  
Cost Effective ◽  
Quality Of Healthcare ◽  
Cancer Diagnostics ◽  
Screening Tests ◽  
Design Strategies ◽  
Excellent Thermal Stability ◽  
Electrochemical Biosensing ◽  
Equipment Size

Improved outcomes for many types of cancer achieved during recent years is due, among other factors, to the earlier detection of tumours and the greater availability of screening tests. With this, non-invasive, fast and accurate diagnostic devices for cancer diagnosis strongly improve the quality of healthcare by delivering screening results in the most cost-effective and safe way. Biosensors for cancer diagnostics exploiting aptamers offer several important advantages over traditional antibodies-based assays, such as the in-vitro aptamer production, their inexpensive and easy chemical synthesis and modification, and excellent thermal stability. On the other hand, electrochemical biosensing approaches allow sensitive, accurate and inexpensive way of sensing, due to the rapid detection with lower costs, smaller equipment size and lower power requirements. This review presents an up-to-date assessment of the recent design strategies and analytical performance of the electrochemical aptamer-based biosensors for cancer diagnosis and their future perspectives in cancer diagnostics.

Towards real-time fire data synthesis using numerical simulations

2021 ◽  
pp. 073490412199344
Author(s):  
Wolfram Jahn ◽  
Frane Sazunic ◽  
Carlos Sing-Long
Keyword(s):  
Real Time ◽  
Computational Fluid Dynamic ◽  
Dynamic Models ◽  
Fluid Dynamic ◽  
Near Field ◽  
Computing Time ◽  
Temperature Correction ◽  
Dynamic Simulations ◽  
Conservation Of Energy ◽  
Fire Scenarios

Synthesising data from fire scenarios using fire simulations requires iterative running of these simulations. For real-time synthesising, faster-than-real-time simulations are thus necessary. In this article, different model types are assessed according to their complexity to determine the trade-off between the accuracy of the output and the required computing time. A threshold grid size for real-time computational fluid dynamic simulations is identified, and the implications of simplifying existing field fire models by turning off sub-models are assessed. In addition, a temperature correction for two zone models based on the conservation of energy of the hot layer is introduced, to account for spatial variations of temperature in the near field of the fire. The main conclusions are that real-time fire simulations with spatial resolution are possible and that it is not necessary to solve all fine-scale physics to reproduce temperature measurements accurately. There remains, however, a gap in performance between computational fluid dynamic models and zone models that must be explored to achieve faster-than-real-time fire simulations.

scholarly journals Chronic senescent human mesenchymal stem cells as possible contributor to the wound healing disorder after exposure to the alkylating agent sulfur mustard

2021 ◽  
Vol 95 (2) ◽  
pp. 727-747
Author(s):  
Simone Rothmiller ◽  
Niklas Jäger ◽  
Nicole Meier ◽  
Thimo Meyer ◽  
Adrian Neu ◽  
...  
Keyword(s):  
Stem Cells ◽  
Wound Healing ◽  
Mesenchymal Stem Cells ◽  
Alkylating Agent ◽  
Chronic Wounds ◽  
Sulfur Mustard ◽  
Morphological Changes ◽  
Human Mesenchymal Stem Cells ◽  
Age Related

AbstractWound healing is a complex process, and disturbance of even a single mechanism can result in chronic ulcers developing after exposure to the alkylating agent sulfur mustard (SM). A possible contributor may be SM-induced chronic senescent mesenchymal stem cells (MSCs), unable to fulfil their regenerative role, by persisting over long time periods and creating a proinflammatory microenvironment. Here we show that senescence induction in human bone marrow derived MSCs was time- and concentration-dependent, and chronic senescence could be verified 3 weeks after exposure to between 10 and 40 µM SM. Morphological changes, reduced clonogenic and migration potential, longer scratch closure times, differences in senescence, motility and DNA damage response associated genes as well as increased levels of proinflammatory cytokines were revealed. Selective removal of these cells by senolytic drugs, in which ABT-263 showed initial potential in vitro, opens the possibility for an innovative treatment strategy for chronic wounds, but also tumors and age-related diseases.

Sign in / Sign up

Export Citation Format

Share Document