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Signed in as:
filler@godaddy.com
Designing scaffolds similar to the structure of trabecular bone requires specialised algorithms. Existing scaffold designs for bone tissue engineering have repeated patterns that do not replicate the random stochastic porous structure of the internal architecture of bones. In this research, the Voronoi tessellation method is applied to create random porous biomimetic structures. A volume mesh created from the shape of a Zygoma fracture acts as a boundary for the generation of random seed points by point spacing to create Voronoi cells and Voronoi diagrams. The Voronoi lattices were obtained by adding strut thickness to the Voronoi diagrams. Gradient Voronoi scaffolds of pore sizes (19.8 µm to 923 µm) similar to the structure of the trabecular bone were designed. A Finite Element Method-based computational fluid dynamics (CFD) simulation was performed on all designed Voronoi scaffolds to predict the pressure drops and permeability of non-Newtonian blood flow behaviour using the power law material model. The predicted permeability (0.33 × 10−9 m2 to 2.17 × 10−9 m2) values of the Voronoi scaffolds from the CFD simulation are comparable with the permeability of scaffolds and bone specimens from other research works.
(CC BY 4.0 : Haja-Sherief N. Musthafa et al. 2024, https://doi.org/10.3390/computation12120241 )
Three-dimensional porous scaffolds are substitutes for traditional bone grafts in bone tissue engineering (BTE) applications to restore and treat bone injuries and defects. The use of computational modelling is gaining momentum to predict the parameters involved in tissue healing and cell seeding procedures in perfusion bioreactors to reach the final goal of optimal bone tissue growth. Computational modelling based on finite element method (FEM) and computational fluid dynamics (CFD) are two standard methodologies utilised to investigate the equivalent mechanical properties of tissue scaffolds, as well as the flow characteristics inside the scaffolds, respectively. The success of a computational modelling simulation hinges on the selection of a relevant mathematical model with proper initial and boundary conditions. This review paper aims to provide insights to researchers regarding the selection of appropriate finite element (FE) models for different materials and CFD models for different flow regimes inside perfusion bioreactors. Thus, these FEM/CFD computational models may help to create efficient designs of scaffolds by predicting their structural properties and their haemodynamic responses prior to in vitro and in vivo tissue engineering (TE) applications.
(CC BY 4.0 : Haja-Sherief N. Musthafa et al. 2024, https://doi.org/10.3390/computation12040074 )
Due to their excellent properties, triply periodic minimal surfaces (TPMS) have been applied to design scaffolds for bone tissue engineering applications. Predicting the mechanical response of bone scaffolds in different loading conditions is vital to designing scaffolds. The optimal mechanical properties can be achieved by tuning their geometrical parameters to mimic the mechanical properties of natural bone. In this study, we designed gyroid scaffolds of different user-specific pore and strut sizes using a combined TPMS and signed distance field (SDF) method to obtain varying architecture and porosities. The designed scaffolds were converted to various meshes such as surface, volume, and finite element (FE) volume meshes to create FE models with different boundary and loading conditions. The designed scaffolds under compressive loading were numerically evaluated using a finite element method (FEM) to predict and compare effective elastic moduli. The effective elastic moduli range from 0.05 GPa to 1.93 GPa was predicted for scaffolds of different architectures comparable to human trabecular bone. The results assert that the optimal mechanical properties of the scaffolds can be achieved by tuning their design and morphological parameters to match the mechanical properties of human bone.
(CC BY 4.0 : Haja-Sherief N. Musthafa et al. 2023, https://doi.org/10.3390/computation11090181 )
FE models under compressive loading. Displacement distribution of gyroid scaffold PS350.
N. Musthafa, Haja-Sherief et al. 2023. https://doi.org/10.3390/computation11090181 (CC BY 4.0)
Epigenetic Upregulation of VEGF-A Decreases Infarct Size in Mouse Myocardium : Magnetic Resonance (MR) Cine Imaging of Left Ventricle
Angiogenic growth factors are used to treat myocardial infarct by improving blood flow and therefore prevent left ventricular remodelling. In this study, we applied cine imaging to evaluate therapeutic effects of intramyocardial lentiviral delivery of promoter targeted shRNA that mediates epigenetic effects. A significant decrease in infarct size was found in shRNA treated mice from day 4 to day 14 after infarction compared to control group. The increased VEGF-A levels detected by using ELISA and histological findings support the MRI (9.4 Tesla) findings and suggest the method a potential way to decrease infarct size and may find clinical applications in the future.
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In this study, we measured T1ρ relaxation times in mouse myocardium before and 1, 3, 7, 14 and 21 days after left anterior descending coronary artery ligation. T1ρ was found to increase in infarcted myocardium when compared to the reference myocardium of the same heart. Infarctions were confirmed by cine MRI (9.4 T) and histology staining. The increase in T1ρ fits well with the time course of granulation and scar tissue formations opening up the possibilities to follow up the responses of therapeutic agent
Funders
Gene therapy such as vascular endothelial growth factors (VEGF) has been used as promising approach for growth of blood vessels in treatment of peripheral and myocardial ischemia. Various imaging modalities including magnetic resonance imaging (MRI) have become important monitoring tools to measure the biodistribution and pharma kinetics of gene therapy. Spin lattice relaxation in rotating frame (T1ρ) has been used to create initial markers for monitoring myocardial infarction and gene therapy response by creating MRI (9.4 T) contrast due to interactions between water and protein molecules in tissues. In this research, the normal myocardium of mouse was intramyocardial injected with VEGF-A165 and related gene therapy response concerning angiogenic effects have been studied in-vivo with help of T1ρ method.
Funders
Haja-Sherief N Musthafa, et. al, Longitudinal rotating frame relaxation time measurements in infarcted mouse myocardium in vivo. Magn Reson Med, 69: 1389-1395. https://doi.org/10.1002/mrm.24382