Tomáš Gregor

Elastic three-dimensional poly (ε-caprolactone) nanofibre scaffold enhances migration, proliferation and osteogenic differentiation of mesenchymal stem cells

We prepared 3D poly (ε‐caprolactone) (PCL) nanofibre scaffolds and tested their use for seeding, proliferation, differentiation and migration of mesenchymal stem cell (MSCs).

Porcine liver vascular bed in Biodur E20 corrosion casts

BACKGROUND Pigs are frequently used as animal models in experimental medicine. To identify processes of vascular development or regression, vascular elements must be recognised and quantified in a three-dimensional (3D) arrangement. Vascular corrosion casts enable the creation of 3D replicas of vascular trees. The aim of our study was to identify suitable casting media and optimise the protocol for porcine liver vascular corrosion casting. MATERIALS AND METHODS Mercox II® (Ladd Research, Williston, Vermont, USA) and Biodur E20® Plus (Biodur Products, Heidelberg, Germany) were tested in 4 porcine livers. The resins (volume approximately 700 mL) were injected via the portal vein. Corrosion casts were examined by macro-computed tomography, micro-computed tomography and scanning electron microscopy. RESULTS For hepatectomies, the operating protocol was optimised to avoid gas or blood clot embolisation. We present a protocol for porcine liver vascular bed casting based on corrosion specimens prepared using Biodur E20® epoxy resin. CONCLUSIONS Only Biodur E20®Plus appeared to be suitable for high-volume vascular corrosion casting due to its optimal permeability, sufficient processing time and minimum fragility. Biodur E20® Plus is slightly elastic, radio-opaque and alcohol-resistant. These properties make this acrylic resin suitable for not only vascular research but also teaching purposes.

Correlating Micro-CT Imaging with Quantitative Histology

Advanced biomechanical models of biological tissues should be based on statistical morphometry of tissue architecture. A quantitative description of the microscopic properties of real tissue samples is an advantage when devising computer models that are statistically similar to biological tissues in physiological or pathological conditions. The recent development of X-ray microtomography (micro-CT) has introduced resolution similar to that of routine histology. The aim of this chapter is to review and discuss both automatic image processing and interactive, unbiased stereological tools available for micro-CT scans and histological micrographs. We will demonstrate the practical usability of micro-CT in two different types of three-dimensional (3-D) ex vivo samples: (i) bone scaffolds used in tissue engineering and (ii) microvascular corrosion casts.

Impact resistance of hetero-phase polymeric materials

Abstract Hetero-phase polymeric materials, such as high-impact polystyrene (hiPS) and impact polypropylene (iPP), have many applications because of their excellent impact resistance. The methodology of discrete element method (DEM) is adopted for numerical simulations of hetero-phase polymer particles hitting the solid wall. Systematic mapping from the parametric space of polymer morphologies to the parametric space of impact-resistance properties was carried out. Distribution of rubbery domains in polymeric materials strongly affects their impact resistance.

Quantification of Liver Microcirculation Using X-Ray Microtomography of Vascular Corrosion Casts

We used corrosion casts and micro-CT for quantitative description of microvascular network in porcine liver. Using stereological methods, manual tracing of microvessels and analysis of orientation in 3D, we quantified the volume fraction, the surface density, the numerical density, the length density and the tortuosity of microvessels in series of images with 1.875 μm pixel resolution. Biodur E 20 resin was more suitable for preparing and quantifying microvascular tree corrosion casts when compared to Mercox II resin. Quantified data could be applicable for correlating 3D models with 2D liver histopathology, for enhancing the interpretation of routine medical CT and for providing data for computer models of tissue perfusion and angiogenesis.

Multiscale Heterogeneity of Bone Microporosities and Tissue Scaffolds

Our aim was to use stereology to quantify the volume fraction of osteocyte lacunes, volume fraction of large blood vessels, numerical density of osteocyte lacunes, volume of osteocyte lacunae and bone surface in series of micro-CT images representing samples of spongy and compact bone of human tibia. The spongy bone had a smaller volume fraction of osteocyte lacunes, a greater numerical density of bone lacunes, a smaller volume of the lacunes within the same bone volume and a greater bone surface density when compared to the compact bone. Stereology provided us with data on hierarchical organization of bone structural heterogeneity with reasonable time costs.