ABSTRACT
Current light microscopic methods such as serial sectioning, confocal microscopy or multiphoton microscopy are severely limited in their ability to analyse rather opaque biological structures in three dimensions, while electron optical methods offer either a good three-dimensional topographic visualization (scanning electron microscopy) or high-resolution imaging of very thin samples (transmission electron microscopy). However, sample preparation commonly results in a significant alteration and the destruction of the three-dimensional integrity of the specimen. Depending on the selected photon energy, the interaction between X-rays and biological matter provides semi-transparency of the specimen, allowing penetration of even large specimens. Based on the projection-slice theorem, angular projections can be used for tomographic imaging. This method is well developed in medical and materials science for structure sizes down to several micrometres and is considered as being non-destructive. Achieving a spatial and structural resolution that is sufficient for the imaging of cells inside biological tissues is difficult due to several experimental conditions. A major problem that cannot be resolved with conventional X-ray sources are the low differences in density and absorption contrast of cells and the surrounding tissue. Therefore, X-ray monochromatization coupled with a sufficiently high photon flux and coherent beam properties are key requirements and currently only possible with synchrotron-produced X-rays. In this study, we report on the three-dimensional morphological characterization of articular cartilage using synchrotron-generated X-rays demonstrating the spatial distribution of single cells inside the tissue and their quantification, while comparing our findings to conventional histological techniques.
Subject(s)
Cartilage, Articular/diagnostic imaging , Cartilage, Articular/ultrastructure , Chondrocytes/diagnostic imaging , Chondrocytes/ultrastructure , Radiographic Image Enhancement/methods , Synchrotrons , Tomography, X-Ray Computed/methods , Animals , Cattle , Cells, Cultured , In Vitro TechniquesABSTRACT
Porous ceramics made of alumina and hydroxyapatite were created using a protein foaming method. Porosity and pore size distribution were successfully varied by means of chemical modification of the foaming protein Bovine serum albumin (BSA). The effectiveness of the BSA and of its chemical modifications as well as the influence of the dispersing agent were investigated using synchrotron tomography. Resulting porous ceramic materials were used as three-dimensional substrates for the cultivation of human peripheral stem cells. The cells proliferated and differentiated in culture. Five cell lines consistent with human blood cell lines were observed.
Subject(s)
Biocompatible Materials/chemistry , Cell Culture Techniques/methods , Ceramics/chemistry , Hematopoietic Stem Cells/cytology , Hematopoietic Stem Cells/physiology , Tissue Engineering/methods , Cell Adhesion/physiology , Cell Differentiation , Cell Proliferation , Cell Survival , Cells, Cultured , Humans , Materials Testing , Porosity , Surface PropertiesABSTRACT
Tomographic images are often superimposed by so called ring artefacts. Ring artefacts are concentric rings in the images around the center of rotation of the tomographic setup caused e.g. by differences in the individual pixel response of the detector. They complicate the post processing of the data, i.e. the segmentation of individual image information. Hence, for a quantitative analysis of the tomographic images a significant reduction of these artefacts is essential. In this paper, a simple but efficient method to eliminate such artefacts during the reconstruction is proposed.
