During the last decade, several tissues and biomaterials for medical applications in replacing bony tissues have been
developed. Three-dimensional cell clusters and mandibular bone grafts are two distinct examples of these developments.
The characterization of the complex three-dimensional structures, however, is still mainly restricted on the twodimensional
analysis of histological slices. The present paper examines the quantitative analysis of mandibular bone
grafts and three-dimensional cell clusters on the basis of synchrotron radiation-based micro computed tomography
measurements. An automated search of pre-defined microstructures through component labeling is applied to the real
datasets in order to identify features that reside independently from other components. The examples demonstrate three
levels of complexity: rather large pieces of bone augmentation material that touch each other, individual adipocytes
difficult to automatically segment in a wet cluster and osmium-stained adipocyte exhibiting higher X-ray absorption than
the surrounding tissue. Although the structures of interest such as the cells can be labeled, de-clustering of the
components requires the incorporation of erosion and dilation algorithms.
Recently the importance of the third dimension in cell biology has been better understood, resulting in a re-orientation towards three-dimensional (3D) cultivation. Yet adequate tools for their morphological characterization have to be established. Synchrotron radiation-based micro computed tomography (SRμCT) allows visualizing such biological systems with almost isotropic micrometer resolution, non-destructively. We have applied SRμCT for studying the internal morphology of human osteoblast-derived, scaffold-free 3D cultures, termed histoids. Primary human osteoblasts, isolated from femoral neck spongy bone, were grown as 2D culture in non-mineralizing osteogenic medium until a rather thick, multi-cellular membrane was formed. This delicate system was intentionally released to randomly fold itself. The folded cell cultures were grown to histoids of cubic milli- or centimeter size in various combinations of mineralizing and non-mineralizing osteogenic medium for a total period of minimum 56 weeks. The SRμCT-measurements were
performed in the absorption contrast mode at the beamlines BW 2 and W 2 (HASYLAB at DESY, Hamburg, Germany), operated by the GKSS-Research Center. To investigate the entire volume of interest several scans were performed under identical conditions and registered to obtain one single dataset of each sample. The histoids grown under different
conditions exhibit similar external morphology of globular or ovoid shape. The SRμCT-examination revealed the distinctly different morphological structures inside the histoids. One obtains details of the histoids that permit to identify and select the most promising slices for subsequent histological characterization.