Regularized phase tomography enables study of mineralized and unmineralized tissue in porous bone scaffold.

Regularized phase tomography was used to image non-calcified fibrous matrix in in vitro cell-cultivated porous bone scaffold samples. 3D micro-architecture of bone and bone scaffold has previously been studied by micro-computed tomography, synchrotron radiation (SR) micro-computed tomography and microdiffraction. However, neither of these techniques can resolve the low-calcified immature pre-bone fibrous structures. Skelite porous scaffold discs were seeded with osteoblasts, a combination of osteoblast and pre-osteoclasts and, as controls, with pre-osteoclasts only, and then cultivated for 8 weeks. They were subsequently imaged using SR propagation-based phase contrast imaging. Reconstructions using a regularized holographic phase tomography approach were compared to standard (absorption) SR micro-computed tomography, which show that quantitative analysis, such as volume and thickness measurements, of both the calcified fraction and the immature bone matrix in the reconstructed volumes is enabled. Indications of the effect of this type of culture on Skelite, such as change in mineralization and deposit of mature bone on the walls of the scaffold, are found. The results are verified with a histological study.

Three-dimensional cultures of osteogenic and chondrogenic cells: a tissue engineering approach to mimic bone and cartilage in vitro.

Capturing the complexity of bone and cartilage into three-dimensional in vitro models remains one of the most important challenges in the field of the tissue engineering. Indeed, the development and the optimization of novel culture systems may be necessary to face the next questions of bone and cartilage physiology. The models should faithfully mimic these tissues, resembling their organization, their mechanical properties and their physiological response to different stimuli. Here we review the recent advances in the field of the three-dimensional cultures of both osteogenic and chondrogenic cells. In particular, we highlight the most important studies that, to our knowledge, have investigated the response of the cells to the three-dimensional environment provided by the diverse types of scaffold.