X-ray phase contrast imaging of calcified tissue and biomaterial structure in bioreactor engineered tissues (Biotechnology and Bioengineering)

Tissues engineered in bioreactor systems have been used clinically to replace damaged tissues and organs. In addition, these systems are under continued development for many tissue engineering applications. The ability to quantitatively assess material structure and tissue formation is critical for evaluating bioreactor efficacy and for pre-implantation assessment of tissue quality. Techniques that allow for the non-destructive and longitudinal monitoring of large engineered tissues within the bioreactor systems will be essential for the translation of these strategies to viable clinical therapies. X-ray Phase Contrast (XPC) imaging techniques have shown tremendous promise for a number of biomedical applications owing to their ability to provide image contrast based on multiple X-ray properties, including absorption, refraction and scatter. In this research, mesenchymal stem cell-seeded alginate hydrogels were prepared and cultured under osteogenic conditions in a perfusion bioreactor. The constructs were imaged at various time points using XPC microcomputed tomography (?CT). Imaging was performed with systems using both synchrotron and tube based X-ray sources. XPC ?CT allowed for simultaneous three-dimensional (3D) quantification of hydrogel size and mineralization, as well as spatial information on hydrogel structure and mineralization. Samples were processed for histological evaluation and XPC showed similar features to histology and quantitative analysis consistent with the histomorphometry. These results provide evidence of the significant potential of techniques based on XPC for non-invasive 3D imaging engineered tissues grown in bioreactors. Biotechnol. Bioeng. © 2014 Wiley Periodicals, Inc.