Characterization of cell constructs generated with inkjet printing technology using in vivo magnetic resonance imaging

We report the use of a high resolution magnetic resonance (MR) imaging technique to monitor the development and maturation of tissue-printed constructs in vivo. Layer-by-layer inkjet printing technology was used to fabricate three different tissue constructs on alginate/collagen gels: bovine aortic endothelial cell-printed (to represent soft tissue), human amniotic fluid-derived stem cell-printed (to represent hard tissue as they underwent osteogenic differentiation in vivo), and cell-free constructs (scaffold only). The constructs were subcutaneously implanted into athymic mice and regularly monitored using a 7 T magnetic resonance imaging (MRI) scanner. The three tissue construct types showed distinct image contrast characteristics due to the different tissue microstructures and biochemical compositions at various time points. In addition, changes in tissue microvasculature were examined with dynamic perfusion MRI. These results indicate that high resolution MRI is a promising method for noninvasive, long-term monitoring of the status of cell-printed construct growth, differentiation, and vascularization.