Acoustofluidic patterning for improved microtissue histology

Microtissues (such as organoids or spheroids) are useful to model healthy or diseased human tissues and organs, with application in drug testing, tissue engineering, and personalized medicine. To characterize their morphology and phenotype, microtissues are often monitored using histology and high-resolution imaging. While this technique is well-established and standard for macroscopic tissue sections, it remains challenging to execute and has low throughput in the context of these sub-millimeter structures, mainly due to the fact that their size makes them difficult to locate within the embedding medium. To enhance the efficiency of microtissue histology, we developed an acoustofluidic device that arranges microtissues in a coplanar arrangement within HistoGel, a widely used embedding medium. Pre-patterning microtissues within HistoGel streamlines downstream processing by positioning the centers of mass of the microtissues at a pre-defined plan in the sample, simplifying sectioning, labeling, and imaging. We validated the method using differently sized HepG2 microtissues and tumor microtissues from osteosarcoma cells (Saos-2, MG-63, HOS), demonstrating that this method can be applied to different microtissue shapes, sizes, and types, without modifying established post-processing techniques. Our approach substantially enhances the microtissue histology workflow and broadens possibilities for microtissue analysis.