Lensfree diffractive tomography for the imaging of 3D cell cultures

International audience; New microscopes are needed to help realize the full potential of 3D organoid culture studies bygathering large quantitative and systematic data over extended period of time while preserving the integrityof the living sample. On another hand, lensfree video microscopy is addressing these needs in the context of2D cell culture, providing label-free and non-phototoxic acquisition of large datasets. As scientistsroutinely adopt 3D culture techniques, the new challenging task is to extend lensfree microscopy techniquesto 3D structures.In order to image such large volume while preserving the ability to catch every single cell, we proposenew imaging platforms based on lensfree microscopy. We have built lensfree diffractive tomography setupsperforming multi-angle acquisitions of 3D organoid culture embedded in Matrigel® and developed adedicated 3D holographic reconstruction algorithm based on the Fourier diffraction theorem.With a first prototype we have been able to reconstruct a 3D volume as large as 21.5 mm^3 of a 3Dorganoid culture of prostatic RWPE1 cells in Matrigel® showing the ability of these cells to assemble in 3Dintricate cellular network at the mesoscopic scale. Comparisons with 2D images showed that it ispossible to detect single cells isolated from the main cellular structure.From results of the first prototype and numerical simulations, a second prototype wasdesigned to improve the reconstructions quality, especially on the vertical axis. First results on dust andbubbles lying at the bottom of a Petri® dish are promising.The adaptation of lensfree microscopy techniques to 3D organoid cultures imaging and thepresentation of the associated algorithms are the scopes of the present communication.