Visualization of the cellulose biosynthesis and cell integration into cellulose scaffolds.

By controlling the microarchitecture of bioengineered scaffolds for artificial tissues, their material and cell-interaction properties can be designed to mimic native correspondents. Current understanding of this relationship is sparse and based on microscopy requiring harsh sample preparation and labeling, leaving it open to which extent the natural morphology is studied. This work introduces multimodal nonlinear microscopy for label-free imaging of tissue scaffolds, exemplified by bacterial cellulose. Unique three-dimensional images visualizing the formation of nanofiber networks throughout the biosynthesis, revealing that supra-structures (layered structures, cavities) are formed. Cell integration in compact scaffolds was visualized and compared with porous scaffolds. While the former showed distinct boundaries to the native tissue, gradual cell integration was observed for the porous material. Thus, the degree of cell integration can be controlled through scaffold supra-structures. This illustrates the potential of nonlinear microscopy for noninvasive imaging of the intriguing interaction mechanisms between scaffolds and cells.