New tool for fabrication of microtissues with anisotropic fibrous structure based on touch-spinning and 3D printing.

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Many human tissues such as bones, muscles, nerves are anisotropic. This anisotropy is provided by extracellular matrix (ECM) structure and orientation of collagen fibrils and it influences the mechanical properties of the tissues as well as organization of cells. 3D printing of anisotropic soft tissues with high resolution is, however, highly challenging task. The main challenge is to combine soft isotropic hydrogel-based materials, cells as well as relatively rigid micro- and nanofibers to fabricate anisotropic constructs similar to native oriented tissues. This interdisciplinary project aims to address this challenge and develop advanced technology for fabrication of anisotropic tissues by combining 3D bioprinting and modern fiber spinning technology.Our approach is based on integration of touch-spinning, which allows precise deposition of fibers, into 3D extrusion-based printing of cell laden hydrogel bioinks. Fabricated fibers mats will be used as substrate for printing of hydrogel-cell bioinks. Multilayer anisotropic constructs will be fabricated by repeating touch-spinning and cell printing. Since fibrous mats provide mechanical stability, diluted non-viscous cell encapsulated hydrogel bioinks can be printed through narrow nozzle without applying high shear force resulting in higher resolution. Nanofiber mats will also act as guidance for cells to form an oriented structure within the hydrogel. Another advantage of touch-spinning process is that it does not require high voltage and it allows spinning of various polymeric fibers. Moreover, it can be used to deposit the fibers on the cell-laden layer independently of the melting point of the polymer. In this project, we will develop the technology and test it for fabrication of skeletal muscle microtissues. The main output of the project will be development of radically new approach for high resolution fabrication of anisotropic tissues. This approach is expected to be a powerful tool for fabrication of different types of anisotropic oriented tissues.