ENABLING TECHNOLOGIES FOR ORGAN PRINTING: TOWARD ORGAN BIOFABRICATION LINE

Objectives: Organ printing is an emerging solid scaffold-free biofabrication technology or layer-by-layer additive bioprinting of functional 3D human tissue and organ constructs from self-assembling tissue spheroids. Bioprinter is a key tool for organ printing. It is becoming increasingly obvious that in order to bioprint human and organ constructs it is necessary to develop series of integrated automated robotic tools or an organ biofabrication line. Methods: The scalable technique for tissue spheroid biofabrication employs micromolded recessed template in non-adhesive agarose hydrogel, wherein the cell suspension automatically loaded into the template self-assembles into tissue spheroids due to gravitational forces. Robotic bioprinter for the precise dispensation of tissue spheroids include three essential elements: X-Y-Z axis robotic precision position system, three automated biomaterial dispensers (two aseptic valve sprayers and one automated tissue spheroids dispenser) and computer-based software enabled operational control. The first two dispensers spray sequentially fibrinogen and thrombin and enable instant biofabrication of thin layers of fibrin hydrogel, whereas another robotic dispenser punches tissue spheroids into sequentially sprayed layer of fibrin hydrogel. Results: It has been demonstrated that the use of micromolded recession in non-adhesive hydrogel, combined with automated cell seeding, is a reliable method for robotic fabrication of uniform size tissue spheroids at large scale. It has been also shown that the combination of hydrogel sprayers and tissue spheroids puncher enables to Implement additive biofabrication of 3D tissue construct. The novel irrigation dripping tripled perfuslon bioreactor with removable porous removable mlnitubes has been designed. Mathematical modeling and computer simulation demonstrated that proposed irrigation dripping circuit system will allow maintain viability of printed tissue constructs until the "build in" intra-organ branched vascular system will mature enough for initiation intravascular perfusion. Conclusions: Thus, presented data strongly indicate that design and development of a fully integrated organ biofabrication line is a challenging but achievable goal.