Biofabrication of a prevascularized functional trachea substitute

• Applicants: Professor Dr.-Ing. Horst Fischer; Professor Dr. Stefan Jockenhövel
• Subject Area: Biomaterials ; Medical Physics, Biomedical Technology
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 256933203

3D printing technologies enable a rapid additive manufacturing that ensures high spatial resolution and complexity of generated parts. Applied on the field of tissue engineering, 3D printing technologies show high potential for the generation of artificial organs which comprise cells and hydrogels and mimic the complexity of natural tissue in structure and composition. A trachea for example consists of several different cell types and different functional tissue types such as muscle, connective tissue, and cartilage.The research project proposed here as a continuation of the project TracheaPrint is based on the hypothesis that the tubular structure of a trachea can be resembled in a 3D drop-on-demand printing procedure. The printing includes two different types of hydrogels: a cell-laden hydrogel blend of agarose and type I collagen and further a cell-free hydrogel that resembles function and shape of native tracheal cartilage. The agarose-collagen blend already proved its printability and high angiogenic potential in the first phase of the project using a co-culture of human endothelial cells and fibroblasts. Particularly, we focus in the second phase of the project on the advancement of a cartilage substitute based on polyethylene glycol (PEG) which forms a hydrogel with tunable mechanical properties. We intend to further shorten the gelation time of a PEG-based hydrogel using a click-chemistry approach avoiding the cytotoxic effect of photo-crosslinkers. The research project includes studies on the cell induced remodeling and tissue maturation in vitro and its influence on angiogenesis and the expression of proangiogenic markers. Furthermore, the integration of pre-vascularized hydrogel samples in a CAM-model will be investigated. Moreover, a novel membrane printing technology best suitable for the specific application will be elaborated and combined with the existing micro-valve based printer. Finally, a cell-laden trachea substitute is printed and cultured in two-step incubation in a pulsatile bioreactor. Additionally, the construct will be epithelialized at the inner surface using a spraying technique. Furthermore, we investigate the general feasibility of employing 3D-bioreactors for tissue engineering of layer-by-layer bioprinted tubular structures. The scientific findings from this project could subsequently be used to develop individualized trachea substitutes.

• DFG Programme: Research Grants