3D printing sacrificial templates for manufacturing hydrogel constructs with channel networks

In hydrogel-based tissue engineering, channel network is an efficient structure for transporting nutrients/oxygen to support cell survival and construct living tissues in vitro. 3D printing can create complex hydrogel-based tissue constructs, however, due to the weak mechanical properties of hydrogel bioinks, cell-laden hydrogel constructs with effective channel networks are difficult to be directly printed. Here, an easy sacrificial 3D printing method based on commercial desktop 3D printer and water-soluble polyvinyl alcohol (PVA) to construct effective hydrogel channel networks is introduced. Specifically, i) commercial PVA consumables are printed to be sacrificial templates; ii) gelatin methacryloyl (GelMA) solution is cast to encapsulate the sacrificial template; iii) the sacrificial template is dissolved to form channel networks. PVA is a water-soluble sacrificial material with sufficient dissolution time and high mechanical strength, which can avoid the disadvantages of classic sacrificial materials (sugar and Pluronic F127). High roundness of printed PVA filaments results in high roundness of the channel networks. The interconnected channel networks accelerate the supply of oxygen/nutrients and promote cell growth. And with a period of culture, the higher the channel networks density, the better the cell growth. Additionally, PVA sacrificial templates have high stability and long-term preservation, facilitating transportation, circulation and use, which is conducive to the manufacturing and promotion of hydrogel-based constructs with channel networks. Taken together, our easy strategy of manufacturing hydrogel constructs with channel networks has broad application prospects, such as 3D cell culture, construction of functional tissue in vitro or tissue repair in vivo etc.