Bioprinting of Cartilaginous Auricular Constructs Utilizing an Enzymatically Crosslinkable Bioink

Abstract

Bioprinting of functional tissues could overcome tissue shortages and allow a more rapid response for treatments. However, despite recent progress in bioprinting, and its outstanding ability to position cells and biomaterials in a precise D manner, its success has been limited, due to insucient maturation of constructs into functional tissue. Here, a novel calcium-triggered enzymatic crosslinking (CTEC) mechanism for bioinks based on the activation cascade of Factor XIII is presented and utilized for the biofabrication of cartilaginous constructs. Hyaluronan transglutaminase (HA-TG), an enzymatically crosslinkable material, has shown excellent characteristics for chondrogenesis and builds the basis of the CTEC bioink. The bioink supports tissue maturation with neocartilage formation and stiening of constructs up to kPa. Bioprinted constructs remain stable in vivo for  weeks and bioprinted auricular constructs transform into cartilaginous grafts. A major limitation of the current study is the deposition of collagen I, indicating the maturation toward fibrocartilage rather than elastic cartilage. Shifting the maturation process toward elastic cartilage will therefore be essential in order for the developed bioinks to oer a novel tissue engineered treatment for microtia patients. CTEC bioprinting furthermore opens up use of enzymatically crosslinkable biopolymers and their modularity to support a multitude of tissues.