Three-dimensional (3D) bioprinting of coral-polyp bio-skin using ultrashort and biofunctionalized peptide bioinks for transplantation on coral skeletons

There is growing interest in applying 3D printing technologies to environmental restoration, particularly for fabricating bio-inspired artificial reefs and printing coral skeletons to attract fish and support coral growth and survival. More recently, tissue engineering and 3D bioprinting strategies have been employed to develop biomimetic biomaterials that more closely replicate the natural coral microenvironment, including the incorporation of coral symbionts, to aid restoration efforts. In this study, we investigate the use of diverse ultrashort peptide- and biofunctionalized peptide-based bioinks to support bail-out polyp re-settlement and subsequent micropropagation. Among the 13 bioinks examined, eight demonstrated polyp biocompatibility and stability under seawater conditions. We focused on two Scleractinia species, Stylophora pistillata and Pocillopora verrucosa, and optimized a culture strategy for microencapsulated bail-out polyps following re-settlement, comparing a single-entity versus clustered-entity approach. These advancements lay the groundwork for polyp transplantation using biomimetic biomaterials. The top-performing bioinks were selected based on bioink underwater stability, polyp biocompatibility, and suitability for 3D bioprinting of polyps onto coral skeletons. This led to the development of a coral-inspired, polyp-containing bio-skin graft designed to promote coral tissue regeneration. Here, we report the first results demonstrating the use of bioinks for coral polyp microencapsulation and 3D bioprinting with ultrashort peptide-based bioinks to support coral regeneration and transplantation on coral skeletons.