Bioprinting of Cell-Laden Microfiber: Can It Become a Standard Product?

Hydrogel microfibers have many fascinating applications as microcarriers for drugs, factors, and cells, such as 3D cell culture, building micro-organoids, and transplantation therapy due to their simple structures. It is unknown whether cell-laden fiber can become a standard-use product like woundplast. Here, from the technical and practical view, the elements required for user-oriented microfibers are first discussed: i) the materials used should promote cell functionalization and be easily processed; ii) follow a manufacturing method for mass fabrication; iii) have the ability to be stored long-term and be available for immediate use. Here, it is demonstrated that bioactive microfibers can be simply fabricated with coaxial bioprinting using gelatin methacrylate due to its tunable biological and mechanical properties. Additionally, programmed microfibers and 3D constructs with controllable composition can also be fabricated. These microfibers can be used to directly build organoids and complex co-culture tissue models. In the present study, vascular organoid, angiogenic sprouts, and tumor angiogenesis are demonstrated. It is also demonstrated, for the first time, that the cell-laden microfibers can be stored long-term via cryopreservation. These results show that cell-laden structures can be developed as a novel type of organoid product, which will open more avenues for tissue engineering and clinical organ repair.