Prolonged Cell Encapsulation and Gravity-independent Filamented Light Biofabrication of Muscle Constructs.

The prospects of fabricating human tissue grafts or models using cell-laden bioresins in space have garnered significant interest in recent years. While there is tremendous progress in extrusion or light-based bioprinting in microgravity conditions, printing of aligned tissues (e.g., muscle, tendon, cardiac, etc.) remains a challenge. Furthermore, current photoresin formulations do not allow long-term cell encapsulation and are difficult to handle in microgravity conditions. In this study, a new gravity-independent filamented light (G-FLight) biofabrication system, which can create viable muscle constructs within seconds, is demonstrated. New photoresin formulations based on gelatin methacrylate (GelMA) for encapsulation of primary cells (murine myoblasts) and storage in printing cuvettes for at least a week at 4 °C or -80 °C are also demonstrated. The tissues printed in microgravity based on the new formulations exhibit higher cell viability, number of proliferating cells, and higher numbers of myotubes and fusion index compared to control formulations (i.e., GelMA dissolved in phosphate-buffered saline). Importantly, the microgravity-printed tissues also featured similar myotube density and fusion index to those printed using the same resins on-ground. The G-Flight printing concept, together with the new resins enabling refrigeration or cryopreservation with encapsulated cells, offers a promising solution for biofabrication in space.