Scaffold for the Minimally Invasive Repair of Soft Tissue Inspired by Soggy Shrunk Puffed Food

Abstract Minimally invasive injection of tissue engineering scaffolds has been gaining attention due to featuring several advantages of requiring a small incision, entailing a simple operation procedure, and involving a quick recovery. However, it remains challenge because larger scaffolds must pass through an extremely thin injection needle. Herein, inspired by the phenomenon that puffed food becomes soggy and shrinks when exposed to air, a novel scaffold treatment method is proposed; namely, lyophilization & dampening (L&D) treatment, which reduces the printed hydrogel scaffold volume by around 90%. Lyophilization treatment can remove water inside the scaffolds; Dampening treatment, that is, placing the freeze-dried scaffolds into a vapor atmosphere, can make scaffolds shrunk to a suitable size for minimally invasive injection. Moreover, unlike existing air-dried technique that feature high mechanical modulus, the soggy scaffolds developed herein feature low mechanical modulus (2.88 kPa), thus minimizing the foreign body sensation after implantation. Furthermore, the injected soggy scaffolds can rapidly swell into their original size and act as tissue regeneration media. Accordingly, a specialized tool namely “BioGun” is designed for the minimally invasive injection of soggy scaffolds ("BioBullet”). This novel strategy would potentially overcome existing technical bottlenecks limiting the clinical soft tissue defect repair.