Self-Growing Scaffold for Spatial and Border Expansive Regeneration

Tissue regeneration and repair techniques approaching personalized treatment are devoted to fabricating high-precision scaffolds that accurately match the size of the defect. However, scaffolds are difficult to implant in situ for obsolete defects with loss of original space, and the size is limited by confined boundary tissue. In nature, the development of fetuses, organs, and even plants all experience a matched growth in volume and border. Inspired by that, this study proposes a space-expanding regeneration model with a self-growing (SG) scaffold, which is then used in refractory alveolar ridge vertical bone augmentation. The SG scaffold contains a multistage hydrophilic polymer network. The initial size can be eliminated for minimally invasive implantation, and gradually increased by orderly absorption of tissue fluid, achieving controlled growth in vivo. The shearing force of the SG scaffold suppresses tissue hematoma and stimulates extracellular matrix remodeling. In addition, macrophages polarize toward M2 and secrete transforming growth factor-β1. Meanwhile, bone regeneration is induced within the expanded space, achieving a ≈5-fold vertical increase of the rat skull, and supporting a 6-mm-long titanium implant. The SG scaffold provides a spatial and border extension model for obsolete injuries.