Injectable phase-separated tetra-armed poly(ethylene glycol) hydrogel scaffold allows sustained release of growth factors to enhance the repair of critical bone defects oleh Shant Nepal, Jinyan Si, Shohei Ishikawa, Masaki Nishikawa, Yasuyuki Sakai, Aya M. Akimoto, Hiroyuki Okada, Shinsuke Ohba, Ung-il Chung, Takamasa Sakai, Hironori Hojo