Laminin-511-functionalized fibrin gel enables in-gel proliferation of human induced pluripotent stem cells

Fibrin is a biocompatible hydrogel that is widely used as a surgical sealant and as a scaffold for in vitro cell culture. Here, we engineered a heterotrimeric chimera between fibrinogen and laminin-511 by connecting the N-terminal self-polymerization domain of fibrinogen with the C-terminal integrin-binding domain of laminin-511 via their coiled-coil regions. The resulting chimeric protein, designated Chimera-511, binds to fibrinogen in a thrombin-dependent manner and exerts integrin-binding activity in a fibrin(ogen)-bound form. Chimera-511 co-polymerizes with fibrinogen to form a fibrin gel endowed with the potent integrin-binding activity of laminin-511, thereby enabling robust three-dimensional proliferation of human induced pluripotent stem cells while maintaining their pluripotency marker expression and trilineage differentiation potential. This functionalized, biodegradable fibrin gel provides a defined and clinically compatible three-dimensional scaffold for stem cell culture, with potential applications in both basic research and regenerative medicine.