Bone regeneration using injectable poly (γ-benzyl-L-glutamate) microspheres loaded with adipose-derived stem cells in a mouse femoral non-union model

Microspheres have gained immense popularity in bone tissue engineering because of their unique properties as injectable scaffolds for bone tissue regeneration. Herein, we evaluated the feasibility of using poly (γ-benzyl-L-glutamate) (PBLG) microspheres for bone engineering by examining the attachment, proliferation, and osteogenic differentiation of adipose-derived stem cells (ASCs) in vitro and the use of PBLG microspheres in healing non-union in vivo. Scanning electron microscopy and fluorescent 3, 30-dioctadecyloxacarbocyanine perchlorate-labeling were performed to study the attachment and growth of ASCs to the PBLG microspheres, and a DNA assay was performed to quantify cell proliferation with time. Osteogenic differentiation of ASCs cultured on the PBLG microspheres was assessed by determining alkaline phosphatase expression and extracellular calcium deposition, which was further confirmed by real-time polymerase chain reaction for osteogenesis-related genes. Femoral non-union were created in mouse models and filled with ASCs/PBLG microspheres in vivo. The results showed that ASCs attached, spread, and showed good osteogenic differentiation on the PBLG microspheres in vitro. Moreover, the ASCs/PBLG microspheres could repair the mouse femoral non-union in vivo. Thus, PBLG microspheres have good biocompatibility and cytocompatibility and are potentially useful as an injectable scaffolds for bone tissue engineering.