Tag-Free Site-Specific BMP-2 Immobilization with Long-Acting Bioactivities via a Simple Sugar-Lectin Interaction

Covalent binding modes between BMP-2-derived peptides and graphene in 3D scaffolds determine their osteoinductivity and capacity for calvarial defect repair in vivo

Covalent introduction of bioactive molecules is one of main strategies to significantly enhance the biological activities of bone repair materials. In this study, three most-commonly used chemical groups were respectively introduced on graphene (GP), followed by covalent binding with bone morphogenetic protein-2 (BMP-2) -derived peptides, ensuring that the same molar mass of peptides was bound to different functionalized GP (f-GP). Then the same amount of composites composed of different f-GP and peptides were respectively compounded with poly (lactic-co-glycolic acid) to fabricate 3D scaffolds. In vivo study demonstrated that the scaffolds containing ammonized GP covalently bound with the peptides through amide binding could reach best efficiency of promoting ectopic bone regeneration and repairing calvarial defect probably because the most positive charges on the peptide chain and surface of the ammonized GP could absorb more specific proteins in vivo and have better interactions with them, thereby differentiating most inducible cells into osteogenic cells. Our results indicate that the performances of scaffolds containing covalently bound bioactive molecules can be controlled by the covalent binding mode, and that our prepared scaffold containing ammonized GP covalently bound with the BMP-2-derived peptides through amide binding possess inspiring potential applicable prospects for bone tissue regeneration and engineering.

Immobilization of Growth Factors for Cell Therapy Manufacturing

Cell therapy products exhibit great therapeutic potential but come with a deterring price tag partly caused by their costly manufacturing processes. The development of strategies that lead to cost-effective cell production is key to expand the reach of cell therapies. Growth factors are critical culture media components required for the maintenance and differentiation of cells in culture and are widely employed in cell therapy manufacturing. However, they are expensive, and their common use in soluble form is often associated with decreased stability and bioactivity. Immobilization has emerged as a possible strategy to optimize growth factor use in cell culture. To date, several immobilization techniques have been reported for attaching growth factors onto a variety of biomaterials, but these have been focused on tissue engineering. This review briefly summarizes the current landscape of cell therapy manufacturing, before describing the types of chemistry that can be used to immobilize growth factors for cell culture. Emphasis is placed to identify strategies that could reduce growth factor usage and enhance bioactivity. Finally, we describe a case study for stem cell factor.