Microgels based on Infernan, a glycosaminoglycan-mimetic bacterial exopolysaccharide, as BMP-2 delivery systems

Bone Morphogenetic Protein (BMP-2) is an osteoinductive growth factor clinically used for bone regeneration. Tuneable sustained strategies for BMP-2 delivery are intensely developed to avoid severe complications related to supraphysiological doses applied. To address this issue, we investigated the ability of the bacterial exopolysaccharide (EPS) called Infernan produced by the deep-sea hydrothermal vent bacterium Alteromonas infernus, exhibiting both glycosaminoglycan-mimetic and physical gelling properties, to efficiently bind and release the bioactive BMP-2. Two delivery systems were designed based on BMP-2 retention in either single or complex EPS-based microgels, both manufactured using a microfluidic approach. BMP-2 release kinetics were highly influenced by the ionic strength, affecting both microgel stability and growth factor/EPS binding, appearing essential for BMP-2 bioactivity. The osteogenic activity of human bone-marrow derived mesenchymal stem cells studied in vitro emphasized that Infernan microgels constitute a promising platform for BMP-2 delivery for further in vivo bone repair.