Bone regeneration using MMP sensitive-hyaluronic acid based hydrogels

Hyaluronic acid (170 kDa)-based hydrogel was synthesized using acrylated hyaluronic acid. Matrix metalloproteinase (MMP) sensitive hyaluronic acid-based hydrogels were prepared by conjugation with two different peptides: cell adhesion peptides containing integrin binding domains (Arg-Gly-Asp: RGD) and a cross-linker with MMP degradable peptides to mimic the remodeling characteristics of natural extracellular matrices (ECMs) by cell-derived MMPs. Mechanical properties of these hydrogels were evaluated with different weight percent (2.5%wt and 3.5%wt) by measuring elastic modulus, viscous modulus and swelling ratio. Human mesenchymal stem cells (hMSCs) were cultured in MMP-sensitive or insensitive hyaluronic acid-based hydrogels and/or immobilized cell adhesive RGD peptides in vitro. Actin staining and image analysis proved that cells cultured in the MMP-sensitive hydrogel with RGD peptides showed dramatic cell spreading and sprouting. For in vivo calvarial defect regeneration, 3 different samples (MMP insensitive hydrogel, MMP sensitive hydrogel, MMP sensitive hydrogel with BMP-2 and hMSC) were prepared. After a 4-week implantation, the Masson-Trichrome (MT) staining and micro CT scan results demonstrated that the MMP sensitive hydrogels with BMP-2 and hMSCs had the highest mature bone formation. This MMP sensitive-hyaluronic acid based hydrogel could be useful in tissue engineering by improving tissue defect regeneration and tissue remodeling.