A novel CKIP-1 SiRNA slow-release coating on porous titanium implants for enhanced osseointegration

Osseointegration between implants and bone tissue lays the foundation for the long-term stability of implants. The incorporation of a porous structure and local slow release of siRNA to silence casein kinase-2 interacting protein-1 (CKIP-1), a downregulator of bone formation, is expected to promote osseointegration. Here, porous implants with a porous outer layer and dense inner core were prepared by metal coinjection molding (MIM). Mg-doped calcium phosphate nanoparticles (CaPNPs)-grafted arginine-glycine-aspartate cell adhesion sequence (RGD) and transcribed activator (TAT) (MCPRT)/CKIP-1 siRNA complex and polylysine (PLL) were coated onto the surface of the porous implants by layer-by-layer (LBL) self-deposition. The in vitro results showed that the MCPRT-siRNA coating promoted MG63 cell adhesion and proliferation, enhanced the protein expressions (ALP and OC) and bone formation-related gene expression (OPN, OC and COL-1α) in vitro. The in vivo results demonstrated that the porous structure enhanced bone ingrowth and that the local slow release of MCPRT-siRNA accelerated new bone formation at the early stage. The porous structure coupled with local CKIP-1 siRNA delivery constitutes a promising approach to achieve faster and stronger osseointegration for dental implants.