In Vitro and In Vivo Evaluation of Zinc-Modified Ca–Si-Based Ceramic Coating for Bone Implants

The host response to calcium silicate ceramic coatings is not always favorable because of their high dissolution rates, leading to high pH within the surrounding physiological environment. Recently, a zinc-incorporated calcium silicate-based ceramic Ca(2)ZnSi(2)O(7) coating, developed on a Ti-6Al-4V substrate using plasma-spray technology, was found to exhibit improved chemical stability and biocompatibility. This study aimed to investigate and compare the in vitro response of osteoblastic MC3T3-E1 cells cultured on Ca(2)ZnSi(2)O(7) coating, CaSiO(3) coating, and uncoated Ti-6Al-4V titanium control at cellular and molecular level. Our results showed Ca(2)ZnSi(2)O(7) coating enhanced MC3T3-E1 cell attachment, proliferation, and differentiation compared to CaSiO(3) coating and control. In addition, Ca(2)ZnSi(2)O(7) coating increased mRNA levels of osteoblast-related genes (alkaline phosphatase, procollagen α1(I), osteocalcin), insulin-like growth factor-I (IGF-I), and transforming growth factor-β1 (TGF-β1). The in vivo osteoconductive properties of Ca(2)ZnSi(2)O(7) coating, compared to CaSiO(3) coating and control, was investigated using a rabbit femur defect model. Histological and histomorphometrical analysis demonstrated new bone formation in direct contact with the Ca(2)ZnSi(2)O(7) coating surface in absence of fibrous tissue and higher bone-implant contact rate (BIC) in the Ca(2)ZnSi(2)O(7) coating group, indicating better biocompatibility and faster osseointegration than CaSiO(3) coated and control implants. These results indicate Ca(2)ZnSi(2)O(7) coated implants have applications in bone tissue regeneration, since they are biocompatible and able to osseointegrate with host bone.