Surface characterizations and cell growth of rough zirconia surfaces immobilized with different BMP-2 concentrations using natural crosslinker genipin

Zirconia (ZrO₂) is widely used in the dental implant industry, due to its good mechanical properties and biocompatibility. However, the bioinert nature of ZrO₂ may hinder osseointegration. This study investigated the responses of human bone marrow mesenchymal stem cells (hMSCs) to sandblasted ZrO₂ surfaces immobilized with bone morphogenetic protein-2 (BMP-2) using the natural crosslinker genipin. The immobilization of BMP on sandblasted ZrO₂ surfaces increased the surface roughness but did not alter the wettability. The focal adhesion activation and later-stage mineralization of hMSCs were higher on BMP-2-modified ZrO₂ surfaces than on untreated surfaces. The BMP-2-modified ZrO₂ surfaces with low (100 ng/mL) and high (500 ng/mL) concentrations showed no significant difference in later-stage osteogenic response. However, ZrO₂ surfaces with low BMP-2 concentration earlier stimulated the p38 (mitogen-activated protein kinase pathway) protein expression, osteogenic early marker osteopontin expression, and later-stage mineralization. This simple but effective process to immobilize BMP-2 on rough ZrO₂ surfaces can benefit future dental implant applications.