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.