Zirconium phosphate nanoplatelets promote osteogenic differentiation via MAPK/AKT pathway activation in MC3T3-E1 cells

Abstract Zirconium-based materials have attracted considerable attention in the field of bone tissue regeneration owing to their exceptional mechanical properties and bioactivity. Zirconium phosphate (ZrP), particularly when applied as coatings or self-assembled nanonetworks on implants, enhance osseointegration and bone formation. However, the exact mechanisms by which ZrP nanoplatelets (NPs) promote osteogenesis remain unclear. This study aimed to investigate how ZrP NPs drive osteogenic differentiation in MC3T3-E1 pre-osteoblasts by analyzing both osteogenic marker expression and intracellular signaling pathways. The synthesized ZrP NPs (< 30 nm in size) demonstrated an excellent biocompatibility and induced dose-dependent increases in calcium deposition and in the alkaline phosphatase (ALP) activity. Gene expression analysis revealed the time-dependent upregulation of early-stage markers, including runt-related transcription factor 2 (RUNX2) and ALP, as well as late-stage markers such as osteocalcin (OCN) and osteopontin (OPN). Western blot analysis further showed that the ZrP NPs activated critical signaling pathways, including the p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinases 1/2 (ERK1/2), and protein kinase B (AKT) pathways. This activation led to the elevated expression of bone morphogenic protein-2 (BMP-2), RUNX2, and OPN. These findings demonstrate that ZrP NPs promote osteogenic differentiation in MC3T3-E1 cells primarily through the activation of the MAPK and AKT signaling pathways. These ZrP NPs can therefore be considered promising candidates for use in bone tissue engineering, particularly in the context of targeted bone defect repair and regeneration.