On the osteogenic differentiation of dental pulp stem cells by a fabricated porous nano-hydroxyapatite scaffold loaded with sodium fluoride

Abstract

In this study, after the extraction of nano-hydroxyapatite (n-HA) powder from carp bone waste, porous n-HA scaffolds were fabricated by a sintering process and subsequently loaded with different amounts of sodium fluoride (NaF) through immersion in NaF suspensions for 10, 7.5, and 5 minutes. The NaF-loaded scaffolds were then examined for their structural properties, loading and release profile, cytotoxicity and osteogenic effect on dental pulp stem cells at the level of RNA and protein expression. Scanning electron microscopy (SEM) images showed that the scaffolds were porous and had rough surfaces, and NaF could be successfully applied. The NaF loaded on the n-HA scaffolds was 6.43, 4.50, and 1.47 mg, respectively at 10-, 7.5-, and 5-minutes immersion in the NaF suspensions. The NaF release rate was fast during the first hour in all groups (38.6%, 29.7%, and 25.7% for 10, 7.5, and 10 min, respectively), and decreased dramatically thereafter, especially after 6h, indicating a slow detachment of NaF. The results of the cytotoxicity assay rejected any toxicity of the fabricated scaffolds on DPSCs, and the cells could adhere to the scaffold surfaces with enlarged morphology. The results obtained showed no effect on osteogenic differentiation at the protein level. Nevertheless, this effect was observed at the gene level.