Ce-Doped Silica-Based Mesoporous Nanoparticles Promote Periodontal Ligament Cells’ Osteogenic Differentiation

Objectives: This study aimed to analyze the potential of silica-based Ce-doped mesoporous nanoparticles (SiCaCe-MSNs) to promote the osteogenic differentiation of human periodontal ligament cells (hPDLCs), targeting periodontal regeneration.
Methods: The synthesis of SiCaCe-MSNs was performed using the Sol-Gel technique, using tetraethyl orthosilicate (TEOS) as a silicon source and Cetyltrimethylammonium bromide (CTAB) as a mesoporous agent in an alkaline environment. hPDLCs were established from human biopsies of periodontal ligament tissues from a healthy donor using the enzymatic dissociation method, and characterized with flow cytometry for the following markers, CD34, CD45, CD146 and STRO-1. Cell viability of hPDLCs cultured with SiCaCe-MSNs was evaluated with the MTT assay at different concentrations (125, 250 and 500 μg/ml). hPDLCs and SiCaCe-MSNs were further cultured in standard culture conditions with or without osteogenic differentiation medium (OM) for up to 21 days and assessed for osteogenic differentiation by means of quantitative real-time reverse-transcription polymerase chain reaction (qPCR), Alkaline phosphatase (ALP) activity, and Alizarin red staining (ARS).
Results: Most of the isolated hPDLCs (83.7%) were double negative for CD34 and CD45. The double negative subpopulation of cells expressed STRO-1 at 97% and CD146 at 98,2%. SiCaCe-MSNs seem to be biocompatible after 3 and 5 days in culture, presenting better cell viability at lower concentrations (125 and 250 μg/ml). qPCR analysis demonstrated a time-dependent increase in RUNX2 and BMP2 expression, while higher concentration of SiCaCe-MSNs enhanced the expression of BMP2 in hPDLCs. A time-dependent decrease in Osteocalcin expression was observed, as well as a slight increase in ALP expression and presence in cell lysates with time. ARS showed high calcium deposition, which increases with higher SiCaCe-MSNs concentration and the presence of OM.
Conclusions: The novel Ce-doped silica-based MSNs show promising properties in terms of promoting osteogenic differentiation and calcium deposition and should be considered favorable candidates for future applications in periodontal regeneration.