Human treated dentin matrices combined with Zn-doped, Mg-based bioceramic scaffolds and human dental pulp stem cells towards targeted dentin regeneration

Abstract

Objective: This study aimed to investigate the potential of Mg-based bioceramic scaffolds combined with human treated-dentin matrices (hTDMs) and dentinogenesis-related morphogens to promote odontogenic differentiation and dentin-like tissue formation by Dental Pulp Stem Cells-DPSCs.

Methods: DPSC cultures were established and characterized by flow cytometry. Experimental cavities were prepared inside crowns of extracted teeth and demineralized by EDTA (hTDMs). Zn-doped, Mg-based bioceramic scaffolds, synthesized by the sol-gel technique, were hosted inside the hTDMs. DPSCs were spotted inside the hTDMs/scaffold constructs with/without additional exposure to DMP-1 or BMP-2 (100ng/ml, 24h). Scanning Electron Microscopy-SEM, live/dead fluorescence staining and MTT assay were used to evaluate cell attachment and viability; Real time PCR for expression of osteo/odontogenic markers; Inductively Coupled Plasma-Atomic Emission Spectrometry-ICP/AES for scaffold elemental release analysis; ELISA for hTDM growth factor release analysis; SEM and X-ray Diffraction-XRD for structural/chemical characterization of the regenerated tissues.

Results: Scaffolds constantly released low concentrations of Mg(2+), Ca(2+), Zn(2+) and Si(4+), while hTDMs growth factors, like DMP-1, BMP-2 and TGFβ-1. hTDMs/scaffold constructs supported DPSC viability, inducing their rapid odontogenic shift, indicated by upregulation of DSPP, BMP-2, osteocalcin and osterix expression. Newly-formed Ca-P tissue overspread the scaffolds partially transforming into bioapatite. Exposure to DMP-1 or BMP-2 pronouncedly enhanced odontogenic differentiation phenomena.

Significance: This is the first study to validate that combining the bioactivity and ion releasing properties of bioceramic materials with growth factor release by treated natural dentin further supported by exogenous addition of key dentinogenesis-related morphogens (DMP-1, BMP-2) can be a promising strategy for targeted dentin regeneration.

Keywords: Dental Pulp Stem Cells-DPSCs; Dentin regeneration; Human Treated Dentin Matrices-hTDMs; Mg-based, Zn-doped bioceramic scaffolds.