Expression and purification recombinant human dentin sialoprotein in Escherichia coli and its effects on human dental pulp cells

Dentin sialoprotein (DSP) is cleaved from dentin sialophosphoprotein (DSPP) and most abundant dentinal non-collagenous proteins in dentin. DSP is believed to participate in differentiation and mineralization of cells. In this study, we first constructed recombinant human DSP (rhDSP) in Escherichia coli (E. coli) and investigated its odontoblastic differentiation effects on human dental pulp cells (hDPCs). Cell adhesion activity was measured by crystal violet assay and cell proliferation activity was measured by MTT assay. To assess mineralization activity of rhDSP, Alizarin Red S staining was performed. In addition, the mRNA levels of collagen type ? (Col ?), alkaline phosphatase (ALP), and osteocalcin (OCN) were measured due to their use as mineralization markers for odontoblast-/osteoblast-like differentiation of hDPCs. The obtained rhDSP in E. coli was approximately identified by SDS-PAGE and Western blot. Initially, rhDSP significantly enhanced hDPCs adhesion activity and proliferation (p<0.05). In Alizarin Red S staining, stained hDPCs increased in a time-dependent manner. This odontoblastic differentiation activity was also verified through mRNA levels of odontoblast-related markers. Here, we first demonstrated that rhDSP may be an important regulatory ECM in determining the hDPCs fate including cell adhesion, proliferation, and odontoblastic differentiation activity. These findings indicate that rhDSP can induce growth and differentiation on hDPCs, leading to improve tooth repair and regeneration.