Induction of mineralization by nacreous water-soluble matrix of Pinctada maxima in cultured human dental pulpal cells

• Main Author: Titikan Laothumthut
• Other Authors: Panjit Chunhabundit
• Language: English
• Published: Mahidol University. Mahidol University Library and Knowledge Center 2023
• Subjects: Connective tissues; Pinctada maxima; Mineralization
• Online Access: https://repository.li.mahidol.ac.th/handle/123456789/89555
• Institution: Mahidol University

For dental treatment, dentin regeneration is required after a tooth injury with dental pulp exposure. During the reparative process of pulp injury in post natal teeth, the pulpal progenitor cells can differentiate into odontoblast-like cells which are mineralized tissue-forming cells. The finding of a potential substance that can induce mineralization is challenging and useful for clinical application. Though nacre, mother of pearl, has been shown to be a good osteoinductive biomaterial for bone cells, the information of its effect on other cell types is very limited. Therefore, it is of interest to study the effects of the water-soluble matrix (WSM) extracted from the nacreous layer of the bivalve Pinctada maxima on human dental pulpal cells in vitro. WSM was obtained by extraction of fresh nacreous powder in double distilled water. Characterization of proteins in WSM were performed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS- PAGE), reversed phase high performance liquid chromatography (RP- HPLC) and matrix assisted laser desorption ionization time-of-flight mass spectrometry ( MALDI- TOF MS). The biological activity of the cultured human dental pulp cell in response to WSM compared to Dulbecco''s Modified Eagle Medium (DMEM) as a normal control and the DMEM supplemented with B glycerophosphate (BGP) as a positive control were investigated. The cell survival rate was analyzed by MTT assay. The induction of a mineralized matrix was observed after staining with Alizarin Red S and Von Kossa. Proteomic profiles among inducers and non inducers with time-dependency were compared by using SDS-PAGE combined with liquid chromatography- tandem mass spectrometry (GeLC-MS/MS). WSM consisted of very hydrophobic proteins with diverse sizes. The highest cell survival rate was in WSM whereas the lowest rate was in BGP. Strong positive staining for mineralized nodules was found in the matrix of cells exposed to BGP, WSM, and DMEM, respectively. Many expressed proteins related induction of calcium deposition, inhibition of calcium deposition, and inhibition of cell growth were identified. These results indicate that WSM of Pinctada maxima has the ability to induce mineralized nodule formation in vitro using human dental pulpal cells. This finding initiated the study to evaluate the suitability of nacre as biomaterial for Dentistry.