Effects of Sodium Tri- and Hexametaphosphate on Proliferation, Differentiation, and Angiogenic Potential of Human Dental Pulp Cells

• Inorganic polyphosphates (poly[P]) are linear polymers of orthophosphate residues linked by energy-rich phosphoanhydride poly(P) compounds promote growth, differentiation, and angiogenesis of pulp cells.
• Inhibition of pyrophosphate reduced poly(P)-induced odontogenic and angiogenic potentials.
• Therapeutic potential of poly(P) to promote pulp regeneration may be possible.

IntroductionThis study aimed to investigate the effects of 2 inorganic polyphosphates (poly[P]) are linear polymers of orthophosphate (Pi) residues linked by energy-rich phosphoanhydride poly(P) compounds, sodium triphosphate (STP, Na5P3O10) and sodium hexametaphosphate (SHMP, Na15P13O40 ∼ Na20P18O40) on the proliferation, odontoblastic differentiation, and angiogenic potential of human dental pulp cells (HDPCs).MethodsDifferentiation was measured by alkaline phosphatase activity, calcified nodule formation by alizarin red staining, and marker messenger RNA (mRNA) levels by reverse-transcription polymerase chain reaction. In vitro angiogenesis was quantified by migration, mRNA levels of angiogenic genes, and endothelial tube formation.ResultsSTP and SHMP dose dependently increased the proliferation and ALP activity and enhanced mineralized nodule formation and odontoblast marker mRNAs of HDPCs. STP and SHMP resulted in the up-regulation of angiogenic genes in HDPCs. Endothelial cells treated with conditioned medium collected from STP- and SHMP-exposed HDPCs showed an increase in migration and capillary tube formation. Knockdown of the expression of the genes encoding of inorganic pyrophosphate by small interfering RNA attenuated the STP- and SHMP-induced odontogenic differentiation and angiogenic potential.ConclusionsThis study showed that STP and SHMP promote the growth, differentiation, and angiogenic potential of HDPCs. These results suggest that STP and SHMP may be candidates for dental pulp tissue engineering and regenerative endodontics.