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

Abstract Introduction This 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, Na 5 P 3 O 10 ) and sodium hexametaphosphate (SHMP, Na 15 P 13 O 40  ∼ Na 20 P 18 O 40 ) on the proliferation, odontoblastic differentiation, and angiogenic potential of human dental pulp cells (HDPCs). Methods Differentiation 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. Results STP 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. Conclusions This 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.