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Abstract

Background/purpose: The pH within infected root canals fluctuates dynamically under pathological conditions, yet its impact on stem cells from the apical papilla (SCAPs) in dental pulp regeneration remains unclear. This study investigated how potential of hydrogen (pH) variations govern SCAPs survival and the associated signaling to identify therapeutic targets for enhancing tissue regeneration.

Materials and methods: SCAPs were cultured at pH 5.4-10.4. Proliferation and apoptosis were assessed using cell counting kit-8 (CCK-8) assays, real-time live-cell analysis, and flow cytometry. RNA-sequencing (RNA-seq) identified differentially expressed genes, which were validated through reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR), Western blotting, and mechanistic target of rapamycin (mTOR) inhibition. The buffering capacity of RATEA16 hydrogel was also evaluated.

Results: Proliferative capacity peaked at pH 7.4, whereas pH 5.4 significantly inhibited proliferation without inducing apoptosis. The phosphoinositide 3-kinase (PI3K)/ protein kinase B (AKT)/mechanistic target of rapamycin complex 1 (mTORC1) signaling axis was identified as the key regulatory node. pH 5.4 suppressed the phosphorylation of PI3K, eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1), and ribosomal protein S6 kinase beta-1 (S6K1). Acid-induced inhibition was reversible upon neutralization. The biocompatible RATEA16 hydrogel maintained microenvironmental neutrality and rescued SCAPs proliferation at pH 5.4.

Conclusion: Acidic environments inhibited SCAPs proliferation via PI3K/AKT/

mTORC1 downregulation. RATEA16 hydrogel restored proliferation through extracellular pH modulation, representing a promising strategy to enhance dental pulp regeneration.

Publication Date

2026

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