Nitric Oxide Nanomatrix Gel on Dental Pulp Stem Cell Promotion

Objectives: The study evaluated the effect of a nitric oxide (NO) releasing biomimetic nanomatrix gel on dental pulp stem cells (DPSCs)’ in regards to proliferation, migration, and differentiation.
Methods: The NO releasing nanomatrix gel was synthesized using self-assembled peptide amphiphiles. DPSCs were treated with NO releasing biomimetic nanomatrix gel in Transwell^® plates. Experiments were performed with four conditions: 1) Basal media without NO nanomatrix gel (B-N), 2) Basal media with NO nanomatrix gel (B+N), 3) Induced media without NO nanomatrix gel (I-N), and 4) Induced media with NO nanomatrix gel (I+N) at 4,7,14, and 21 days. DPSCs’ proliferation, and differentiation, were evaluated using CyQuant^®, Alkaline Phosphatase (ALP) assay, Alizarin red staining, and Real Time Quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR). The migration testing was performed by using a microchannel system.
Results: The NO releasing nanomatrix gel promoted DPSC proliferation at day seven with NO. ALP activity was significantly increased by NO with a fivefold increase at day 7 and a twofold increase at day 14 compared to the B-N condition. The real time qRT-PCR demonstrated increased mRNA gene expression of dentin sialophosphoprotein (DSPP) of I+N by 2.2 fold at day 4, 4.6 fold at day 7, and 5.2 fold at day 14 in comparison to B-N. Dentin matrix acidic phosphoprotein 1 gene expression also showed similar pattern as DSPP. ALP gene expression was demonstrated after the day 14 with a 4.6 fold increase in I+N compared to B-N. DPSC migration was observed after 24 hours and I+N showed greater migration in comparison to B-N.
Conclusions: In vitro data shows that NO releasing nanomatrix gel functions as a favorable biocompatible and bio-inducible extracellular matrix-mimicking microenvironment to promote DPSC differentiation and migration. Further studies will be performed to determine its therapeutic potential in pulp-tissue revitalization.