Protecting Pulp by Restoring Reparative Cellular Function in ECM Culture
Objectives: Dentin mineral protects the pulp against infections. Products secreted from oral bacteria and monomers leaching out from adhesive restorations may compromise the cells and inhibit dentinogenesis. This study validates/quantifies dental pulp cells’ ability to deposit mineral in extracellular matrix (ECM) after being challenged by triethylene glycol dimethacrylate (TEGDMA) and treated with the drug N-Acetyl Cysteine (NAC).
Cell differentiation and mineral deposition were assessed at different time points (14 and 21 days) via alkaline phosphatase (ALP) detection and alizarin red S (ARS) staining. Mineral spread pattern was detected on a 2.5D ECM cultures and analyzed by quantitative phase imaging. At TEGDMA concentrations of 0-2.5 mmol/L and with administered 10 mmol/L NAC, the hydroxyapatite content, spatial localization and covering area were validated by Raman microscopy, confocal imaging and Osteoimage/ARS staining.
Results: After 14 days, the percentage of the differentiating cells expressing ALP increased more than seven-fold compared to the non-induced counterparts. After 21 days, the mineral covered approximately 78% of the entire area/frame. At early and late stages, the focal accumulation of the mineral was replaced by a gradient pattern with an optical thickness peak of 3-4 µm and distance of and 500 µm. With increasing TEGDMA concentration, the percentage area covered decreased from 3- to 85-fold. The administration of NAC prevented the formation/deposition of the mineral in healthy cells but restored its deposition in the affected ones. The percentage area covered by the mineral in cultures exposed to 1.5 mmol/L TEGDMA increased 6-fold when treated with NAC and the hydroxyapatite peak increased more than three times compared to the non-treated ones.
Conclusions: Our study authenticates the dental pulp/ECM platform as an efficient tool for validating the impact of molecules such as NAC to restore mineral deposition in the compromised tissue and maintain reparative dentin formation.