Hydrogel Drug Delivery Vehicle Cytotoxicity for Pulp Capping in vitro

Objectives: Direct pulp capping is a treatment for preserving the vital pulp. However, a satisfactory material for caries-exposed inflamed pulp in permanent teeth is not currently available. Thus, a biologically-based material that promotes the continued formation of a new dentin-pulp complex is needed. A hydrogel drug delivery vehicle is a promising material, however its cytotoxicity has barely been explored. The aim of this study is to evaluate the cytotoxicity of a hydrogel drug delivery vehicle and its components in a cell culture system in vitro.          

Methods: The hydrogel solution was prepared by mixing poly(ethylene glycol)maleate-citrate (45% w/v)[PEGMC], acrylic acid (5% w/v)[AA], 2,2’-Azobis(2-methylpropionamidine) dihydrochloride photoinitiator (0.1% w/v)[AAPH], and deionized water. Various concentrations of the hydrogel and its components were prepared in the cell culture medium. L929 cells were seeded into 96-well plates at 3x10³ cells/well and cultured with each concentration of the tested materials. Cells cultured only with the culture medium served as a control. After incubation the cytotoxicity was evaluated by MTS assay. The data was analyzed by ANOVA, Student’s t-tests for pair-wise comparisons between groups.

Results: For the hydrogel vehicle, cell viability dropped to 46.3% at 25% concentration (p=0.002); there was no cell survival at 100% concentration (p<0.0001). In PEGMC, cell viability dropped to 2.56% at 0.352 % concentration (p=0.006); there was no cell survival at 1.41% to 45% concentration (p=0.005). In AA, no cell survival observed at all concentrations. In AAPH, cell viability remained 100% up to 1% concentration. However, cell viability dropped to 15.6% at 2% concentration (p=0.002); there was no cell survival at 4% concentration (p<0.0001).

Conclusions: When redesigning hydrogel vehicle for dental pulp, its cytotoxicity and the individual component amounts within their biocompatibility range should be considered. Supported by NIH KL2RR024983(TK)/UL1RR024982.