The study tested LL‑37 and similar peptides on dental‑like cells and found that LL‑37, at a certain concentration, boosted markers of mineral formation without killing the cells, but it didn’t change key genes linked to dentin growth. The other peptides were less effective or toxic at higher doses.

To evaluate the effect of analogues of cationic peptides on the viability and the expression of phenotypic and genotypic markers of dentin mineralization in MDPC-23 odontoblast-like cells. Cells were exposed to serial dilutions of analogues of cationic peptides hBD-3-1C^V and KR-12-a5 compared to peptide LL-37 and their viability was assessed by methyltetrazolium assay. Next, peptides (0.78-62.5 μg/mL) were applied on the MDPC-23 cells for evaluating the total protein (TP) production, alkaline phosphatase (ALP) activity and mineralized nodule deposition. Gene expression of mineralization markers (DSPP and DMP-1) was also determined by quantitative PCR. LL-37 and hBD-3-1C^V treatment did not affect cellular viability at concentrations below 62.5 μg/mL. KR-12-a5 reduced cell viability above 31.25 μg/mL. TP production was similar for all groups compared with the control group, except by hBD-3-1C^V (at 15.62 μg/mL). LL-37 (at 62.5 μg/mL) induced higher ALP activity than control and other experimental groups. LL-37 and hBD-3-1C^V, at 62.5 μg/mL and KR-12-a5 at 31.25 μg/mL stimulated the highest deposition of mineralized nodule. Overall, no statistical differences were observed between the groups for DSPP-1 and DMP-1 expressions. LL-37 was the only peptide that induced both ALP activity and mineralized nodules deposition, without affecting cell viability. None of peptides tested induced the expression of DSPP or DMP-1, genes commonly involved in active dentin mineralization.