Effect of rhCEMP1 Protein on the Osteogenic Differentiation of DPSCs

Objectives: Dental pulp stem cells (DPSCs), cultured with growth factors have the potential to differentiate towards the osteogenic lineage; therefore they are widely used in bone tissue engineering. It is suggested that recombinant human CEMP1 protein (rhCEMP1), can induce differentiations of human gingival fibroblasts and human periodontal ligament cells towards mineralizing lineage. However, the effect of the protein on DPSCs is unknown. The purpose of this study was to evaluate the effect of the rhCEMP1 protein on the expression of osteogenic markers of DPSCs cultured on Poly (Lactideco-Glycolide)/hydroxyapatite (PLGA/HA) scaffolds.
Methods: An experimental study, previously approved by the institutional ethics committee, was developed. The effect of different concentrations of the rhCEMP1 protein on the proliferation, viability and osteogenic differentiation genes expression of monolayer cultured DPSCs, was evaluated by RTqPCR. The expression of Runx2, OSX, ALP, OP, OC and COLI of the cells cultured on PLGA/HA scaffolds, with the protein, at a concentration of 2.5 µg /ml, was determined. Finally, a critical size bone defect model in rat calvaria was implemented, to evaluate the regenerative capacity of scaffolds with DPSCs/ rhCEMP1. Comparisons between groups were made with ANOVA one-way analysis and bonferroni post-hoc test.
Results: The results showed that concentrations of 2.5 and 5 µg/ml of rhCEMP1, did not compromise cell viability and induce increased proliferation of DPSCs. The findings suggest that the protein inhibits the OC marker and decreases the expression of Runx2, ALP, COLI and OP of DPSCs in scaffolds of PLGA/HA when compared to the gene profile of the same cells cultured on PLGA/HA with osteogenic induction medium. Histomorphometric analysis of the defect zone treated with the scaffold, DPSCs/rhCEMP1, in rats for 8 weeks, showed the formation of a fibrous tissue but no bone formation.
Conclusions: The results indicated that the rhCEMP1 does not promote the differentiation of DPSCs towards osteogenic lineage.