Aspirin promotes osteogenic differentiation of human dental pulp stem cells

Human dental pulp stem cells (hDPSCs) possess self-renewal and osteogenic differentiation properties, and have been used for orofacial bone regeneration and periodontal treatment. Aspirin has been demonstrated to enhance the regeneration of bone marrow mesenchymal stem cells (MSCs); however, the impact of aspirin on the osteogenic differentiation of hDPSCs remains unknown. In the present study, hDPSCs were characterized by flow cytometry, while their clonogenic potential and multipotency were assessed using alizarin red, Oil red O and alcian blue staining. The effect of aspirin on hDPSC viability was assessed using Cell Counting Kit-8 assay. Osteogenic capacity was examined by alkaline phosphatase activity, alizarin red staining, reverse transcription-polymerase chain reaction and western blotting. Furthermore, in vivo cranial defects were established in Sprague-Dawley rats to evaluate the effect of aspirin on hDPSC-based bone regeneration. Anorganic bovine bone was used as a bone replacement material and as the carrier for hDPSCs. New bone formation was observed through radiographic and histological analysis. The study demonstrated that hDPSCs expressed MSC markers and possessed multipotency in vitro. Aspirin was non-toxic to hDPSCs at a concentration of ≤100 μg/ml and enhanced the osteogenesis of hDPSCs in vitro. Aspirin significantly increased hDPSC-based bone formation in the rat cranial defect model at 8 or 12 weeks post-implantation (P<0.05). The data suggested that aspirin promotes the osteogenic potential of hDPSCs in vitro and in vivo. Overall, the present study indicated that aspirin improves the bone regeneration capacity of hDPSCs.