Dental pulp stem cells and hydroxyapatite: a promising combination for maxillary bone regeneration

BACKGROUND: Stem cells from human exfoliated deciduous teeth (SHED) and dental pulp stem cells (DPSC) exhibit significant potential for bone regeneration therapies. However, the optimal scaffold material for maximising their osteogenic potential remains unclear. AIM: This study investigated the comparative efficacy of hydroxyapatite (HA) and polycaprolactone (PCL) scaffolds in supporting SHED and DPSC proliferation and osteogenic differentiation for maxillary bone regeneration. METHODS: Cells were extracted from the dental pulp of deciduous and permanent teeth using enzymatic digestion and cultured until passage three. Characterisation of SHED and DPSC was conducted using morphological observation, stemness markers, proliferation analysis, and an alkaline phosphatase (ALP) assay. SHED and DPSC were then cultured on HA and PCL scaffolds, and in vitro cell proliferation and osteogenic potential (FESEM morphological analysis, ALP-specific activity, and osteoblast markers) were determined prior to in vivo transplantation. In vivo study involved the transplantation of cells with scaffolds into an artificial bone defect of 4 mm length and 1.5 mm depth in the rat’s left maxilla. Three-dimensional analysis via micro-computed tomography (micro-CT) and histological evaluations were performed six weeks post-transplantation. RESULTS: Characterised SHED and DPSC populations displayed mesenchymal stem cell markers (CD73+, CD105+, CD146+) and lacked hematopoietic markers (CD11B−, CD34−, CD45−). Both cell types exhibited proliferation capacity and osteogenic potential. Although early osteogenic differentiation was observed on PCL scaffolds, HA scaffolds promoted robust osteoblast differentiation, with enhanced mineralisation, ALP-specific activity, and increased expression of osteoblast markers (RUNX2+, COL1A1+, ALPL+). Notably, SHED showed enhanced proliferation on the HA scaffold, accompanied by increased osteoblastic phenotypes. In vivo transplantation in rat maxillary defects confirmed these findings. Micro-CT analysis and histological evaluations revealed significantly greater (p < 0.05) new bone formation in the HA scaffold seeded with either SHED or DPSC as compared to PCL scaffolds. CONCLUSION: This study demonstrated the superior compatibility of SHED and DPSC with HA scaffold in promoting osteogenesis and maxillary bone regeneration. These findings suggest that the combination of dental pulp stem cells and HA shows promising potential for maxillary bone regeneration in preclinical models, with possible translational relevance for future clinical applications. CLINICAL TRIAL NUMBER: Not applicable.