Dental pulp stem cells overexpressing stromal-derived factor-1α and vascular endothelial growth factor in dental pulp regeneration.

Abstract

The current study aimed to investigate the effects of vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1α (SDF-1α) overexpressing dental pulp stem cells (DPSCs) in vascularized dental pulp regeneration in vivo. Human DPSCs were transfected with VEGF or SDF-1α using premade lentiviral particles. Overexpression was verified by quantitative polymerase chain reaction (q-PCR), enzyme-linked immunosorbent assay (ELISA), and western blot analysis. Effects of SDF-1α and VEGF overexpressing DPSCs on their proliferation (CCK-8 and MTT assays) and endothelial vascular-tube formation (Matrigel assay) were investigated in vitro. Human tooth roots sectioned into 6-mm segments were injected with gene-modified DPSCs encapsulated in PuraMatrix hydrogel and implanted in the dorsum of severe-combined-immunodeficient (SCID) mice. Implants were retrieved after 4weeks and examined for regenerated pulp-like tissue and vascularization using histology and immunohistochemistry. p < 0.05 was considered statistically significant. Gene-modified DPSCs expressed significantly high levels (p < 0.05) of SDF-1α and VEGF mRNA and proteins, respectively. Transfected DPSCs showed a significantly higher cell proliferation compared to that of wild-type DPSCs. Furthermore, they enhanced endothelial cell migration and vascular-tube formation on Matrigel in vitro. When injected into tooth root canals and implanted in vivo, DPSCs/SDF-1α + DPSCs/VEGF-mixed group resulted in significantly increased length of regenerated pulp-like tissue within the root canals compared to that of wild-type DPSCs/VEGF and DPSCs/SDF-1α groups. Vessel area density was significantly higher in DPSCs/SDF-1α and mixed DPSCs/SDF-1α + DPSCs/VEGF groups than in DPSCs-VEGF alone or wild-type DPSCs groups. A combination of VEGF-overexpressing and SDF-1α-overexpressing DPSCs could enhance the area of vascularized dental pulp regeneration in vivo. Enhancing vascularization in pulp regeneration is crucial to overcome the clinical limitation of the limited blood supply to the root canals via a small apical foramen enclosed by hard dentin.