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

Objectives: 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.

Materials and methods: 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 4 weeks and examined for regenerated pulp-like tissue and vascularization using histology and immunohistochemistry. p < 0.05 was considered statistically significant.

Results: 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.

Conclusion: A combination of VEGF-overexpressing and SDF-1α-overexpressing DPSCs could enhance the area of vascularized dental pulp regeneration in vivo.

Clinical relevance: 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.