SDF-1α and VEGF overexpressing DPSCs in dental pulp regeneration in-vivo

Abstract

Objectives: The current study aimed to overexpress vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1α (SDF-1α) in dental pulp stem cells (DPSCs) and investigate its effects on vascularized dental pulp regeneration in-vivo. 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), endothelial cell migration (wound-healing assay) and 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 four 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 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 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 and single-transfected groups. Angiogenesis induced by gene-modified DPSCs seemed to be less dependent on sprouting (angiogenesis) but occurred via an increase in the diameter of blood vessels. However, no significant increase in vessel density as compared with wild-type DPSCs was observed. This pattern of enlarged vessel was more accentuated in DPSCs-SDF-1α and mixed DPSCs-SDF-1α + DPSCs-VEGF groups than in DPSCs-VEGF alone group. Conclusions: A combination of VEGF-transfected and SDF-1α-transfected DPSCs could enhance the diameter of blood vessels and the length of pulp regeneration in-vivo.