Resolvin E1 accelerates pulp repair by regulating inflammation and stimulating dentin regeneration in dental pulp stem cells

Abstract

Background Unresolved inflammation and tissue destruction are considered to underlie failure of dental pulp repair. As key mediators of the injury response, dental pulp stem cells (DPSCs) play a critical role in pulp tissue repair and regeneration. Resolvin E1 (RvE1), a major dietary omega-3 polyunsaturated fatty-acid metabolite, is effective in resolving inflammation and activating wound healing. However, whether RvE1 facilitates injured pulp-tissue repair and regeneration through timely resolution of inflammation and rapid mobilization of DPSCs is unknown. Therefore, we established a pulp injury model and investigated the effects of RvE1 on DPSC-mediated inflammation resolution and injured pulp repair. Methods A pulp injury model was established using eight-week-old Sprague-Dawley rats. Animals were sacrificed on days 1, 3, 7, 14, 21, and 28 after pulp capping with a collagen sponge immersed in PBS with RvE1 or PBS. Hematoxylin-eosin and Masson’s trichrome staining, immunohistochemistry, and immunohistofluorescence were used to evaluate the prohealing properties of RvE1. hDPSCs were incubated with lipopolysaccharide (LPS) to induce an inflammatory response, and the expression of inflammatory factors after RvE1 application was measured. Effects of RvE1 on hDPSC proliferation, chemotaxis, and odontogenic differentiation were evaluated by CCK-8 assay, transwell assay, alkaline phosphatase (ALP) staining, alizarin red staining, and quantitative PCR, and possible signaling pathways were explored using western blotting. Results In vivo, RvE1 promoted injured pulp repair and reparative dentin formation. Further, it enhanced dentin sialoprotein and nestin expression and accelerated pulp inflammation resolution by suppressing TNF-α and CD68 expression. RvE1 enhanced the recruitment of CD146+ and CD105+ DPSCs to the damaged molar pulp mesenchyme. Isolated primary cells exhibited the mesenchymal stem cell immunophenotype and differentiation. RvE1 promoted hDPSC proliferation and chemotaxis. RvE1 significantly attenuated pro-inflammatory cytokine (TNF-α, CD68, IL-6, and IL-1β) release and enhanced ALP activity, nodule mineralization, and especially, expression of the odontogenesis-related genes DMP-1, DSPP, and BSP in LPS-stimulated DPSCs. RvE1 regulated Akt, ERK, and rS6 phosphorylation. Conclusions RvE1 promotes pulp inflammation resolution and dentin regeneration and positively influences the proliferation, chemotaxis, and differentiation of LPS-stimulated hDPSCs. This response is, at least partially, dependent on Akt, ERK, and rS6-associated signaling. RvE1 has promising application potential in regenerative endodontics.

Combination of resolvin E1 and lipoxin A4 promotes the resolution of pulpitis by inhibiting NF‐κB activation through upregulating sirtuin 7 in dental pulp fibroblasts

“…Horibe et al found that ALX could be observed in odontoblastic layer during physiological and reparative dentin formation 38 . Our group has previously shown that RvE1 can accelerate repair of injured pulp by regulating inflammation and promoting odontogenic differentiation in dental pulp stem cells 21 . These results highlight the pro‐regeneration function of SPMs in dental pulp, but gaps remain regarding understanding of inflammatory regulation.…”

“…38 Our group has previously shown that RvE1 can accelerate repair of injured pulp by regulating inflammation and promoting odontogenic differentiation in dental pulp stem cells. 21 These results highlight the proregeneration function of SPMs in dental pulp, but gaps remain regarding understanding of inflammatory regulation. Our previous study also verified that using RvE1 alone could inhibit inflammatory reactions and NF-κB activation to a certain extent but failed to achieve complete resolution of pulpitis.…”

“…Dondoni et al first illustrated the protective role in a rat model of pulpitis 19 . We previously showed that RvE1 could suppress inflammatory infiltration and accelerate pulp repair in pulpitis by reducing activation of nuclear factor kappa B (NF‐κB) in lipopolysaccharide (LPS)‐induced DPFs to some extent, but not to normal levels 20,21 . This is because SPMs are biosynthesized during resolution in a certain order and act on different stages and aspects of resolution 22,23 .…”

“…19 We previously showed that RvE1 could suppress inflammatory infiltration and accelerate pulp repair in pulpitis by reducing activation of nuclear factor kappa B (NF-κB) in lipopolysaccharide (LPS)-induced DPFs to some extent, but not to normal levels. 20,21 This is because SPMs are biosynthesized during resolution in a certain order and act on different stages and aspects of resolution. 22,23 Thus, complete inhibition of inflammatory pathway signalling and resolution cannot be achieved by using RvE1 alone, which is only synthesized in the later stage of resolution.…”

Conditioned medium derived from 3D tooth germs: A novel cocktail for stem cell priming and early in vivo pulp regeneration

“…Relative transcription levels of human dentin matrix protein 1 (DMP 1), dentin sialophosphoprotein (DSPP), bone sialoprotein (BSP), and osterix (OSX) were analysed using glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) as a normalized reference. Forward and reverse primers used are listed in Table 30,31 …”