Epigenetic regulation of dental pulp stem cells and its potential in regenerative endodontics

Regenerative endodontics(RE)therapy means physiologically replacing damaged pulp tissue and regaining functional dentin–pulp complex.Current clinical RE procedures recruit endogenous stem cells from the apical papilla,periodontal tissue,bone marrow and peripheral blood,with or without application of scaffolds and growth factors in the root canal space,resulting in cementum-like and bone-like tissue formation.Without the involvement of dental pulp stem cells(DPSCs),it is unlikely that functional pulp regeneration can be achieved,even though acceptable repair can be acquired.DPSCs,due to their specific odontogenic potential,high proliferation,neurovascular property,and easy accessibility,are considered as the most eligible cell source for dentin–pulp regeneration.The regenerative potential of DPSCs has been demonstrated by recent clinical progress.DPSC transplantation following pulpectomy has successfully reconstructed neurovascularized pulp that simulates the physiological structure of natural pulp.The self-renewal,proliferation,and odontogenic differentiation of DPSCs are under the control of a cascade of transcription factors.Over recent decades,epigenetic modulations implicating histone modifications,DNA methylation,and noncoding(nc)RNAs have manifested as a new layer of gene regulation.These modulations exhibit a profound effect on the cellular activities of DPSCs.In this review,we offer an overview about epigenetic regulation of the fate of DPSCs;in particular,on the proliferation,odontogenic differentiation,angiogenesis,and neurogenesis.We emphasize recent discoveries of epigenetic molecules that can alter DPSC status and promote pulp regeneration through manipulation over epigenetic profiles.

Cells and material-based strategies for regenerative endodontics

The carious process leads to inflammation of pulp tissue.Current care options include root canal treatment or apexification.These procedures,however,result in the loss of tooth vitality,sensitivity,and healing.Pulp capping and dental pulp regeneration are continually evolving techniques to regenerate pulp tissue,avoiding necrosis and loss of vitality.Many studies have successfully employed stem/progenitor cell populations,revascularization approaches,scaffolds or material-based strategies for pulp regeneration.Here we outline advantages and disadvantages of different methods and techniques which are currently being used in the field of regenerative endodontics.We also summarize recent findings on efficacious peptide-based materials which target the dental niche..

Autologous platelet-rich-fibrin-induced revascularization sequelae:Two case reports Autologous platelet-rich-fibrin-induced revascularization sequelae:Two case reports

BACKGROUND A key requirement for biomimetic regeneration of tissues is a 3D scaffold.The gold standard scaffold for revascularization is the blood clot,however,an adequate blood clot cannot always be achieved in narrow canals or mature roots.Hereby,we document the effects of platelet-rich fibrin(PRF)for the regenerative endodontic treatment(RET)of two immature permanent teeth with necrotic pulps for up to 48 mo.CASES SUMMARY The first patient was a 22-year-old female with history of trauma in tooth#9 with a sinus tract and a large periapical lesion.The second was a 9-year-old male presenting with a badly decayed tooth#14.Both cases were treated with RET and PRF prepared from the patients’blood.PRF and its extract were used as a scaffold for RET.Patients were followed-up to 9 and 48 mo(4 years),respectively.Both patients,were asymptomatic after treatment.At the 9-mo-follow-up of case#1,there was radiographic evidence of periapical bone healing,however,the root apex was still open.In case#2,the roots exhibited apical closure and normal periapical bone architecture at 12-mo follow-up,while no root lengthening was observed.After 48 mo,case#2 showed extensive intracanal calcification in all root canals that complicated conventional root canal treatment.CONCLUSION RET with PRF and its extract could be used in revascularization of immature permanent teeth.However,proper case selection to comply with long-term follow-up is necessary and adverse events such as calcification and canal obliteration should be planned for.

Hypoxia-Mediated Upregulation of Semaphorin 3A during Pulp Revascularization

Semaphorin 3A could be involved in angiogenesis and also enhanced bone formation was investigated in many researches. In our current study, we firstly investigated that canal obliteration might be present in some regenerative endodontic procedures cases clinically. After the establishment of the model of apical periodontitis in the maxillary first molars of rats, pulp revascularization was performed in mesial root canal. Histological sections showed that most of the tissues growing into the root canal were not real pulp tissue, but cementoid, osteoid and periodontal-like membrane. Moreover, we detected that the expression of Semaphorin 3A increased in the mesial root canal. When we used CoCl2 to induce hypoxic environment, the expression of genes and proteins, Hypoxia inducible factor-1α, Vascular endothelial growth factor, and Semaphorin 3A in dental pulp stem cells were both upregulated. In conclusion, hypoxia mediated the high expression of Semaphorin 3A in DPSC might be involved tissue regeneration during pulp vascularization.

Antibiofilm and immunomodulatory resorbable nanofibrous filing for dental pulp regenerative procedures

Multifunctional scaffolds with host defense peptides designed for regenerative endodontics are desirable nanobiotechnological tools for dentistry.Here,different scaffolds were tested for use during the pulp revascularization process,including poly(vinyl alcohol)-PVA hydrogels or resins,collagen hydrogels and poly(vinyl alcohol)PVA/Chitosan(PVA/CS)nanofibers.Based on time to degradation(21 days),nanofibers were chosen to be incorporated with ciprofloxacin and IDR-1002(each at 50 mg/g).Nanofibers containing ciprofloxacin and IDR-1002 had anti-biofilm activity against Enterococcus faecalis,Staphylococcus aureus and a multispecies oral biofilm,besides anti-inflammatory activities.The in vivo subcutaneous tissue response to tooth fragments filled with nanofibers demonstrated a pulp-like tissue formation,when compared to empty teeth fragments.Thus,we designed a strong antimicrobial,immunomodulatory and regenerative candidate for pulp revascularization and regeneration procedures.

Epigenetic therapeutics in dental pulp treatment: Hopes, challenges and concerns for the development of next-generation biomaterials

This opinion-led review paper highlights the need for novel translational research in vital-pulp-treatment(VPT),but also discusses the challenges in translating evidence to clinics.Traditional dentistry is expensive,invasive and relies on an outmoded mechanical understanding of dental disease,rather than employing a biological perspective that harnesses cell activity and the regenerative-capacity.Recent research has focussed on developing minimally-invasive biologically-based‘fillings’that preserve the dental pulp;research that is shifting the paradigm from expensive high-technology dentistry,with high failure rates,to smart restorations targeted at biological processes.Current VPTs promote repair by recruiting odontoblast-like cells in a material-dependent process.Therefore,exciting opportunities exist for development of next-generation biomaterials targeted at regenerative processes in the dentin-pulp complex.This article analyses recent research using pharmacological-inhibitors to therapeutically-target histone-deacetylase(HDAC)enzymes in dental-pulp-cells(DPCs)that stimulate pro-regenerative effects with limited loss of viability.Consequently,HDAC-inhibitors have the potential to enhance biomaterial-driven tissue responses at low concentration by influencing the cellular processes with minimal side-effects,providing an opportunity to develop a topically-placed,inexpensive bio-inductive pulp-capping material.Despite positive results,clinical translation of these innovations requires enterprise to counteract regulatory obstacles,dental-industry priorities and to develop strong academic/industry partnerships.The aim of this opinion-led review paper is to discuss the potential role of therapeutically-targeting epigenetic modifications as part of a topical VPT strategy in the treatment of the damaged dental pulp,while considering the next steps,material considerations,challenges and future for the clinical development of epigenetic therapeutics or other‘smart’restorations in VPT.

iPSC-derived cranial neural crest-like cells can replicate dental pulp tissue with the aid of angiogenic hydrogel

The dental pulp has irreplaceable roles in maintaining healthy teeth and its regeneration is a primary aim of regenerative endodontics.This study aimed to replicate the characteristics of dental pulp tissue by using cranial neural crest(CNC)-like cells(CNCLCs);these cells were generated by modifying several steps of a previously established method for deriving NC-like cells from induced pluripotent stem cells(iPSCs).CNC is the anterior region of the neural crest in vertebrate embryos,which contains the primordium of dental pulp cells or odontoblasts.The produced CNCLCs showed approximately 2.5-12,000-fold upregulations of major CNC marker genes.Furthermore,the CNCLCs exhibited remarkable odontoblastic differentiation ability,especially when treated with a combination of the fibroblast growth factors(FGFs)FGF4 and FGF9.The FGFs induced odontoblast marker genes by 1.7-5.0-fold,as compared to bone morphogenetic protein 4(BMP4)treatment.In a mouse subcutaneous implant model,the CNCLCs briefly fated with FGF4+FGF9 replicated dental pulp tissue characteristics,such as harboring odontoblast-like cells,a dentin-like layer,and vast neovascularization,induced by the angiogenic self-assembling peptide hydrogel(SAPH),SLan.SLan acts as a versatile biocompatible scaffold in the canal space.This study demonstrated a successful collaboration between regenerative medicine and SAPH technology.

Biomaterial scaffolds for clinical procedures in endodontic regeneration

Regenerative endodontic procedures have been rapidly evolving over the past two decades and are employed extensively in clinical endodontics.These procedures have been perceived as valuable adjuvants to conventional strategies in the treatment of necrotic immature permanent teeth that were deemed to have poor prognosis.As a component biological triad of tissue engineering(i.e.,stem cells,growth factors and scaffolds),biomaterial scaffolds have demonstrated clinical potential as an armamentarium in regenerative endodontic procedures and achieved remarkable advancements.The aim of the present review is to provide a broad overview of biomaterials employed for scaffolding in regenerative endodontics.The favorable properties and limitations of biomaterials organized in naturally derived,host-derived and synthetic material categories were discussed.Preclinical and clinical studies published over the past five years on the performance of biomaterial scaffolds,as well as current challenges and future perspectives for the application of biomaterials for scaffolding and clinical evaluation of biomaterial scaffolds in regenerative endodontic procedures were addressed in depth.