Regeneration Of Pulp-like Tissue Research Articles

Allogeneic Bone Marrow Mesenchymal Stromal Cell Transplantation Induces Dentin Pulp Complex-like Formation in Immature Teeth with Pulp Necrosis and Apical Periodontitis

IntroductionDental pulp regeneration is challenging in endodontics. Cellular therapy is an alternative approach to induce dental pulp regeneration. Mesenchymal stromal cells (MSCs) have the capacity to induce dental pulp-like tissue formation. In this study, we evaluated the capacity of allogeneic bone marrow MSCs (BM-MSCs) to regenerate pulp following necrosis and apical periodontitis in children's permanent immature apex teeth. MethodsPatients aged 8 to 12 years with pulp necrosis and apical periodontitis were evaluated. The study included 15 teeth (13 incisors and 2 molars) from 14 patients (8 boys and 6 girls). Radiographic evaluation showed periapical radiolucency and immature apex teeth. There was no response to cold or electric pulp testing. The root canal of each tooth was cleaned, shaped, and Ca(OH)2 used as an interappointment medication. Cryopreserved allogeneic BM-MSCs were thawed, expanded, incorporated into preclotted platelet-rich plasma, and implanted into the tooth's pulp cavity. They were sealed with bioceramic cement and composite. Sensibility, apical foramen, calcium deposits within the root canal, and resolution of periapical lesions were evaluated in each tooth over the following 12 months. ResultsBased on 9 variables established for dental pulp-like tissue regeneration, all MSC-treated teeth showed evidence of successful regeneration. Clinical and radiographic evaluation of the treated teeth showed periapical lesion healing, sensitivity to cold and electricity, decreased width of the apical foramen, and mineralization within the canal space. ConclusionsTransplantation of allogeneic MSCs induces the formation of dental pulp-like tissue in permanent immature apex teeth with pulp necrosis and apical periodontitis. Implant of MSCs constitutes a potential therapy in regenerative endodontics in pediatric dentistry. Future studies incorporating a larger sample size may confirm these results.

Injectable decellularized dental pulp matrix-functionalized hydrogel microspheres for endodontic regeneration.

The sufficient imitation of tissue structures and components represents an effective and promising approach for tissue engineering and regenerative medicine applications. Dental pulp disease is one of the most common oral diseases, although functional pulp regeneration remains challenging. Herein, we propose a strategy that employs hydrogel microspheres incorporated with decellularized dental pulp matrix-derived bioactive factors to simulate a pulp-specific three-dimensional (3D) microenvironment. The dental pulp microenvironment-specific microspheres constructed by this regenerative strategy exhibited favorable plasticity, biocompatibility, and biological performances. Human dental pulp stem cells (hDPSCs) cultured on the constructed microspheres exhibited enhanced pulp-formation ability in vitro. Furthermore, the hDPSCs-microcarriers achieved the regeneration of pulp-like tissue and new dentin in a semi-orthotopic model in vivo. Mechanistically, the decellularized pulp matrix-derived bioactive factors mediated the multi-directional differentiation of hDPSCs to regenerate the pulp tissue by eliciting the secretion of crucial bioactive cues. Our findings demonstrated that a 3D dental pulp-specific microenvironment facilitated by hydrogel microspheres and dental pulp-specific bioactive factors regenerated the pulp-dentin complex and could be served as a promising treatment option for dental pulp disease. STATEMENT OF SIGNIFICANCE: Injectable bioscaffolds are increasingly used for regenerative endodontic treatment. Despite their success related to their ability to load stem cells, bioactive factors, and injectability, conventional bulk bioscaffolds have drawbacks such as ischemic necrosis in the central region. Various studies have shown that ischemic necrosis in the central region can be corrected by injectable hydrogel microspheres. Unfortunately, pristine microspheres or microspheres without dental pulp-specific bioactive factor would oftentimes fail to regulate stem cells fates in dental pulp multi-directional differentiation. Our present study reported the biofabrication of dental pulp-derived decellularized matrix functionalized gelatin microspheres, which contained dental pulp-specific bioactive factors and have the potential application in endodontic regeneration.

Bone morphogenetic protein 7 mediates stem cells migration and angiogenesis: therapeutic potential for endogenous pulp regeneration

Pulp loss is accompanied by the functional impairment of defense, sensory, and nutrition supply. The approach based on endogenous stem cells is a potential strategy for pulp regeneration. However, endogenous stem cell sources, exogenous regenerative signals, and neovascularization are major difficulties for pulp regeneration based on endogenous stem cells. Therefore, the purpose of our research is to seek an effective cytokines delivery strategy and bioactive materials to reestablish an ideal regenerative microenvironment for pulp regeneration. In in vitro study, we investigated the effects of Wnt3a, transforming growth factor-beta 1, and bone morphogenetic protein 7 (BMP7) on human dental pulp stem cells (h-DPSCs) and human umbilical vein endothelial cells. 2D and 3D culture systems based on collagen gel, matrigel, and gelatin methacryloyl were fabricated to evaluate the morphology and viability of h-DPSCs. In in vivo study, an ectopic nude mouse model and an in situ beagle dog model were established to investigate the possibility of pulp regeneration by implanting collagen gel loading BMP7. We concluded that BMP7 promoted the migration and odontogenic differentiation of h-DPSCs and vessel formation. Collagen gel maintained the cell adhesion, cell spreading, and cell viability of h-DPSCs in 2D or 3D culture. The transplantation of collagen gel loading BMP7 induced vascularized pulp-like tissue regeneration in vivo. The injectable approach based on collagen gel loading BMP7 might exert promising therapeutic application in endogenous pulp regeneration.

Results of “proroot mta” application in treatment of chronic periodontitis in teeth with incomplete root formation

Based on the literature data, the article analyzes the features of the morphological structure of the endodontic teeth with incomplete root formation, pathomorphological characteristics of the development of periodontal inflammation in children and the features of the tactics of conservative endodontic treatment of chronic periodontitis.
 In detail discussed methods of treatment aimed at the formation of a barrier separating the lumen of the canal and the periodontium, the main of which is apexification.
 The technique of apexification using calcium hydroxide Ca(OH)2 and mineral trioxide aggregate (MTA), as well as the technique of revascularization or regeneration of pulp-like tissue (RPT), their advantages, limitations and possible complications are considered. Indications are formulated for choosing a particular treatment method.
 The features of the application of the discussed methods are illustrated by a clinical case.

Gelatin methacryloyl-alginate core-shell microcapsules as efficient delivery platforms for prevascularized microtissues in endodontic regeneration

Combined injectable cell-laden microspheres and angiogenesis approaches are promising for functional vascularized endodontic regeneration. However, advanced microsphere designs and production techniques that benefit practical applications are rarely developed. Herein, gelatin methacryloyl (GelMA)-alginate core-shell microcapsules were fabricated to co-encapsulate human dental pulp stem cells (hDPSCs) and human umbilical vein endothelial cells (HUVECs) based on a coaxial electrostatic microdroplet technique. This technique enables high-throughput production, convenient collection, and minimal material waste. The average diameter of core-shell microcapsules was ∼359 µm, and that of GelMA cores was ∼278 µm. There were higher proliferation rates for hDPSCs and HUVECs co-encapsulated in the GelMA cores than for hDPSCs or HUVECs monoculture group. HUVECs assembled to form 3D capillary-like networks in co-culture microcapsules. Moreover, HUVECs promoted the osteo/odontogenic differentiation of hDPSCs in microcapsules. After 14 days of cultivation, prevascularized microtissues formed in microcapsules that contained abundant deposited extracellular matrix (ECM); no microcapsule aggregation occurred. In vivo studies confirmed that better microvessel formation and pulp-like tissue regeneration occurred in the co-culture group than in hDPSCs group. Thus, an effective platform for prevascularization microtissue preparation was proposed and showed great promise in endodontic regeneration and tissue engineering applications. Statement of significanceCell-laden microspheres combined with the proangiogenesis approach are promising in endodontic regeneration. We proposed GelMA-alginate core-shell microcapsules generated via the coaxial electrostatic microdroplet (CEM) method, which utilizes a double-lumen needle to allow for core-shell structures to form. The microcapsules were used for co-culturing hDPSCs and HUVECs to harvest large amounts of prevascularized microtissues, which further showed improved vascularization and pulp-like tissue regeneration in vivo. This CEM method and the microcapsule system have advantages of high-throughput generation, convenient collection, and avoid aggregation during long-term culturing. We proposed a high-effective platform for mass production of prevascularized microtissues, which exhibit great promise in the clinical transformation of endodontic regeneration and other applications in regenerative medicine.

Vascularized pulp regeneration via injecting simvastatin functionalized GelMA cryogel microspheres loaded with stem cells from human exfoliated deciduous teeth.

Dental pulp necrosis are serious pathologic entities that causes tooth nutrition deficiency and abnormal root development, while regeneration of functional pulp tissue is of paramount importance to regain tooth vitality. However, existing clinical treatments, which focus on replacing the necrotic pulp tissue with inactive filling materials, fail to restore pulp vitality and functions, thus resulting in a devitalized and weakened tooth. Currently, dental pulp regeneration via stem cell-based therapy for pulpless teeth has raised enormous attention to restore the functional pulp. Here, a novel design of injectable simvastatin (SIM) functionalized gelatin methacrylate (GelMA) cryogel microspheres (SMS) loaded with stem cells from human exfoliated deciduous teeth (SHEDs) was established to refine SHEDs biological behaviors and promote in vivo vascularized pulp-like tissue regeneration. In this system, SIM encapsulated poly (lactide-co-glycolide) (PLGA) nanoparticles were incorporated into GelMA cryogel microspheres via cryogelation and O1/W/O2 emulsion method. SMS with sustained release of SIM promoted SHEDs adhesion, proliferation and exhibited cell protection properties during the injection process. Furthermore, SMS enhanced SHEDs odontogenic differentiation and angiogenic potential, and SHEDs loaded SMS (SHEDs/SMS) are beneficial for human umbilical vein endothelial cells (HUVECs) migration and angiogenesis, demonstrating their potential for use in promoting vascularized tissue regeneration. SHEDs/SMS complexes were injected into cleaned human tooth root segments for subcutaneous implantation in nude mice. Our results demonstrated that SHEDs/SMS could induce vessel-rich pulp-like tissue regeneration in vivo and that such an injectable nano-in-micro multistage system for the controlled delivery of bioactive reagents would be suitable for clinical application in endodontic regenerative dentistry.

Regenerative Endodontic Therapy Using Platelet-Rich Plasma (PRP) and Amelogenin for the Treatment of Non-vital Immature Permanent Teeth with Apical Periodontitis: An Animal Study

Background: Platelet-rich plasma (PRR) was proposed to serve as a possible scaffold model for regenerative endodontic therapies. However, its treatment outcomes are still controversial. Amelogenin protein has been shown to induce stem cell proliferation and differentiation. Thus, the aim of this study was to investigate whether the addition of amelogenin to PRP in non-vital immature permanent teeth with apical periodontitis can improve their treatment outcomes. Methods: Root canals of both maxillary and mandibular premolars in 8 mongrel dogs (n= 128) were instrumented and left open. After 14 days, in a second surgical procedure, canals were cleaned, irrigated, and treated with PRP (n=64) and PRP + amelogenin (n=64). After 1 and 3 months, animals were killed, and treated teeth were evaluated for histological and immune detection for nestin markers. Results: After 1 and 3 months post-surgery, PRP-treated canals showed full closure of opened apexes but minimal cementum, periodontal ligament (PDL), and bone regeneration. Importantly, no pulp regeneration was recognized. In contrast, PRP + amelogenin-treated canals at 1 and 3 months showed full closure of opened apexes, significant deposition of cementum, bone, regeneration of PDL, and pulp-like tissue regeneration compared to PRP-treated groups (p<0.001). By the 3-month period, full regeneration of all the lost dental-pulp complex tissues was seen, including vascular pulp-like tissue. Conclusions: PRP alone did not achieve the desired treatment outcomes, but after addition of amelogenin protein, it induced pulpal regeneration and regenerated the whole attachment apparatus. This combination could serve as a novel approach for regenerative endodontic therapy in non-vital immature permanent teeth with apical periodontitis. However, additional research is warranted to further evaluate the effect of such a combination in different animal settings before administrating this approach in clinical cases.

Platelet lysate functionalized gelatin methacrylate microspheres for improving angiogenesis in endodontic regeneration

Rapid angiogenesis is one of the challenges in endodontic regeneration. Recently, tailored polymeric microsphere system that loaded pro-angiogenic growth factors (GFs) is promising in facilitating vascularization in dental pulp regeneration. In addition, the synergistic effect of multiple GFs is considered more beneficial, but combination usage of them is rather complex and costly. Herein, we aimed to incorporate human platelet lysate (PL), a natural-derived pool of multiple GFs, into gelatin methacrylate (GelMA) microsphere system (GP), which was further modified by Laponite (GPL), a nanoclay with efficient drug delivery ability. These hybrid microspheres were successfully fabricated by electrostatic microdroplet technique with suitable size range (180∼380 µm). After incorporation of the PL and Laponite with GelMA, the Young's modulus of the hybrid hydrogel increased up to about 3-fold and the swelling and degradation rate decreased simultaneously. The PL-derived GFs continued to release up to 28 days from both the GP and GPL microspheres, while the latter released relatively more slowly. What's more, the released GFs could effectively induce tubule formation of human umbilical endothelial cells (HUVECs) and also promote human dental pulp stem cells (hDPSCs) migration. Additionally, the PL component in the GelMA microspheres significantly improved the proliferation, spreading, and odontogenic differentiation of the encapsulated hDPSCs. As further verified by the subcutaneous implantation results, both of the GP and GPL groups enhanced microvascular formation and pulp-like tissue regeneration. This work demonstrated that PL-incorporating GelMA microsphere system was a promising functional vehicle for promoting vascularized endodontic regeneration. Statement of significancePolymeric microsphere system loaded with pro-angiogenic growth factors (GFs) shows great promise for regeneration of vascularized dental pulp. Herein, we prepared a functional GelMA microsphere system incorporated with human platelet lysates (PL) and nanoclay Laponite by the electrostatic microdroplet method. The results demonstrated that the GelMA/PL/Laponite microspheres significantly improved the spreading, proliferation, and odontogenic differentiation of the encapsulated hDPSCs compared with pure GelMA microspheres. Moreover, they also enhanced microvascular formation and pulp-like tissue regeneration in vivo. This hybrid microsphere system has great potential to accelerate microvessel formation in regenerated dental pulp and other tissues.

In Situ Oxygen Generation Enhances the SCAP Survival in Hydrogel Constructs

Prolonged and severe hypoxia is the main cause of death of transplanted cells prior to the establishment of functional circulation. In situ generation of oxygen by oxygen-producing scaffolds—a unique solution that could produce and deliver oxygen to the adjacent cells independently of blood perfusion—has attracted considerable attention to enhance the survivability of the transplanted cells. However, the application of oxygen-generating scaffolds for facilitating cell survival in pulp-like tissue regeneration is yet to be explored. In this study, gelatin methacryloyl (GelMA)—a biocompatible scaffolding material that closely mimics the native extracellular matrix and is conducive to cell proliferation and differentiation—was used to fabricate oxygen-generating scaffolds by loading various concentrations of CaO2. The CaO2 distribution, topography, swelling, and pore size of CaO2-GelMA hydrogels were characterized in detail. The release of O2 by the scaffold and the viability, spreading, and proliferation of stem cells from apical papilla (SCAPs) encapsulated in the GelMA hydrogels with various concentrations of CaO2 under hypoxia were evaluated. In addition, cellular constructs were engineered into root canals, and cell viability within the apical, middle, and coronal portions was assessed. Our findings showed that 0.5% CaO2-GelMA was sufficient to supply in situ oxygen for maintaining the embedded SCAP viability for 1 wk. Furthermore, the 0.5% CaO2-GelMA hydrogels improved the survivability of SCAPs within the coronal portion of the engineered cellular constructs within the root canals. This work demonstrated that 0.5% CaO2-GelMA hydrogels offer a potential promising scaffold that enhances survival of the embedded SCAPs in endodontic regeneration.

BMP4-regulated human dental pulp stromal cells promote pulp-like tissue regeneration in a decellularized dental pulp matrix scaffold.

Pulp regeneration with stem cells is a promising alternative for treating periapical and pulp diseases of young permanent teeth. The aim of this study was to characterize decellularized dental pulp extracellular matrix (dECM) and investigate whether bone morphogenetic protein 4 (BMP4) regulates dental pulp stromal cells (DPSC)-mediated pulp regeneration combined with dECM. Dental pulp isolated from healthy third molars was decellularized with 10% sodium dodecyl sulfate (SDS) and Triton X-100. H&E staining, DAPI staining and electron microscopy were used to observe the dECM structure. The Cell Counting Kit-8 assay was used to analyse cell proliferation. Recombinant adenovirus was used to overexpress BMP4 in DPSCs. The cells were cultured in dECM and dECM + three-dimensional (3D) Vitrogel systems, and bone/dentin/angiogenesis marker expression was evaluated by real-time polymerase chain reaction (RT-PCR) and ALP staining. DPSCs mixed with dECM and BMP4 were transplanted into nude mice, and pulp-like tissue formation was evaluated. The expression of osteogenic and angioblastic genes was increased, and pulp-like tissue formed in vivo. Thus, dECM promotes DPSC proliferation, BMP4 and dECM together accelerate pulp-like tissue formation by DPSCs in vitro.

Human Umbilical Cord Mesenchymal Stem Cell Differentiation Into Odontoblast-Like Cells and Endothelial Cells: A Potential Cell Source for Dental Pulp Tissue Engineering.

ObjectivesDental pulp regeneration is considered an ideal approach for treating dental pulp disease. Because pulp is composed of various cells, determining the proper seed cells is critical. We explored the potential of human umbilical cord mesenchymal stem cells (hUCMSCs) as seed cells for dental pulp regeneration.MethodsLiquid extract of human treated dentin matrix (LE-TDM) was acquired to culture hUCMSCs. Odontoblast-specific markers were detected by western blot, qRT-PCR, and immunofluorescence assays. Endothelial differentiation of hUCMSCs was examined according to VEGF induction by western blot, qRT-PCR, and Matrigel assays. hUCMSCs and VEGF-induced hUCMSCs (V-hUCMSCs) were also cocultured in vivo for the Matrigel plug assay and in vitro for RNA-sequencing (RNA-seq). Finally, encapsulated mono-cultured hUCMSCs or cocultured hUCMSCs and V-hUCMSCs in scaffolds were injected into the root segments and transplanted into immunodeficient mice for dental pulp regeneration.ResultsUnder LE-TDM induction, hUCMSCs expressed specific odontoblast markers (DSPP, DMP-1, DSP). Under VEGF induction, hUCMSCs expressed functional endothelial markers (CD31, eNOs, vWF). In vivo, the Matrigel plug assay indicated that cocultured hUCMSCs and V-hUCMSCs formed extensive vessel-like structures. RNA-seq results indicated that cocultured V-hUCMSCs exhibited high Hif-1 signaling pathway activity. Both the hUCMSCs mono-culture and coculture groups showed pulp-like tissue regeneration. The cocultured group showed more extracellular matrix and vascularization than the mono-cultured group in vivo.ConclusionhUCMSCs can differentiate into odontoblast-like cells and functional endothelial cells. Cocultured hUCMSCs and V-hUCMSCs formed vessel-like structures and regenerated dental pulp-like tissue. Therefore, hUCMSCs can be used as an alternative seed cell source for angiogenesis and dental pulp regeneration.

Cotransplantation of human umbilical cord mesenchymal stem cells and endothelial cells for angiogenesis and pulp regeneration in vivo

AimsTo explored the potential of human umbilical cord mesenchymal stem cells (hUCMSCs) as seed cells for dental pulp regeneration and the possibility of cotransplantation hUCMSCs and endothelial cells (ECs) for angiogenesis and pulp regeneration in vivo. Materials and methodshUCMSCs and human umbilical vein endothelial cells (HUVECs) were cocultured for matrigel angiogenesis assay in vitro and Matrigel plug assay in vivo. Next, we used the transwell coculture system to coculture hUCMSCs and HUVECs in vitro for RNA- sequencing (RNA-seq). Last, encapsulated hUCMSCs and HUVECs in scaffolds were injected into the root segments, and transplanted into immunodeficient mice for dental pulp regeneration. Key findingsIn vitro Matrigel angiogenesis assay and in vivo Matrigel plug assay indicated that cocultured hUCMSCs and HUVECs promote vascular formation of HUVECs, especially in 1:5 (hUCMSCs:HUVECs) coculture group. The RNA-seq result indicated that cocultured HUVECs exhibited high Hif-1 signaling pathway activity. We performed the cell transfection assay to knock down HIF1A-AS2 in HUVECs and then coculture with hUCMSCs, and the expression of VEGFA, HIF1A and PECAM1 were reduced. In pulp regeneration assay, Cotransplantation of hUCMSCs and HUVECs (1,5) group showed pulp-like tissue regeneration. SignificanceCocultured hUCMSCs and HUVECs can promote vascular formation of HUVECs, and the optimal coculture ration is 1:5 (hUCMSCs:HUVECs). hUCMSCs promote angiogenesis of HUVECs through the long noncoding RNA HIF1A-AS2-activation of the Hif-1 signaling pathway. Cotransplantation of hUCMSCs and HUVECs can regenerate dental pulp-like tissue in vivo.

Regenerative Endodontics: A Paradigm Shift in Clinical Endodontics.

ABSTRACTPreserving the natural dentition in its normal form and function is one of the major goals of endodontic treatment. Re-establishing the lost vitality and development of root maturation in immature permanent teeth with pulp necrosis/apical periodontitis is quiet challenging clinically. The very basis of regenerative endodontics relies on the concept of tissue engineering using stem cells, biomimetic scaffold, and bioactive growth factors to regenerate the pulp tissue damaged by microbial infection, injury, or developmental defects. In clinical endodontics, this approach is referred to as a “paradigm shift.” Even though repair instead of true regeneration is achieved with current protocols, it is hoped that further research in the area of stem-cell-based tissue engineering will allow for true regeneration and improved treatment outcomes. The aim of this review is to discuss about the various aspects of regenerative endodontics, current clinical protocols, and the future of pulp regeneration techniques.

Effect of photobiomodulation therapy on regenerative endodontic procedures: a scoping review

The loss of dental pulp vitality and the subsequent need for conventional endodontic treatment have caused undesirable clinical outcomes, which become even more critical when dealing with immature permanent teeth. Photobiomodulation therapy could overcome these impairments by improving the environmental conditions, once it can compensate oxidative stress and increase blood supply to implanted stem cells, improving their survival rate and preventing their premature death. This study aimed to conduct a scoping review to evaluate if photobiomodulation therapy is able to influence the outcome of regenerative endodontic procedures. Relevant articles were searched and obtained from library sources and the following online databases: MEDLINE/PubMed database, SciVerseScopusTM (SS), and ISI Web of a ScienceTM up to November 2018. From 96 potentially relevant studies initially identified, 6 papers fulfilled the eligibility criteria and were considered for this review. These were in vitro (n = 4) and in vivo studies (n = 2) that applied wavelengths of 810 nm (n = 3) or 660 nm (n = 3), all in continuous wave. The energy densities applied were mostly between 2 and 5 J/cm2. Five out of the six studies showed that photobiomodulation therapy led to greater stem cell differentiation rates in vitro and improved pulp-like tissue regeneration in vivo, increasing tertiary dentin volumes and also improving pulp-like tissue formation. The studies showed that photobiomodulation therapy led to greater stem cell differentiation rates in vitro and improved pulp-like tissue regeneration in vivo, increasing tertiary dentin volumes and also improving pulp-like tissue formation. This scoping review showed that photobiomodulation therapy is able to influence positively the outcome of regenerative endodontic procedures. However, due to the small number of studies evaluated here, a secondary evaluation should be held forward as a continuation of this scoping review in order to warrant a safe and effective future use in humans.

Resolvin D2 Induces Resolution of Periapical Inflammation and Promotes Healing of Periapical Lesions in Rat Periapical Periodontitis.

Periapical periodontitis results from pulpal infection leading to pulpal necrosis and resorption of periapical bone. The current treatment is root canal therapy, which attempts to eliminate infection and necrotic tissue. But, in some cases periapical inflammation doesn't resolve even after treatment. Resolvins belongs to a large family of specialized pro-resolving lipid mediators that actively resolves inflammation signaling via specific receptors. Resolvin D2 (RvD2), a metabolite of docosahexaenoic acid (DHA), was tested as an intracanal medicament in rats in vivo. Mechanism was evaluated in rat primary dental pulp cells (DPCs) in vitro. The results demonstrate that RvD2 reduces inflammatory cell infiltrate, periapical lesion size, and fosters pulp like tissue regeneration and healing of periapical lesion. RvD2 enhanced expression of its receptor, GPR18, dentin matrix acidic phosphoprotein 1 (DMP1) and mineralization in vivo and in vitro. Moreover, RvD2 induces phosphorylation of Stat3 transcription factor in dental pulp cells. We conclude that intracanal treatment with RvD2 resolves inflammation and promoting calcification around root apex and healing of periapical bone lesions. The data suggest that RvD2 induces active resolution of inflammation with pulp-like tissue regeneration after root canal infection and thus maybe suitable for treating periapical lesions.

Pulp Regeneration Concepts for Nonvital Teeth: From Tissue Engineering to Clinical Approaches.

Following the basis of tissue engineering (Cells-Scaffold-Bioactive molecules), regenerative endodontic has emerged as a new concept of dental treatment. Clinical procedures have been proposed by endodontic practitioners willing to promote regenerative therapy. Preserving pulp vitality was a first approach. Later procedures aimed to regenerate a vascularized pulp in necrotic root canals. However, there is still no protocol allowing an effective regeneration of necrotic pulp tissue either in immature or mature teeth. This review explores in vitro and preclinical concepts developed during the last decade, especially the potential use of stem cells, bioactive molecules, and scaffolds, and makes a comparison with the goals achieved so far in clinical practice. Regeneration of pulp-like tissue has been shown in various experimental conditions. However, the appropriate techniques are currently in a developmental stage. The ideal combination of scaffolds and growth factors to obtain a complete regeneration of the pulp-dentin complex is still unknown. The use of stem cells, especially from pulp origin, sounds promising for pulp regeneration therapy, but it has not been applied so far for clinical endodontics, in case of necrotic teeth. The gap observed between the hope raised from in vitro experiments and the reality of endodontic treatments suggests that clinical success may be achieved without external stem cell application. Therefore, procedures using the concept of cell homing, through evoked bleeding that permit to recreate a living tissue that mimics the original pulp has been proposed. Perspectives for pulp tissue engineering in the near future include a better control of clinical parameters and pragmatic approach of the experimental results (autologous stem cells from cell homing, controlled release of growth factors). In the coming years, this therapeutic strategy will probably become a clinical reality, even for mature necrotic teeth.

PDGF-BB, NGF and BDNF enhance pulp-like tissue regeneration via cell homing

In this study, we investigated the cytobiological effects of PDGF-BB, NGF and BDNF on the culture of BMSCs from rats and explored a viable approach for regenerating ectopic dental pulp-like tissueviacell homing.

Histologic Observation of a Human Immature Permanent Tooth with Irreversible Pulpitis after Revascularization/Regeneration Procedure

IntroductionHistological studies of immature human permanent necrotic teeth with or without apical periodontitis after revascularization have not been reported. This case report describes the histological findings of tissue formed in the canal space of an immature permanent tooth #9 with irreversible pulpitis without apical periodontitis after revascularization. MethodsAn immature human permanent tooth #9 was fractured 3.5 weeks after revascularization and could not be retained. The tooth was extracted and prepared for routine histological and immunohistochemical evaluation in order to examine the nature of tissue formed in the root canal following the revascularization procedure. ResultsAt 3.5 weeks after revascularization, more than one half of the canal was filled with loose connective tissue similar to the pulp tissue. A layer of flattened odontoblast-like cells lined along the predentin. Layers of epithelial-like cells, similar to the Hertwig's epithelial root sheath, surrounded the root apex. No hard tissue was formed in the canal. ConclusionsBased on the histological findings in the present case, regeneration of pulp-like tissue is possible after revascularization. In this case, both the apical papilla and the Hertwig's epithelial root sheath survived in an immature permanent tooth despite irreversible pulpitis but without apical periodontitis.