Human dental pulp stem/stromal cells in clinical practice

Dental pulp stem/stromal cells(DPSCs)are fibroblast-like,neural crest-derived,and multipotent cells that can differentiate into several lineages.They are relatively easy to isolate from healthy and inflamed pulps,with little ethical concerns and can be successfully cryopreserved and thawed.The therapeutic effects of DPSCs derived from animal or human sources have been extensively studied through in-vitro and in-vivo animal experiments and the findings indicated that DPSCs are effective not only for dental diseases but also for systemic diseases.Understanding that translational research is a critical step through which the fundamental scientific discoveries could be translated into applicable diagnostics and therapeutics that directly benefit humans,several clinical studies were carried out to generate evidence for the efficacy and safety of autogenous or allogeneic human DPSCs(hDPSCs)as a treatment modality for use in cell-based therapy,regenerative medicine/dentistry and tissue engineering.In clinical medicine,hDPSCs were effective for treating acute ischemic stroke and human exfoliated deciduous teeth-conditioned medium(SHED-CM)repaired vascular damage of the corpus cavernous,which is the main cause of erectile dysfunction.Whereas in clinical dentistry,autologous SHED was able to rege-nerate necrotic dental pulp after implantation into injured teeth,and micrografts enriched with autologous hDPSCs and collagen sponge were considered a treatment option for human intrabony defects.In contrast,hDPSCs did not add a significant regenerative effect when they were used for the treatment of post-extraction sockets.Large-scale clinical studies across diverse populations are still lacking to provide robust evidence on the safety and efficacy of hDPSCs as a new treatment option for various human diseases including dental-related problems.

Therapeutic potential of periodontal ligament stem cells

Inflammatory periodontal disease known as periodontitis is one of the most common conditions that affect human teeth and often leads to tooth loss.Due to the complexity of the periodontium,which is composed of several tissues,its regeneration and subsequent return to a homeostatic state is challenging with the therapies currently available.Cellular therapy is increasingly becoming an alternative in regenerative medicine/dentistry,especially therapies using mesenchymal stem cells,as they can be isolated from a myriad of tissues.Periodontal ligament stem cells(PDLSCs)are probably the most adequate to be used as a cell source with the aim of regenerating the periodontium.Biological insights have also highlighted PDLSCs as promising immunomodulator agents.In this review,we explore the state of knowledge regarding the properties of PDLSCs,as well as their therapeutic potential,describing current and future clinical applications based on tissue engineering techniques.

Wnt and BMP signaling crosstalk in regulating dental stem cells:Implications in dental tissue engineering

Tooth is a complex hard tissue organ and consists of multiple cell types that are regulated by important signaling pathways such as Wnt and BMP signaling.Serious injuries and/or loss of tooth or periodontal tissues may significantly impact aesthetic appearance,essential oral functions and the quality of life.Regenerative dentistry holds great promise in treating oral/dental disorders.The past decade has witnessed a rapid expansion of our understanding of the biological features of dental stem cells,along with the signaling mechanisms governing stem cell self-renewal and differentiation.In this review,we first summarize the biological characteristics of seven types of dental stem cells,including dental pulp stem cells,stem cells from apical papilla,stem cells from human exfoliated deciduous teeth,dental follicle precursor cells,periodontal ligament stem cells,alveolar bone-derived mesenchymal stem cells(MSCs),and MSCs from gingiva.We then focus on how these stem cells are regulated by bone morphogenetic protein(BMP)and/or Wnt signaling by examining the interplays between these pathways.Lastly,we analyze the current status of dental tissue engineering strategies that utilize oral/dental stem cells by harnessing the interplays between BMP and Wnt pathways.We also highlight the challenges that must be addressed before the dental stem cells may reach any clinical applications.Thus,we can expect to witness significant progresses to be made in regenerative dentistry in the coming decade.

Development and challenges of cells-and materials-based tooth regeneration

Tooth defect and loss are common clinical diseases in stomatology.With the extension of life expectancy,there is an increasing demand for tooth tissue and whole tooth regeneration.Compared with traditional oral prosthetic treatment,tooth regeneration has unique advantages and has become one of the hotspots towards oral biomedical treatment.In this review,we discussed the development and challenges of tooth regeneration based on cells and materials,including tooth enamel,dentin,dental pulp,cementum,dentin-pulp complex,and the whole tooth regeneration,in order to provide a comprehensive,up-to-date,illustrative overview of tooth regeneration issues.The mechanisms of the regeneration were also summarized and discussed.Moreover,this review hints the future perspective and research direction of tooth regeneration in the challenging field of regenerative dentistry.