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Mesenchymal Stem Cells from Dental Tissues
Published in Vincenzo Guarino, Marco Antonio Alvarez-Pérez, Current Advances in Oral and Craniofacial Tissue Engineering, 2020
Febe Carolina Vázquez Vázquez, Jael Adrián Vergara-Lope Núñez, Juan José Montesinos, Patricia González-Alva
In their study, Seo et al. (Seo et al. 2004) demonstrated that PDLSCs were similar to other MSCs regarding their expression of STRO-1/CD146, and suggested that PDLSCs might also be derived from a population of perivascular cells. Moreover, later works showed that PDLSCs’ differentiation could be promoted by Hertwig’s epithelial root sheath cells in vitro (Sonoyama et al. 2007). Besides, the lineages of differentiation for PDLSCs are cementoblast-like cells, adipocytes and fibroblasts that secrete collagen type I (Sedgley and Botero 2012).
Odontogenic Epithelium and its Residues
Published in Roger M. Browne, Investigative Pathology of the Odontogenic Cysts, 2019
There have been several reports of immunocytochemical studies at both light- and electron microscopical levels using polyclonal antisera raised to enamel proteins.79–86 One group using a rabbit antiserum raised to 26 kDa, SDS-denatured mouse amelogenins, but reactive with both amelogenins and enamelins, have investigated the immunoelectron microscopical localization of enamel proteins in the continuously erupting rat incisor.80,81 These studies demonstrated localization within synthetic and secretory organelles and within lysosomal structures of ameloblasts, during both secretory and maturation phases of amelogenesis, suggesting that the synthesis, secretion, and degradation of enamel proteins occurs simultaneously. Unfortunately, as polyclonal antisera react with both amelogenins and enamelins it was not possible to determine whether one or both classes of enamel proteins were involved in synthetic, secretory and degradative phases. Furthermore, there is no indication of whether the antiserum reacted with any tissues other than enamel organ/matrix. More recently, similar studies have been performed on feline tooth germs as cat teeth have been proposed as a good model for enamel formation in man.87 The similar localization patterns obtained82 suggest that the observations are generally applicable to exhibiting limited eruption. In another study a polyclonal rabbit antiserum raised to the ‘tuft’ protein of mature human enamel86 stained endoplasmic reticulum, Golgi and secretory vesicles of ameloblasts in addition to material between the Tomes processes. Interestingly, although no cross-reactivity with tonofilaments was observed immunocytochemically, this antiserum did react with epidermal keratins on Western blot analysis suggesting a possible relationship between keratins and enamel proteins. Further support for such a relationship has been obtained and extended using both polyclonal and monoclonal antibodies to keratins in immunoblotting and immunocytochemical studies at the light microscopical level.3 This latter study, which also investigated the reactivity of a monoclonal antibody to a dentin protein, indicated that keratins, enamel matrix proteins and matrix proteins of dentin and bone were antigenically related. The concept that matrix proteins from various tooth tissues are antigenically related is also supported by recent in vitro and in vivo studies11 demonstrating that Hertwig’s epithelial root sheath (HERS) cells synthesize and secrete enamel-related proteins along the forming root surfaces of mouse molars. These HERS derived intermediate cementum proteins shared one or more epitopes but had different amino acid compositions.
The dental manifestations and orthodontic implications of hypoparathyroidism in childhood
Published in Journal of Orthodontics, 2018
Amy Arora Gallacher, M. N. Pemberton, D. T. Waring
Previous case reports have reported a number of dental anomalies in patients with both hypoparathyroidism and pseudohypoparathyroidism occurring in childhood including hypodontia, microdontia, shortened and round roots, enamel hypoplasia, malformed root, enlarged pulp chambers, pulp calcifications and delayed tooth eruption (Greenburg et al. 1969; Nally 1970; Weltman et al. 2010; Kamarthi et al. 2013; Sirangarajan et al. 2014). It appears that these dental anomalies occur as a result of the low serum calcium that occurs as a result of the reduced PTH coinciding with dental development (Bronsky et al. 1958). Disturbances in mineralisation, alterations in the formation of the Hertwig epithelial root sheath, lack of differentiation of odontoblasts and disturbed resorptive processes (Jensen et al. 1981) have been proposed as mechanisms for these anomalies.
Dental stem cells for tooth regeneration: how far have we come and where next?
Published in Expert Opinion on Biological Therapy, 2023
The result of the latter study seems to contradict the use of xenogeneic materials, but such side effects can also be useful for successful cell therapy. For example, new insights have been gained from basic research on apoptotic death after stem cell implantation in an ischemic-hypoxic environment. Li et al. explored the role played by the extracellular vesicles (EVs) derived from apoptotic cells [54]. They used apoptotic vesicles from SHED and showed that these vesicles were taken up by endothelial cells and elevated the expression of angiogenesis-related genes, resulting in pulp revascularization [54]. These results point to the importance of apoptosis in tissue regeneration, which has previously also been discussed for osteogenic differentiation of mesenchymal stem cells [55]. Moreover, another study is also an excellent example of EVs for dental stem cell-based regenerative therapies. Guo et al. showed that exosomes, which are membrane bound EVs, strengthened bone regeneration of DPSCs through the activation of mitochondrial aerobic metabolism. They showed that exosomes were rich in mRNA for mitochondrial transcription factor A, which shuttled to promote osteogenic differentiation by activating mitochondrial aerobic metabolism [56]. A possible alternative to the manipulation of the mitochondrial metabolic state by EVs could be thermoplasmonic regulation with a laser-based treatment, which could significantly improve the differentiation of DPSCs [57]. Interestingly, another study exploited the idea that the formation of dentin-pulp involves complex epithelial–mesenchymal interactions between Hertwig’s epithelial root sheath cells (HERS) and dental papilla cells (DPCs) [58]. They showed that EVs derived from Hertwig’s epithelial root sheath cells were also able to promote the regeneration of dentin-pulp tissue in an in vivo tooth root slice model.
Dental stem cells in tooth regeneration and repair in the future
Published in Expert Opinion on Biological Therapy, 2018
Christian Morsczeck, Torsten E. Reichert
For the initiation of the tooth root development the Hertwig’s epithelial root sheath is formed as an extension of the enamel organ. This thin cell-sheath separates a second dental mesenchymal tooth-germ tissue from the dental mesenchymal pulp/dentin complex. This tooth germ tissue is known as the dental sac or the dent follicle and surrounds the tooth germ. The dental follicle is crucial both for tooth eruption and for the development of the tooth root [79,80]. It contains dental mesenchymal progenitor cells for the periodontium, which consists of the alveolar bone, the PDL, and the cementum. Moreover, this tissue contains also epithelial cells, which are derived from the epithelial cells of the Hertwig’s epithelial root sheath, which disappears during tooth root development [79]. The dental follicle is similar to the dental apical pad-like tissue and can be isolated from impacted human wisdom teeth. It contains multipotent ectomesenchymal stem cells that are known as dental follicle precursor cells, dental follicle stem cells, or dental follicle cells (DFCs). Human DFCs were initially isolated as plastic-adherent and clonogenic cells [81]. They have a DPSC-like morphology and also express typical markers of progenitor/stem cells such as NESTIN, NOTCH-1, CD44, CD105, and STRO-1 [81,82]. DFCs can be cultivated under serum-free cell culture conditions for an extended period of time and then behave like neural progenitor cells [83]. DFCs are multipotent stem cells, and especially the genuine precursor cells of periodontal tissue cells [81–85]. Even under in vitro condition, DFCs formed a robust connective tissue-like structure with many mineralized clusters after long-term cultures in osteogenic differentiation medium. Interestingly, this periodontium-like tissue occasionally had blood-vessel-like structures [81]. We suppose that DFCs should be considered for the treatment of periodontitis and/or for the reconstruction of a tooth attachment apparatus [86,87]. Tian and colleagues, for example, showed that rat DFCs formed a tooth root when seeded on scaffolds of a treated dentin matrix (TDM) and transplanted into alveolar fossa microenvironment [88]. Interestingly, this particular environment is necessary for the production of a tooth root, since DFCs do not form a tooth root after transplantation in skull and omental pockets [88]. Unfortunately, autologous TDM is rare as scaffolds and the use of xenogenic scaffolds, for example, porcine TDM, in combination with allogeneic DFCs is problematic, since this combination induces bone resorption [89]. DFCs are also considered for bone regeneration, because they support bone regeneration in critical size defect models of the calvaria of immunocompromised rats [86]. Here, compared to untreated animals, stem cells improved the process of bone regeneration. Therefore, DFCs as the genuine progenitors of alveolar osteoblasts are an attractive source for bone tissue engineering. We expect DFCs to be taken into account for dental stem cell-based therapies in the future.