Stem Cells of Dental Origin: Current Research Trends and Key Milestones towards Clinical Application

International audienceDental Mesenchymal StemCells (MSCs), includingDental Pulp StemCells (DPSCs), StemCells fromHuman ExfoliatedDeciduous teeth (SHED), and Stem Cells From Apical Papilla (SCAP), have been extensively studied using highly sophisticated in vitro and in vivo systems, yielding substantially improved understanding of their intriguing biological properties. Their capacity to reconstitute various dental and nondental tissues and the inherent angiogenic, neurogenic, and immunomodulatory properties of their secretome have been a subject of meticulous and costly research by various groups over the past decade. Key milestone achievements have exemplified their clinical utility in Regenerative Dentistry, as surrogate therapeutic modules for conventional biomaterial-based approaches, offering regeneration of damaged oral tissues instead of simply ``filling the gaps.'' Thus, the essential next step to validate these immense advances is the implementation of well-designed clinical trials paving the way for exploiting these fascinating research achievements for patient well-being: the ultimate aim of this ground breaking technology. This review paper presents a concise overviewof the major biological properties of the human dental MSCs, critical for the translational pathway ``from bench to clinic.'

Location Leakage in Federated Signal Maps

We consider the problem of predicting cellular network performance (signal maps) from measurements collected by several mobile devices. We formulate the problem within the online federated learning framework: (i) federated learning (FL) enables users to collaboratively train a model, while keeping their training data on their devices; (ii) measurements are collected as users move around over time and are used for local training in an online fashion. We consider an honest-but-curious server, who observes the updates from target users participating in FL and infers their location using a deep leakage from gradients (DLG) type of attack, originally developed to reconstruct training data of DNN image classifiers. We make the key observation that a DLG attack, applied to our setting, infers the average location of a batch of local data, and can thus be used to reconstruct the target users' trajectory at a coarse granularity. We build on this observation to protect location privacy, in our setting, by revisiting and designing mechanisms within the federated learning framework including: tuning the FL parameters for averaging, curating local batches so as to mislead the DLG attacker, and aggregating across multiple users with different trajectories. We evaluate the performance of our algorithms through both analysis and simulation based on real-world mobile datasets, and we show that they achieve a good privacy-utility tradeoff

Characterization of the soft-tissue wall lining residual periodontal pockets and implications in periodontal wound healing

AIM To characterize the soft-tissue wall of remaining periodontal pockets for wound healing-related parameters versus healthy gingival crevices in the same individuals. MATERIALS AND METHODS Gingival tissues collected from the diseased interface of pockets (GT biopsies) and from healthy gingival crevices (G biopsies) were subjected to RT$^{2}$-profiler PCR Array for wound healing-related markers and network analysis of differentially expressed genes. Lymphangiogenesis-related gene expression was determined by qRT-PCR. The migration potential of mesenchymal stem cells isolated from GT biopsies (GT-MSCs) and G biopsies (G-MSCs) was evaluated by the scratch- and the transwell migration assays. The total collagen protein content was determined in GT-MSCs and G-MSCs homogenates. RESULTS Gene-ontology analysis on significantly upregulated genes expressed in GT biopsies revealed enrichment of several genes involved in processes related to matrix remodeling, collagen deposition, and integrin signaling. No significantly expressed genes were seen in G biopsies. Regarding lymphangiogenesis-related genes, GT biopsies demonstrated greater expression for PROX1 than G biopsies (p = 0.05). Lower migration potential (p < 0.001), yet greater production of collagen protein (p = 0.05), was found for GT-MSCs over G-MSCs. CONCLUSION Differential expression patterns of various molecular pathways in biopsies and cell cultures of diseased versus healthy gingival tissues indicate a potential of the former for tissue remodeling and repair. CLINICAL RELEVANCE In the course of periodontitis, granulation tissue is formed within a periodontal defect in an attempt to reconstruct the site. Following treatment procedures periodontal granulation tissue remains inflamed but appears to retain healing potential

Design of a laboratory bioreactor for engineering articular cartilage based on 3D printed nasal septum-like scaffolds

«Η εκφύλιση των χόνδρων είναι μια σοβαρή πάθηση που επηρεάζει μεγάλο μέρος του πληθυσμού σε όλο το ηλικιακό φάσμα. Επί του παρόντος χρησιμοποιούνται διάφορες τεχνικές αποκατάστασης για μικρής έκτασης βλάβες όπως η αρθροπλαστική απόξεσης και ο υποχονδρικός τρυπανισμός, οι οποίες δεν μπορούν να επιδιορθώσουν βλάβες μεγαλύτερης έκτασης. Η Αναγεννητική Ιατρική προωθεί την Μηχανική Ιστών στο προσκήνιο των σύγχρονων μηχανικών τεχνικών, συνδυάζοντας καινοτόμα βιοσυμβατά υλικά, νέες μεθόδους μηχανικής ιστών όπως η τεχνολογία 3D εκτύπωσης και βιοδιαδικασίες που αποσκοπούν στην δημιουργία ποιοτικών μοσχευμάτων για εκτεταμένες βλάβες των χόνδρων. Κατάλληλο κυτταρικό περιβάλλον για δημιουργία ιστών μπορεί να επιτευχθεί με την ανάπτυξη αυτών των μοσχευμάτων σε βιοαντιδραστήρες. O κάθε βιοαντιδραστήρας χρησιμοποιεί διαφορετικές αρχές καλλιέργειας, και ορισμένοι από αυτούς όπως οι μικτού τύπου και οι βιοαντιδραστήρες διαπότισης επιστρατεύουν την άσκηση μηχανικών δυνάμεων επί του ικριώματος ώστε να επιτευχθεί μεγάλη κυτταρική πυκνότητα και ενισχυμένες μηχανικές ιδιότητες που οδηγούν στην δημιουργία καλύτερης ποιότητας χόνδρου. Αυτές οι ιδιαιτερότητες των βιοαντιδραστήρων μπορούν να αποτελέσουν εφαλτήριο κατασκευής εργαστηριακών βιοαντιδραστήρων, για την καλλιέργεια 3D εκτυπωμένων ρινικών διαφραγμάτων ως ένα λειτουργικό παράδειγμα υαλώδους χόνδρου».Cartilage degeneration is a severe disease affecting a significant part of the population at all ages. Various treatment modalities are currently used for small-sized cartilage defects, such as abrasion arthroplasty and subchondral drilling, but fail to repair larger-scale damages. Regenerative Medicine pushes Tissue Engineering (TE) to the forefront of modern engineering techniques combining novel biocompatible materials, new tissue engineering methods, like 3D printing technology and bioprocesses trying to create quality transplants for large cartilage defects. The appropriate cell environment for engineered tissues can be achieved through growth of the tissue-engineered constructs into bioreactors. Each bioreactor uses different principles for culturing processes, and some of them mostly mixed and perfusion bioreactors, use different kind of mechanical forces on the scaffold to achieve high cell densities, enhanced mechanical properties leading to better quality of engineered cartilage. These advantageous particularities can be used to create a laboratory bioreactor design, for culturing 3D printed nasal septum cartilage as a working example of hyaline cartilage

Translational research for nasal septum cartilage regeneration with chondrocytes derived from differentiated human adipose mesenchymal stem cells

Η εργασία αφορά στη μεταφραστική έρευνα ιστοτεχνολογίας και συγκεκριμένα στη δημιουργία ανθρώπινου ρινικού διαφράγματος με τη χρήση ηλεκτρονικά υποβοηθούμενου σχεδιασμού και τρισδιάστατης εκτύπωσης τρισδιάστατου (3D) πορώδους ικριώματος χιτοζάνης/ζελατίνης (CAD/CAM). Το ικρίωμα θα χρησιμοποιηθεί για να αποικιστεί από χρονδροκύτταρα που προκύπτουν από διαφοροποιημένα μεσεγχυματικά κύτταρα ανθρώπου προερχόμενα από λιπώδη ιστό (Adipose Tissue Mesenchymal Stem Cells-AD- MSCs). Η όλη διαδικασία επιτυγχάνεται με τη χρήση βιοαντιδραστήρα.Τα μεσεγχυματικά κύτταρα είναι πολυδύναμα βλαστοκύτταρα που μπορούν να απομονωθούν από το μυελό των οστώνκαι το λιπώδη ιστό. Τα κύτταρα αυτά έχουν τη δυνατότητα να διαφοροποιούνται, υπό εργαστηριακές συνθήκες, σε οστεοκύτταρα, χονδροκύτταρα, και λιποκύτταρα. Στην παρούσα μελέτη ανθρώπινα μεσεγχυματικά κύτταρα απομονώθηκαν από λιπώδη ιστό και καλλιεργήθηκαν in vitro. Η έκφραση των αντιγόνων επιφανείας CD90, CD73, σε συνδυασμό με την απουσία του μάρτυρα CD45 επιβεβαιώνουν την επιτυχή απομόνωση μεσεγχυματικών βλαστικών κυττάρων, με χρήση κυτταρομετρίας ροής. Έπειτα από 21 ημέρες από την επαγωγή στοχευόμενης διαφοροποίησης τα βλαστοκύτταρα διαφοροποιήθηκαν σε χονδροκύτταρα και χαρακτηρίστηκαν ιστολογικά με χρώση κυανού της τολουιδίνης και μοριακά με RTPCR για δείκτες διαφοροποίησης όπως η αγκρεκάνη. Με τη χρήση του τρισδιάστατου εκτυπωτή δημιουργήθηκε υπό κλίμακα ικρίωμα ρινικού χόνδρου από PLA. Η διαδικασία θα ολοκληρωθεί με την εκτύπωση του υπό διερεύνηση υλικού χιτοζάνης/ζελατίνης σε 3D ικρίωμα και αφού εμποτιστεί με χονδροκύτταρα θα μεταφερθεί στον βιοαντιδραστήρα.Mesenchymal stem cells (MSCs) are multipotent cells isolated from various tissues, mainly from the bone marrow and adipose tissue. Their ability to differentiate into osteoblasts, chondrocytes or adipocytes renders them a promising clinical tool for injury repair and tissue regeneration. In the current study, MSCs were isolated from human adipose tissue (hAD-MSCs) and were triggered to differentiate into chondrocytes in vitro. Expression of mesenchymal stem cell markers, such as CD90 and CD73, in combination with the absence of hematopoietic markers, such as CD45, proves via flow cytometry the successful isolation of MSCs. Histologic staining with Toluidine blue and real time PCR analysis for the expression of the chondrogenic marker aggrecan (ACAN) verified the successful chondrogenic differentiation of AD-MSCs. Using Poly Lactic-Acid as scaffolding material, a three-dimensional scaffold with customized architecture, controlled porosity and interconnected porous structure was fabricated using 3D printing. The produced scaffold represents the morphology of the nasal septum cartilage. We aspire, to see this scaffold with the differentiated chondrocytes and culture the complex under the appropriate micoenvironmental conditions of a bioreactor system in order to regenerate a potential cartilage transplant. This in vitro study expands the potentials of human AD-MSCs to be used in clinic for alleviation of cartilage defects and tissue engineering in Greece and worldwide

Sol-Gel Derived Mg-Based Ceramic Scaffolds Doped with Zinc or Copper Ions: Preliminary Results on Their Synthesis, Characterization, and Biocompatibility

Glass-ceramic scaffolds containing Mg have shown recently the potential to enhance the proliferation, differentiation, and biomineralization of stem cells in vitro, property that makes them promising candidates for dental tissue regeneration. An additional property of a scaffold aimed at dental tissue regeneration is to protect the regeneration process against oral bacteria penetration. In this respect, novel bioactive scaffolds containing Mg2+ and Cu2+ or Zn2+, ions known for their antimicrobial properties, were synthesized by the foam replica technique and tested regarding their bioactive response in SBF, mechanical properties, degradation, and porosity. Finally their ability to support the attachment and long-term proliferation of Dental Pulp Stem Cells (DPSCs) was also evaluated. The results showed that conversely to their bioactive response in SBF solution, Zn-doped scaffolds proved to respond adequately regarding their mechanical strength and to be efficient regarding their biological response, in comparison to Cu-doped scaffolds, which makes them promising candidates for targeted dental stem cell odontogenic differentiation and calcified dental tissue engineering

Molecular Toxicology of Substances Released from Resin–Based Dental Restorative Materials

Resin-based dental restorative materials are extensively used today in dentistry. However, significant concerns still remain regarding their biocompatibility. For this reason, significant scientific effort has been focused on the determination of the molecular toxicology of substances released by these biomaterials, using several tools for risk assessment, including exposure assessment, hazard identification and dose-response analysis. These studies have shown that substances released by these materials can cause significant cytotoxic and genotoxic effects, leading to irreversible disturbance of basic cellular functions. The aim of this article is to review current knowledge related to dental composites’ molecular toxicology and to give implications for possible improvements concerning their biocompatibility

Molecular Toxicology of Substances Released from Resin–Based Dental Restorative Materials

Resin-based dental restorative materials are extensively used today in dentistry. However, significant concerns still remain regarding their biocompatibility. For this reason, significant scientific effort has been focused on the determination of the molecular toxicology of substances released by these biomaterials, using several tools for risk assessment, including exposure assessment, hazard identification and dose-response analysis. These studies have shown that substances released by these materials can cause significant cytotoxic and genotoxic effects, leading to irreversible disturbance of basic cellular functions. The aim of this article is to review current knowledge related to dental composites’ molecular toxicology and to give implications for possible improvements concerning their biocompatibility