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

Standardization of antimicrobial testing of dental devices

Objective: Dental device is a very broad term that can be used to include any foreign material or product that is introduced in the host oral cavity to replace missing tissues. These devices are subjected to different environments which include dental hard tissues, tissue fluids, blood and saliva. All dental devices are continuously challenged microbiologically and a number of failures in clinical management are related to microbial colonization. Thus, the assessment of the antimicrobial properties of dental devices are extremely important. In this paper, a classification of dental devices is being proposed. This classification distinguishes the devices based on whether they are implantable or not, and also sub-classified based on their specific application and the substrate receiving the device. Methods and Results A literature search was conducted to identify how dental devices have been tested with relation to the microbial strains used and whether the testing has been performed in isolation or reported with other relevant tests such as material characterization and biological activity. The results of the literature review were analyzed and recommendations for antimicrobial testing of dental devices are proposed. These recommendations include the need for the setting up of pre-testing parameters such as ageing and the details of the pre-testing sterilization procedures, as these may affect the material chemistry and the specification for antimicrobial testing to be done with specific single strains or polymicrobial that are native to the region where the device is located are also suggested. Testing can be undertaken in vitro, ex vivo and in vivo. Since the antimicrobial and biological activities influence/condition one another and the material chemistry may affect both the antimicrobial and biological testing this document also makes recommendations regarding biological assessment which can be carried out in isolation or integrated with the microbiological testing and also material testing methods including chemical and physical characterization of bulk, surface, eluted and degraded materials as well as physical characterization methods. Significance The level of standardization of antimicrobial testing for the dental devices needs to be based on the device location and host interaction in order to increase the clinical applicability of the mentioned tests

Advanced in Vitro Experimental Models for Tissue Engineering-based Reconstruction of a 3D Dentin/pulp Complex: a Literature Review

International audienc

THE INFLUENCE OF SANDBLASTING AND AGING ON Y-TZP CERAMIC DURING STATIC AND DYNAMIC LOADING

The purpose of this in vitro study was to investigate the mechanical response of zirconia ceramic during torsional, bending and vibrational loading, before and after aging and surface treatments. Three types of loading where imposed upon zirconia specimens, torsion, bending and vibration. The effects of aging, sandblasting and both on the shear modulus, Young's modulus, Poisson's ratio, storage modulus, loss modulus and tanδ were investigated, while surface characterization was performed through Scanning Electron Microscopy (SEM) and X-Ray Diffraction Analysis (XRD). Sandblasting as well as the aging environment caused a raise of zirconia's shear modulus, young's modulus and storage modulus. The most prominent increase, in these parameters was observed when both treatments where combined. Under the limitations of this in-vitro study it can be concluded that the proposed sandblasting and aging procedures do not impair the mechanical properties of zirconia ceramics, as long as the amount of monoclinic zirconia content is kept under low values, capable to induce the transformation toughening mechanism

The Use of Lasers in Dental Materials: A Review

Lasers have been well integrated in clinical dentistry for the last two decades, providing clinical alternatives in the management of both soft and hard tissues with an expanding use in the field of dental materials. One of their main advantages is that they can deliver very low to very high concentrated power at an exact point on any substrate by all possible means. The aim of this review is to thoroughly analyze the use of lasers in the processing of dental materials and to enlighten the new trends in laser technology focused on dental material management. New approaches for the elaboration of dental materials that require high energy levels and delicate processing, such as metals, ceramics, and resins are provided, while time consuming laboratory procedures, such as cutting restorative materials, welding, and sintering are facilitated. In addition, surface characteristics of titanium alloys and high strength ceramics can be altered. Finally, the potential of lasers to increase the adhesion of zirconia ceramics to different substrates has been tested for all laser devices, including a new ultrafast generation of lasers

Biocompatibility assessment of resin-based cements on vascularized dentin/pulp tissue-engineered analogues

International audienceObjectives. A three-dimensional (3D) dentin/pulp tissue analogue, resembling the human natural tissue has been engineered in an in vitro setup, aiming to assess the cytocompatibility of resin-based dental restorative cements. Methods. Stem Cells from Apical Papilla (SCAP) and Human Umbilical Vein Endothelial Cells (HUVEC) were embedded in Collagen-I/Fibrin hydrogels at 1:3 ratio within 24-well plates. Hanging culture inserts were placed over the hydrogels, housing an odontoblast-like cell layer and a human treated-dentin barrier. Shear modulus of the hydrogels at 3.5 and 5 mg/ml was evaluated by dynamic mechanical analysis. Eluates of two resin-based cements, a dual-cure-(Breeze TM , Pentron: Cement-1/C1), and a self-adhesive cement (SpeedCEMplus TM , Ivoclar-Vivadent: Cement-2/C2) were applied into the dentin/pulp tissue analogue after prestimulation with LPS. Cytocompatibility was assessed by MTT assay, live/dead staining and real-time PCR analysis. Results. Both hydrogel concentrations showed similar shear moduli to the natural pulp until day (D) 7, while the 5 mg/ml-hydrogel substantially increased stiffness by D14. Both cements caused no significant toxicity to the dentin/pulp tissue analogue. C1 induced stimulation (p < 0.01) of cell viability (158 ± 3%, 72 h), while pre-stimulation with LPS attenuated this effect. C2 (±LPS) caused minor reduction of viability (15-20%, 24 h) that recovered at 72 h for the LPS+ group. Both cements caused upregulation of VEGF, ANGP-1, and downregulation of the respective receptors VEGFR-2 and Tie-1