Nanoengineered Osteoinductive and Elastomeric Scaffolds for Bone Tissue Engineering

Comparative study of iodine-doped and undoped pyrrole grafting with plasma on poly (glycerol sebacate) scaffolds and its human dental pulp stem cells compatibility

This study addresses the morphological and chemical characterization of PGS scaffolds after (6, 12, 18, 24, and 30 min) residence in undoped pyrrole plasma (PGS-PPy) and the evaluation of cell viability with human dental pulp stem cells (hDPSCs). The results were compared with a previous study that used iodine-doped pyrrole (PGS-PPy/I). Analyses through SEM and AFM revealed alterations in the topography and quantity of deposited PPy particles. FTIR spectra of PGS-PPy scaffolds confirmed the presence of characteristic absorption peaks of PPy, with higher intensities observed in the nitrile and -C≡C- groups compared to PGS-PPy/I scaffolds, while raman spectra indicated a lower presence of polaron N+ groups. On the other hand, PGS scaffolds modified with PPy exhibited lower cytotoxicity compared to PGS-PPy/I scaffolds, as evidenced by the Live/Dead assay. Furthermore, the PGS-PPy scaffolds at 6 and 12 min, and particularly the PGS-PPy/I scaffold at 6 min, showed the best results in terms of cell viability by the fifth day of culture. The findings of this study suggest that undoped pyrrole plasma modification for short durations could also be a viable option to enhance the interaction with hDPSCs, especially when the treatment times range between 6 min and 12 min.

Nano-laponite encapsulated coaxial fiber scaffold promotes endochondral osteogenesis

Osteoinductive supplements without side effects stand out from the growth factors and drugs widely used in bone tissue engineering. Lithium magnesium sodium silicate hydrate (laponite) nanoflake is a promising bioactive component for bone regeneration, attributed to its inherent biosafety and effective osteoinductivity. Up to now, the in vivo osteogenic potential and mechanisms of laponite-encapsulated fibrous membranes remain largely unexplored. This study presents a unique method for homogeneously integrating high concentrations of laponite RDS into a polycaprolactone (PCL) matrix by dispersing laponite RDS sol into the polymer solution. Subsequently, a core-shell fibrous membrane (10RP-PG), embedding laponite-loaded PCL in its core, was crafted using coaxial electrospinning. The PCL core's slow degradation and the shell's gradient degradation enabled the sustained release of bioactive ions (Si and Mg) from laponite. In vivo studies on a critical-sized calvarial bone defect model demonstrated that the 10RP-PG membrane markedly enhanced bone formation and remodeling by accelerating the process of endochondral ossification. Further transcriptome analysis suggested that osteogenesis in the 10RP-PG membrane is driven by Mg and Si from endocytosed laponite, activating pathways related to ossification and endochondral ossification, including Hippo, Wnt and Notch. The fabricated nanocomposite fibrous membranes hold great promise in the fields of critical-sized bone defect repair.

Preparation of Cu2+/TA/HAP composite coating with anti-bacterial and osteogenic potential on 3D-printed porous Ti alloy scaffolds for orthopedic applications

Because of stress shielding effects, traditional titanium (Ti) alloy scaffolds have a high elastic modulus, which might promote looseness and bone disintegration surrounding the implant, increasing the likelihood of a second surgery. In contrast, 3D-printed porous Ti alloy scaffolds can reduce the scaffold weight while enhancing biocompatibility. Further, these scaffolds' porous nature allows bone tissue ingrowth as well as strong pore connectivity, which can improve nutrient absorption. Nevertheless, bare Ti alloy implants may fail because of inadequate bone integration; hence, adding a coating on the implant surface is an effective technique for improving implant stability. In this study, a composite coating comprising hydroxyapatite (HAP), chitosan (CS), tannic acid (TA) and copper ions (Cu2+) (Cu2+/TA/HAP composite coating) was prepared on the surface of 3D printed porous Ti alloy scaffolds using electrophoretic deposition. Using the standard plate count method, Live/Dead bacteria staining assay, FITC Phalloidin and 4',6-diamidino-2-phenylindole staining assay, and live/dead staining of cells we determined that the composite coating has better antibacterial properties and cytocompatibility as well as lower cytotoxicity. The Alkaline Phosphatase assay revealed that the coating results showed good osteogenesis potential. Overall, the composite coatings produced in this investigation give new potential for the application of Ti alloys in clinics.

Development of a rapid-shaping and user-friendly membrane with long-lasting space maintenance for guided bone regeneration

The success of guided bone regeneration (GBR) surgery depends largely on the use of GBR membranes to maintain space for bone regeneration and prevent soft tissue ingrowth. However, currently available commercial degradable GBR membranes are often limited by poor space maintenance ability and require additional suture or nail for fixation. To overcome these limitations, we developed a rapid-shaping, adhesive, and user-friendly GBR membrane (PLGA film-PGN) with long-lasting space maintenance by immersing an electrospun poly(lactide-co-glycolic acid) film in a photo-crosslinkable hydrogel composed of polyethylene glycol diacrylate, gelatin methacryloyl, and nanosilicate (PGN). The PGN hydrogel significantly improved the mechanical strength of the PLGA film-PGN and endowed it with plasticity and adhesive properties, making it more maneuverable. The maximum bending force that the PLGA film-PGN could withstand was over 55 times higher than that of the HEAL ALL film (a commonly used commercial GBR membrane). PLGA film-PGN also promoted the proliferation and osteogenic differentiation of rBMSCs. According to a critical-size rat calvarial defect model, PLGA film-PGN maintained the space within the defect area and significantly enhanced bone formation 4 weeks after the surgery. To conclude, the study provided a novel perspective on GBR membrane design and the multifunctional PLGA film-PGN membrane demonstrated great potential for bone defect reconstruction.

Chitosan, Gelatin, and Collagen Hydrogels for Bone Regeneration

Hydrogels are versatile biomaterials characterized by three-dimensional, cross-linked, highly hydrated polymeric networks. These polymers exhibit a great variety of biochemical and biophysical properties, which allow for the diffusion of diverse molecules, such as drugs, active ingredients, growth factors, and nanoparticles. Meanwhile, these polymers can control chemical and molecular interactions at the cellular level. The polymeric network can be molded into different structures, imitating the structural characteristics of surrounding tissues and bone defects. Interestingly, the application of hydrogels in bone tissue engineering (BTE) has been gathering significant attention due to the beneficial bone improvement results that have been achieved. Moreover, essential clinical and osteoblastic fate-controlling advances have been achieved with the use of synthetic polymers in the production of hydrogels. However, current trends look towards fabricating hydrogels from biological precursors, such as biopolymers, due to the high biocompatibility, degradability, and mechanical control that can be regulated. Therefore, this review analyzes the concept of hydrogels and the characteristics of chitosan, collagen, and gelatin as excellent candidates for fabricating BTE scaffolds. The changes and opportunities brought on by these biopolymers in bone regeneration are discussed, considering the integration, synergy, and biocompatibility features.

A sustained-release PDGF-BB nanocomposite hydrogel for DM-associated bone regeneration

Regeneration of bone tissue in the environment of diabetes mellitus (DM) remains one of the clinical challenges, with malfunction of stem cells in a high-glucose microenvironment being the primary obstacle. We designed an injectable sustained-release PDGF-BB nanocomposite hydrogel. PDGF-BB, a star molecule for treating various complications of DM, was used for the first time for DM-associated bone regeneration, and we showed that it restored stem cell proliferation and migration and facilitated osteogenesis inhibition under high glucose stimulation by activating ERK and AKT pathways. To address the requirements for continuous PDGF-BB release in GelMA while also increasing mechanical strength, nanoclay LAPONITE® was added, which may still exhibit pro-osteogenic activity in diabetic environments by releasing bioactive ions (Si⁴⁺, Mg²⁺, and Li⁺). This injectable hydrogel heals calvarial lesions successfully in diabetic rats and has the potential to be used as a direct and effective tool for treating diabetic patients.

Biofabrication of Poly(glycerol sebacate) Scaffolds Functionalized with a Decellularized Bone Extracellular Matrix for Bone Tissue Engineering

The microarchitecture of bone tissue engineering (BTE) scaffolds has been shown to have a direct effect on the osteogenesis of mesenchymal stem cells (MSCs) and bone tissue regeneration. Poly(glycerol sebacate) (PGS) is a promising polymer that can be tailored to have specific mechanical properties, as well as be used to create microenvironments that are relevant in the context of BTE applications. In this study, we utilized PGS elastomer for the fabrication of a biocompatible and bioactive scaffold for BTE, with tissue-specific cues and a suitable microstructure for the osteogenic lineage commitment of MSCs. In order to achieve this, the PGS was functionalized with a decellularized bone (deB) extracellular matrix (ECM) (14% and 28% by weight) to enhance its osteoinductive potential. Two different pore sizes were fabricated (small: 100-150 μm and large: 250-355 μm) to determine a preferred pore size for in vitro osteogenesis. The decellularized bone ECM functionalization of the PGS not only improved initial cell attachment and osteogenesis but also enhanced the mechanical strength of the scaffold by up to 165 kPa. Furthermore, the constructs were also successfully tailored with an enhanced degradation rate/pH change and wettability. The highest bone-inserted small-pore scaffold had a 12% endpoint weight loss, and the pH was measured at around 7.14. The in vitro osteogenic differentiation of the MSCs in the PGS-deB blends revealed a better lineage commitment of the small-pore-sized and 28% (w/w) bone-inserted scaffolds, as evidenced by calcium quantification, ALP expression, and alizarin red staining. This study demonstrates a suitable pore size and amount of decellularized bone ECM for osteoinduction via precisely tailored PGS elastomer BTE scaffolds.

Synergistic effects of nanoattapulgite and hydroxyapatite on vascularization and bone formation in a rabbit tibia bone defect model

Hydroxyapatite (HA) is a promising scaffold material for the treatment of bone defects. However, the lack of angiogenic properties and undesirable mechanical properties (such as fragility) limits the application of HA. Nanoattapulgite (ATP) is a nature-derived clay mineral and has been proven to be a promising bioactive material for bone regeneration due to its ability to induce osteogenesis. In this study, polyvinyl alcohol/collagen/ATP/HA (PVA/COL/ATP/HA) scaffolds were printed. Mouse bone marrow mesenchymal stem/stromal cells (BMSCs) and human umbilical vein endothelial cells (HUVECs) were used in vitro to assess the biocompatibility and the osteogenesis and vascularization induction potentials of the scaffolds. Subsequently, in vivo micro-CT and histological staining were carried out to evaluate new bone formation in a rabbit tibial defect model. The in vitro results showed that the incorporation of ATP increased the printing fidelity and mechanical properties, with values of compressive strengths up to 200% over raw PC-H scaffolds. Simultaneously, the expression levels of osteogenic-related genes and vascularization-related genes were significantly increased after the incorporation of ATP. The in vivo results showed that the PVA/COL/ATP/HA scaffolds exhibited synergistic effects on promoting vascularization and bone formation. The combination of ATP and HA provides a promising strategy for vascularized bone tissue engineering.

Biodegradable and Biocompatible Adhesives for the Effective Stabilisation, Repair and Regeneration of Bone

Bone defects and complex fractures present significant challenges for orthopaedic surgeons. Current surgical procedures involve the reconstruction and mechanical stabilisation of complex fractures using metal hardware (i.e., wires, plates and screws). However, these procedures often result in poor healing. An injectable, biocompatible, biodegradable bone adhesive that could glue bone fragments back together would present a highly attractive solution. A bone adhesive that meets the many clinical requirements for such an application has yet to be developed. While synthetic and biological polymer-based adhesives (e.g., cyanoacrylates, PMMA, fibrin, etc.) have been used effectively as bone void fillers, these materials lack biomechanical integrity and demonstrate poor injectability, which limits the clinical effectiveness and potential for minimally invasive delivery. This systematic review summarises conventional approaches and recent developments in the area of bone adhesives for orthopaedic applications. The required properties for successful bone repair adhesives, which include suitable injectability, setting characteristics, mechanical properties, biocompatibility and an ability to promote new bone formation, are highlighted. Finally, the potential to achieve repair of challenging bone voids and fractures as well as the potential of new bioinspired adhesives and the future directions relating to their clinical development are discussed.

Lipase-Catalyzed Poly(glycerol-1,8-octanediol-sebacate): Biomaterial Engineering by Combining Compositional and Crosslinking Variables

This study examined poly(glycerol-1,8-octanediol-sebacate) (PGOS) copolymers with low-level substitution of O (1,8-octanediol) for G (glycerol) units (G/O ratios 0.5:0.5, 0.66:0.33, 0.75:0.25, 0.8:0.2, and 0.91:0.09) prepared in bulk by immobilized Candida antarctica Lipase B (N435) catalysis. The central question explored was the extent that exchanging less than half of poly(glycerol sebacate) (PGS) glycerol units with 1,8-octanediol can be used as a strategy to fine-tune biomaterial properties. Synthesized copolymers having G/O ratios of 0.66:0.33, 0.75:0.25, 0.8:0.2, and 0.91:0.09 have similar molecular weights, where M_w varied from 52,800 to 63,800 g/mol, M_n varied from 5100 to 6450 g/mol, and Đ_M (molecular mass dispersity, M_w/M_n) values were also similar (8.4-11.4). All of the copolymers were branched, and dendritic glycerol units reached 11% for PGOS-0.91:0.09:1.0. Analysis of DSC second heating scans revealed that copolymers with higher 1,8-octanediol contents have relatively higher T_m and ΔH_f values. Over the copolymer compositional range studied herein, T_m and ΔH_f values varied from 5.3 to 21.1 °C and 8.0 to 23.1 J/g, respectively. Stress-strain curves of PGOS copolymers cured at 140 °C for 48 h exhibited either a unimodal, bimodal, or trimodal response to tensile loading. Varying G/O from 10:1 to 2:1 resulted in significant increases in the peak stress (0.26-4.01 MPa), preyield modulus (0.65-62.59 MPa), failure to strain (64-110%), and failure toughness (0.1-0.56 MPa). This demonstrates that altering the G/O ratio over a narrow compositional range provides biomaterials with widely different yet tunable mechanical properties. Further investigation of PGOS-0.75:0.25:1.0 films revealed that varying the cure conditions from 120 to 160 °C for periods of 24-72 h provides access to biomaterials with a failure strain range from 15 to 224% and Young's modulus from 1.17 to 10.85 MPa. Hence, using the dual variables of compositional variation and changes in cure conditions provides an exciting platform for PGS analogues to optimize material-tissue interactions. Increased contents of 1,8-octanediol slowed in vitro degradation. Slowed degradation of PGOS relative to PGS will be valuable for use in slower healing wounds.

Laponite/amoxicillin-functionalized PLA nanofibrous as osteoinductive and antibacterial scaffolds

In this study, Amoxicillin (AMX) was loaded on laponite (LAP) nanoplates and then immobilized on the surface of electrospun polylactic acid (PLA) nanofibers to fabricate scaffolds with osteoinductive and antibacterial activities. The highest loading efficiency (49%) was obtained when the concentrations of AMX and LAP were 3 mg/mL and 1 mg/mL, respectively. FTIR and XRD spectroscopies and zeta potentiometry confirmed the successful encapsulating of AMX within LAP nanoplates. The immobilization of AMX-loaded LAPs on the surface of PLA nanofibers was verified by SEM and FTIR spectroscopy. In vitro release study showed a two-phase AMX release profile for the scaffolds; an initial burst release within the first 48 h and a later sustained release up to 21 days. In vitro antibacterial tests against Staphylococcus aureus and Escherichia coli presented the ability of scaffolds to inhibit the growth of both bacteria. The biocompatibility assays revealed the attachment and viability of human bone marrow mesenchymal stem cells (hBMSCs) cultured on the surface of scaffolds (p ≤ 0.05). The increased ALKALINE PHOSPHATASE (ALP) activity (p ≤ 0.001), calcium deposition, and expression of ALP and OSTEONECTIN genes indicated the osteoinductivity of functionalized scaffolds for hBMSCs. These LAP/AMX-functionalized scaffolds might be desirable candida for the treatment of bone defects.

Exploring the emerging applications of the advanced 2-dimensional material borophene with its unique properties

Borophene, a crystalline allotrope of monolayer boron, with a combination of triangular lattice and hexagonal holes, has stimulated wide interest in 2-dimensional materials and their applications. Although their properties are theoretically confirmed, they are yet to be explored and confirmed experimentally. In this review article, we present advancements in research on borophene, its synthesis, and unique properties, including its advantages for various applications with theoretical predictions. The uniqueness of borophene over graphene and other 2-dimensional (2D) materials is also highlighted along with their various structural stabilities. The strategy for its theoretical simulations, leading to the experimental synthesis, could also be helpful for the exploration of many newer 2D materials.

A Comprehensive Study on the Applications of Clays into Advanced Technologies, with a Particular Attention on Biomedicine and Environmental Remediation

In recent years, a great interest has arisen around the integration of naturally occurring clays into a plethora of advanced technological applications, quite far from the typical fabrication of traditional ceramics. This “second (technological) life” of clays into fields of emerging interest is mainly due to clays’ peculiar properties, in particular their ability to exchange (capture) ions, their layered structure, surface area and reactivity, and their biocompatibility. Since the maximization of clay performances/exploitations passes through the comprehension of the mechanisms involved, this review aims at providing a useful text that analyzes the main goals reached by clays in different fields coupled with the analysis of the structure-property correlations. After providing an introduction mainly focused on the economic analysis of clays global trading, clays are classified basing on their structural/chemical composition. The main relevant physicochemical properties are discussed (particular attention has been dedicated to the influence of interlayer composition on clay properties). Lastly, a deep analysis of the main relevant nonconventional applications of clays is presented. Several case studies describing the use of clays in biomedicine, environmental remediation, membrane technology, additive manufacturing, and sol-gel processes are presented, and results critically discussed.

Lipase-Catalyzed Synthesis and Characterization of Poly(glycerol sebacate)

This study demonstrated that immobilized Candida antarctica lipase B (N435) catalysis in bulk leads to higher molecular weight poly(glycerol sebacate), PGS, than self-catalyzed condensation polymerization. Since the glass-transition temperature, fragility, modulus, and strength for rubbery networks are inversely dependent on the concentration of chain ends, higher molecular weight PGS prepolymers will enable the preparation of cross-linked PGS matrices with unique mechanical properties. The evolution of molecular species during the prepolymerization step conducted at 120 °C for 24 h, prior to enzyme addition, revealed regular decreases in sebacic acid and glycerol-sebacate dimer with corresponding increases in oligomers with chain lengths from 3 to 7 units such that a homogeneous liquid substrate has resulted. At 67 h, for N435-catalyzed PGS synthesis, the carboxylic acid conversion reached 82% without formation of a gel fraction, and number-average molecular weight (M_n) and weight-average molecular weight (M_w) values reached 6000 and 59 400 g/mol, respectively. In contrast, self-catalyzed PGS condensation polymerizations required termination at 55 h to avoid gelation, reached 72% conversion, and M_n and M_w values of 2600 and 13 800 g/mol, respectively. We also report the extent that solvent fractionation can enrich PGS in higher molecular weight chains. The use of methanol as a nonsolvent increased M_n and M_w by 131.7 and 18.3%, respectively, and narrower dispersity (Đ) decreased by 47.7% relative to the nonfractionated product.

Facile extrusion 3D printing of gelatine methacrylate/Laponite nanocomposite hydrogel with high concentration nanoclay for bone tissue regeneration

The extrusion 3D printing of hydrogels has evolved as a promising approach that can be applied for specific tissue repair. However, the printing process of hydrogel scaffolds with high shape fidelity is inseparable from the complex crosslinking strategy, which significantly increases the difficulty and complexity of printing. The aim of this study was to develop a printable hydrogel that can extrude at room temperature and print scaffolds with high shape fidelity without any auxiliary crosslinking during the printing process. To this end, a novel formulation consisting of a Laponite suspension with a high solid concentration and a gelatine methacrylate (GelMA) nanocomposite hydrogel was developed. A homogeneously dispersed high-concentration (up to 20% w/v) Laponite suspension was obtained by stirring at 0 °C. The addition of Laponite with high concentration improved the rheological properties, the degradation stability, and the mechanical strength of the hydrogel. The formulation of 15% (w/v) GelMA and 8% (w/v) Laponite nanocomposite hydrogel exhibited desirable printability and biocompatibility. The GelMA/Laponite hydrogels significantly promoted bone marrow mesenchymal stem cell (BMSC) proliferation and osteogenic differentiation. Both desirable printability under mild conditions and cyto-compatibility enable composite hydrogel a potential candidate as biomaterial inks to be applied for bone tissue regeneration.

Nanoclay Reinforced Biomaterials for Mending Musculoskeletal Tissue Disorders

Nanoclay-reinforced biomaterials have sparked a new avenue in advanced healthcare materials that can potentially revolutionize treatment of musculoskeletal defects. Native tissues display many important chemical, mechanical, biological, and physical properties that engineered biomaterials need to mimic for optimal tissue integration and regeneration. However, it is time-consuming and difficult to endow such combinatorial properties on materials via feasible and nontoxic procedures. Fortunately, a number of nanomaterials such as graphene, carbon nanotubes, MXenes, and nanoclays already display a plethora of material properties that can be transferred to biomaterials through a simple incorporation procedure. In this direction, the members of the nanoclay family are easy to functionalize chemically, they can significantly reinforce the mechanical performance of biomaterials, and can provide bioactive properties by ionic dissolution products to upregulate cartilage and bone tissue formation. For this reason, nanoclays can become a key component for future orthopedic biomaterials. In this review, we specifically focus on the rapidly decreasing gap between clinic and laboratory by highlighting their application in a number of promising in vivo studies.

A Review: Optimization for Poly(glycerol sebacate) and Fabrication Techniques for Its Centered Scaffolds

Poly(glycerol sebacate) (PGS), an emerging promising thermosetting polymer synthesized from sebacic acid and glycerol, has attracted considerable attention due to its elasticity, biocompatibility, and tunable biodegradation properties. But it also has some drawbacks such as harsh synthesis conditions, rapid degradation rates, and low stiffness. To overcome these challenges and optimize PGS performance, various modification methods and fabrication techniques for PGS-based scaffolds have been developed in recent years. Outlining the current modification approaches of PGS and summarizing the fabrication techniques for PGS-based scaffolds are of great importance to accelerate the development of new materials and enable them to be appropriately used in potential applications. Thus, this review comprehensively overviews PGS derivatives, PGS composites, PGS blends, processing for PGS-based scaffolds, and their related applications. It is envisioned that this review could instruct and inspire the design of the PGS-based materials and facilitate tissue engineering advances into clinical practice.

Poly(Glycerol Sebacate) in Biomedical Applications-A Review of the Recent Literature

Poly(glycerol sebacate) (PGS) continues to attract attention for biomedical applications owing to its favorable combination of properties. Conventionally polymerized by a two-step polycondensation of glycerol and sebacic acid, variations of synthesis parameters, reactant concentrations or by specific chemical modifications, PGS materials can be obtained exhibiting a wide range of physicochemical, mechanical, and morphological properties for a variety of applications. PGS has been extensively used in tissue engineering (TE) of cardiovascular, nerve, cartilage, bone and corneal tissues. Applications of PGS based materials in drug delivery systems and wound healing are also well documented. Research and development in the field of PGS continue to progress, involving mainly the synthesis of modified structures using copolymers, hybrid, and composite materials. Moreover, the production of self-healing and electroactive materials has been introduced recently. After almost 20 years of research on PGS, previous publications have outlined its synthesis, modification, properties, and biomedical applications, however, a review paper covering the most recent developments in the field is lacking. The present review thus covers comprehensively literature of the last five years on PGS-based biomaterials and devices focusing on advanced modifications of PGS for applications in medicine and highlighting notable advances of PGS based systems in TE and drug delivery.

The role of lithium in the osteogenic bioactivity of clay nanoparticles

LAPONITE® clay nanoparticles are known to exert osteogenic effects on human bone marrow stromal cells (HBMSCs), most characteristically, an upregulation in alkaline phosphatase activity and increased calcium deposition. The specific properties of LAPONITE® that impart its bioactivity are not known. In this study the role of lithium, a LAPONITE® degradation product, was investigated through the use of lithium salts and lithium modified LAPONITE® formulations. In contrast to intact particles, lithium ions applied at concentrations equivalent to that present in LAPONITE®, failed to induce any significant increase in alkaline phosphatase (ALP) activity. Furthermore, no significant differences were observed in ALP activity with modified clay structures and the positive effect on osteogenic gene expression did not correlate with the lithium content of modified clays. These results suggest that other properties of LAPONITE® nanoparticles, and not their lithium content, are responsible for their bioactivity.

Broadband Nonlinear Photonics in Few-Layer Borophene

In this paper, 2D borophene is synthesized through a liquid-phase exfoliation. The morphology and structure of as-prepared borophene are systemically analyzed, and the Z-scan is used to measure the nonlinear optical properties. It is found that the saturable absorber (SA) properties of borophene make it serve as an excellent broadband optical switch, which is strongly used for mode-locking in near- and mid-infrared laser systems. Ultrastable pulses with durations as short as 792 and 693 fs are successfully delivered at the central wavelengths of 1063 and 1560 nm, respectively. Furthermore, stable pulses at a wavelength of 1878 nm are demonstrated from a thulium mode-locked fiber laser based on the same borophene SA. This research reveals a significant potential for borophene used in lasers helping extending the frontiers of photonic technologies.

Clinical Application of Bone Marrow Mesenchymal Stem/Stromal Cells to Repair Skeletal Tissue

There has been an escalation in reports over the last decade examining the efficacy of bone marrow derived mesenchymal stem/stromal cells (BMSC) in bone tissue engineering and regenerative medicine-based applications. The multipotent differentiation potential, myelosupportive capacity, anti-inflammatory and immune-modulatory properties of BMSC underpins their versatile nature as therapeutic agents. This review addresses the current limitations and challenges of exogenous autologous and allogeneic BMSC based regenerative skeletal therapies in combination with bioactive molecules, cellular derivatives, genetic manipulation, biocompatible hydrogels, solid and composite scaffolds. The review highlights the current approaches and recent developments in utilizing endogenous BMSC activation or exogenous BMSC for the repair of long bone and vertebrae fractures due to osteoporosis or trauma. Current advances employing BMSC based therapies for bone regeneration of craniofacial defects is also discussed. Moreover, this review discusses the latest developments utilizing BMSC therapies in the preclinical and clinical settings, including the treatment of bone related diseases such as Osteogenesis Imperfecta.

Poly (Glycerol Sebacate)-Based Bio-Artificial Multiporous Matrix for Bone Regeneration

In recent years, bone repair biomaterials that combine cells and bioactive factors are superior to autologous and allogeneic bone implants. However, neither natural nor synthetic biomaterials can possess all desired qualities such as strength, porosity, and biological activity. In this study, we used poly (glycerol sebacate) (PGS), a synthetic material with great osteogenic potential that has attracted more attention in the field of tissue (such as bone tissue) regeneration owing to its good biocompatibility and high elasticity. It also has the advantage of being regulated by material synthesis to match the bone tissue's strength and can be easily modified to become functional. However, pure PGS lacks functional groups and hydrophilicity. Therefore, we used PGS as the substrate to graft the adhesive ligands RGD and vascular endothelial growth factor mimetic peptide. The bone repair scaffold can be prepared through photo crosslinking, as it not only improves hydrophobicity but also promotes vascularization and accelerates osteogenesis. Simultaneously, we improved the preparation method of hydrogels after freeze-drying and crosslinking to form a sponge-like structure and to easily regenerate blood vessels. In summary, a bone repair scaffold was prepared to meet the structural and biological requirements. It proved to serve as a potential bone-mimicking scaffold by enhancing tissue regenerative processes such as cell infiltration and vascularization and subsequent replacement by the native bone tissue.

Establishment and neural differentiation of neural crest-derived stem cells from human dental pulp in serum-free conditions

The potential of obtaining cell cultures with neural crest resemblance (neural crest-derived stem cells [NCSCs]) from dental-related tissues, including human dental pulp cells (hDPCs), has been discussed in the literature. However, most reports include the use of serum-rich conditions and do not describe the potential for neural differentiation, slowing translation to the clinic. Therefore, we aimed to culture and characterize NCSCs from the human dental pulp in vitro and evaluate their ability to differentiate into neurons; we also investigated the effectiveness of the addition of BMP4 to enhance this potential. Cultures were established from a varied cohort of patient samples and grown, as monolayers, in serum, serum-free, and also under sphere-aggregation conditions to induce and identify a NCSC phenotype. hDPC cultures were characterized by immunocytochemistry and reverse transcription quantitative polymerase chain reaction. Monolayer cultures expressed stem cell, neural progenitor and neural crest-related markers. Culturing hDPCs as neurospheres (hDPC-NCSCs) resulted in an increased expression of neural crest-related genes, while the addition of BMP4 appeared to produce better NCSC characteristics and neural differentiation. The neural-like phenotype was evidenced by the expression of TUJ1, peripherin, NFH, TAU, SYN1, and GAP43. Our results describe the establishment of hDPC cultures from a large variety of patients in serum-free medium, as NCSC that differentiate into neural-like cells, as well as an important effect of BMP4 in enhancing the neural crest phenotype and differentiation of hDPCs.

Hydroxyapatite Nanoparticles Fortified Xanthan Gum-Chitosan Based Polyelectrolyte Complex Scaffolds for Supporting the Osteo-Friendly Environment

Nanoparticle-reinforced polymer-based scaffolding matrices as artificial bone-implant materials are potential suitors for bone regenerative medicine as they simulate the native bone. In the present work, a series of bioinspired, osteoconductive tricomposite scaffolds made up of nano-hydroxyapatite (NHA) embedded xanthan gum-chitosan (XAN-CHI) polyelectrolyte complex (PEC) are explored for their bone-regeneration potential. The Fourier transform infrared spectroscopy studies confirmed complex formation between XAN and CHI and showed strong interactions between the NHA and PEC matrix. The X-ray diffraction studies indicated regulation of the nanocomposite (NC) scaffold crystallinity by the physical cues of the PEC matrix. Further results exhibited that the XAN-CHI/NHA5 scaffold, with a 50/50 (polymer/NHA) ratio, has optimized porous structure, appropriate compressive properties, and sufficient swelling ability with slower degradation rates, which are far better than those of CHI/NHA and other XAN-CHI/NHA NC scaffolds. The simulated body fluid studies showed XAN-CHI/NHA5 generated apatite-like surface structures of a Ca/P ratio ∼1.66. Also, the in vitro cell-material interaction studies with MG-63 cells revealed that relative to the CHI/NHA NC scaffold, the cellular viability, attachment, and proliferation were better on XAN-CHI/NHA scaffold surfaces, with XAN-CHI/NHA5 specimens exhibiting an effective increment in cell spreading capacity compared to XAN-CHI/NHA4 and XAN-CHI/NHA6 specimens. The presence of an osteo-friendly environment is also indicated by enhanced alkaline phosphatase expression and protein adsorption ability. The higher expression of extracellular matrix proteins, such as osteocalcin and osteopontin, finally validated the induction of differentiation of MG-63 cells by tricomposite scaffolds. In summary, this study demonstrates that the formation of PEC between XAN and CHI and incorporation of NHA in XAN-CHI PEC developed tricomposite scaffolds with robust potential for use in bone regeneration applications.

Laser-Induced Differentiation of Human Adipose-Derived Stem Cells to Temporomandibular Joint Disc Cells

BACKGROUND AND OBJECTIVES

Temporomandibular disorder (TMD) is an incapacitating disease with temporomandibular joint (TMJ) disc degenerative changes in patients. Despite several research attempts to find a definitive treatment, there is no evidence of a permanent solution. The objective of the current study was to observe the role of 660 nm diode laser in the differentiation of human adipose-derived stem cells (ADSCs) to fibroblasts and chondrocytes.

STUDY DESIGN/MATERIALS AND METHODS

After irradiation, the morphology, viability, and adenosine triphosphate (ATP) proliferation of the ADSCs were analyzed at different time intervals. The differentiation of ADSCs toward fibroblastic and chondrogenic phenotypes was supported using flow cytometry and immunofluorescence at 1- and 2-week post-irradiation.

RESULTS

More than 90% of viable cells were observed in all experimental groups, with an increase in ATP proliferation. Flow cytometry analyses and immunofluorescence demonstrated the presence of chondrogenic and fibroblastic cell surface markers at 1- and 2-week post-irradiation.

CONCLUSION

This study has demonstrated methods to induce the differentiation of ADSCs toward fibroblastic and chondrogenic phenotypes with a 660 nm diode laser. The study also proposes a future alternative method of treatment for patients with degenerative TMJ disc disorders and presents a positive prospect in the application of photobiomodulation and ADSCs in the treatment of degenerative TMJ disc. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Dental stem cells: The role of biomaterials and scaffolds in developing novel therapeutic strategies

Dental stem cells (DSCs) are self-renewable cells that can be obtained easily from dental tissues, and are a desirable source of autologous stem cells. The use of DSCs for stem cell transplantation therapeutic approaches is attractive due to their simple isolation, high plasticity, immunomodulatory properties, and multipotential abilities. Using appropriate scaffolds loaded with favorable biomolecules, such as growth factors, and cytokines, can improve the proliferation, differentiation, migration, and functional capacity of DSCs and can optimize the cellular morphology to build tissue constructs for specific purposes. An enormous variety of scaffolds have been used for tissue engineering with DSCs. Of these, the scaffolds that particularly mimic tissue-specific micromilieu and loaded with biomolecules favorably regulate angiogenesis, cell-matrix interactions, degradation of extracellular matrix, organized matrix formation, and the mineralization abilities of DSCs in both in vitro and in vivo conditions. DSCs represent a promising cell source for tissue engineering, especially for tooth, bone, and neural tissue restoration. The purpose of the present review is to summarize the current developments in the major scaffolding approaches as crucial guidelines for tissue engineering using DSCs and compare their effects in tissue and organ regeneration.

Organoids in Translational Oncology

Translational medicine aims to translate the most promising preclinical research into clinical practice. Oncology is a continuously growing medical field: the scientific research on cancer biology is currently based on in vitro experiments, carried out on tissue culture plates (TCPs) and other 2D samples. In this context, 3D printing has greatly improved the biofabrication of new biological matrices that mimic the extracellular environments, which may characterize healthy from cancerous tissues. Organoids have recently been described in several reports on scientific literature. The term that better describes such organoids-based tumoral tissues is "tumoroids". Tumoroids are substantially "tumor-like organoids", typically deriving from primary tumors harvested from patients. This topical review aims to give an update on organoids applied in translational medicine, paying specific attention to their use in the investigation of the main molecular mechanisms of cancer onset and growth, and on the most impacting strategies for effective targeted therapies.

Probiotics-A complete oral healthcare package

Probiotics are living bacterial cells that have significant therapeutic potential for treating human infectious diseases. There is a huge market for probiotics in the pharmaceutical sector. They have been frequently used to treat the gastrointestinal diseases and improve gut immunity. In this review, the strains currently in use for manufacturing oral probiotic formulations are discussed. The review further recommends the use of probiotics for the control of various oral health disorders, like dental caries, periodontitis, gingivitis, halitosis, burning mouth syndrome, and oral cancer. Finally, this review also explores the use of various commercial probiotic products in maintaining oral health, their market values, and government acts and regulations that are relevant to the production and marketing of probiotics. Probiotics have tremendous therapeutic potential and more in-depth research must be done on these beneficial bacteria to make them one of the leading drugs in treating oral disorders.

Long non-coding RNA MALAT1 promotes odontogenic differentiation of human dental pulp stem cells by impairing microRNA-140-5p-dependent downregulation of GIT2

Accumulating research continues to highlight the notable role of microRNAs (miRs) and long non-coding RNAs (lncRNAs) as important regulators in the process of human dental pulp stem cell (hDPSCs) differentiation. The current study aimed to investigate the novel regulatory circuitry of lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)/miR-140-5p/G protein-coupled receptor (GPCR)-kinase 2 interacting protein 2 (GIT2) on the odontogenic differentiation of hDPSCs. In hDPSCs, miR-140-5p was downregulated during the odontogenic differentiation, which was verified to directly target GIT2. RNA crosstalk determined by dual-luciferase reporter and RNA pull-down assays revealed that MALAT1 could bind to miR-140-5p to upregulate the expression of GIT2. After that, the levels of MALAT1, miR-140-5p, and GIT2 in hDPSCs were up- or downregulated by exogenous transfection or lentivirus infection in order to investigate their effects on the differentiation of hDPSCs. It was observed that elevation of miR-140-5p or knockdown of GIT2 resulted in inhibited alkaline phosphatase (ALP) activity, expression of dentin sialophosphoprotein (DSPP), dentin matrix-protein-1 (DMP-1), and distal-less homeobox 3 (DLX3) as well as positive expression of desmoplakin (DSP) protein. The promotive effects of MALAT1 on odontogenic differentiation were diminished by restoration of miR-140-5p or inhibition of GIT2. Taken together, this study provides valuable evidence suggesting MALAT1 as a potential contributor to the odontogenic differentiation of hDPSCs.

Synthesis of Injectable Shear-Thinning Biomaterials of Various Compositions of Gelatin and Synthetic Silicate Nanoplatelet

Injectable shear-thinning biomaterials (iSTBs) have great potential for in situ tissue regeneration through minimally invasive therapeutics. Previously, an iSTB was developed by combining gelatin with synthetic silicate nanoplatelets (SNPs) for potential application to hemostasis and endovascular embolization. Hence, iSTBs are synthesized by varying compositions of gelatin and SNPs to navigate their material, mechanical, rheological, and bioactive properties. All compositions (each component percentage; 1.5-4.5%/total solid ranges; 3-9%) tested are injectable through both 5 Fr general catheter and 2.4 Fr microcatheter by manual pressure. In the results, an increase in gelatin contents causes decrease in swellability, increase in freeze-dried hydrogel scaffold porosity, increase in degradability and injection force during iSTB fabrication. Meanwhile, the amount of SNPs in composite hydrogels is mainly required to decrease degradability and increase shear thinning properties of iSTB. Finally, in vitro and in vivo biocompatibility tests show that the 1.5-4.5% range gelatin-SNP iSTBs are not toxic to the cells and animals. All results demonstrate that the iSTB can be modulated with specific properties for unmet clinical needs. Understanding of mechanical and biological consequences of the changing gelatin-SNP ratios through this study will shed light on the biomedical applications of iSTB on specific diseases.

The Effectiveness and Safety of General and Spinal Anesthesia on Systemic Inflammatory Response in Patients with Tumor-Type Total Knee Arthroplasty

BACKGROUND

The anesthesia procedure in tumor-type total knee arthroplasty (TKA) may contribute to systemic inflammatory response. Therefore, we aim to investigate the effectiveness and safety of general and spinal anesthesia in patients with tumor-type TKA.

PATIENTS AND METHODS

Twenty-five patients with tumors around the knee undergoing primary unilateral TKA were randomly divided into the general anesthesia group (n = 13) and spinal anesthesia group (n = 12). Knee joint HSS scores and Western Ontario and McMaster University osteoarthritis index (WOMAC osteoarthritis) were recorded before surgery and 12 months after surgery. Visual analogue scale, C-reactive protein (CPR), tumor necrosis factor-α (TNF-α), and interleukin-8 (IL-8) concentration were measured preoperatively (T0), on the day of the operation (T1), and on the first day (T2) after the operation. Complications in the two groups were recorded.

RESULTS

The operative time, intraoperative blood loss, postoperative drainage, tourniquet time, and complication rate were not significantly different between the general anesthesia and spinal anesthesia groups (all p > 0.05). There were no significant differences in CPR (7.6 ± 3.1, 8.1 ± 4.1, 91.3 ± 24.2 vs. 7.1 ± 2.9, 7.6 ± 3.8, 85.1 ± 19.3 pg/mL, respectively), IL-8 (12.2 ± 6.6, 13.4 ± 7.3, 19.2 ± 10.5 vs. 11.9 ± 5.7, 12.9 ± 8.6, 22.2 ± 12.4 pg/mL, respectively), and TNF-α (2.5 ± 1.7, 2.2 ± 1.9, 2.8 ± 2.1 vs. 2.4 ± 1.3, 2.7 ± 2.1, 2.9 ± 1.6 pg/mL, respectively) between the two groups at T0, T1, and T2 (all p > 0.05). There were no statistical differences in pre- and postoperative HSS knee scores (39.78 ± 11.3, 90.24 ± 15.3 vs. 42.68 ± 12.5, 91.21 ± 16.3) and WOMAC indexes (49.89 ± 7.9, 25.12 ± 6.2 vs. 51.3 ± 8.3, 23.15 ± 5.3) between the two groups (p > 0.05).

CONCLUSION

General anesthesia and spinal anesthesia in patients with tumor-type TKA had the same effectiveness and safety.

Photobiomodulation and Stem Cell Therapy for Temporomandibular Joint Disc Disorders

Background: Temporomandibular disorder (TMD) refers to a group of disorders affecting the temporomandibular joint (TMJ) and its related muscles. The two commonly used treatment modalities for TMD are occlusal splint therapy and relaxation therapy. Neither comprises definitive treatment. Objective: The objective of this review was to report updated information on photobiomodulation and stem cells, as an alternative treatment for the degenerative TMJ disc as a part of TMJ disorders. Materials and methods: With only a few research studies reported till date, this review also proposes the mechanism of laser irradiation on inflammatory mediators to treat TMD. Results: Photobiomodulation of stem cells with and without scaffolds could be used indirectly or directly as modulation of degenerative changes of the TMJ disc. Conclusions: The need for a distinct shift of the research margin in this field of dentistry is evident, specifically regarding the application of photobiomodulation and stem cells for tissue engineering of the TMJ disc.

Bioactive Gum Arabic/κ-Carrageenan-Incorporated Nano-Hydroxyapatite Nanocomposites and Their Relative Biological Functionalities in Bone Tissue Engineering

The present frontiers of bone tissue engineering are being pushed by novel biomaterials that exhibit phenomenal biocompatibility and adequate mechanical strength. In this work, we fabricated a ternary system incorporating nano-hydroxyapatite (n-HA)/gum arabic (GA)/κ-carrageenan (κ-CG) with varying concentrations, i.e., 60/30/10 (CHG1), 60/20/20 (CHG2), and 60/10/30 (CHG3). A binary system with n-HA and GA was also prepared with a ratio of 60/40 (HG) and compared with the ternary system. A rapid mineralization of the apatite layer was observed for the ternary systems after incubation in simulated body fluid (SBF) for 15 days as corroborated by scanning electron microscopy (SEM). CHG2 exhibited the maximum apatite layer deposition. Further, the nanocomposites were physicochemically analyzed by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and mechanical testing. Their results revealed a substantial interaction among the components, appropriate crystallinity, and significantly enhanced compressive strength and modulus for the ternary nanocomposites. The greatest mechanical strength was achieved by the scaffold containing equal amounts of GA and κ-CG. The cytotoxicity was evaluated by culturing osteoblast-like MG63 cells, which exhibited the highest cell viability for the CHG2 nanocomposite system. It was further supported by confocal microscopy, which revealed the maximum cell proliferation for the CHG2 scaffold. In addition, enhanced antibacterial activity, protein adsorption, biodegradability, and osteogenic differentiation were observed for the ternary nanocomposites. Osteogenic gene markers, such as osteocalcin (OCN), osteonectin (ON), and osteopontin (OPN), were present in higher quantities in the CHG2 and CHG3 nanocomposites as confirmed by western blotting. These results substantiated the pertinence of n-HA-, GA-, and κ-CG-incorporated ternary systems to bone implant materials.

Mesenchymal stromal cells; a new horizon in regenerative medicine

In recent decades, mesenchymal stromal cells (MSCs) biomedical utilizing has attracted worldwide growing attention. After the first report of the human MSCs obtaining from the bone marrow (BM) tissue, these cells were isolated from wide types of the other tissues, ranging from adipose tissue to dental pulp. Their specific characteristics, comprising self-renewality, multipotency, and availability accompanied by their immunomodulatory properties and little ethical concern denote their importance in the context of regenerative medicine. Considering preclinical studies, MSCs can modify immune reactions during tissue repair and restoration, providing suitable milieu for tissue recovery; on the other hand, they can be differentiated into comprehensive types of the body cells, such as osteoblast, chondrocyte, hepatocyte, cardiomyocyte, fibroblast, and neural cells. Though a large number of studies have investigated MSCs capacities in regenerative medicine in varied animal models, the oncogenic capability of unregulated MSCs differentiation must be more assessed to enable their application in the clinic. In the current review, we provide a brief overview of MSCs sources, isolation, and expansion as well as immunomodulatory activities. More important, we try to collect and discuss recent preclinical and clinical research and evaluate current challenges in the context of the MSC-based cell therapy for regenerative medicine.

Growth and Osteogenic Differentiation of Discarded Gingiva-Derived Mesenchymal Stem Cells on a Commercial Scaffold

BACKGROUND

In periodontal patients with jawbone resorption, the autologous bone graft is considered a "gold standard" procedure for the placing of dental prosthesis; however, this procedure is a costly intervention and poses the risk of clinical complications. Thanks to the use of adult mesenchymal stem cells, smart biomaterials, and active biomolecules, regenerative medicine and bone tissue engineering represent a valid alternative to the traditional procedures.

AIMS

In the past, mesenchymal stem cells isolated from periodontally compromised gingiva were considered a biological waste and discarded during surgical procedures. This study aims to test the osteoconductive activity of FISIOGRAFT Bone Granular® and Matriderm® collagen scaffolds on mesenchymal stem cells isolated from periodontally compromised gingiva as a low-cost and painless strategy of autologous bone tissue regeneration.

MATERIALS AND METHODS

We isolated human mesenchymal stem cells from 22 healthy and 26 periodontally compromised gingival biopsy tissues and confirmed the stem cell phenotype by doubling time assay, colony-forming unit assay, and expression of surface and nuclear mesenchymal stem cell markers, respectively by cytofluorimetry and real-time quantitative PCR. Healthy and periodontally compromised gingival mesenchymal stem cells were seeded on FISIOGRAFT Bone Granular® and Matriderm® scaffolds, and in vitro cell viability and bone differentiation were then evaluated.

RESULTS

Even though preliminary, the results demonstrate that FISIOGRAFT Bone Granular® is not suitable for in vitro growth and osteogenic differentiation of healthy and periodontally compromised mesenchymal stem cells, which, instead, are able to grow, homogeneously distribute, and bone differentiate in the Matriderm® collagen scaffold.

CONCLUSION

Matriderm® represents a biocompatible scaffold able to support the in vitro cell growth and osteodifferentiation ability of gingival mesenchymal stem cells isolated from waste gingiva, and could be employed to develop low-cost and painless strategy of autologous bone tissue regeneration.

Sensory nerve-deficient microenvironment impairs tooth homeostasis by inducing apoptosis of dental pulp stem cells

OBJECTIVES

The aim of this study is to investigate the role of sensory nerve in tooth homeostasis and its effect on mesenchymal stromal/stem cells (MSCs) in dental pulp.

MATERIALS AND METHODS

We established the rat denervated incisor models to identify the morphological and histological changes of tooth. The groups were as follows: IANx (inferior alveolar nerve section), SCGx (superior cervical ganglion removal), IANx + SCGx and Sham group. The biological behaviour of dental pulp stromal/stem cells (DPSCs) was evaluated. Finally, we applied activin B to DPSCs from sensory nerve-deficient microenvironment to analyse the changes of proliferation and apoptosis.

RESULTS

Incisor of IANx and IANx + SCGx groups exhibited obvious disorganized tooth structure, while SCGx group only showed slight decrease of dentin thickness, implying sensory nerve, not sympathetic nerve, contributes to the tooth homeostasis. Moreover, we found sensory nerve injury led to disfunction of DPSCs via activin B/SMAD2/3 signalling in vitro. Supplementing activin B promoted proliferation and reduced apoptosis of DPSCs in sensory nerve-deficient microenvironment.

CONCLUSIONS

This research first demonstrates that sensory nerve-deficient microenvironment impairs tooth haemostasis by inducing apoptosis of DPSCs via activin B/SMAD2/3 signalling. Our study provides the evidence for the crucial role of sensory nerve in tooth homeostasis.

Promising Scaffold-Free Approaches in Translational Dentistry

Regenerative medicine has recently improved the principal therapies in several medical fields. In the past ten years, the continuous search for novel approaches to treat the most common dental pathologies has developed a new branch called regenerative dentistry. The main research fields of translational dentistry involve biomimetic materials, orally derived stem cells, and tissue engineering to populate scaffolds with autologous stem cells and bioactive growth factors. The scientific literature has reported two main research trends in regenerative dentistry: scaffold-based and scaffold-free approaches. This article aims to critically review the main biological properties of scaffold-free regenerative procedures in dentistry. The most impactful pros and cons of the exosomes, the leading role of hypoxia-based mesenchymal stem cells (MSCs), and the strategic use of heat shock proteins in regenerative dentistry will be highlighted and discussed in terms of the use of such tools in dental regeneration and repair.

Diagnostic Drama. Use of ICDAS II and Fluorescence-Based Intraoral Camera in Early Occlusal Caries Detection: A Clinical Study

BACKGROUND

Early diagnosis of occlusal caries is of paramount importance for a minimally invasive approach in dentistry. The aim of the present in vivo clinical prospective study was to compare the diagnostic outcomes of visual subjective evaluation between the International Caries Detection and Assessment System (ICDAS-II) and an intraoral fluorescence-based camera (VistaCam iX Proof, Dürr Dental, Bietigheim-Bissingen, Germany) for the detection of pits and fissures in early caries lesions of posterior teeth.

METHODS

The study included 1011 posterior teeth in 255 patients aged 13-20 years (mean age 16 ± 2.2 years). Two blinded operators evaluated all the occlusal surfaces and the first assigned an ICDAS-II code, while the second assessed the VistaCam score: sound enamel (score 0-1.2); initial enamel decay (score 1.2-1.5); dentine caries (score 1.5-3).

RESULTS

Some 283 (28%) of the assessed teeth were ICDAS-II code 0; 334 (33%) code 1; 189 (18.7%) code 2; 176 (17.4%) code 3; and 29 (2.9%) code 4. The level of agreement between the two procedures was expressed by using Cohen's and Fleiss' kappa statistics and performing McNemar's test. VistaCam assessed in 513 (50.7%) sound enamel; in 292 (28.9%) initial enamel decay; and in 206 (20.4%) dentine caries.

CONCLUSIONS

This comparative study showed a poor agreement between the two diagnostic methods, especially between ICDAS-II 0, 1 and 2 codes and fluorescence assessments.

Management of Endodontic and Periodontal Lesions: the Role of Regenerative Dentistry and Biomaterials

Regenerative dentistry represents a novel interdisciplinary approach involving biomaterials, several molecules and mesenchymal stem cells (MSCs), preferably derived from oral tissues. The pivotal role of MSCs depends on the fact that they can differentiate into different cell lineages and have the strategic role to release bioactive substances that stimulate the renewal and regeneration of damaged tissues. The role of regenerative dentistry is promising in all the branches of dentistry: the most intriguing application is related to the management of endodontic and periodontal defects, overcoming the surgical approach and the implantology as a consequence of a poorly efficient therapeutic plan.

Antimicrobial Silver Multilayer Coating for Prevention of Bacterial Colonization of Orthopedic Implants

Due to increasing rates of periprosthetic joint infections (PJI), new approaches are needed to minimize the infection risk. The first goal of this study was to modify a well-established infection model to test surface-active antimicrobial systems. The second goal was to evaluate the antimicrobial activity of a silver multilayer (SML) coating. In vitro tests with SML items showed a >4 Log reduction in a proliferation assay and a 2.2 Log reduction in an agar immersion test (7 d). In the in vivo model blank and SML coated K-wires were seeded with ~2 × 104 CFU of a methicillin-sensitive Staphylococcus epidermidis (MSSE) and inserted into the intramedullary tibial canal of rabbits. After 7 days, the animals were sacrificed and a clinical, microbiological and histological analysis was performed. Microbiology showed a 1.6 Log pathogen reduction on the surface of SML items (p = 0.022) and in loosely attached tissue (p = 0.012). In the SML group 7 of 12 SML items were completely free of pathogens (cure rate = 58%, p = 0.002), while only 1 of 12 blank items were free of pathogens (cure rate = 8%, p = 0.110). No silver was detected in the blood or urine of the SML treated animals and only scarcely in the liver or adjacent lymph nodes. In summary, an in vivo infection model to test implants with bacterial pre-incubation was established and the antimicrobial activity of the SML coating was successfully proven.

Effect of a Bone Marrow-Derived Extracellular Matrix on Cell Adhesion and Neural Induction of Dental Pulp Stem Cells

Extracellular matrix (ECM) represents an essential component of the cellular niche. In this conditioned microenvironment, the proliferation rates and differentiation states of stem cells are regulated by several factors. In contrast, in in vitro experimental models, cell growth, or induction procedures toward specific cell lines usually occur in contact with plastic, glass, or biogel supports. In this study, we evaluated the effect of a decellularized ECM, derived from bone marrow stem cells, on the neuronal differentiation of mesenchymal stem cells (MSCs) extracted from dental pulp (Dental Pulp Stem Cells - DPSCs). Since DPSCs derive from neuroectodermal embryonic precursors, they are thought to have a greater propensity toward neuronal differentiation than MSCs isolated from other sources. We hypothesized that the presence of a decellularized ECM scaffold could act positively on neuronal-DPSC differentiation through reproduction of an in vivo-like microenvironment. Results from scanning electron microscopy, immunofluorescence, and gene expression assays showed that ECM is able to positively influence the morphology of cells and their distribution and the expression of specific neuronal markers (i.e., NF-L, NF-M, NF-H, PAX6, MAP2).

Application of Computational Fluid Dynamics Analysis after Bimaxillary Orthognathic Surgery

Bimaxillary orthognathic surgery is widely used to treat skeletal class III malocclusion. Changes in jaw position affect the shape of surrounding soft tissues. We used computational fluid dynamics (CFD) simulation to observe changes in airways observed in a patient who underwent bimaxillary orthognathic surgery. For CFD simulation, we performed cone beam computed tomography (CBCT) preoperatively (T0), 3 days postoperatively (T1), and 7 months postoperatively (T2). The values of velocity, pressure drop (ΔP), and wall shear stress all increased 7 months after surgery (Vmax 7.038 m/s to 12.054 m/s, ΔP −7.723 Pa to −53.739 Pa, WSSmax 4.214 Pa to 14.323 Pa). Locations where the velocity and pressure gradients are large included the velopharynx, oropharynx, and epiglottis, with narrow cross-sectional areas. Wall shear stress was also observed at these locations. The velopharynx, oropharynx, and epiglottis are structures most vulnerable to morphological changes, that is, they can easily become obstructed.

Salivary Osteocalcin as Potential Diagnostic Marker of Periodontal Bone Destruction among Smokers

: The objective of the study was to assess the levels and diagnostic accuracy of salivary osteocalcin (OC), osteonectin (ON), and deoxypyridinoline-containing degradation fragment of the C-terminal telopeptide region of type I collagen (CTX) in adult smokers with periodontal bone destruction. Towards this, ninety systemically healthy patients (groups I: healthy, II: periodontitis with non-smokers, and III: periodontitis with current smokers) were included in the study. The results showed a positive correlation (weak to moderate) was observed for OC, ON, and CTX with probing pocket depth (PPD; r = 0.40, 0.32, and 0.36) and alveolar bone loss (BL; r = 0.58, 0.38, and 0.51) (p < 0.01). Smoker periodontitis was best discriminated from healthy controls using 15.25 ng/mL of OC (AUC: 0.870; 95% CI: 0.757-0.943; YI (Youden Index): 0.693; p < 0.0001). However, with a cut-off of BL at 33.33%, 19.24 ng/mL of salivary OC gave the best discrimination (AUC: 0.809; 95% CI: 0.686-0.900; Se: 80.0%; Sp: 73.47%, and YI: 0.534). A 16.45 ng/mL amount of OC gave excellent discrimination (AUC: 0.811; 95% CI: 0.688-0.901; Se: 92.31%; Sp: 65.22%, and YI: 0.575) among healthy and smoker periodontitis when PD at 6mm was considered as cut-off. Conclusion: The best discrimination between healthy controls and smoker periodontitis was obtained at 15.25 ng/mL of salivary OC.

Oral Mesenchymal Stem/Progenitor Cells: The Immunomodulatory Masters

Oral mesenchymal stem/progenitor cells (MSCs) are renowned in the field of tissue engineering/regeneration for their multilineage differentiation potential and easy acquisition. These cells encompass the periodontal ligament stem/progenitor cells (PDLSCs), the dental pulp stem/progenitor cells (DPSCs), the stem/progenitor cells from human exfoliated deciduous teeth (SHED), the gingival mesenchymal stem/progenitor cells (GMSCs), the stem/progenitor cells from the apical papilla (SCAP), the dental follicle stem/progenitor cells (DFSCs), the bone marrow mesenchymal stem/progenitor cells (BM-MSCs) from the alveolar bone proper, and the human periapical cyst-mesenchymal stem cells (hPCy-MSCs). Apart from their remarkable regenerative potential, oral MSCs possess the capacity to interact with an inflammatory microenvironment. Although inflammation might affect the properties of oral MSCs, they could inversely exert a multitude of immunological actions to the local inflammatory microenvironment. The present review discusses the current understanding about the immunomodulatory role of oral MSCs both in periodontitis and systemic diseases, their "double-edged sword" uniqueness in inflammatory regulation, their affection of the immune system, and the underlying mechanisms, involving oral MSC-derived extracellular vesicles.

Highly Proliferative Immortalized Human Dental Pulp Cells Retain the Odontogenic Phenotype when Combined with a Beta-Tricalcium Phosphate Scaffold and BMP2

Human dental pulp cells (HDPCs) play a vital role in dentin formation and reparative dentinogenesis, which indicated their potential application in regenerative medicine. However, HDPCs, which can only be obtained from scarce human pulp tissues, also have a limited lifespan in vitro, and stem cells usually lose their original characteristics over a large number of passages. To overcome these challenges, we successfully immortalized human dental pulp cells using the piggyBac system which was employed to efficiently overexpress the SV40 T-Ag, and we then comprehensively described the cell biological behavior. The immortalized human dental pulp cells (iHDPCs) acquired long-term proliferative activity and expressed most HDPC markers. The iHDPCs maintained multiple differentiation potential and could be induced to differentiate into chondrogenic, osteogenic, and adipogenic cells in vitro. We also proved that the iHDPCs gained a stronger ability to migrate than the primary cells, while apoptosis was inhibited. Furthermore, highly proliferative iHDPCs displayed no oncogenicity when subcutaneously implanted into athymic nude mice. Finally, iHDPCs exhibited odontogenic differentiation ability and secreted dentin sialophosphoprotein (DSPP) when combined with a beta-tricalcium phosphate scaffold and bone morphogenetic protein-2 (BMP2) in vivo. Conclusively, the established iHDPCs are a valuable resource for mechanistic study of dental pulp cell differentiation and dental pulp injury repair, as well as for applications in tooth regeneration.