3D Bioprinting tissue analogs: Current development and translational implications.

Three-dimensional (3D) bioprinting is a promising and rapidly evolving technology in the field of additive manufacturing. It enables the fabrication of living cellular constructs with complex architectures that are suitable for various biomedical applications, such as tissue engineering, disease modeling, drug screening, and precision regenerative medicine. The ultimate goal of bioprinting is to produce stable, anatomically-shaped, human-scale functional organs or tissue substitutes that can be implanted. Although various bioprinting techniques have emerged to develop customized tissue-engineering substitutes over the past decade, several challenges remain in fabricating volumetric tissue constructs with complex shapes and sizes and translating the printed products into clinical practice. Thus, it is crucial to develop a successful strategy for translating research outputs into clinical practice to address the current organ and tissue crises and improve patients' quality of life. This review article discusses the challenges of the existing bioprinting processes in preparing clinically relevant tissue substitutes. It further reviews various strategies and technical feasibility to overcome the challenges that limit the fabrication of volumetric biological constructs and their translational implications. Additionally, the article highlights exciting technological advances in the 3D bioprinting of anatomically shaped tissue substitutes and suggests future research and development directions. This review aims to provide readers with insight into the state-of-the-art 3D bioprinting techniques as powerful tools in engineering functional tissues and organs.

Physicochemical, Biological, and Antibacterial Properties of Four Bioactive Calcium Silicate-Based Cements.

Calcium silicate-based cement (CSC) is a pharmaceutical agent that is widely used in dentistry. This bioactive material is used for vital pulp treatment due to its excellent biocompatibility, sealing ability, and antibacterial activity. Its drawbacks include a long setting time and poor maneuverability. Hence, the clinical properties of CSC have recently been improved to decrease its setting time. Despite the widespread clinical usage of CSC, there is no research comparing recently developed CSCs. Therefore, the purpose of this study is to compare the physicochemical, biological, and antibacterial properties of four commercial CSCs: two powder-liquid mix types (RetroMTA® [RETM]; Endocem® MTA Zr [ECZR]) and two premixed types (Well-Root™ PT [WRPT]; Endocem® MTA premixed [ECPR]). Each sample was prepared using circular Teflon molds, and tests were conducted after 24 h of setting. The premixed CSCs exhibited a more uniform and less rough surface, higher flowability, and lower film thickness than the powder-liquid mix CSCs. In the pH test, all CSCs showed values between 11.5 and 12.5. In the biological test, cells exposed to ECZR at a concentration of 25% showed greater cell viability, but none of the samples showed a significant difference at low concentration (p > 0.05). Alkaline phosphatase staining revealed that cells exposed to ECZR underwent more odontoblast differentiation than the cells exposed to the other materials; however, no significant difference was observed at a concentration of 12.5% (p > 0.05). In the antibacterial test, the premixed CSCs showed better results than the powder-liquid mix CSCs, and ECPR yielded the best results, followed by WRPT. In conclusion, the premixed CSCs showed improved physical properties, and of the premixed types, ECPR exhibited the highest antibacterial properties. For biological properties, none of these materials showed significant differences at 12.5% dilution. Therefore, ECPR may be a promising material with high antibacterial activity among the four CSCs, but further investigation is needed for clinical situations.

Physicochemical, Pre-Clinical, and Biological Evaluation of Viscosity Optimized Sodium Iodide-Incorporated Paste.

This study aimed to investigate the impact of different viscosities of silicone oil on the physicochemical, pre-clinical usability, and biological properties of a sodium iodide paste. Six different paste groups were created by mixing therapeutic molecules, sodium iodide (D30) and iodoform (I30), with calcium hydroxide and one of the three different viscosities of silicone oil (high (H), medium (M), and low (L)). The study evaluated the performance of these groups, including I30H, I30M, I30L, D30H, D30M, and D30L, using multiple parameters such as flow, film thickness, pH, viscosity, and injectability, with statistical analysis (p < 0.05). Remarkably, the D30L group demonstrated superior outcomes compared to the conventional iodoform counterpart, including a significant reduction in osteoclast formation, as examined through TRAP, c-FOS, NFATc1, and Cathepsin K (p < 0.05). Additionally, mRNA sequencing showed that the I30L group exhibited increased expression of inflammatory genes with upregulated cytokines compared to the D30L group. These findings suggest that the optimized viscosity of the sodium iodide paste (D30L) may lead to clinically favorable outcomes, such as slower root resorption, when used in primary teeth. Overall, the results of this study suggest that the D30L group shows the most satisfactory outcomes, which may be a promising root-filling material that could replace conventional iodoform-based pastes.

Immunomodulatory and Anti-inflammatory effect of Neural Stem/Progenitor Cells in the Central Nervous System.

Neuroinflammation is a critical event that responds to disturbed homeostasis and governs various neurological diseases in the central nervous system (CNS). The excessive inflammatory microenvironment in the CNS can adversely affect endogenous neural stem cells, thereby impeding neural self-repair. Therapies with neural stem/progenitor cells (NSPCs) have shown significant inhibitory effects on inflammation, which is mainly achieved through intercellular contact and paracrine signalings. The intercellular contact between NSPCs and immune cells, the activated CNS- resident microglia, and astrocyte plays a critical role in the therapeutic NSPCs homing and immunomodulatory effects. Moreover, the paracrine effect mainly regulates infiltrating innate and adaptive immune cells, activated microglia, and astrocyte through the secretion of bioactive molecules and extracellular vesicles. However, the molecular mechanism involved in the immunomodulatory effect of NSPCs is not well discussed. This article provides a systematic analysis of the immunomodulatory mechanism of NSPCs, discusses efficient ways to enhance its immunomodulatory ability, and gives suggestions on clinical therapy.

Nanoceria-GO-intercalated multicellular spheroids revascularize and salvage critical ischemic limbs through anti-apoptotic and pro-angiogenic functions.

Critical limb ischemia (CLI) is a serious form of peripheral arterial disease that involves severe blockage of blood flow in lower extremities, often leading to foot necrosis and limb loss. Lack of blood flow and high pro-inflammation with overproduced reactive oxygen species (ROS) in CLI aggravate the degenerative events. Among other therapies, cell delivery is considered potential for restoring regenerative capacity, and preservation of cell survival under high oxidative stress has been challenging and prerequisite to harness cellular functions. Here, we introduce a multicellular delivery system that is intercalated with nanoceria-decorated graphene oxide (CeGO), which is considered to have high ROS scavenging ability while providing cell-matrix interaction signals. The CeGO nano-microsheets (8-nm-nanoceria/0.9-µm-GO) incorporated in HUVEC/MSC (7/3) could form cell-material hybrid spheroids mediated by cellular contraction. Under in vitro oxidative-stress-challenge with H2O2, the CeGO-intercalation enhanced the survival and anti-apoptotic capacity of cellular spheroids. Pro-angiogenic events of cellular spheroids, including cell sprouting and expression of angiogenic markers (HIF1α, VEGF, FGF2, eNOS) were significantly enhanced by the CeGO-intercalation. Proteomics analysis also confirmed substantial up-regulation of a series of angiogenesis-related secretome molecules. Such pro-angiogenic events with CeGO-intercalation were proven to be mediated by the APE/Ref-1 signaling pathway. When delivered to ischemic hindlimb in mice, the CeGO-cell spheroids could inhibit the accumulation of in vivo ROS rapidly, preserving high cell survival rate (cells were more proliferative and less apoptotic vs. those in cell-only spheroids), and up-regulated angiogenic molecular expressions. Monitoring over 28 days revealed significantly enhanced blood reperfusion and tissue recovery, and an ultimate limb salvage with the CeGO-cell delivery (∼60% salvaged vs. ∼29% in cell-only delivery vs. 0% in ischemia control). Together, the CeGO intercalated in HUVEC/MSC delivery is considered a potential nano-microplatform for CLI treatment, by scavenging excessive ROS and enhancing transplanted cell survival, while stimulating angiogenic events, which collectively help revascularization and tissue recovery, salvaging critical ischemic limbs.

One-pot synthesis and enzyme-responsiveness of amphiphilic doxorubicin prodrug nanomicelles for cancer therapeutics.

In this study, we report a one-pot synthesis and enzyme-responsiveness of polyethylene glycol (PEG) and glutamic acid (Glu)-based amphiphilic doxorubicin (DOX) prodrug nanomicelles for cancer therapeutics. The nanomicelles were accomplished by esterification and amidation reactions. The nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) data confirmed the structure of nanomicelles. The DOX-loaded nanomicelles showed a DLS-measured average size of 107 nm and excellent stability in phosphate-buffered saline (PBS) for 7 days. The drug loading and cumulative release rates were measured by ultraviolet-visible (UV-vis) spectrophotometry at 481 nm. The cumulative release rate could reach 100% in an enzyme-rich environment. Further, the therapeutic efficiency of nanomicelles to cancer cells was determined by cell viability and cellular uptake and distribution using HeLa cells. The cell viability study showed that the DOX-loaded nanomicelles could effectively inhibit the HeLa cell proliferation. The cellular uptake study confirmed that the nanomicelles could be effectively ingested by HeLa cells and distributed into cell nuclei. Based on the collective experimental data, this study demonstrated that the synthesized nanomicellar prodrug of DOX is a potential candidate for cancer therapeutics.

The Potential Application of Human Gingival Fibroblast-Conditioned Media in Pulp Regeneration: An In Vitro Study.

Regenerative endodontic treatment based on tissue engineering has recently gained interest in contemporary restorative dentistry. However, low survival rates and poor potential differentiation of stem cells could undermine the success rate of pulp regenerative therapy. Human gingival fibroblast-conditioned medium (hGF-CM) has been considered a potential therapy for tissue regeneration due to its stability in maintaining multiple factors essential for tissue regeneration compared to live cell transplantation. This study aimed to investigate the potency of hGF-CM on stem cells from human dental pulp (DPSC) in pulp regeneration. A series of experiments confirmed that hGF-CM contributes to a significant increase in proliferation, migration capability, and cell viability of DPSC after H2O2 exposure. Moreover, it has been proved to facilitate the odontogenic differentiation of DPSC via qRT-PCR, ALP (alkaline phosphatase), and ARS (Alizarin Red S) staining. It has been discovered that such highly upregulated odontogenesis is related to certain types of ECM proteins (collagen and laminin) from hGF-CM via proteomics. In addition, it is found that the ERK pathway is a key mechanism via inhibition assay based on RNA-seq result. These findings demonstrate that hGF-CM could be beneficial biomolecules for pulp regeneration.

Premixed Calcium Silicate-Based Root Canal Sealer Reinforced with Bioactive Glass Nanoparticles to Improve Biological Properties.

Recently, bioactive glass nanoparticles (BGns) have been acknowledged for their ability to promote interactions with the periapical tissue and enhance tissue regeneration by releasing therapeutic ions. However, there have been no studies on calcium silicate sealers with bioactive glass nanoparticle (BGn) additives. In the present study, a premixed calcium silicate root canal sealer reinforced with BGn (pre-mixed-RCS@BGn) was developed and its physicochemical features and biological effects were analyzed. Three specimens were in the trial: 0%, 0.5%, and 1% bioactive glass nanoparticles (BGns) were gradually added to the premixed type of calcium silicate-based sealer (pre-mixed-RCS). To elucidate the surface properties, scanning electron microscopy, X-ray diffraction, and energy-dispersive spectroscopy were used and flowability, setting time, solubility, and radiopacity were analyzed to evaluate the physical properties. Chemical properties were investigated by water contact angle, pH change, and ion release measurements. The antibacterial effects of the bioactive set sealers were tested with Enterococcus faecalis and the viability of human bone marrow-derived mesenchymal stem cells (hMSCs) with this biomaterial was examined. In addition, osteogenic differentiation was highly stimulated, which was confirmed by ALP (Alkaline phosphatase) activity and the ARS (Alizarin red S) staining of hMSCs. The pre-mixed-RCS@BGn satisfied the ISO standards for root canal sealers and maintained antimicrobial activity. Moreover, pre-mixed-RCS@BGn with more BGns turned out to have less cytotoxicity than pre-mixed-RCS without BGns while promoting osteogenic differentiation, mainly due to calcium and silicon ion release. Our results suggest that BGns enhance the biological properties of this calcium silicate-based sealer and that the newly introduced pre-mixed-RCS@BGn has the capability to be applied in dental procedures as a root canal sealer. Further studies focusing more on the biocompatibility of pre-mixed-RCS@BGn should be performed to investigate in vivo systems, including pulp tissue.

Photocatalytic effect-assisted antimicrobial activities of acrylic resin incorporating zinc oxide nanoflakes.

To overcome the deficiency of the antimicrobial effect of polymer, zinc oxide nanoparticles have been widely utilized as advanced nanofillers due to their antimicrobial and photocatalytic activity. However, the underlying antimicrobial mechanism has not been fully understood apart from topological and physical characteristics. In this study, we prepared zinc oxide nanoparticles-based acrylic resin to explore its antimicrobial mechanism under controlled mechanophysical conditions by using silane-treated zinc oxide nanoflakes (S-ZnNFs). S-ZnNFs incorporated acrylic resin (poly(methyl methacrylate), PMMA) composites up to 2 wt% were selected based on comparable mechanophysical properties (e.g., roughness, wettability, strength and hardness), possibly affecting antimicrobial properties beyond the zinc oxide nanoparticle effect, to bare PMMA. Antimicrobial adhesion results were still observed in 2 wt% S-ZnNFs incorporated PMMA using Candida albicans (C. albicans), one of the fungal infection species. In order to confirm the antimicrobial effects by photocatalysis, we pre-exposed the UV light on 2 wt% S-ZnNF composites before cell seeding, revealing synergetic antimicrobial effect via additional reactive oxygen species (ROS) generation to C. albicans over zinc oxide nanoparticle-induced one. RNA-seq analysis revealed distinguished cellular responses between zinc oxide nanoparticles and UV-mediated photocatalytic effect, but both linked to generation of intracellular ROS. Thus, the above data suggest that induction of high intracellular ROS of C. albicans was the main antimicrobial mechanism under controlled mechanophysical parameters and synergetic ROS accumulation can be induced by photocatalysis, recapitulating a promising use of a S-ZnNFs or possibly zinc oxide nanoparticles as intracellular-ROS-generating antimicrobial nanofillers in acrylic composite for biomedical applications.

Investigating the Effects of Conditioned Media from Stem Cells of Human Exfoliated Deciduous Teeth on Dental Pulp Stem Cells.

Pulp regeneration has recently attracted interest in modern dentistry. However, the success ratio of pulp regeneration is low due to the compromising potential of stem cells, such as their survival, migration, and odontoblastic differentiation. Stem cells from human exfoliated deciduous teeth (SHED) have been considered a promising tool for regenerative therapy due to their ability to secrete multiple factors that are essential for tissue regeneration, which is achieved by minimally invasive procedures with fewer ethical or legal concerns than those of other procedures. The aim of this study is to investigate the potency of SHED-derived conditioned media (SHED CM) on dental pulp stem cells (DPSCs), a major type of mesenchymal stem cells for dental pulp regeneration. Our results show the promotive efficiency of SHED CM on the proliferation, survival rate, and migration of DPSCs in a dose-dependent manner. Upregulation of odontoblast/osteogenic-related marker genes, such as ALP, DSPP, DMP1, OCN, and RUNX2, and enhanced mineral deposition of impaired DPSCs are also observed in the presence of SHED CM. The analysis of SHED CM found that a variety of cytokines and growth factors have positive effects on cell proliferation, migration, anti-apoptosis, and odontoblast/osteogenic differentiation. These findings suggest that SHED CM could provide some benefits to DPSCs in pulp regeneration.

Investigating the mechanophysical and biological characteristics of therapeutic dental cement incorporating copper doped bioglass nanoparticles.

OBJECTIVE: This study was investigated the mechanophysical properties of zinc phosphate cement (ZPC) with or without the copper doped bioglass nanoparticles (Cu-BGn) and their biological effect on dental pulp human cells and bacteria. MATERIALS AND METHODS: Cu-BGn were synthesized and characterized firstly and then, the experimental (Cu-ZPC) and control (ZPC) samples were fabricated with similar sizes and/or dimensions (diameter: 4 mm and height: 6 mm) based on the International Organization of Standards (ISO). Specifically, various concentrations of Cu-BGn were tested, and Cu-BGn concentration was optimized at 2.5 wt% based on the film thickness and overall setting time. Next, we evaluated the mechanophysical properties such as compressive strength, elastic modulus, hardness, and surface roughness. Furthermore, the biological behaviors including cell viability and odontoblastic differentiation by using dental pulp human cells as well as antibacterial properties were investigated on the Cu-ZPC. All data were analyzed statistically using SPSS® Statistics 20 (IBM®, USA). p < 0.05 (*) was considered significant, and 'NS' represents nonsignificant. RESULTS: Cu-BGn was obtained via a sol-gel method and added onto the ZPC for fabricating a Cu-ZPC composite and for comparison, the Cu-free-ZPC was used as a control. The film thickness (≤ 25 µm) and overall setting time (2.5-8 min) were investigated and the mechanophysical properties showed no significance ('NS') between Cu-ZPC and bare ZPC. However, cell viability and odontoblastic differentiation, alkaline phosphate (ALP) activity and alizarin red S (ARS) staining were highly stimulated in the extracts from the Cu-ZPC group compared to the ZPC group. Additionally, the antibacterial test showed that the Cu-ZPC extracts were more effective than the ZPC extracts (p < 0.05). SIGNIFICANCE: Cu-ZPC showed adequate mechanophysical properties (compressive strength, hardness, and surface roughness) and enhanced odontoblastic differentiation as well as antibacterial properties compared to the ZPC-only group. Based on the findings, the fabricated Cu-ZPC might have the potential for use in the field of dental medicine and clinical applications.

Revascularization and limb salvage following critical limb ischemia by nanoceria-induced Ref-1/APE1-dependent angiogenesis.

In critical limb ischemia (CLI), overproduction of reactive oxygen species (ROS) and impairment of neovascularization contribute to muscle damage and limb loss. Cerium oxide nanoparticles (CNP, or 'nanoceria') possess oxygen-modulating properties which have shown therapeutic utility in various disease models. Here we show that CNP exhibit pro-angiogenic activity in a mouse hindlimb ischemia model, and investigate the molecular mechanism underlying the pro-angiogenic effect. CNP were injected into a ligated region of a femoral artery, and tissue reperfusion and hindlimb salvage were monitored for 3 weeks. Tissue analysis revealed stimulation of pro-angiogenic markers, maturation of blood vessels, and remodeling of muscle tissue following CNP administration. At a dose of 0.6 mg CNP, mice showed reperfusion of blood vessels in the hindlimb and a high rate of limb salvage (71%, n = 7), while all untreated mice (n = 7) suffered foot necrosis or limb loss. In vitro, CNP promoted endothelial cell tubule formation via the Ref-1/APE1 signaling pathway, and the involvement of this pathway in the CNP response was confirmed in vivo using immunocompetent and immunodeficient mice and by siRNA knockdown of APE1. These results demonstrate that CNP provide an effective treatment of CLI with excessive ROS by scavenging ROS to improve endothelial survival and by inducing Ref-1/APE1-dependent angiogenesis to revascularize an ischemic limb.

Nano-graphene oxide/polyurethane nanofibers: mechanically flexible and myogenic stimulating matrix for skeletal tissue engineering.

For skeletal muscle engineering, scaffolds that can stimulate myogenic differentiation of cells while possessing suitable mechanical properties (e.g. flexibility) are required. In particular, the elastic property of scaffolds is of importance which helps to resist and support the dynamic conditions of muscle tissue environment. Here, we developed highly flexible nanocomposite nanofibrous scaffolds made of polycarbonate diol and isosorbide-based polyurethane and hydrophilic nano-graphene oxide added at concentrations up to 8%. The nano-graphene oxide incorporation increased the hydrophilicity, elasticity, and stress relaxation capacity of the polyurethane-derived nanofibrous scaffolds. When cultured with C2C12 cells, the polyurethane-nano-graphene oxide nanofibers enhanced the initial adhesion and spreading of cells and further the proliferation. Furthermore, the polyurethane-nano-graphene oxide scaffolds significantly up-regulated the myogenic mRNA levels and myosin heavy chain expression. Of note, the cells on the flexible polyurethane-nano-graphene oxide nanofibrous scaffolds could be mechanically stretched to experience dynamic tensional force. Under the dynamic force condition, the cells expressed significantly higher myogenic differentiation markers at both gene and protein levels and exhibited more aligned myotubular formation. The currently developed polyurethane-nano-graphene oxide nanofibrous scaffolds, due to their nanofibrous morphology and high mechanical flexibility, along with the stimulating capacity for myogenic differentiation, are considered to be a potential matrix for future skeletal muscle engineering.

Nanoscale Calcium Salt-Based Formulations As Potential Therapeutics for Osteoporosis.

Osteoporosis causes severe bone damage, posing potential risks to human health, patient quality of life, and society. Calcium has been widely shown to enhance bone density and prevent osteoporosis-related bone fractures. Here, we focused on calcium salt formulations containing natural substances and their possible therapeutic effects on osteoporosis. In particular, we developed a nanoscale calcium salt of natural origin and formulated nanocomposite tablets supplemented with vitamin D (Vit D), herb Rhodiola rosea (R. rosea) and natural mineral Shilajit that are known to be antiosteoporotic. The calcium salt nanocomposites exhibited no toxicity, and particularly the formulation containing R. rosea stimulated osteogenic differentiation. The calcium salt nanocomposites inhibited osteoclastic activity, including RANKL expression, as shown by a decrease in tartrate-resistant acid phosphatase (TRAP)-positive cells. When administered orally to osteoporotic rats for 45 days, the calcium salt nanocomposites reduced bone resorption, as evidenced by the significantly higher bone volume and density, increase in osteoblasts and decrease in osteoclasts compared to those in nontreated control rats. Systemic administration of the nanocomposites caused no severe stomach toxicity or damage over the test period, during which no renal stone growth was observed. On the basis of their significant bilateral effects in stimulating osteoblasts and inhibiting osteoclasts and the resultant efficacy in an osteoporotic model, the nanocomposite tablets composed of a calcium salt and natural products can be considered novel nanotherapeutics for osteoporosis treatment.

Author Correction: Performance of a glucose-reactive enzyme-based biofuel cell system for biomedical applications.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Angiogenesis-promoted bone repair with silicate-shelled hydrogel fiber scaffolds.

Promoting angiogenesis is a key strategy for stimulating the repair of damaged tissues, including bone. Among other proangiogenic factors, ions have recently been considered a potent element that can be incorporated into biomaterials and then released at therapeutic doses. Silicate-based biomaterials have been reported to induce neovascularization through vascular endothelial growth factor signaling pathway, potentiating acceleration of bone regeneration. Here, we designed a silicate-shelled hydrogel fiber scaffold with a hard/soft layered structure to investigate the possibility of silicate coating on biopolymer for enhancing biological properties. An alginate hydrogel was injected to form a fiber scaffold with shape-tunability that was then coated with a thin silicate layer with various sol-gel compositions. The silicate/alginate scaffold could release calcium and silicate ions, and in particular, silicate ion release was highly sustainable for over one week at therapeutically relevant levels. The ionic release was highly effective in stimulating the mRNA expression of angiogenic markers (VEGF, KDR, eNOS, bFGF, and HIF1-α) in endothelial cells (HUVECs). Moreover, the in vitro tubular networking of cells was significantly enhanced (1.5 times). In vivo implantation in subcutaneous tissue revealed more pronounced blood vessel formation around the silicate-shelled scaffolds than around silicate-free scaffolds. The presence of a silicate shell was also shown to accelerate acellular mineral (hydroxyapatite) formation. The cellular osteogenesis potential of the silicate/alginate scaffold was further proven by the enhanced expression of osteogenic genes (Col1a1, ALP and OCN). When implanted in a rat calvarium defect, the silicate-shelled scaffold demonstrated significantly improved bone formation (2-3 times higher in bone volume and density) with a concurrent sign of proangiogenesis. This work highlights that the surface-layering of silicate composition is an effective approach for improving the bone regeneration capacity of polymeric hydrogel scaffolds by stimulating ion-induced angiogenesis and providing bone bioactivity to the surface.

Performance of a glucose-reactive enzyme-based biofuel cell system for biomedical applications.

A glucose-reactive enzyme-based biofuel cell system (EBFC) was recently introduced in the scientific community for biomedical applications, such as implantable artificial organs and biosensors for drug delivery. Upon direct contact with tissues or organs, an implanted EBFC can exert effects that damage or stimulate intact tissue due to its byproducts or generated electrical cues, which have not been investigated in detail. Here, we perform a fundamental cell culture study using a glucose dehydrogenase (GDH) as an anode enzyme and bilirubin oxidase (BOD) as a cathode enzyme. The fabricated EBFC had power densities of 15.26 to 38.33 nW/cm2 depending on the enzyme concentration in media supplemented with 25 mM glucose. Despite the low power density, the GDH-based EBFC showed increases in cell viability (~150%) and cell migration (~90%) with a relatively low inflammatory response. However, glucose oxidase (GOD), which has been used as an EBFC anode enzyme, revealed extreme cytotoxicity (~10%) due to the lethal concentration of H2O2 byproducts (~1500 µM). Therefore, with its cytocompatibility and cell-stimulating effects, the GDH-based EBFC is considered a promising implantable tool for generating electricity for biomedical applications. Finally, the GDH-based EBFC can be used for introducing electricity during cell culture and the fabrication of organs on a chip and a power source for implantable devices such as biosensors, biopatches, and artificial organs.

Dual-ion delivery for synergistic angiogenesis and bactericidal capacity with silica-based microsphere.

Inhibition of bacterial growth with the simultaneous promotion of angiogenesis has been challenging in the repair and regeneration of infected tissues. Here, we aim to tackle this issue through the use of cobalt-doped silicate microspheres that can sustainably release dual ions (silicate and cobalt) at therapeutically-relevant doses. The cobalt was doped up to 2.5 wt% within a sol-gel silicate glass network, and microspheres with the size of ∼300 µm were generated by an emulsification method. The cobalt and silicate ions released were shown to synergistically upregulate key angiogenic genes, such as HIF1-α, VEGF and the receptor KDR. Moreover, the incorporation of ions promoted the polarization, migration, homing and sprouting angiogenesis of endothelial cells. Neo-vascular formation was significantly higher in the dual-ion delivered microspheres, as evidenced in a chicken chorioallantoic membrane model. When cultured with bacterial species, the cobalt-doped microspheres effectively inhibited bacteria growth in both indirect or direct contacts. Of note, the bacteria/endothelial cell coculture model proved the efficacy of dual-ion releasing microcarriers for maintaining the endothelial survivability against bacterial contamination and their cell-cell junction. The current study demonstrates the multiple actions (proangiogenic and antibacterial) of silicate and cobalt ions released from microspheres, and the concept provided here can be extensively applied to repair and regenerate infected tissues as a growth factor- or drug-free delivery system. STATEMENT OF SIGNIFICANCE: While several ions have been introduced to biomaterials for therapeutic purposes, relaying the effects of antibacterial into tissue regenerative (e.g., angiogenesis) has been a significant challenge. In this study, we aim to develop a biomaterial platform that has the capacity of both 'antibacterial' and 'proangiogenic' from a microsphere sustainably releasing multiple ions (herein cobalt and silicate). Here, dual-actions of the microspheres revealed the stimulated endothelial functions as well as the inhibited growth of different bacterial species. In particular, protecting endothelial survivability against bacterial contamination was reported using the bacterial/endothelial co-culture model. The current concept of drug-free yet multiple-ion delivery biomaterials can be applicable for the repair and regeneration of infected tissues with dual actions of angiogenesis and suppressing bacterial activity.

Intra-articular biomaterials-assisted delivery to treat temporomandibular joint disorders.

The temporomandibular joint disorder, also known as myofascial pain syndrome, is considered one of the prevalent chronic pain diseases caused by muscle inflammation and cartilage degradation in head and neck, and thus influences even biopsychosocial conditions in a lifetime. There are several current treatment methodologies relieving inflammation and preventing degradation of the joint complex. One of the promising non-surgical treatment methods is an intra-articular injection of drugs such as corticosteroids, analgesics, and anti-depressants. However, the side effects of drugs due to frequent injections and over-doses, including dizziness, dry mouth, and possible drug dependency are considered limitations. Thus, the delivery of therapeutic molecules through the use of nano/microparticles is currently considered as a promising strategy primarily due to the controlled release. This review highlights the nano/microparticle systems for effective intra-articular therapeutics delivery to prevent cartilage degradation and protect subchondral bone in a temporomandibular joint.

Feasibility of Defect Tunable Bone Engineering Using Electroblown Bioactive Fibrous Scaffolds with Dental Stem Cells.

Healing and repair of damaged bones with various geometries are challenging issues in personalized regenerative medicine. Herein, we examine if the engineered electroblown scaffolds can be suitable to this purpose with the ability to shape and fill defects, populate stem cells, and stimulate the regeneration process of defected bone. The electroblowing method could generate bioactive nanocomposite scaffolds made of poly(caprolactone) and bioactive glass nanoparticles, of which the macrostructure is highly spaced and fibrous networked. The scaffolds were easily formable to different shapes with space filling ability, and were hydrophilic to soak water and blood rapidly. Multipotent stem cells from dental pulp effectively infiltrated the scaffold networks, anchored the fiber surface within few hours, proliferated actively over weeks, and were stimulated to differentiate into osteogenic cells. The cell/scaffold constructs, implanted to tooth-extracted, irregular-shaped alveolar bone defects, were shown to fit the defect and to stimulate early new bone formation. Taken together, the electroblown bioactive fibrous scaffolds and their constructs with multipotent dental stem cells may be useful as a potential 3D platform for future personalized bone tissue engineering.