Poly(Dopamine) Coating on 3D-Printed Poly-Lactic-Co-Glycolic Acid/β-Tricalcium Phosphate Scaffolds for Bone Tissue Engineering

3D-Printed Demineralized Bone Matrix-Based Conductive Scaffolds Combined with Electrical Stimulation for Bone Tissue Engineering Applications

Bone is remodeled through a dynamic process facilitated by biophysical cues that support cellular signaling. In healthy bone, signaling pathways are regulated by cells and the extracellular matrix and transmitted via electrical synapses. To this end, combining electrical stimulation (ES) with conductive scaffolding is a promising approach for repairing damaged bone tissue. Therefore, "smart" biomaterials that can provide multifunctionality and facilitate the transfer of electrical cues directly to cells have become increasingly more studied in bone tissue engineering. Herein, 3D-printed electrically conductive composite scaffolds consisting of demineralized bone matrix (DBM) and polycaprolactone (PCL), in combination with ES, for bone regeneration were evaluated for the first time. The conductive composite scaffolds were fabricated and characterized by evaluating mechanical, surface, and electrical properties. The DBM/PCL composites exhibited a higher compressive modulus (107.2 MPa) than that of pristine PCL (62.02 MPa), as well as improved surface properties (i.e., roughness). Scaffold electrical properties were also tuned, with sheet resistance values as low as 4.77 × 105 Ω/sq for our experimental coating of the highest dilution (i.e., 20%). Furthermore, the biocompatibility and osteogenic potential of the conductive composite scaffolds were tested using human mesenchymal stromal cells (hMSCs) both with and without exogenous ES (100 mV/mm for 5 min/day four times/week). In conjunction with ES, the osteogenic differentiation of hMSCs grown on conductive DBM/PCL composite scaffolds was significantly enhanced when compared to those cultured on PCL-only and nonconductive DBM/PCL control scaffolds, as determined through xylenol orange mineral staining and osteogenic protein analysis. Overall, these promising results suggest the potential of this approach for the development of biomimetic hybrid scaffolds for bone tissue engineering applications.

The H2O2 Self-Sufficient 3D Printed β-TCP Scaffolds with Synergistic Anti-Tumor Effect and Reinforced Osseointegration

Tumor recurrence and massive bone defects are two critical challenges for postoperative treatment of oral and maxillofacial tumor, posing serious threats to the health of patients. Herein, in order to eliminate residual tumor cells and promote osteogenesis simultaneously, the hydrogen peroxide (H2O2) self-sufficient TCP-PDA-CaO2-CeO2 (TPCC) scaffolds are designed by preparing CaO2 or/and CeO2 nanoparticles (NPs)/chitosan solution and modifying the NPs into polydopamine (PDA)-modified 3D printed TCP scaffolds by rotary coating method. CaO2 NPs loaded on the scaffolds can release Ca2+ and sufficient H2O2 in the acidic tumor microenvironment (TME). The generated H2O2 can further produce hydroxyl radicals (·OH) under catalysis effect by peroxidase (POD) activity of CeO2 NPs, in which the photothermal effect of the PDA coating enhances its POD catalytic effect. Overall, NPs loaded on the scaffold chemically achieve a cascade reaction of H2O2 self-sufficiency and ·OH production, while functionally achieving synergistic effects on anti-tumor and bone promotion. In vitro and in vivo studies show that the scaffolds exhibit effective osteo-inductivity, induced osteoblast differentiation and promote osseointegration. Therefore, the multifunctional composite scaffolds not only validate the concept of chemo-dynamic therapy (CDT) cascade therapy, but also provide a promising clinical strategy for postoperative treatment of oral and maxillofacial tumor.

Mussel inspired 3D elastomer enabled rapid calvarial bone regeneration through recruiting more osteoprogenitors from the dura mater

Currently, the successful healing of critical-sized calvarial bone defects remains a considerable challenge. The immune response plays a key role in regulating bone regeneration after material grafting. Previous studies mainly focused on the relationship between macrophages and bone marrow mesenchymal stem cells (BMSCs), while dural cells were recently found to play a vital role in the calvarial bone healing. In this study, a series of 3D elastomers with different proportions of polycaprolactone (PCL) and poly(glycerol sebacate) (PGS) were fabricated, which were further supplemented with polydopamine (PDA) coating. The physicochemical properties of the PCL/PGS and PCL/PGS/PDA grafts were measured, and then they were implanted as filling materials for 8 mm calvarial bone defects. The results showed that a matched and effective PDA interface formed on a well-proportioned elastomer, which effectively modulated the polarization of M2 macrophages and promoted the recruitment of dural cells to achieve full-thickness bone repair through both intramembranous and endochondral ossification. Single-cell RNA sequencing analysis revealed the predominance of dural cells during bone healing and their close relationship with macrophages. The findings illustrated that the crosstalk between dural cells and macrophages determined the vertical full-thickness bone repair for the first time, which may be the new target for designing bone grafts for calvarial bone healing.

Bioinspired poly-dopamine/nano-hydroxyapatite: an upgrading biocompatible coat for 3D-printed polylactic acid scaffold for bone regeneration

Poly-lactic acid (PLA) has been proposed in dentistry for several regenerative procedures owing to its biocompatibility and biodegradability. However, the presence of methyl groups renders PLA hydrophobic, making the surface less ideal for cell attachment, and it does not promote tissue regeneration. Upgrading PLA with inductive biomaterial is a crucial step to increase the bioactivity of the PLA and allow cellular adhesion. Our purpose is to evaluate biocompatibility, bioactivity, cellular adhesion, and mechanical properties of 3D-printed PLA scaffold coated with poly-dopamine (PDA) and nano-hydroxyapatite (n-HA) versus PLA and PLA/n-HA scaffolds. The fused deposition modelling technique was used to print PLA, PLA with embedded n-HA particles, and PLA scaffold coated with PDA/n-HA by immersion. After matrices characterization for their chemical composition and surface properties, testing the compressive strength was pursued using a universal testing machine. The bioactivity of scaffolds was evaluated by monitoring the formation of calcium phosphate compounds after simulated body fluid immersion. The PLA/PDA/n-HA scaffold showed the highest compressive strength which was 29.11 ± 7.58 MPa with enhancing calcium phosphate crystals deposition with a specific calcium polyphosphate phase formed exclusively on PLA/PDA/n-HA. With cell viability assay, the PDA/n-HA-coated matrix was biocompatible with increase in the IC50, reaching ⁓ 176.8 at 72 without cytotoxic effect on the mesenchymal stem cells, promoting their adhesion and proliferation evaluated by confocal microscopy. The study explored the biocompatibility, bioactivity, and the cell adhesion ability of PDA/n-HA coat on a 3D-printed PLA scaffold that qualifies its use as a promising regenerative material.

Surface Modification Progress for PLGA-Based Cell Scaffolds

Poly(lactic-glycolic acid) (PLGA) is a biocompatible bio-scaffold material, but its own hydrophobic and electrically neutral surface limits its application as a cell scaffold. Polymer materials, mimics ECM materials, and organic material have often been used as coating materials for PLGA cell scaffolds to improve the poor cell adhesion of PLGA and enhance tissue adaptation. These coating materials can be modified on the PLGA surface via simple physical or chemical methods, and coating multiple materials can simultaneously confer different functions to the PLGA scaffold; not only does this ensure stronger cell adhesion but it also modulates cell behavior and function. This approach to coating could facilitate the production of more PLGA-based cell scaffolds. This review focuses on the PLGA surface-modified materials, methods, and applications, and will provide guidance for PLGA surface modification.

Fabrication and Characterization of a Polydopamine-Modified Bacterial Cellulose and Sugarcane Filter Cake-Derived Hydroxyapatite Composite Scaffold

The search for environmentally friendly and sustainable sources of raw materials has been ongoing for quite a while, and currently, the utilization and applications of agro-industrial biomass residues in biomedicine are being researched. In this study, a polydopamine (PDA)-modified bacterial cellulose (BC) and hydroxyapatite (HA) composite scaffold was fabricated using the freeze-drying method. The as-prepared hydroxyapatite was synthesized via the chemical precipitation method using sugarcane filter cake as a calcium source, as reported in a previous study. X-ray diffraction analysis revealed a carbonated phase of the prepared hydroxyapatite, similar to that of the natural bone mineral. Wide-angle X-ray scattering analysis revealed the successful fabrication of BC/HA composite scaffolds, while X-ray photoelectron spectroscopy suggested that PDA was deposited on the surface of the BC/HA composite scaffolds. In vitro cell viability assays indicated that BC/HA and PDA-modified composite scaffolds did not induce cytotoxicity and were biocompatible with MC3T3-E1 preosteoblasts. PDA-modified composite scaffolds showed enhanced protein adsorption capacity in vitro compared to the unmodified scaffolds. On a concluding note, these results demonstrate that agro-industrial biomass residues have the potential to be used in biomedical applications and that PDA-modified BC/HA composite scaffolds are a promising biomaterial for bone tissue engineering.

Use of 3D-printed polylactic acid/bioceramic composite scaffolds for bone tissue engineering in preclinical in vivo studies: A systematic review

3D-printed composite scaffolds have emerged as an alternative to deal with existing limitations when facing bone reconstruction. The aim of the study was to systematically review the feasibility of using PLA/bioceramic composite scaffolds manufactured by 3D-printing technologies as bone grafting materials in preclinical in vivo studies. Electronic databases were searched using specific search terms, and thirteen manuscripts were selected after screening. The synthesis of the scaffolds was carried out using mainly extrusion-based techniques. Likewise, hydroxyapatite was the most used bioceramic for synthesizing composites with a PLA matrix. Among the selected studies, seven were conducted in rats and six in rabbits, but the high variability that exists regarding the experimental process made it difficult to compare them. Regarding the results, PLA/Bioceramic composite scaffolds have shown to be biocompatible and mechanically resistant. Preclinical studies elucidated the ability of the scaffolds to be used as bone grafts, allowing bone growing without adverse reactions. In conclusion, PLA/Bioceramics scaffolds have been demonstrated to be a promising alternative for treating bone defects. Nevertheless, more care should be taken when designing and performing in vivo trials, since the lack of standardization of the processes, which prevents the comparison of the results and reduces the quality of the information. STATEMENT OF SIGNIFICANCE: 3D-printed polylactic acid/bioceramic composite scaffolds have emerged as an alternative to deal with existing limitations when facing bone reconstruction. Since preclinical in vivo studies with animal models represent a mandatory step for clinical translation, the present manuscript analyzed and discussed not only those aspects related to the selection of the bioceramic material, the synthesis of the implants and their characterization. But provides a new approach to understand how the design and perform of clinical trials, as well as the selection of the analysis methods, may affect the obtained results, by covering authors' knowledgebase from veterinary medicine to biomaterial science. Thus, this study aims to systematically review the feasibility of using polylactic acid/bioceramic scaffolds as grafting materials in preclinical trials.

Mussel-inspired polydopamine decorated silane modified-electroconductive gelatin-PEDOT:PSS scaffolds for bone regeneration

This study seeks to simulate both the chemistry and piezoelectricity of bone by synthesizing electroconductive silane-modified gelatin-poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) scaffolds using the freeze drying technique. In order to enhance hydrophilicity, cell interaction, and biomineralization, the scaffolds were functionalized with polydopamine (PDA) inspired by mussels. Physicochemical, electrical, and mechanical analyses were conducted on the scaffolds, as well as in vitro evaluations using the osteosarcoma cell line MG-63. It was found that scaffolds had interconnected porous structures, so the PDA layer formation reduced the size of pores while maintaining scaffold uniformity. PDA functionalization reduced the electrical resistance of the constructs while improving their hydrophilicity, compressive strength, and modulus. As a result of the PDA functionalization and the use of silane coupling agents, higher stability and durability were achieved as well as an improvement in biomineralization capability after being soaked in SBF solution for a month. Additionally, the PDA coating enabled the constructs to enhance viability, adhesion, and proliferation of MG-63 cells, as well as to express alkaline phosphatase and deposit HA, indicating that scaffolds can be used for bone regeneration. Therefore, the PDA-coated scaffolds developed in this study and the non-toxic performance of PEDOT:PSS present a promising approach for further in vitro and in vivo studies.

Covalently Grafted Biomimetic Matrix Reconstructs the Regenerative Microenvironment of the Porous Gradient Polycaprolactone Scaffold to Accelerate Bone Remodeling

Integrating a biomimetic extracellular matrix to improve the microenvironment of 3D printing scaffolds is an emerging strategy for bone substitute design. Here, a "soft-hard" bone implant (BM-g-DPCL) consisting of a bioactive matrix chemically integrated on a polydopamine (PDA)-coated porous gradient scaffold by polyphenol groups is constructed. The PDA-coated "hard" scaffolds promoted Ca²⁺ chelation and mineral deposition; the "soft" bioactive matrix is beneficial to the migration, proliferation, and osteogenic differentiation of stem cells in vitro, accelerated endogenous stem cell recruitment, and initiated rapid angiogenesis in vivo. The results of the rabbit cranial defect model (Φ = 10 mm) confirmed that BM-g-DPCL promoted the integration between bone tissue and implant and induced the deposition of bone matrix. Proteomics confirmed that cytokine adhesion, biomineralization, rapid vascularization, and extracellular matrix formation are major factors that accelerate bone defect healing. This strategy of highly chemically bonded soft-hard components guided the construction of the bioactive regenerative scaffold.

3D-Printed conductive polymeric scaffolds with direct current electrical stimulation for enhanced bone regeneration

Various methods have been used to treat bone defects caused by genetic disorders, injury, or disease. Yet, there is still great need to develop alternative approaches to repair damaged bone tissue. Bones naturally exhibit piezoelectric potential, or the ability to convert mechanical stresses into electrical impulses. This phenomenon has been utilized clinically to enhance bone regeneration in conjunction with electrical stimulation (ES) therapies; however, oftentimes with critical-sized bone defects, the bioelectric potential at the site of injury is compromised, resulting in less desirable outcomes. In the present study, the potential of a 3D-printed conductive polymer blend to enhance bone formation through restoration of the bioelectrical microenvironment was evaluated. A commercially available 3D printer was used to create circular, thin-film scaffolds consisting of either polylactide (PLA) or a conductive PLA (CPLA) composite. Preosteoblast cells were seeded onto the scaffolds and subjected to direct current ES via a purpose-built cell culture chamber. It was found that CPLA scaffolds had no adverse effects on cell viability, proliferation or differentiation when compared with control scaffolds. The addition of ES, however, resulted in a significant increase in the expression of osteocalcin, a protein indicative of osteoblast maturation, after 14 days of culture. Furthermore, xylenol orange staining also showed the presence of increased mineralized calcium nodules in cultures undergoing stimulation. This study demonstrates the potential for low-cost, conductive scaffolding materials to support cell viability and enhance in vitro mineralization in conjunction with ES.

Polydopamine-coated 3D-printed β-tricalcium phosphate scaffolds to promote the adhesion and osteogenesis of BMSCs for bone-defect repair: mRNA transcriptomic sequencing analysis

Cellular bioactivity and tissue regeneration can be affected by coatings on tissue-engineered scaffolds. Using mussel-inspired polydopamine (PDA) is a convenient and effective approach to surface modification. Therefore, 3D-printed β-tricalcium phosphate (β-TCP) scaffolds were coated with PDA in this study. The effects of the scaffolds on the adhesion and osteogenic differentiation of seeded bone marrow mesenchymal stem cells (BMSCs) in vitro and on new-bone formation in vivo were investigated. The potential mechanisms and related differential genes were assessed using mRNA sequencing. It was seen that PDA coating increased the surface roughness of the 3D-printed β-TCP scaffolds. Furthermore, it prompted the adhesion and osteogenic differentiation of seeded BMSCs. mRNA sequencing analysis revealed that PDA coating might affect the osteogenic differentiation of BMSCs through the calcium signaling pathway, Wnt signaling pathway, TGF-beta signaling pathway, etc. Moreover, the expression of osteogenesis-related genes, such as R-spondin 1 and chemokine c-c-motif ligand 2, was increased. Finally, both the 3D-printed β-TCP scaffolds and PDA-coated scaffolds could significantly accelerate the formation of new bone in critical-size calvarial defects in rats compared with the control group; and the new bone formation was obviously higher in the PDA-coated scaffolds than in β-TCP scaffolds. In summary, 3D-printed β-TCP scaffolds with a PDA coating can improve the physicochemical characteristics and cellular bioactivity of the scaffold surface for bone regeneration. Potential differential genes were identified, which can be used as a foundation for further research.

Advances in materials-based therapeutic strategies against osteoporosis

Osteoporosis is caused by the disruption in homeostasis between bone formation and bone resorption. Conventional management of osteoporosis involves systematic drug administration and hormonal therapy. These treatment strategies have limited curative efficacy and multiple adverse effects. Biomaterials-based therapeutic strategies have recently emerged as promising alternatives for the treatment of osteoporosis. The present review summarizes the current status of biomaterials designed for managing osteoporosis. The advantages of biomaterials-based strategies over conventional systematic drug treatment are presented. Different anti-osteoporotic delivery systems are concisely addressed. These materials include injectable hydrogels and nanoparticles, as well as anti-osteoporotic bone tissue engineering materials. Fabrication techniques such as 3D printing, electrostatic spinning and artificial intelligence are appraised in the context of how the use of these adjunctive techniques may improve treatment efficacy. The limitations of existing biomaterials are critically analyzed, together with deliberation of the future directions in biomaterials-based therapies. The latter include discussion on the use of combination strategies to enhance therapeutic efficacy in the osteoporosis niche.

Three-Dimensional Impression of Biomaterials for Alveolar Graft: Scoping Review

Craniofacial bone defects are one of the biggest clinical challenges in regenerative medicine, with secondary autologous bone grafting being the gold-standard technique. The development of new three-dimensional matrices intends to overcome the disadvantages of the gold-standard method. The aim of this paper is to put forth an in-depth review regarding the clinical efficiency of available 3D printed biomaterials for the correction of alveolar bone defects. A survey was carried out using the following databases: PubMed via Medline, Cochrane Library, Scopus, Web of Science, EMBASE, and gray literature. The inclusion criteria applied were the following: in vitro, in vivo, ex vivo, and clinical studies; and studies that assessed bone regeneration resorting to 3D printed biomaterials. The risk of bias of the in vitro and in vivo studies was performed using the guidelines for the reporting of pre-clinical studies on dental materials by Faggion Jr and the SYRCLE risk of bias tool, respectively. In total, 92 publications were included in the final sample. The most reported three-dimensional biomaterials were the PCL matrix, β-TCP matrix, and hydroxyapatite matrix. These biomaterials can be combined with different polymers and bioactive molecules such as rBMP-2. Most of the included studies had a high risk of bias. Despite the advances in the research on new three-dimensionally printed biomaterials in bone regeneration, the existing results are not sufficient to justify the application of these biomaterials in routine clinical practice.

A critical review on polydopamine surface-modified scaffolds in musculoskeletal regeneration

Increasing concern about age-related diseases, particularly musculoskeletal injuries and orthopedic conditions, highlights the need for strategies such as tissue engineering to address them. Surface modification has been developed to create pro-healing interfaces, personalize scaffolds and provide novel medicines. Polydopamine, a mussel-inspired adhesive polymer with highly reactive functional groups that adhere to nearly all substrates, has gained attention in surface modification strategies for biomaterials. Polydopamine was primarily developed to modify surfaces, but its effectiveness has opened up promising approaches for further applications in bioengineering as carriers and nanoparticles. This review focuses on the recent discoveries of the role of polydopamine as a surface coating material, with focus on the properties that make it suitable for tackling musculoskeletal disorders. We report the evolution of using it in research, and discuss papers involving the progress of this field. The current research on the role of polydopamine in bone, cartilage, muscle, nerve, and tendon regeneration is discussed, thus giving comprehensive overview about the function of polydopamine both in-vitro and in-vivo. Finally, the report concludes presenting the critical challenges that must be addressed for the clinical translation of this biomaterial while exploring future perspectives and research opportunities in this area.

Surface polydopamine modification of bone defect repair materials: Characteristics and applications

Bone defects are a common challenge for clinical orthopedic surgeons. The existing bone defect repair materials are difficult to achieve satisfactory osseointegration between the material and the bone. Therefore, it is increasingly important to find effective methods to improve the integration of the materials with the bone and thus facilitate bone defect repair. Researchers have found that polydopamine (PDA) has a structure and properties similar to the adhesive proteins secreted by mussels in nature, with good biocompatibility, bioactivity, hydrophilicity, bio-adhesion and thermal stability. PDA is therefore expected to be used as a surface modification material for bone repair materials to improve the bonding of bone repair materials to the bone surface. This paper reviews research related to PDA-modified bone repair materials and looks at their future applications.

Engineered 3D-Printed Polyvinyl Alcohol Scaffolds Incorporating β-Tricalcium Phosphate and Icariin Induce Bone Regeneration in Rat Skull Defect Model

The skull defects are challenging to self-heal, and autologous bone graft repair has numerous drawbacks. The scaffolds for the rapid and effective repair of skull defects have become an important research topic. In this study, polyvinyl alcohol (PVA)/β-tricalcium phosphate(β-TCP) composite scaffolds containing icariin (ICA) were prepared through direct-ink three-dimensional (3D) printing technology. β-TCP in the composite scaffold had osteoconductive capability, and the ICA molecule had osteoinductive capacity. The β-TCP and ICA components in the composite scaffold can enhance the capability to repair skull defects. We show that ICA exhibited a slow-release behaviour within 80 days. This behaviour helped the scaffold to continuously stimulate the formation of new bone. The results of in vitro cell compatibility experiments showed that the addition of ICA molecules contributed to the adhesion and proliferation of MC-3T3-E1 cells. The level of alkaline phosphatase secretion demonstrated that the slow release of ICA can promote the osteogenic differentiation of MC-3T3-E1 cells. The introduction of ICA molecules accelerated the in situ bone regeneration in in vivo. It is concluded that the 3D-printed PVA scaffold with β-TCP and ICA has a wide range of potential applications in the field of skull defect treatment.

Aspirin effect on bone remodeling and skeletal regeneration: Review article

Bone tissues are one of the most complex tissues in the body that regenerate and repair themselves spontaneously under the right physiological conditions. Within the limitations of treating bone defects, mimicking tissue engineering through the recruitment of scaffolds, cell sources and growth factors, is strongly recommended. Aspirin is one of the non-steroidal anti-inflammatory drugs (NSAIDs) and has been used in clinical studies for many years due to its anti-coagulant effect. On the other hand, aspirin and other NSAIDs activate cytokines and some mediators in osteoclasts, osteoblasts and their progenitor cells in a defect area, thereby promoting bone regeneration. It also stimulates angiogenesis by increasing migration of endothelial cells and the newly developed vessels are of emergency in bone fracture repair. This review covers the role of aspirin in bone tissue engineering and also, highlights its chemical reactions, mechanisms, dosages, anti-microbial and angiogenesis activities.

Hybprinting for musculoskeletal tissue engineering

This review presents bioprinting methods, biomaterials, and printing strategies that may be used for composite tissue constructs for musculoskeletal applications. The printing methods discussed include those that are suitable for acellular and cellular components, and the biomaterials include soft and rigid components that are suitable for soft and/or hard tissues. We also present strategies that focus on the integration of cell-laden soft and acellular rigid components under a single printing platform. Given the structural and functional complexity of native musculoskeletal tissue, we envision that hybrid bioprinting, referred to as hybprinting, could provide unprecedented potential by combining different materials and bioprinting techniques to engineer and assemble modular tissues.

Additive Manufacturing Technologies for Fabrication of Biomaterials for Surgical Procedures in Dentistry: A Narrative Review

PURPOSE

To screen and critically appraise available literature regarding additive manufacturing technologies for bone graft material fabrication in dentistry.

MATERIAL AND METHODS

PubMed and Scopus were searched up to May 2021. Studies reporting the additive manufacturing techniques to manufacture scaffolds for intraoral bone defect reconstruction were considered eligible. A narrative review was synthesized to discuss the techniques for bone graft material fabrication in dentistry and the biomaterials used.

RESULTS

The databases search resulted in 933 articles. After removing duplicate articles (128 articles), the titles and abstracts of the remaining articles (805 articles) were evaluated. A total of 89 articles were included in this review. Reading these articles, 5 categories of additive manufacturing techniques were identified: material jetting, powder bed fusion, vat photopolymerization, binder jetting, and material extrusion.

CONCLUSIONS

Additive manufacturing technologies for bone graft material fabrication in dentistry, especially 3D bioprinting approaches, have been successfully used to fabricate bone graft material with distinct compositions.

Developing photothermal-responsive and anti-oxidative silk/dopamine nanoparticles decorated with drugs which were incorporated into silk films as a depot-based drug delivery

Photothermal-responsive (PTR) and anti-oxidative silk fibroin/dopamine nanoparticles (SD NPs) mediated by tyrosinase were produced, and decorated either by curcumin or albumin (BSA) to produce SD/curcumin or SD/BSA NPs as drug delivery vehicles, respectively. Both drug loaded NPs were further blended into SF solutions to produce SD films, as a depot-based drug delivery. The reaction mechanisms for producing new SD NPs were proposed. Anti-oxidative activities for SD NPs were examined by H₂O₂ scavenge capacities of NPs. NPs were not cytotoxic at concentration of 1000μg/mL. Moreover, heparin was coated to SD films to produce SDH films for temporary implants. Cumulative release profiles for drugs loaded SDH films showed fast releases and then sustained releases stages. Furthermore, the releases of curcumin in sustained stages for varying SD/curcumin NPs loaded into SDH films were dependent on amounts of NPs. BSA releases profiles for SD/BSA NPs loaded into SDH films were similar to those profiles for the films carried with SD/curcumin NPs but release periods of BSA were short. Degrees of PTR effects with irradiation of near infrared on the releases of two drugs loaded films were different. Blood clot at wound areas of rats with SDH films implantations was not found for 24 h study.

Tissue Engineering Through 3D Bioprinting to Recreate and Study Bone Disease

The applications of 3D bioprinting are becoming more commonplace. Since the advent of tissue engineering, bone has received much attention for the ability to engineer normal bone for tissue engraftment or replacement. While there are still debates on what materials comprise the most durable and natural replacement of normal tissue, little attention is given to recreating diseased states within the bone. With a better understanding of the cellular pathophysiology associated with the more common bone diseases, these diseases can be scaled down to a more throughput way to test therapies that can reverse the cellular pathophysiology. In this review, we will discuss the potential of 3D bioprinting of bone tissue in the following disease states: osteoporosis, Paget's disease, heterotopic ossification, osteosarcoma, osteogenesis imperfecta, and rickets disease. The development of these 3D bioprinted models will allow for the advancement of novel therapy testing resulting in possible relief to these chronic diseases.

Biomaterial-based strategies for maxillofacial tumour therapy and bone defect regeneration

Issues caused by maxillofacial tumours involve not only dealing with tumours but also repairing jaw bone defects. In traditional tumour therapy, the systemic toxicity of chemotherapeutic drugs, invasive surgical resection, intractable tumour recurrence, and metastasis are major threats to the patients' lives in the clinic. Fortunately, biomaterial-based intervention can improve the efficiency of tumour treatment and decrease the possibility of recurrence and metastasis, suggesting new promising antitumour therapies. In addition, maxillofacial bone tissue defects caused by tumours and their treatment can negatively affect the physiological and psychological health of patients, and investment in treatment can result in a multitude of burdens to society. Biomaterials are promising options because they have good biocompatibility and bioactive properties for stimulation of bone regeneration. More interestingly, an integrated material regimen that combines tumour therapy with bone repair is a promising treatment option. Herein, we summarized traditional and biomaterial-mediated maxillofacial tumour treatments and analysed biomaterials for bone defect repair. Furthermore, we proposed a promising and superior design of dual-functional biomaterials for simultaneous tumour therapy and bone regeneration to provide a new strategy for managing maxillofacial tumours and improve the quality of life of patients in the future.

Co-modification of calcium phosphate cement to achieve rapid bone regeneration in osteoporotic femoral condyle defect with lithium and aspirin

Local application of lithium or aspirin with biological scaffold has been identified as a potent means to improve bone formation. In this study, lithium and aspirin modified calcium phosphate cement (Asp-Li/CPC) was prepared, and the feasibility of this biological scaffold in the treatment of osteoporotic bone defect was observed in vivo and in vitro. In vitro experiments confirmed that Asp-Li/CPC had better ability to promote MC3T3-E1 cells differentiation into osteoblasts, osteoblast mineralization and viability, and promote cell expression of ALP, OP, RUNX-2, OC and COL-1 protein than simple CPC or lithium modified CPC by MTT, Alizarin red staining and Western blot evaluation. In vivo experiments confirmed that Asp-Li/CPC presented the strongest effect on bone regeneration and bone mineralization through the comparison with CPC group and Li/CPC group with X-ray images, Micro-CT and Histological evaluation. RT-qPCR analysis showed that Asp-Li/CPC, Li/CPC group and CPC group demonstrated increased BMP2, Smad1, OPG than the OVX group (P<0.05), while Asp-Li/CPC exhibited decreased TNF-α, IFN-γ and RANKL than the OVX group (P<0.05). Experiments in vivo and in vitro show that Asp-Li/CPC is a scheme for rapid repair of femoral condylar defects, and these effects may be achieved by inhibiting local inflammation and through BMP-2/Smad1 and OPG/RANKL signaling pathway.

Clinical application and accuracy analysis of 3D printing guide plate based on polylactic acid in mandible reconstruction with fibula flap

Background

Due to the special anatomy morphology and physiological function of the mandible, it has always become a challenge to accurately reconstruct the mandibular defect in maxillofacial surgery. Digital three dimensions (3D) printing surgical guide, as the effective method for individual and accurate surgery, is a hotspot of clinical research at present. In this study, 3D printing PLA surgical guide plate was applied to reconstruct the mandibular defect with fibula flap, its clinical effect and accuracy were evaluated, which aimed to improve the accurate reconstruction of mandibular defects.

Methods

After sterilization, the dimension deformation of the PLA standard specimen were measured. Eighteen patients diagnose with mandibular tumor were collected as observation objects. Then partial mandible resection and simultaneous mandible reconstruction with fibula graft were implemented according to the computer-aided design plan. The clinical effects of 3D printing PLA guide plates application were evaluated by facial contours, occlusal stability and chewing function. Through registering the postoperative computed images reconstruction with preoperative designed shape, the reconstruction accuracy was evaluated by detecting the maximum difference including the distance between lateral convex point of the condyles, the distance between medial convex point of the condyles and the horizontal contained angle between long axis of the condyles.

Results

After high temperature steam sterilization, the curvature of the PLA specimen with 100% filling rate and 4.8 mm thickness were the smallest and their dimension deformation had no statistical significance (P>0.05). The minimally deformed 3D printing PLA guide plate were smoothly placed in the right place during the operation. After surgery, the face was symmetrical, the occlusal relationship was restored well and no deviation of the mandibular movement were found. The spiral computed tomography (SCT) scanning showed that the distance between lateral/medial convex points of the condyle and the horizontal contained angle were 128.34±8.68 mm, 88.69±6.75 mm and 145.87°±12.01°. Compared with preoperative design, the maximum deviation of the actual postoperative registration was 1.67±0.63, and the difference was not statistically significant (P>0.05).

Conclusions

The application of 3D printing PLA guide plate in the segmental section and reconstruction of the mandible can effectively simplify the operation, and better reconstruct the continuity of the mandible. The surgical accuracy can fully meet clinical needs with relatively low prices.

Polyphenol scaffolds in tissue engineering

Polyphenols are a class of ubiquitous compounds distributed in nature, with fascinating inherent biocompatible, bioadhesive, antioxidant, and antibacterial properties. The unique polyphenolic structures based on catechol or pyrogallol moieties allow for strong non-covalent interactions (e.g., multiple hydrogen bonding, electrostatic, and cation-π interactions) as well as covalent interactions (e.g., Michael addition/Schiff-base reaction, radical coupling reaction, and dynamic coordination interactions with boronate or metal ions). This review article provides an overview of the polyphenol-based scaffolds including the hydrogels, films, and nanofibers that have emerged from chemical and functional signatures during the past years. A full description of the structure-function relationships in terms of their utilization in wound healing, bone regeneration, and electroactive tissue engineering is also carefully discussed, which may pave the path towards the rational design and facile preparation of next-generation polyphenol scaffolds for tissue engineering applications.

Aspirin modified strontium-doped β-tricalcium phosphate can accelerate the healing of femoral metaphyseal defects in ovariectomized rats

The purpose was to observe whether local administration Strontium (Sr) and Aspirin (Asp) can enhance the efficacy of β-Tricalcium phosphate(β-TCP) in the treatment of osteoporotic bone defect. The MC3T3-E1 cells were co-cultured with β-TCP, Sr/β-TCP, Asp-Sr/β-TCP scaffold and induced to osteogenesis, and the cell viability, mineralization ability were observed by MTT, Alizarin Red staining(ARS) and Western blotting(WB). Then this scaffolds were implanted into the femoral epiphysis bone defect model of ovariectomized(OVX) rats for 8 weeks. X-ray, Micro-CT, histology and Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis were used to observe the therapeutic effect and explore the possible mechanism. MTT, ARS results show that the cell mineralization and viability of Asp-Sr/β-TCP group is significantly higher than Control group, β-TCP group and Sr/β-TCP group. Protein expression show that the osteogenic protein expression such as ALP、OP、RUNX-2、OC and COL-1 of Asp-Sr/β-TCP group is significantly higher than Control group, β-TCP group and Sr/β-TCP group. X-ray images, Micro-CT and Histological analysis evaluation show that, group Asp-Sr/β-TCP presented the strongest effect on bone regeneration and bone mineralization, when compared with β-TCP group and Sr/β-TCP group. RT-qPCR analysis show that Asp-Sr/β-TCP, β-TCP group and Sr/β-TCP group showed increased BMP2, Smad1, OPG than the OVX group(p < 0.05), while Asp-Sr/β-TCP exhibited decreased TNF-α、IFN-γ and RANKL than the OVX group(p < 0.05). Our current study demonstrated that Asp-Sr/ β-TCP is a scheme for rapid repair of femoral condylar defects, and these effects may be achieved by inhibiting local inflammation and through BMP-2/Smad1 and OPG/RANKL signaling pathway.

Melanin and Melanin-Like Hybrid Materials in Regenerative Medicine

Melanins are a group of dark insoluble pigments found widespread in nature. In mammals, the brown-black eumelanins and the reddish-yellow pheomelanins are the main determinants of skin, hair, and eye pigmentation and play a significant role in photoprotection as well as in many biological functions ensuring homeostasis. Due to their broad-spectrum light absorption, radical scavenging, electric conductivity, and paramagnetic behavior, eumelanins are widely studied in the biomedical field. The continuing advancements in the development of biomimetic design strategies offer novel opportunities toward specifically engineered multifunctional biomaterials for regenerative medicine. Melanin and melanin-like coatings have been shown to increase cell attachment and proliferation on different substrates and to promote and ameliorate skin, bone, and nerve defect healing in several in vivo models. Herein, the state of the art and future perspectives of melanins as promising bioinspired platforms for natural regeneration processes are highlighted and discussed.

3D Hierarchical, Nanostructured Chitosan/PLA/HA Scaffolds Doped with TiO2/Au/Pt NPs with Tunable Properties for Guided Bone Tissue Engineering

Bone tissue is the second tissue to be replaced. Annually, over four million surgical treatments are performed. Tissue engineering constitutes an alternative to autologous grafts. Its application requires three-dimensional scaffolds, which mimic human body environment. Bone tissue has a highly organized structure and contains mostly inorganic components. The scaffolds of the latest generation should not only be biocompatible but also promote osteoconduction. Poly (lactic acid) nanofibers are commonly used for this purpose; however, they lack bioactivity and do not provide good cell adhesion. Chitosan is a commonly used biopolymer which positively affects osteoblasts' behavior. The aim of this article was to prepare novel hybrid 3D scaffolds containing nanohydroxyapatite capable of cell-response stimulation. The matrixes were successfully obtained by PLA electrospinning and microwave-assisted chitosan crosslinking, followed by doping with three types of metallic nanoparticles (Au, Pt, and TiO2). The products and semi-components were characterized over their physicochemical properties, such as chemical structure, crystallinity, and swelling degree. Nanoparticles' and ready biomaterials' morphologies were investigated by SEM and TEM methods. Finally, the scaffolds were studied over bioactivity on MG-63 and effect on current-stimulated biomineralization. Obtained results confirmed preparation of tunable biomimicking matrixes which may be used as a promising tool for bone-tissue engineering.