Human dental pulp stem cell-derived exosomes decorated titanium scaffolds for promoting bone regeneration.

Exosomes, nanoscale extracellular vesicles crucial for intercellular communication, hold great promise as a therapeutic avenue in cell-free tissue regeneration. In this study, we identified and utilized exosomes to adorn anodized titanium scaffolds, inducing osteogenic differentiation in human dental pulp stem cells (hDPSCs). The osteogenesis of hDPSCs was stimulated by exosomes derived from hDPSCs that underwent various periods of osteogenic differentiation. After purification, these exosomes were loaded onto anodized titanium scaffolds. Notably, the scaffolds loaded with exosomes deriving from osteogenic differentiated hDPSCs demonstrated superior bone tissue regeneration compared to those loaded with exosomes deriving from hDPSCs within 10-week. RNA-sequencing analysis shed light on the underlying mechanism, revealing that the osteogenic exosomes carried specific cargo, which is due to upregulated miRNAs (Hsa-miR-29c-5p, Hsa-miR-378a-5p, Hsa-miR-10b-5p and Hsa-miR-9-3p) associated with osteogenesis. And down-regulated anti-osteogenic miRNA (Hsa-miR-31-3p, Hsa-miR-221-3p, Hsa-miR-183-5p and Hsa-miR-503-5p). In conclusion, the identification and utilization of exosomes derived from osteogenic differentiated stem cells offer a novel and promising strategy for achieving cell-free bone regeneration.

A study on the antibacterial property and biocompatibility of ramie fiber.

Ramie fiber (RF) has excellent tensile strength and breathability, making it a promising material for biomedical applications. However, few studies on the antibacterial properties and biocompatibility of RF have been reported. This study aimed to investigate the antibacterial property and biocompatibility of RF with bacteria and fibroblasts. The results showed that the antibacterial activity of RF was better than that of natural cotton fiber (NCF) and close to that of medical cotton fiber (MCF) for bothStaphylococcus aureus(S. aureus) andEscherichia coli(E.coli), and RF was more antibacterial againstS. aureusthanE.coli. The RF, MCF and NCF promoted the proliferation and spread of mouse fibroblast (L929) cells. The results indicated that RF has excellent antibacterial properties and biocompatibility, making it a potential biomaterial for biomedical applications.

The response of bioactive titanium surfaces with different structure to UVC-irradiation to eliminate the negative effect on biological properties during aging time.

The biological aging of titanium implants affects the service lifetime negatively in clinical applications, and Ultraviolet (UV) irradiation is an applicable method to overcome the biological aging. This study investigated the changes in surface characteristics and biological properties of bioactive titanium surfaces with different structure and topography after Ultraviolet C (UVC) irradiation. The bioactive titanium surfaces were prepared by anodizing (AO), sandblasting and acid-etching (SLA), acid-alkali etching (AA), alkali-heat etching (AH) methods. Samples were stored at dark for 7 weeks to simulate biological aging process and then irradiated by UVC for 2 h. The results showed that the hydroxyl groups (Ti-OH) on surfaces, which are crucial to enhance the biological properties, were easier to be generated on AO surfaces by UVC-irradiation, owing to a mixture of anatase and rutile on surfaces. UVC-irradiation had the strongest effect on AO surfaces to enhance the bioactivity in bone-like apatite deposition and better biocompatibility in mesenchymal stem cells (MSCs) attachment and proliferation. Therefore, titanium surfaces with a mixture phase of anatase and rutile have the potential to effectively utilize the benefits of UVC-irradiation to overcome the negative effects of the biological aging and have a promising clinical application prospect.

Novel dental implant modifications with two-staged double benefits for preventing infection and promoting osseointegration in vivo and in vitro.

Peri-implantitis are a major problem causing implant failure these days. Accordingly, anti-infection during the early stage and subsequent promotion of osseointegration are two main key factors to solve this issue. Micro-arc oxidation (MAO) treatment is a way to form an oxidation film on the surface of metallic materials. The method shows good osteogenic properties but weak antibacterial effect. Therefore, we developed combined strategies to combat severe peri-implantitis, which included the use of a novel compound, PD, comprising dendrimers poly(amidoamine) (PAMAM) loading dimethylaminododecyl methacrylate (DMADDM) as well as MAO treatment. Here, we explored the chemical properties of the novel compound PD, and proved that this compound was successfully synthesized, with the loading efficiency and encapsulation efficiency of 23.91% and 31.42%, respectively. We further report the two-stage double benefits capability of PD + MAO: (1) in the first stage, PD + MAO could decrease the adherence and development of biofilms by releasing DMADDM in the highly infected first stage after implant surgery both in vitro and in vivo; (2) in the second stage, PD + MAO indicated mighty anti-infection and osteoconductive characteristics in a rat model of peri-implantitis in vivo. This study first reports the two-staged, double benefits of PD + MAO, and demonstrates its potential in clinical applications for inhibiting peri-implantitis, especially in patients with severe infection risk.

Effects of statherin on the biological properties of titanium metals subjected to different surface modification.

The failure of dental implants is usually caused by bacteria infection, poor bioactivity and biocompatibility. It is a common phenomenon clinically. Statherin, a salivary protein, plays a crucial role of mediator between materials and cells/bacteria. However, the conformation of statherin might be changed by the implants in vivo. In this study, we investigated the effects of statherin on the bioactivities, antibacterial abilities and biocompatibilities of the titanium metals and the reaction mechanism. We found that the conformation of statherin was mainly influenced by surface composition, surface structure, surface roughness, surface hydrophilia and Ti-OH groups of materials. Statherin could decrease the cell biocompatibility of the titanium metals including pure titanium (PT), anodic oxidation (AO), sandblasting and etching (SLA) and plasma spraying hydroxyapatite (HA) coating in HGF cell experiments, regulate the bio-mineralization ability of HA coating in SBF, and enhance the antibacterial properties of PT and HA coating. This study revealed that surface properties of materials could change the conformation of statherin, which influenced the bioactivities, antibacterial properties and biocompatibilities of the materials in return.

Study on microstructure, microhardness, bioactivity, and biocompatibility of La2 O3 -containing bioceramic coating doping SiO2 fabricated by laser cladding.

To solve the lack of strength of calcium phosphate ceramic coatings in load-bearing applications, gradient Ca-P bioceramic coatings doped with La2 O3 and SiO2 are fabricated by laser cladding on Ti-6Al-4 V. The effect of SiO2 on microstructure, microhardness, bioactivity, and biocompatibility of coatings was investigated. The experimental results illustrate that the coating doped with La2 O3 and SiO2 has excellent metallurgical bonding. The XRD analysis confirms that the amount of hydroxyapatite and tricalcium phosphate in the coating reached maximum when doping amount of SiO2 is 10 wt %. SiO2 -doped coatings show a significantly higher bone-like apatite precipitation after immersion in SBF than that of other coatings. in vitro experiment also shows that coating with 10 wt % SiO2 is more suitable for the attachment and proliferation of MG63 cells, indicating that coating with 10 wt % SiO2 exhibits best bioactivity and biocompatibility. These results suggest that the addition of SiO2 improves the bonding strength, bioactivity, and biocompatibility of coatings.

[Expert consensus on biomechanical research of dental implant].

Current biomechanical research of dental implants focuses on the mechanical damage and enhancement mechanism of the implant-abutment interface as well as how to obtain better mechanical strength and longer fatigue life of dental implants. The mechanical properties of implants can be comprehensively evaluated by strain gauge analysis, photo elastic stress analysis, digital image correlation, finite element analysis, implant bone bonding strength test, and measurement of mechanical properties. Finite element analysis is the most common method for evaluating stress distribution in dental implants, and static pressure and fatigue tests are commonly used in mechanical strength test. This article reviews biomechanical research methods and evaluation indices of dental implants. Results provide methodology guidelines in the field of biomechanics by introducing principles, ranges of application, advantages, and limitations, thereby benefitting researchers in selecting suitable methods. The influencing factors of the experimental results are presented and discussed to provide implant design ideas for researchers.

[Advances in titanium dental implant surface modification].

Titanium dental implants have wide clinical application due to their many advantages, including comfort, aesthetics, lack of damage to adjacent teeth, and significant clinical effects. However, the failure of osseointegration, bone resorption, and peri-implantitis limits their application. Physical-chemical and bioactive coatings on the surface of titanium implants could improve the successful rate of dental implants and meet the clinical application requirements. This paper reviews the characteristics of surface modification of titanium implants from the aspects of physics, chemistry, and biology. Results provide information for research and clinical application of dental implant materials.

[Criteria for success in dental implants].

With the comprehensive application and development of implant dentistry in recent years, multi-institutional data have supported a large number of clinical research findings. A consensus was gradually reached on the evaluation of the state and effect of implants and types of indicators that were selected after restoration. This study aims to examine the frequently used criteria to define treatment success in implant dentistry.

[A review of peri-implant microbiology].

Dental implants represent the majority of treatment strategies used to replace missing teeth. However, peri-implant diseases caused by disturbance in peri-implant microbiological balance are among the reasons for implant failure. Since the 1980s, peri-implant microorganisms have been a hot research topic in dental microbiology. The bacterial ecology between the disease and health largely differs, which directly or indirectly increases the risk of peri-implant diseases. Accordingly, the determination of the 'core microbiome' of peri-implantitis and peri-implant mucositis is a key point of recent research.

Effect of magnesium on reducing the UV-induced oxidative damage in marrow mesenchymal stem cells.

Oxidative stress could cause damage to lipids, proteins and DNA, which is induced by the imbalance between the production of reactive oxygen species (ROS) and the biological system ability to counteract or detoxify their harmful effects. The oxidative stress damage significantly contributes to a number of diseases. Magnesium (Mg) is endowed with a novel function of removing excess ROS by releasing H2 during the degradation. In this study, in order to explore the property of anti-oxidative damage of Mg metal, rat bone marrow mesenchymal stem cells (MSCs) oxidative damaged by ultraviolet (UV) radiation was employed to co-culture with Mg metal. The effect of Mg metal on the response of antioxidant enzymes and mitochondria in MSCs was studied. We found that Mg metal could reduce the cellular oxidative stress damage and elevate the activities of antioxidant enzymes to maintain redox homeostasis. In addition, Mg metal could reduce the risk of UV-induced cell apoptosis by increasing the ratio of Bcl-2/Bax, elevating the mitochondrial membrane potential and blocking the release of cytochrome c. This finding showed Mg metal might have the potential for treating diseases caused by oxidative stress damage. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1253-1263, 2019.

Dual modulation of crystallinity and macro-/microstructures of 3D printed porous titanium implants to enhance stability and osseointegration.

The macro architecture and micro surface topological morphology of implants play essential roles in bone tissue regeneration. 3D printing technology provides enormous advantages for the rapid fabrication of personalized bone tissue repair implants. This study presents a demonstration of dual-modulation (DM) 3D printed porous titanium implants to enhance stability and osseointegration. Titanium implants with the first level of modulation of macro porous architecture and mechanical properties are obtained using macro architecture design and 3D printing fabrication. The first level of modulation achieved scaffolds with a wide range of compressive strengths (36.76-139.97 MPa) when varying the scaffold macro architectures. In the second level of modulation of surface topological morphology, alkali treatment, heat treatments and electrochemical deposition of hydroxyapatite coating were conducted for further regulating the biological function of implants. DM 3D printed scaffolds significantly promoted bone marrow mesenchyme stem cell adhesion and proliferation, indicating good cytocompatibility. In addition, in vivo osseointegration experiments indicated that the DM scaffolds formed better tissue-materials interfaces. New bone formation rates in DM scaffolds are higher than those in conventional 3D printed scaffolds after 6 months of implantation (58.1% versus 36.1%). These results demonstrate that DM scaffolds could enhance early stability and osseointegration. This study may provide new insights into the design, fabrication and post-processing of 3D printed porous titanium implants for various applications in personalized bone tissue regeneration.

The controllable lanthanum ion release from Ca-P coating fabricated by laser cladding and its effect on osteoclast precursors.

Several studies have suggested that rare earth oxides can improve properties of bioceramic coating, and bone resorption of osteoclast can be inhibited by rare earth ion releasing certain concentration. However, the effects of lanthanum ion (La3+) released from Ca-P coating on osteoclast precursors is not clear. In this work, La2O3-doped gradient bioceramic coatings were fabricated on Ti alloy (Ti-6Al-4V) by laser cladding with mixed powders of CaHPO4·2H2O, CaCO3 and La2O3. And the bioactivity, mechanical properties and the La3+ release from coating were investigated in vitro. Human osteosarcoma cells (MG63) were used as a cell model to evaluate the biocompatibility of coatings. Mouse macrophage RAW264.7 cells were cultured on coatings to study the effect of La3+ release from Ca-P coating on osteoclast precursors. The XRD results reveal that the amount of HA + TCP reaches maximum (2θ = 32-33°) when the content of La2O3 is 0.6 wt%, and the proliferation of MG63 cells is up to highest value, which indicates that compared with other groups, the bioceramic coating with 0.6 wt% La2O3 is of best biocompatibility. Furthermore, the differentiation of RAW264.7 cells into osteoclast could be inhibited by controllable releasing La3+ from Ca-P coating when soaked in SBF, which demonstrates that controllable La3+ release from Ca-P coating is an effective method to prevent osteoclast formation. And a prospective therapy is provided to cure the disease of wear debris in replacement of artificial joint.

Surface modification of ultrahigh molecular weight polyethylene by plasma-induced in-situ grafting with vinyl triethoxysilane.

Ultrahigh molecular weight polyethylene (UHMWPE) is an excellent material with high performance, but it is very difficult to covalently introduce functional groups on its surface owing to its inherently inert structure, which constrains its further application. In this study, vinyl triethoxysilane (VTEOS) containing hydrolysable alkoxyl groups was in situ grafted on UHMWPE by air plasma treatment. The plasma treatment conditions for VTEOS grafting were optimized. The structure of the modified UHMWPE was characterized with FTIR and XPS. The relatively high VTEOS content was obtained when the treating conditions were about 20 W, 125 Pa for 10 min. And FTIR results showed that the grafted structure on the surface was stable for long time duration in the ambient environment. After the treatment, the roughness of the surface increased and the water contact angle of the modified sample dropped to 47.5° from 92.8° of the unmodified one. TGA and XRD results indicated that plasma treatment would not change the bulk structure of UHMWPE greatly. Cell culture experiments showed that fibroblasts on the modified samples had notably high viability and proliferation rate with good adhesion shape. Hence, it might be an effective method to improve the surface properties of UHMWPE for biomedical applications by plasma-induced in-situ grafting with VTEOS. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 321-332, 2018.

Regulating the osteogenic function of rhBMP 2 by different titanium surface properties.

Bone morphogenetic protein 2 (BMP-2) is important for regulating the osteogenic differentiation of mesenchymal stem cells and the response of bone tissue. It adsorbs on the surface of biomedical implants immediately and plays a role of mediator between the materials surfaces and the host cells. Studies usually connect the material surface properties and the new bone formation directly. However, interaction between the adsorbed BMP-2 on the implant surface and the cells in the tissue is the key to explaining the osteogenic properties of the material. So, in this article, we investigated the conformational and functional changes induced by the surface modified titanium metals. We found that the α-helix and ß-sheet structure of rhBMP-2 can be well maintained on the anodic oxidation treated titanium surface. The osteogenic function of rhBMP-2 can sustain for a relatively long time even though there is less amount adhere to the surface compared with that on the acid alkali treated titanium. Surface properties, especially the morphology enable a larger amount of rhBMP-2 to adsorb to the surface of the acid alkali treated titanium, but the conformation of the protein is severely influenced. The percentage of α-helix structure is also significantly decreased so that the efficacy of rhBMP-2 is only maintained in the early time. This study indicated that different surface modification of the surface could regulate the structure of rhBMP-2 and then further influence its osteogenic function. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1882-1893, 2016.

On the antitumor properties of biomedical magnesium metal.

H2 is a therapeutic agent for tumors because it could scavenge free radicals, which is one of the causes for this disease in the human body. Biomedical magnesium (Mg) could release H2 in the biodegradation process, thus it might have antitumor properties. In this study, Mg metal (P-Mg) was subjected to anodic oxidation plus heat treatment to get AO-HT-Mg covered with MgO. In SBF experiments AO-HT-Mg showed bioactivity as it could induce calcium phosphate deposition. The MgO layer played a protective role in the biodegradation process and controlled the H2 releasing rate. In MRMT-1 rat breast carcinoma cell culture experiments, both P-Mg and AO-HT-Mg could inhibit free radical expression in the cells, and AO-HT-Mg showed higher inhibiting ability. In the animal experiments with 72 mice divided into 4 groups, both P-Mg and AO-HT-Mg could inhibit tumor growth. After implantation in the animals, P-Mg showed higher inhibiting ability at the initial stage, and AO-HT-Mg showed higher inhibiting ability after 26 days. The tumor inhibiting properties depended on H2 releasing rates. The results confirm Mg metal has antitumor properties in vivo, and it is possible to optimize its antitumor properties by surface modification.

Surface modification of ultrahigh molecular weight polyethylene by the poly(ethylene glycol)-grafted method and its effect on the adsorption of proteins and the adhesion of blood platelets.

With the help of a silane coupling agent, poly(ethylene glycol) (PEG), a well-biocompatable agent, was grafted onto the surface of ultrahigh molecular weight polyethylene (UHMWPE) by ultraviolet initiation. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis proved the success of PEG grafting. Water contact angle measurement showed that the modified UHMWPE was obviously improved in surface hydrophilicity and thermogravimetric analysis result showed that its thermostability did not decline even it was pretreated by strong acids. Then, the protein adsorption of the modified UHMWPE was investigated using three model proteins including bovine serum albumin, lysozyme, and fibrinogen. Rabbit blood was used to study the platelet adhesion on the surface of modified UHMWPE. The results indicated that the quantity of protein adsorption on the modified UHMWPE grafted PEG reduced apparently for all the model proteins while there was some specific differences or exceptions among them. It was ascribed to the changed surface chemical composition, surface hydrophilicity and surface topography after modification. The adhesive ability of blood platelets on the modified surface of UHMWPE decreased after PEG grafting. Owing to the improved resistance to fibrinogen adsorption and platelet adhesion, the surface modification might endow the UHWMPE surface better anticoagulation ability according to clotting mechanism.

Anti-inflammatory properties of bioactive titanium metals.

Anti-inflammatory properties of bioactive titanium metals prepared by anodic oxidation (AO-Ti) and alkali-heat (AH-Ti) treatments were studied by bacterial adhesion test and myeloperoxidase (MPO) activity assay methods. The bioactivities of the metals were also evaluated by apatite formation ability and osteoblasts culture experiments. Both metals could induce apatite formation and support osteoblasts proliferation. At the condition with normal incandescent light shine, both bioactive titanium metals had antibacterial adhesion properties compared with the titanium metal without treatment. The MPO activity assay proved that they both showed anti-inflammatory properties in vivo. The bioactive AO-Ti had better anti-inflammatory properties than the AH-Ti. It indicated that it is possible to optimize the anti-inflammatory properties of the bioactive titanium metals by different preparation methods.

Bioactive nano-titania ceramics with biomechanical compatibility prepared by doping with piezoelectric BaTiO(3).

Piezoelectric BaTiO(3) was employed as a crystal growth inhibitor additive for the preparation of bioactive nano-titania ceramics in this study. It is found that the additive could significantly inhibit nano-titania ceramic crystal growth during the pressureless sintering process. This inhibitory ability has great effects on the mechanical properties and bioactivities of the nano-titania ceramics, making it possible to obtain bioactive nano-titania ceramics with mechanical properties analogous to human bone. In this study, the crystal grain sizes of the nano-titania ceramics ranged from 18 to 68nm and the particle sizes ranged from 187 to 580nm by changing the additive content from 1% to 20%. The elastic modulus of the nano-titania ceramics ranged from 6.2 to 10.6GPa, which is analogous to that of human bone, by adjusting the additive content. The piezoelectric properties of the additive also showed the enhancing effects on the bioactivity of the nano-titania ceramics, which made the osteoblasts proliferate faster on the nano-titania ceramics in cell culture experiments. It might be a potential way to prepare bioactive nano-titania ceramics with biomechanical compatibility by using BaTiO(3) as a crystal growth inhibitor.

Collagen nanofilm immobilized on at surfaces by electrodeposition method.

A simple electrodeposition method is presented for the preparing of collagen nanofilms (EAT) on anodic oxidized titanium surfaces (AT). The nanofilms were observed by scanning electron microscopy and atomic force microscopy. Functional TiOx layers with anionic groups of --PO(4), --SO(4) and --OH were investigated on the AT surface by X-ray photoelectron spectroscopy; X-ray diffraction results indicated that the AT surface was composed mainly of anatase and rutile. The bioactive electrodeposited TiOx layers on the AT surface showed lower water contact angles and higher surface energy than pure titanium surfaces (CT) and displayed higher collagen molecule immobilization.