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.

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.

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.