Current Tissue Engineering Approaches for Cartilage Regeneration

Cartilage is one of the critical tissues existed in human and animal bodies. Unlike most tissues, cartilage does not have blood vessels, nerves, and lymphatics. Most cartilage tissues in vivo are subjected to large mechanical loads, and its principal function is to provide a smooth and lubricated surface to facilitate the transmission of mechanical loads with a low frictional coefficient. As a result, cartilage tissues are easily injured. Cartilage defects are frequently caused by trauma, aging, congenital diseases (osteochondritis), and many more factors such as endocrine pathologies and cancer. The damaged cartilage has a limited capacity for healing and repairing. Thus, restoration of normal structure and function to damaged cartilage is one of the most challenging areas in orthopedic research and sports medicine. Tissue engineering provides a prospective alternative strategy by seeding chondrogenic cells into or onto biocompatible scaffolds to produce engineer cartilage for damaged cartilage repair. This book chapter has summarized recent progress in cartilage tissue engineering including stem cells, growth factors, bioactive molecules, and biomaterial scaffolds used for cartilage regeneration. The procedures for some new approaches have also been described

Photodegradation of Methylene Blue by TiO 2

Fe3O4-bentonite nanoparticles have been prepared by a coprecipitation technique under a nitrogen atmosphere. An aqueous suspension of bentonite was first modified with FeCl2 and FeCl3. TiO2 was then loaded onto the surface of the Fe3O4-bentonite by a sol-gel method. After sufficient drying, the colloidal solution was placed in a muffle furnace at 773 K to obtain the TiO2-Fe3O4-bentonite composite. The material has been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, and vibrating sample magnetometry (VSM). Morphological observation showed that Fe3O4 and TiO2 nanoparticles had been adsorbed on the surface of bentonite nanoneedles. The material was then applied for the photodegradation of the azo dye methylene blue (MB). It was found that the removal efficiency of MB exceeded 90% under UV illumination, and that only a 20% mass loss was incurred after six cycles. The composite material thus showed good photocatalytic performance and recycling properties

Design and engineering of silk fibroin scaffolds with biomimetic hierarchical structures

Singapore ARF Project [T206B1114]; National Natural Science Foundation of China [50928301, 51203108]; China MOE Chang Jiang Scholars ProgramSilk scaffolds having biomimetic hierarchical porous structures were achieved by carefully tuning liquid-liquid separation in regenerated silk fibroin solutions. Such scaffolds show greatly enhanced cellular responses

Roadmap on energy harvesting materials

Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere

Robust self tuner for variable time delay systems

A robust self tuner is presented for systems with unknown or variable time delay systems. A stability protection function is included in the controller to safeguard against instability caused by changes in the time delay of the process. Based on the behaviour of the self tuner in variable time delay systems, a simple time delay tracking technique is used to track the estimated process time delay parameter d0 every r sampling periods. Robustness of the proposed self tuner is achieved by combining the above two techniques. A simulation example will be presented to illustrate the proposed self tuner.link_to_subscribed_fulltex

METTL3 promotes SMSCs chondrogenic differentiation by targeting the MMP3, MMP13, and GATA3

Objective: Synovium-derived mesenchymal stem cells (SMSCs) are multipotential non-hematopoietic progenitor cells that can differentiate into various mesenchymal lineages in adipose and bone tissue, especially in chondrogenesis. Post-transcriptional methylation modifications are relative to the various biological development procedures. N6-methyladenosine (m6A) methylation has been identified as one of the abundant widespread post-transcriptional modifications. However, the connection between the SMSCs differentiation and m6A methylation remains unknown and needs further exploration. Methods: SMSCs were derived from synovial tissues of the knee joint of male Sprague–Dawley (SD) rats. In the chondrogenesis of SMSCs, m6A regulators were detected by quantitative real-time PCR (RT-PCR) and Western blot (WB). We observed the situation that the knockdown of m6A “writer” protein methyltransferase-like (METTL)3 in the chondrogenesis of SMSCs. We also mapped the transcript-wide m6A landscape in chondrogenic differentiation of SMSCs and combined RNA-seq and MeRIP-seq in SMSCs by the interference of METTL3. Results: The expression of m6A regulators were regulated in the chondrogenesis of SMSCs, only METTL3 is the most significant factor. In addition, after the knockdown of METTL3, MeRIP-seq and RNA-seq technology were applied to analyze the transcriptome level in SMSCs. 832 DEGs displayed significant changes, consisting of 438 upregulated genes and 394 downregulated genes. DEGs were enriched in signaling pathways regulating the glycosaminoglycan biosynthesis-chondroitin sulfate/dermatan sulfate and ECM-receptor interaction via Kyoto Encyclopedia of genes and genomes (KEGG) pathway enrichment analysis. The findings of this study indicate a difference in transcripts of MMP3, MMP13, and GATA3 containing consensus m6A motifs required for methylation by METTL3. Further, the reduction of METTL3 decreased the expression of MMP3, MMP13, and GATA3. Conclusion: These findings confirm the molecular mechanisms of METTL3-mediated m6A post-transcriptional change in the modulation of SMSCs differentiating into chondrocytes, thus highlighting the potential therapeutic effect of SMSCs for cartilage regeneration