Biomimetic photo-responsive hydrogels for articular cartilage defects repair

Osteoarthritis (OA) is one of the most prevalent chronic diseases and severely impacts the quality of patients’ life and brings burdens to society. Cartilage defects are important pathological features of OA. Challenges remain in both partial-thickness cartilage defects and osteochondral defects: it is difficult to fix the materials used for partial-thickness cartilage defects and the scaffolds for osteochondral defects require high performance in biological properties as well as structural properties. As a three-dimensional polymer network containing a large amount of water, hydrogels have become widespread in cartilage repair and other biomedical applications for their biomimetic properties and multifunctionalities. Here, based on the cartilage matrix, biomimetic hydrogels for articular cartilage defects repairment were developed. For partial-thickness cartilage defects, a two-step biomimetic adhesive hydrogel was developed; besides, a one-step adhesive hydrogel was developed by improving the components design of the previous strategy; for osteochondral defects, high-precision 3D hydrogel bioprinting system was developed for the preparation of biomimetic scaffolds. The research mainly includes the following contents: 1. ‘Two-step’ photo-responsive biomimetic tissue-adhesive hydrogel for partial-thickness cartilage defect repair. Partial-thickness cartilage defect is the most common symptom of OA but till now it is less focused with no proven clinical treatments and relatively less research on partial-thickness cartilage defect repair. Mimicking the natural cartilage, the tissue adhesive hydrogel “joint paint” is comprised of a gelatin methacrylate (GelMA)/ hyaluronic acid (HA) surface layer and a chondroitin sulfate (CS) layer that can bridge the surface layer and the cartilage. The joint paint can rapidly gel at the defect area under light exposure and the formed binding is tight enough for long-term maintenance. Being able to keep main cartilage matrix components such as glycosaminoglycan and inhibit cell apoptosis, this hydrogel functions well in rabbit partial-thickness cartilage defect models with good tissue integration and regeneration capability. 2. One-step photoresponsive biomimetic tissue adhesive hydrogel for partial-thickness cartilage defect repair Based on the strategy of in situ photoresponsive adhesive hydrogels for partial-thickness cartilage defects repairment, the material formulation was improved to avoid the two-step usage in Chapter 3, making it more suitable for clinical application and translation. The photoinduced imine crosslinking strategy was used to provide the adhesion ability between hydrogels and tissues. O-nitrobenzyl compound NB was grafted onto CS, and hydrogels containing GelMA, CSNB, and HA were prepared according to the proportion of natural cartilage matrix components. This double-network hydrogel can gel rapidly on cartilage surface in a single step and shows good efficacy for partial-thickness cartilage defects regeneration in large animal models. 3. High precision stereolithography 3D bioprinting system for the preparation of osteochondral tissue engineering scaffolds with biomimetic structure Osteochondral defect is one of the manifestations of the terminal progression of osteoarthritis. Structure-free hydrogels cannot meet the needs of osteochondral defect repair. However, due to technical limitations, the current osteochondral tissue engineering scaffolds rarely improve their performance through structures. 3D printing technology is a powerful means of creating complex structures. The application of CSNB in stereolithography 3D printing solves the problem that the printing resolution, the mechanical properties of products, and the cell-laden ability cannot be achieved simultaneously in the current 3D bioprinting technologies. CSNB system was used to print osteochondral scaffolds with a tidemark structure that could disperse mechanical load and the in vivo repair function of the scaffolds was assessed

PTS is activated by ATF4 and promotes lung adenocarcinoma development via the Wnt pathway

BACKGROUND: The effects and mechanism of 6-pyruvoyl-tetrahydropterin synthase ( METHODS: RESULTS: CONCLUSIONS

Discovery of Potential piRNAs from Next Generation Sequences of the Sexually Mature Porcine Testes

Piwi- interacting RNAs (piRNAs), a new class of small RNAs discovered from mammalian testes, are involved in transcriptional silencing of retrotransposons and other genetic elements in germ line cells. In order to identify a full transcriptome set of piRNAs expressed in the sexually mature porcine testes, small RNA fractions were extracted and were subjected to a Solexa deep sequencing. We cloned 6,913,561 clean reads of Sus Scrofa small RNAs (18–30 nt) and performed functional characterization. Sus Scrofa small RNAs showed a bimodal length distribution with two peaks at 21 nt and 29 nt. Then from 938,328 deep-sequenced small RNAs (26–30 nt), 375,195 piRNAs were identified by a k-mer scheme and 326 piRNAs were identified by homology searches. All piRNAs predicted by the k-mer scheme were then mapped to swine genome by Short Oligonucleotide Analysis Package (SOAP), and 81.61% of all uniquely mapping piRNAs (197,673) were located to 1124 defined genomic regions (5.85 Mb). Within these regions, 536 and 501 piRNA clusters generally distributed across only minus or plus genomic strand, 48 piRNA clusters distributed on two strands but in a divergent manner, and 39 piRNA clusters distributed on two strands in an overlapping manner. Furthermore, expression pattern of 7 piRNAs identified by homology searches showed 5 piRNAs displayed a ubiquitous expression pattern, although 2 piRNAs were specifically expressed in the testes. Overall, our results provide new information of porcine piRNAs and their specific expression pattern in porcine testes suggests that piRNAs have a role in regulating spermatogenesis

Study on the Catalytic Oxidation Modification Effect of Heavy Oil at Low Temperature under the Action of Different Ligand Ferric-Based Systems

This work explores the low-temperature catalytic oxidation of heavy oil (140 °C), resulting in structural changes with reduced heavy components and increased light components. The catalytic oxidation system consists of a catalyst, an oxidant, and a proton donor. Four different complexes of iron-based catalysts were utilized: ferric oleate, iron naphthenate, EDTA–FeNa, and EDDHA–FeNa. Catalytic oxidation processes with these catalysts produced four types of oxygenated oil, which were then analyzed using group composition analysis and a viscosity test. The results show that EDDHA–FeNa is more favorable for the catalytic oxidation of heavy oil in a low-temperature environment, achieving a viscosity reduction rate of 78.57%. Furthermore, the catalytic performance of heavy oil oxidation was investigated using EDDHA–FeNa as catalyst under three conditions: the amount of catalyst, oxidant and reaction temperature. These findings may provide researchers valuable guidance and principles for the investigation and development of advanced catalytic viscosity reduction of heavy oil

Effects of artificial aging on physiological quality and cell ultrastructure of maize (Zea mays L.)

‘Qiule 368’ (flour maize) and ‘Zhengdan 958’ (flint maize) seeds were artificially aged at 46 °C and 95% relative humidity to investigate the changes in physiological quality of maize seeds during aging. The vigor of the seeds, their reactive oxygen species (ROS) content, cell membrane status, antioxidant enzyme system, and cellular ultrastructure were all investigated. The results showed that the germination energy, germination rate, superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities decreased during artificial aging, whereas the content of malondialdehyde (MDA), hydrogen peroxide (H2O2), superoxide anion (O2·–), and carbonyl protein as well as relative electrical conductivity (REC) increased during artificial aging. SOD and CAT activities showed highly significant negative correlation with aging time (p < 0.01), MDA, H2O2, O2·– content and REC showed highly significant positive correlation with aging time (p < 0.01), whereas POD activity showed significant negative correlation with aging time (p < 0.05). After aging, the cell membrane ruptured, and negative changes in amyloplast and protein bodies and in liposomes were all observed. This study provided guidelines for the meaningful study of changes in maize seed physiological quality during storage

Transmissible Gastroenteritis Virus: An Update Review and Perspective

Transmissible gastroenteritis virus (TGEV) is a member of the alphacoronavirus genus, which has caused huge threats and losses to pig husbandry with a 100% mortality in infected piglets. TGEV is observed to be recombining and evolving unstoppably in recent years, with some of these recombinant strains spreading across species, which makes the detection and prevention of TGEV more complex. This paper reviews and discusses the basic biological properties of TGEV, factors affecting virulence, viral receptors, and the latest research advances in TGEV infection-induced apoptosis and autophagy to improve understanding of the current status of TGEV and related research processes. We also highlight a possible risk of TGEV being zoonotic, which could be evidenced by the detection of CCoV-HuPn-2018 in humans

Transmissible Gastroenteritis Virus: An Update Review and Perspective

Transmissible gastroenteritis virus (TGEV) is a member of the alphacoronavirus genus, which has caused huge threats and losses to pig husbandry with a 100% mortality in infected piglets. TGEV is observed to be recombining and evolving unstoppably in recent years, with some of these recombinant strains spreading across species, which makes the detection and prevention of TGEV more complex. This paper reviews and discusses the basic biological properties of TGEV, factors affecting virulence, viral receptors, and the latest research advances in TGEV infection-induced apoptosis and autophagy to improve understanding of the current status of TGEV and related research processes. We also highlight a possible risk of TGEV being zoonotic, which could be evidenced by the detection of CCoV-HuPn-2018 in humans