新型稀土固体超强酸S2O82-/Sb2O3/La3+的制备与再生

以金属醇盐水解法制得前氧体 Sb_2O_3,采用浸渍法制备了稀土固体超强酸 S_2O_8~(-2)/Sb_2O_3/La~(3+)催化剂,以催化合成乙酸苄酯为探针反应考察了催化剂的制备条件。结果表明:以1.5 mol/L 的(NH_4)_2S_2O_8 和ω[La(NO_3)_3]=2.71%的 La(NO_3)_3混合液浸渍锑前氧体,经110℃烘干,于500℃焙烧3 h 所得催化剂活性较好。采用了 TG/DTA 考察了催化剂的失活原因,其最佳再生方法是:用无水乙醇洗涤,500℃焙烧再生。     

Effects of Exosomes Derived from Adipose-Derived Mesenchymal Stem Cells on Pyroptosis and Regeneration of Injured Liver

Although accumulating evidence indicates that exosomes have a positive therapeutic effect on hepatic ischemia–reperfusion injury (HIRI), studies focusing on the alleviation of liver injury by exosomes derived from adipose-derived mesenchymal stem cells (ADSCs-Exo) based on the inhibition of cell pyroptosis have not yet been reported. Exosomes contain different kinds of biologically active substances such as proteins, lipids, mRNAs, miRNAs, and signaling molecules. These molecules are widely involved in cell–cell communication, cell signal transmission, proliferation, migration, and apoptosis. Therefore, we investigated the positive effects exerted by ADSCs-Exo after hepatic ischemia–reperfusion with partial resection injury in rats. In this study, we found that the post-operative tail vein injection of ADSCs-Exo could effectively inhibit the expression of pyroptosis-related factors such as NLRP3, ASC, caspase-1, and GSDMD-N, and promote the expression of regeneration-related factors such as Cyclin D1 and VEGF. Moreover, we found that the above cellular activities were associated with the NF-κB and Wnt/β-catenin signaling pathways. According to the results, ADSCs and ADSCs-Exo can reduce pyroptosis in the injured liver and promote the expression of those factors related to liver regeneration, while they can inhibit the NF-κB pathway and activate the Wnt/β-catenin pathway. However, although adipose-derived mesenchymal stem cell (ADSC) transplantation can reduce liver injury, it leads to a significant increase in the pyroptosis-related protein GSDMD-N expression. In conclusion, our study shows that ADSCs-Exo has unique advantages and significance as a cell-free therapy to replace stem cells and still has a broad research prospect in the clinical diagnosis and treatment of liver injuries.     

Mlig-SKP1 Gene Is Required for Spermatogenesis in the Flatworm Macrostomum lignano

In a free-living flatworm, Macrostomum lignano, an S-phase kinase-associated protein 1 (SKP1) homologous gene was identified as enriched in proliferating cells, suggesting that it can function in the regulation of stem cells or germline cells since these are the only two types of proliferating cells in flatworms. SKP1 is a conserved protein that plays a role in ubiquitination processes as a part of the Skp1-Cullin 1-F-box (SCF) ubiquitin ligase complex. However, the exact role of Mlig-SKP1 in M. lignano was not established. Here, we demonstrate that Mlig-SKP1 is neither involved in stem cell regulation during homeostasis, nor in regeneration, but is required for spermatogenesis. Mlig-SKP1(RNAi) animals have increased testes size and decreased fertility as a result of the aberrant maturation of sperm cells. Our findings reinforce the role of ubiquitination pathways in germ cell regulation and demonstrate the conserved role of SKP1 in spermatogenesis.     

Skeletal Muscle Regeneration in Cardiotoxin-Induced Muscle Injury Models

Skeletal muscle injuries occur frequently in daily life and exercise. Understanding the mechanisms of regeneration is critical for accelerating the repair and regeneration of muscle. Therefore, this article reviews knowledge on the mechanisms of skeletal muscle regeneration after cardiotoxin-induced injury. The process of regeneration is similar in different mouse strains and is inhibited by aging, obesity, and diabetes. Exercise, microcurrent electrical neuromuscular stimulation, and mechanical loading improve regeneration. The mechanisms of regeneration are complex and strain-dependent, and changes in functional proteins involved in the processes of necrotic fiber debris clearance, M1 to M2 macrophage conversion, SC activation, myoblast proliferation, differentiation and fusion, and fibrosis and calcification influence the final outcome of the regenerative activity.     

The Stress Response of the Holothurian Central Nervous System: A Transcriptomic Analysis

Injury to the central nervous system (CNS) results in permanent damage and lack of function in most vertebrate animals, due to their limited regenerative capacities. In contrast, echinoderms can fully regenerate their radial nerve cord (RNC) following transection, with little to no scarring. Investigators have associated the regenerative capacity of some organisms to the stress response and inflammation produced by the injury. Here, we explore the gene activation profile of the stressed holothurian CNS. To do this, we performed RNA sequencing on isolated RNC explants submitted to the stress of transection and enzyme dissection and compared them with explants kept in culture for 3 days following dissection. We describe stress-associated genes, including members of heat-shock families, ubiquitin-related pathways, transposons, and apoptosis that were differentially expressed. Surprisingly, the stress response does not induce apoptosis in this system. Other genes associated with stress in other animal models, such as hero proteins and those associated with the integrated stress response, were not found to be differentially expressed either. Our results provide a new viewpoint on the stress response in the nervous system of an organism with amazing regenerative capacities. This is the first step in deciphering the molecular processes that allow echinoderms to undergo fully functional CNS regeneration, and also provides a comparative view of the stress response in other organisms.     

Tissue Characteristics in Endodontic Regeneration: A Systematic Review

The regenerative endodontic procedure (REP) represents a treatment option for immature necrotic teeth with a periapical lesion. Currently, this therapy has a wide field of pre-clinical and clinical applications, but no standardization exists regarding successful criteria. Thus, by analysis of animal and human studies, the aim of this systematic review was to highlight the main characteristics of the tissue generated by REP. A customized search of PubMed, EMBASE, Scopus, and Web of Science databases from January 2000 to January 2022 was conducted. Seventy-five human and forty-nine animal studies were selected. In humans, the evaluation criteria were clinical 2D and 3D radiographic examinations. Most of the studies identified a successful REP with an asymptomatic tooth, apical lesion healing, and increased root thickness and length. In animals, histological and radiological criteria were considered. Newly formed tissues in the canals were fibrous, cementum, or bone-like tissues along the dentine walls depending on the area of the root. REP assured tooth development and viability. However, further studies are needed to identify procedures to successfully reproduce the physiological structure and function of the dentin–pulp complex.     

Preparation and Characterization of Nanofibrous Membranes Electro-Spun from Blended Poly(l-lactide-co-ε-caprolactone) and Recombinant Spider Silk Protein as Potential Skin Regeneration Scaffold

Biomaterial scaffolding serves as an important strategy in skin tissue engineering. In this research, recombinant spider silk protein (RSSP) and poly(L-lactide-co-ε-caprolactone) (PLCL) were blended in different ratios to fabricate nanofibrous membranes as potential skin regeneration scaffolds with an electro-spinning process. Scanning electron microscopy (SEM), water contact angles measurement, Fourier transform infrared (FTIR) spectroscopy, wide angle X-ray diffraction (WAXD), tensile mechanical tests and thermo-gravimetric analysis (TGA) were carried out to characterize the nanofibrous membranes. The results showed that the blending of RSSP greatly decreased the nanofibers’ average diameter, enhanced the hydrophilicity, changed the microstructure and thermal properties, and could enable tailored mechanical properties of the nanofibrous membranes. Among the blended membranes, the PLCL/RSSP (75/25) membrane was chosen for further investigation on biocompatibility. The results of hemolysis assays and for proliferation of human foreskin fibroblast cells (hFFCs) confirmed the membranes potential use as skin-regeneration scaffolds. Subsequent culture of mouse embryonic fibroblast cells (NIH-3T3) demonstrated the feasibility of the blended membranes as a human epidermal growth factor (hEGF) delivery matrix. The PLCL/RSSP (75/25) membrane possessed good properties comparable to those of human skin with high biocompatibility and the ability of hEGF delivery. Further studies can be carried out on such membranes with chemical or genetic modifications to make better scaffolds for skin regeneration.     

双膜法处理污水厂尾水效能分析与膜再生研究

为提高污水厂出水水质,寻求适合处理污水厂尾水滤膜的再生方法,采用超滤—纳滤双膜工艺,针对辽宁省本溪市某城市污水厂二级尾水开展深度处理研究。考察了进水流速、累积过滤水量(超滤进水流速为25 L/min,纳滤进水流速为4 L/min)对膜分离效果的影响,同时开展了超滤和纳滤膜再生方式及效果研究。结果表明:在考察范围内,超滤装置的分离性能受进水流速影响较小,主要与进水污染程度有关,对COD、TP、氨氮的平均去除率分别为48%、55%、27%。当纳滤单元进水流速为4 L/min时,双膜法对COD、TP、氨氮的平均去除率分别为87%、96%、68%。双膜法对COD、TP的去除率随着进水污染程度的减轻而降低,氨氮去除率受累积过滤水量的影响较小,这与原水污染程度有关。随着累积过滤水量的增加,膜分离性能呈减弱趋势。超滤膜轻微污染时采用物理清洗效果良好,严重污染时需采用化学清洗的方法。超滤有效延缓了纳滤膜污染,纳滤膜轻微污染时采用酸碱浸泡法再生效果良好。     

Recent Advances in Hydroxyapatite-Based Biocomposites for Bone Tissue Regeneration in Orthopedics

Bone tissue is a nanocomposite consisting of an organic and inorganic matrix, in which the collagen component and the mineral phase are organized into complex and porous structures. Hydroxyapatite (HA) is the most used ceramic biomaterial since it mimics the mineral composition of the bone in vertebrates. However, this biomimetic material has poor mechanical properties, such as low tensile and compressive strength, which make it not suitable for bone tissue engineering (BTE). For this reason, HA is often used in combination with different polymers and crosslinkers in the form of composites to improve their mechanical properties and the overall performance of the implantable biomaterials developed for orthopedic applications. This review summarizes recent advances in HA-based biocomposites for bone regeneration, addressing the most widely employed inorganic matrices, the natural and synthetic polymers used as reinforcing components, and the crosslinkers added to improve the mechanical properties of the scaffolds. Besides presenting the main physical and chemical methods in tissue engineering applications, this survey shows that HA biocomposites are generally biocompatible, as per most in vitro and in vivo studies involving animal models and that the results of clinical studies on humans sometimes remain controversial. We believe this review will be helpful as introductory information for scientists studying HA materials in the biomedical field.     

Modulation of Specific Sphingosine-1-Phosphate Receptors Augments a Repair Mediating Schwann Cell Phenotype

Transdifferentiation of Schwann cells is essential for functional peripheral nerve regeneration after injury. By activating a repair program, Schwann cells promote functional axonal regeneration and remyelination. However, chronic denervation, aging, metabolic diseases, or chronic inflammatory processes reduce the transdifferentiation capacity and thus diminish peripheral nerve repair. It was recently described that the sphingosine-1-phosphate receptor (S1PR) agonist Fingolimod enhances the Schwann cell repair phenotype by activation of dedifferentiation markers and concomitant release of trophic factors resulting in enhanced neurite growth. Since Fingolimod targets four out of five S1PRs (S1P1, S1P3-5) possibly leading to non-specific adverse effects, identification of the main receptor(s) responsible for the observed phenotypic changes is mandatory for future specific treatment approaches. Our experiments revealed that S1P3 dominates and that along with S1P1 acts as the responsible receptor for Schwann cell transdifferentiation as revealed by the combinatory application of specific agonists and antagonists. Targeting both receptors reduced the expression of myelin-associated genes, increased PDGF-BB representing enhanced trophic factor expression likely to result from c-Jun induction. Furthermore, we demonstrated that S1P4 and S1P5 play only a minor role in the adaptation of the repair phenotype. In conclusion, modulation of S1P1 and S1P3 could be effective to enhance the Schwann cell repair phenotype and thus stimulate proper nerve repair.