CRISPR-Cas9 library screening combined with an exosome-targeted delivery system addresses tumorigenesis/TMZ resistance in the mesenchymal subtype of glioblastoma.

Rationale: The large-scale genomic analysis classifies glioblastoma (GBM) into three major subtypes, including classical (CL), proneural (PN), and mesenchymal (MES) subtypes. Each of these subtypes exhibits a varying degree of sensitivity to the temozolomide (TMZ) treatment, while the prognosis corresponds to the molecular and genetic characteristics of the tumor cell type. Tumors with MES features are predominantly characterized by the NF1 deletion/alteration, leading to sustained activation of the RAS and PI3K-AKT signaling pathways in GBM and tend to acquire drug resistance, resulting in the worst prognosis compared to other subtypes (PN and CL). Here, we used the CRISPR/Cas9 library screening technique to detect TMZ-related gene targets that might play roles in acquiring drug resistance, using overexpressed KRAS-G12C mutant GBM cell lines. The study identified a key therapeutic strategy to address the chemoresistance against the MES subtype of GBM. Methods: The CRISPR-Cas9 library screening was used to discover genes associated with TMZ resistance in the U87-KRAS (U87-MG which is overexpressed KRAS-G12C mutant) cells. The patient-derived GBM primary cell line TBD0220 was used for experimental validations in vivo and in vitro. Chromatin isolation by RNA purification (ChIRP) and chromatin immunoprecipitation (ChIP) assays were used to elucidate the silencing mechanism of tumor suppressor genes in the MES-GBM subtype. The small-molecule inhibitor EPIC-0412 was obtained through high-throughput screening. Transmission electron microscopy (TEM) was used to characterize the exosomes (Exos) secreted by GBM cells after TMZ treatment. Blood-derived Exos-based targeted delivery of siRNA, TMZ, and EPIC-0412 was optimized to tailor personalized therapy in vivo. Results: Using the genome-wide CRISPR-Cas9 library screening, we found that the ERBIN gene could be epigenetically regulated in the U87-KRAS cells. ERBIN overexpression inhibited the RAS signaling and downstream proliferation and invasion effects of GBM tumor cells. EPIC-0412 treatment inhibited tumor proliferation and EMT progression by upregulating the ERBIN expression both in vitro and in vivo. Genome-wide CRISPR-Cas9 screening also identified RASGRP1(Ras guanine nucleotide-releasing protein 1) and VPS28(Vacuolar protein sorting-associated protein 28) genes as synthetically lethal in response to TMZ treatment in the U87-KRAS cells. We found that RASGRP1 activated the RAS-mediated DDR pathway by promoting the RAS-GTP transformation. VPS28 promoted the Exos secretion and decreased intracellular TMZ concentration in GBM cells. The targeted Exos delivery system encapsulating drugs and siRNAs together showed a powerful therapeutic effect against GBM in vivo. Conclusions: We demonstrate a new mechanism by which ERBIN is epigenetically silenced by the RAS signaling in the MES subtype of GBM. Restoration of the ERBIN expression with EPIC-0412 significantly inhibits the RAS signaling downstream. RASGRP1 and VPS28 genes are associated with the promotion of TMZ resistance through RAS-GDP to RAS-GTP transformation and TMZ efflux, as well. A quadruple combination therapy based on a targeted Exos delivery system demonstrated significantly reduced tumor burden in vivo. Therefore, our study provides new insights and therapeutic approaches for regulating tumor progression and TMZ resistance in the MES-GBM subtype.

Retraction of "Universal theranostic CRISPR/Cas13a RNA-editing system for glioma".

[This retracts the article DOI: 10.7150/thno.84429.].

Electron syntrophy between mixed hydrogenogens and Geobacter metallireducens boosted dark hydrogen fermentation: Clarifying roles of electroactive extracellular polymeric substances.

To modulate the electron transfer behavior of hydrogen-producing bacteria (HPB) for enhanced hydrogen production, Geobacter metallireducens culture (GM) was introduced as an electron syntrophy partner and redox balance regulator in dark fermentation systems with hydrogen-producing sludge (HPS) as inoculum. The highest hydrogen yield was 306.5 mL/g-COD at the GM/HPS volatile solids ratio of 0.08, which was 65.2 % higher than the HPS group. The multi-layered extracellular polymeric substances (EPS) of GM played a significant role in promoting hydrogen production, with c-type cytochromes probably serving as electroactive functional components. The addition of GM significantly improved the NADH/NAD+ ratio, electron transport system activity, hydrogenase activity, and electrochemical properties of HPS. Furthermore, the microbial community structure and metabolic functions were optimized due to the potential syntrophic interaction between Clostridium sensu stricto (dominant HPB) and Geobacter, thus promoting hydrogen production. This study provided novel insights into the interactions among exoelectrogens, electroactive EPS, and mixed HPB.

Atomic Pyridinic Nitrogen as Highly Active Metal-Free Coordination Sites at the Biotic-Abiotic Interface for Bio-Electrochemical CO2 Reduction.

Bio-electrochemical conversion of anthropogenic CO2 into value-added products using cost-effective metal-free catalysts represents a promising strategy for sustainable fuel production. Herein, N-doped carbon nanosheets synthesized via pyrolysis of the zeolitic-imidazolate framework (ZIF) are developed for constructing efficient biohybrids to facilitate CO2 -to-CH4 conversion. The microbial enrichment and bio-interfacial charge transfer are significantly affected by the proportion of the co-existed graphitic-N, pyridinic-N, and pyrrolic-N in the defective carbon nanosheets. It is unfolded that pyridinic-N and pyrrolic-N with the doped N atoms near the edge can significantly enhance the adsorption of their adjacent C atoms toward O, leading to improved microbe enrichment. Especially, pyridinic-N which can provide one p electron to the aromatic π system, greatly enhances the electron-donating capability of the carbon nanosheets to the microorganisms. Correspondingly, due to its largest amount of pyridinic-N doping, the N-doped carbon nanosheets derived from ZIF pyrolysis at 900 °C (denoted 900-NC) achieve the highest methane production of ≈215.7 mmol m-2  day-1 with a high selectivity (Faradaic efficiency = ≈94.2%) at -0.9 V versus Ag/AgCl. This work demonstrates the effectiveness of N-doped carbon catalysts for bio-electrochemical CO2 fixation and contributes to the understanding of N functionalities toward microbiome response and biotic-abiotic charge transfer in various bio-electrochemical systems.

Blockage of EGFR/AKT and mevalonate pathways synergize the antitumor effect of temozolomide by reprogramming energy metabolism in glioblastoma.

BACKGROUND: Metabolism reprogramming plays a vital role in glioblastoma (GBM) progression and recurrence by producing enough energy for highly proliferating tumor cells. In addition, metabolic reprogramming is crucial for tumor growth and immune-escape mechanisms. Epidermal growth factor receptor (EGFR) amplification and EGFR-vIII mutation are often detected in GBM cells, contributing to the malignant behavior. This study aimed to investigate the functional role of the EGFR pathway on fatty acid metabolism remodeling and energy generation. METHODS: Clinical GBM specimens were selected for single-cell RNA sequencing and untargeted metabolomics analysis. A metabolism-associated RTK-fatty acid-gene signature was constructed and verified. MK-2206 and MK-803 were utilized to block the RTK pathway and mevalonate pathway induced abnormal metabolism. Energy metabolism in GBM with activated EGFR pathway was monitored. The antitumor effect of Osimertinib and Atorvastatin assisted by temozolomide (TMZ) was analyzed by an intracranial tumor model in vivo. RESULTS: GBM with high EGFR expression had characteristics of lipid remodeling and maintaining high cholesterol levels, supported by the single-cell RNA sequencing and metabolomics of clinical GBM samples. Inhibition of the EGFR/AKT and mevalonate pathways could remodel energy metabolism by repressing the tricarboxylic acid cycle and modulating ATP production. Mechanistically, the EGFR/AKT pathway upregulated the expressions of acyl-CoA synthetase short-chain family member 3 (ACSS3), acyl-CoA synthetase long-chain family member 3 (ACSL3), and long-chain fatty acid elongation-related gene ELOVL fatty acid elongase 2 (ELOVL2) in an NF-κB-dependent manner. Moreover, inhibition of the mevalonate pathway reduced the EGFR level on the cell membranes, thereby affecting the signal transduction of the EGFR/AKT pathway. Therefore, targeting the EGFR/AKT and mevalonate pathways enhanced the antitumor effect of TMZ in GBM cells and animal models. CONCLUSIONS: Our findings not only uncovered the mechanism of metabolic reprogramming in EGFR-activated GBM but also provided a combinatorial therapeutic strategy for clinical GBM management.

Universal theranostic CRISPR/Cas13a RNA-editing system for glioma.

Background: The CRISPR/Cas13a system offers the advantages of rapidity, precision, high sensitivity, and programmability as a molecular diagnostic tool for critical illnesses. One of the salient features of CRISPR/Cas13a-based bioassays is its ability to recognize and cleave the target RNA specifically. Simple and efficient approaches for RNA manipulation would enrich our knowledge of disease-linked gene expression patterns and provide insights into their involvement in the underlying pathomechanism. However, only a few studies reported the Cas13a-based reporter system for in vivo molecular diagnoses. Methods: A tiled crRNA pool targeting a particular RNA transcript was generated, and the optimally potential crRNA candidates were selected using bioinformatics modeling and in vitro biological validation methods. For in vivo imaging assessment of the anti-GBM effectiveness, we exploited a human GBM patient-derived xenograft model in nude mice. Results: The most efficient crRNA sequence with a substantial cleavage impact on the target RNA as well as a potent collateral cleavage effect, was selected. In the xenografted GBM rodent model, the Cas13a-based reporter system enabled us in vivo imaging of the tumor growth. Furthermore, systemic treatments using this approach slowed tumor progression and increased the overall survival time in mice. Conclusions: Our work demonstrated the clinical potential of a Cas13a-based in vivo imaging method for the targeted degradation of specific RNAs in glioma cells, and suggested the feasibility of a tailored approach like Cas13a for the modulation of diagnosis and treatment options in glioma.

Co-NC@Co-NP hierarchical nanoforest steering charge exchange efficiency at biotic-abiotic interface for microbial electrochemical carbon reduction.

Converting anthropogenic carbon dioxide (CO2) to value-added products using bio-electrochemical conversions represents a promising strategy for producing sustainable fuel. However, the reaction kinetics are hindered by insufficient attachment of microorganisms and limited charge extraction at the bioinorganic interface. A hierarchical nanoforest with doped cobalt­nitrogen-doped carbon covering cobalt nanoparticle (Co-NC@Co-NP) was integrated with a CO2-to-CH4 conversion microbiome for methane production to address these shortcomings. In-situ nanoforests were developed on the nanosheet by chemical vapor deposition with Co nanoparticles catalyzed. The bio-nanowire-like carbon nanotubes enhanced the electrostatic force for microbe enrichment via the tip effect, providing a maximum of 3.6-fold electron-receiving microbes to utilize reducing equivalents. The Co-NC@Co-NP enhanced the direct electron transfer between microbes and electrodes, reducing the adoption of energy barriers for heme-like proteins. Thus, the optimized electron transfer pathway improved selectivity by a factor of 2.0 compared to the pristine nanosheet biohybrid. Furthermore, the adjusted microbial community structure provided sufficient methanogenesis genes to match the strong electron flow, achieving maximal methane production rates (311.1 mmol/m2/day at -0.9 V vs. Ag/AgCl), 8.62 times higher than those of the counterpart nanosheet biohybrid (36.06 mmol/m2/day). This work demonstrates a comprehensive assessment of biotic-abiotic energy transfer, which may serve as a guiding principle for designing efficient bio-electrochemical systems.

Revealing Co-N4 @Co-NP Bridge-Enabled Fast Charge Transfer and Active Intracellular Methanogenesis in Bio-Electrochemical CO2 -Conversion with Methanosarcina Barkeri.

To significantly advance the bio-electrochemical CO2 -conversion rate and unfold the correlation between the abiotic electrode and the attached microorganisms, an atomic-nanoparticle bridge of Co-N4 @Co-NP crafted in metal-organic frameworks-derived nanosheets is integrated with a model methanogen of Methanosarcina barkeri (M. barkeri). The direct bonding of N in Co-N4 and Fe in member protein of Cytochrome b (Cytb) activates a fast direct electron transfer path while the Co nanoparticles further strengthen this bonding via decreasing the energy gap between the p-band center of N and the d-band center of Fe. This multiorbital tuning operation of Co nanoparticles also enhances the coenzyme F420-mediated electron transfer by enabling the electron flow direct to the hydrogenation sites. Particularly, the increased surface electric field of the Co-N4 @Co-NP bridge-based nanosheet electrode facilitates the interfacial Na+ accumulation to expedite ATPase transport for powering intracellular CO2 conversion. Remarkably, the self-assembled M.barkeri-Co-N4 @Co-NP biohybrid achieves a high methane production rate of 3860 mmol m-2 day-1 , which greatly outperforms other reported biohybrid systems. This work demonstrates a comprehensive scrutinization of biotic-abiotic energy transfer, which may serve as a guiding principle for efficient bio-electrochemical system design.

Identification of the E2F1-RAD51AP1 axis as a key factor in MGMT-methylated GBM TMZ resistance.

OBJECTIVE: Epidermal growth factor receptor variant III (EGFRvIII) is a constitutively-activated mutation of EGFR that contributes to the malignant progression of glioblastoma multiforme (GBM). Temozolomide (TMZ) is a standard chemotherapeutic for GBM, but TMZ treatment benefits are compromised by chemoresistance. This study aimed to elucidate the crucial mechanisms leading to EGFRvIII and TMZ resistance. METHODS: CRISPR-Cas13a single-cell RNA-seq was performed to thoroughly mine EGFRvIII function in GBM. Western blot, real-time PCR, flow cytometry, and immunofluorescence were used to determine the chemoresistance role of E2F1 and RAD51-associated protein 1 (RAD51AP1). RESULTS: Bioinformatic analysis identified E2F1 as the key transcription factor in EGFRvIII-positive living cells. Bulk RNA-seq analysis revealed that E2F1 is a crucial transcription factor under TMZ treatment. Western blot suggested enhanced expression of E2F1 in EGFRvIII-positive and TMZ-treated glioma cells. Knockdown of E2F1 increased sensitivity to TMZ. Venn diagram profiling showed that RAD51AP1 is positively correlated with E2F1, mediates TMZ resistance, and has a potential E2F1 binding site on the promoter. Knockdown of RAD51AP1 enhanced the sensitivity of TMZ; however, overexpression of RAD51AP1 was not sufficient to cause chemotherapy resistance in glioma cells. Furthermore, RAD51AP1 did not impact TMZ sensitivity in GBM cells with high O6-methylguanine-DNA methyltransferase (MGMT) expression. The level of RAD51AP1 expression correlated with the survival rate in MGMT-methylated, but not MGMT-unmethylated TMZ-treated GBM patients. CONCLUSIONS: Our results suggest that E2F1 is a key transcription factor in EGFRvIII-positive glioma cells and quickly responds to TMZ treatment. RAD51AP1 was shown to be upregulated by E2F1 for DNA double strand break repair. Targeting RAD51AP1 could facilitate achieving an ideal therapeutic effect in MGMT-methylated GBM cells.

Expert opinion on translational research for advanced glioblastoma treatment.

Malignant gliomas are known to be one of the most difficult diseases to diagnose and treat because of the infiltrative growth pattern, rapid progression, and poor prognosis. Many antitumor drugs are not ideal for the treatment of gliomas due to the blood-brain barrier. Temozolomide (TMZ) is a DNA alkylating agent that can cross the blood-brain barrier. As the only first-line chemotherapeutic drug for malignant gliomas at present, TMZ is widely utilized to provide a survival benefit; however, some patients are inherently insensitive to TMZ. In addition, patients could develop acquired resistance during TMZ treatment, which limits antitumor efficacy. To clarify the mechanism underlying TMZ resistance, numerous studies have provided multilevel solutions, such as improving the effective concentration of TMZ in tumors and developing novel small molecule drugs. This review discusses the in-depth mechanisms underlying TMZ drug resistance, thus aiming to provide possibilities for the establishment of personalized therapeutic strategies against malignant gliomas and the accelerated development and transformation of new targeted drugs.

Dual fluorescent hollow silica nanofibers for in situ pH monitoring using an optical fiber.

This study reports a sensitive and robust pH sensor based on dual fluorescent doped hollow silica nanofibers (hSNFs) for in situ and real-time pH monitoring. Fluorescein isothiocyanate (FITC) and tris(2,2'-bipyridyl)dichlororuthenium(ii) hexahydrate (Ru(BPY)3) were chosen as a pH sensitive dye and reference dye, respectively. hSNFs were synthesized using a two-step method in a reverse micelle system and were shown to have an average length of 6.20 µm and average diameter of 410 nm. The peak intensity ratio of FITC/Ru(BPY)3 was used to calibrate to solution pH changes. An optical-fiber-based fluorescence detection system was developed that enabled feasible and highly efficient near-field fluorescence detection. The developed system enables fully automated fluorescence detection, where components including the light source, detector, and data acquisition unit are all controlled by a computer. The results show that the developed pH sensor works in a linear range of pH 4.0-9.0 with a fast response time of less than 10 s and minimal sample volume of 50 µL, and can be stored under dark conditions for one month without failure. In addition, the as-prepared hSNF-based pH sensors also have excellent long-term durability. Experimental results from ratiometric sensing confirm the high feasibility, accuracy, stability and simplicity of the dual fluorescent hSNF sensors for the detection of pH in real samples.

Thermal plasma vitrification treatment of oil-based drill cuttings: Product characterization and harmless transformation.

Oil-based drill cuttings (OBDCs) are hazardous wastes associated with the process of oil and gas extraction. In this paper, OBDCs were treated using a self-designed plasma vitrification system. The basic physicochemical properties of the OBDCs were analyzed, followed by a plasma vitrification mechanism investigation of the OBDCs. The environmental pollution risk of the vitreous slags obtained from thermal plasma treatment was also evaluated with the heavy metal extraction toxicity procedure. The batch of vitreous slags with an average glass phase content of 98.60% had a dense and smooth surface and an oxygen-to-silicon (O/Si) ratio ranging from 3.68 to 4.32, according to the findings. The melting temperature and treatment duration have a great effect on the loss ratio on acid dissolution. The leaching concentrations of Pb and Zn were 0.0004 mg/L and 0.068 mg/L, respectively, consistent with the chlorination reaction promoted by thermal plasma. Fourier transform infrared spectroscopy analysis showed that there was no organic matter in the vitreous slag, achieving the goal of harmless transition. The specific energy consumption of vitreous slags was predicted and verified by response surface methodology (RSM). This study describes the vitrification process and harmless treatment of OBDCs by thermal plasma technology, and vitreous slags have great potential for resource utilization.

MUC1 promotes glioblastoma progression and TMZ resistance by stabilizing EGFRvIII.

Epidermal growth factor receptor variant III (EGFRvIII) is a mutant isoform of EGFR with a deletion of exons 2-7 making it insensitive to EGF stimulation and downstream signal constitutive activation. However, the mechanism underlying the stability of EGFRvIII remains unclear. Based on CRISPR-Cas9 library screening, we found that mucin1 (MUC1) is essential for EGFRvIII glioma cell survival and temozolomide (TMZ) resistance. We revealed that MUC1-C was upregulated in EGFRvIII-positive cells, where it enhanced the stability of EGFRvIII. Knockdown of MUC1-C increased the colocalization of EGFRvIII and lysosomes. Upregulation of MUC1 occurred in an NF-κB dependent manner, and inhibition of the NF-κB pathway could interrupt the EGFRvIII-MUC1 feedback loop by inhibiting MUC1-C. In a previous report, we identified AC1Q3QWB (AQB), a small molecule that could inhibit the phosphorylation of NF-κB. By screening the structural analogs of AQB, we obtained EPIC-1027, which could inhibit the NF-κB pathway more effectively. EPIC-1027 disrupted the EGFRvIII-MUC1-C positive feedback loop in vitro and in vivo, inhibited glioma progression, and promoted sensitization to TMZ. In conclusion, we revealed the pivotal role of MUC1-C in stabilizing EGFRvIII in glioblastoma (GBM) and identified a small molecule, EPIC-1027, with great potential in GBM treatment.

Plasmonic nanosensors for point-of-care biomarker detection.

Advancement of materials along with their fascinating properties play increasingly important role in facilitating the rapid progress in medicine. An excellent example is the recent development of biosensors based on nanomaterials that induce surface plasmon effect for screening biomarkers of various diseases ranging from cancer to Covid-19. The recent global pandemic re-confirmed the trend of real-time diagnosis in public health to be in point-of-care (POC) settings that can screen interested biomarkers at home, or literally anywhere else, at any time. Plasmonic biosensors, thanks to its versatile designs and extraordinary sensitivities, can be scaled into small and portable devices for POC diagnostic tools. In the meantime, efforts are being made to speed up, simplify and lower the cost of the signal readout process including converting the conventional heavy laboratory instruments into lightweight handheld devices. This article reviews the recent progress on the design of plasmonic nanomaterial-based biosensors for biomarker detection with a perspective of POC applications. After briefly introducing the plasmonic detection working mechanisms and devices, the selected highlights in the field focusing on the technology's design including nanomaterials development, structure assembly, and target applications are presented and analyzed. In parallel, discussions on the sensor's current or potential applicability in POC diagnosis are provided. Finally, challenges and opportunities in plasmonic biosensor for biomarker detection, such as the current Covid-19 pandemic and its testing using plasmonic biosensor and incorporation of machine learning algorithms are discussed.

Neuronal STAT3/HIF-1α/PTRF axis-mediated bioenergetic disturbance exacerbates cerebral ischemia-reperfusion injury via PLA2G4A.

Ischemic stroke is an acute and severe neurological disease with high mortality and disability rates worldwide. Polymerase I and transcript release factor (PTRF) plays a pivotal role in regulating cellular senescence, glucose intolerance, lipid metabolism, and mitochondrial bioenergetics, but its mechanism, characteristics, and functions in neuronal cells following the cerebral ischemia-reperfusion (I/R) injury remain to be determined. Methods: Transcription factor motif analysis, chromatin immunoprecipitation (ChIP), luciferase and co-Immunoprecipitation (co-IP) assays were performed to investigate the mechanisms of PTRF in neuronal cells after I/R injury. Lentiviral-sgRNA against PTRF gene was introduced to HT22 cells, and adeno-associated virus (AAV) encoding a human synapsin (hSyn) promoter-driven construct was transduced a short hairpin RNA (shRNA) against PTRF mRNA in primary neuronal cells and the cortex of the cerebral I/R mice for investigating the role of PTRF in neuronal damage and PLA2G4A change induced by the cerebral I/R injury. Results: Here, we reported that neuronal PTRF was remarkably increased in the cerebral penumbra after I/R injury, and HIF-1α and STAT3 regulated the I/R-dependent expression of PTRF via binding to its promoter in neuronal cells. Moreover, overexpression of neuronal PTRF enhanced the activity and stability of PLA2G4A by decreasing its proteasome-mediated degradation pathway. Subsequently, PTRF promoted reprogramming of lipid metabolism and altered mitochondrial bioenergetics, which could lead to oxidative damage, involving autophagy, lipid peroxidation, and ferroptosis via PLA2G4A in neuronal cells. Furthermore, inhibition of neuronal PTRF/PLA2G4A-axis markedly reduced the neurological deficits, cerebral infarct volumes, and mortality rates in the mice following cerebral I/R injury. Conclusion: Our results thus identify that the STAT3/HIF-1α/PTRF-axis in neurons, aggravating cerebral I/R injury by regulating the activity and stability of PLA2G4A, might be a novel therapeutic target for ischemic stroke.

Single Ni active sites with a nitrogen and phosphorus dual coordination for an efficient CO2 reduction.

Transition metal single-atom catalysts (SACs) have emerged as a research hotspot in CO2RRs. However, tuning the electronic configuration of a metal single-atom by employing new heteroatoms still remains a challenge. Herein, a carbon matrix loaded with a N and P co-coordinated Ni single-atom (denoted as Ni-NPC) was prepared for an efficient CO2RR. XANES and EXAFS were conducted to explore the coordination environment and charge distribution of the Ni-NPC catalyst. DFT calculations indicated that the Ni atom gained electrons from the P atom, and the Ni-NPC sample had a decreased energy barrier of +0.97 eV after doping with P atoms, which was favorable to overcome the limiting-step bottleneck for promoting CO2RR. Due to the rich Ni atomic active sites and superior P-doping effect, Ni-NPC exhibited a maximum FECO of 92% with a high current density of 22.6 mA cm-2 at -0.8V vs. RHE, which was far superior to those of NC, NPC and Ni-NC catalysts. Moreover, both the FECO and current density of the Ni-NPC catalyst remained stable for more than 16 h at -0.8 V vs. RHE, indicating a high stability for long-term CO2RR experiments.

Engineering Biomimetic Extracellular Matrix with Silica Nanofibers: From 1D Material to 3D Network.

Biomaterials at nanoscale is a fast-expanding research field with which extensive studies have been conducted on understanding the interactions between cells and their surrounding microenvironments as well as intracellular communications. Among many kinds of nanoscale biomaterials, mesoporous fibrous structures are especially attractive as a promising approach to mimic the natural extracellular matrix (ECM) for cell and tissue research. Silica is a well-studied biocompatible, natural inorganic material that can be synthesized as morpho-genetically active scaffolds by various methods. This review compares silica nanofibers (SNFs) to other ECM materials such as hydrogel, polymers, and decellularized natural ECM, summarizes fabrication techniques for SNFs, and discusses different strategies of constructing ECM using SNFs. In addition, the latest progress on SNFs synthesis and biomimetic ECM substrates fabrication is summarized and highlighted. Lastly, we look at the wide use of SNF-based ECM scaffolds in biological applications, including stem cell regulation, tissue engineering, drug release, and environmental applications.

Glioma-derived exosomes hijack the blood-brain barrier to facilitate nanocapsule delivery via LCN2.

Exosomes are small extracellular vehicles which could transport genetic materials and proteins between cells. Although there are reports about exosomes crossing the blood-brain barrier (BBB), the underlying mechanisms still need further study. We found that exosomes from primary brain tumors could upregulate the expression of Lipocalin-2 (LCN2) in bEnd.3 brain microvascular endothelial cells (BMVECs). Furthermore, exosomes increased the membrane fluidity of bEnd.3 cells in an LCN2 dependent manner. Both intraperitoneal injection and caudal vein injection of LCN2 increased the number of nanocapsules crossing the BBB. Evans Blue staining revealed that LCN2 does not interrupt the integrity of the BBB, as observed in the traumatic brain injury model. Tandem mass tags quantitative proteomics and bioinformatics analysis revealed that LCN2 is upregulated by exosomes via the JAK-STAT3 pathway, but not delivered from exosomes. Knocking down LCN2 in bEnd.3 cells significantly abrogated the effect of exosomes on BMVEC membrane fluidity. Previously, we have reported that 2-methacryloyloxyethyl phosphorylcholine (MPC) and a peptide crosslinker could encapsulate mAbs to achieve nanocapsules. The nanocapsules containing choline analogs could effectively penetrate the BBB to deliver therapeutic monoclonal antibodies (tAbs) to the glioma. However, the delivered tAbs could be significantly reduced by blocking the release of exosomes from the gliomas. Application of tAb nanocapsules prior to treatment with MK2206, an AKT pathway inhibitor that has been shown to inhibit the production of exosomes, resulted in a better combination. Insights from this study provide a mechanistic framework with regard to how glioblastomas hijack BMVECs using exosomes. In addition, we provide a strategy for maximizing the effect of the choline-containing nanocapsules and MK2206 combination. These results also demonstrate the therapeutic role of tAbs in glioblastoma and brain tumor metastasis, by shedding new light on strategies that can be used for BBB-penetrating therapies.

Electron transfer from Geobacter sulfurreducens to mixed methanogens improved methane production with feedstock gases of H2 and CO2.

In order to solve problems of poor utilization of H2 and CO2 in biomethane conversion with mixed methanogens due to multi-channel competition and nondirectional electron transfer, Geobacter sulfurreducens were cocultured with mixed methanogens to promote oriented metabolic pathway of H2 and CO2 to produce CH4. When inoculation volume ratio of G. sulfurreducens to mixed methanogens was 2:4, CH4 yield increased to 0.24 mL/ml H2 (close to the maximum theoretical yield of 0.25 mL/ml H2) and conversion efficiency of H2 to CH4 increased from 72 to 96%. Electrochemical detection and three-dimensional fluorescence spectra showed that the co-culture system had an increased metabolic capacity and spectral intensity of fulvic acid-like compounds was enhanced, which mediated direct interspecific electron transfer to produce CH4. The 16S rRNA gene sequencing showed that relative abundance of G. sulfurreducens and Methanoculleus increased, indicating an established syntrophic relationship between G. sulfurreducens and Methanoculleus.