Conductive single-wall carbon nanotubes/extracellular matrix hybrid hydrogels promote the lineage-specific development of seeding cells for tissue repair through reconstructing an integrin-dependent niche.

BACKGROUND: The niche of tissue development in vivo involves the growth matrix, biophysical cues and cell-cell interactions. Although natural extracellular matrixes may provide good supporting for seeding cells in vitro, it is evitable to destroy biophysical cues during decellularization. Reconstructing the bioactivities of extracellular matrix-based scaffolds is essential for their usage in tissue repair. RESULTS: In the study, a hybrid hydrogel was developed by incorporating single-wall carbon nanotubes (SWCNTs) into heart-derived extracellular matrixes. Interestingly, insoluble SWCNTs were well dispersed in hybrid hydrogel solution via the interaction with extracellular matrix proteins. Importantly, an augmented integrin-dependent niche was reconstructed in the hybrid hydrogel, which could work like biophysical cues to activate integrin-related pathway of seeding cells. As supporting scaffolds in vitro, the hybrid hydrogels were observed to significantly promote seeding cell adhesion, differentiation, as well as structural and functional development towards mature cardiac tissues. As injectable carrier scaffolds in vivo, the hybrid hydrogels were then used to delivery stem cells for myocardial repair in rats. Similarly, significantly enhanced cardiac differentiation and maturation(12.5 ± 2.3% VS 32.8 ± 5%) of stem cells were detected in vivo, resulting in improved myocardial regeneration and repair. CONCLUSIONS: The study represented a simple and powerful approach for exploring bioactive scaffold to promote stem cell-based tissue repair.

Identification and inactivation of Gordonia, a new chlorine-resistant bacterium isolated from a drinking water distribution system.

Chlorine-resistant bacteria threaten drinking water safety in water distribution systems. In this study, a novel chlorine-resistant bacterium identified as Gordonia was isolated from the drinking water supply system of Jinan City for the first time. We examined the resistance and inactivation of the isolate by investigating cell survival, changes in cell morphology, and the permeability of cell membranes exposed to chlorine. After 240 min chlorine exposure, the chlorine residual was greater than 0.5 mg L-1 and the final inactivation was about 3 log reduction, which showed that the Gordonia strain had high chlorine tolerance. Flow-cytometric analysis indicated that, following sodium hypochlorite treatments with increasing membrane permeability, culturable cells enter a viable but nonculturable state and then die. We also investigated the inactivation kinetics of Gordonia following chlorine dioxide and ultraviolet radiation treatment. We found that these treatments can effectively inactivate Gordonia, which suggests that they may be used for the regulation of chlorine-resistant microorganisms.

TCR-like bispecific antibodies toward eliminating infected hepatocytes in HBV mouse models.

Therapeutics for eradicating hepatitis B virus (HBV) infection are still limited and current nucleos(t)ide analogs (NAs) and interferon are effective in controlling viral replication and improving liver health, but they cannot completely eradicate the hepatitis B virus and only a very small number of patients are cured of it. The TCR-like antibodies recognizing viral peptides presented on human leukocyte antigens (HLA) provide possible tools for targeting and eliminating HBV-infected hepatocytes. Here, we generated three TCR-like antibodies targeting three different HLA-A2.1-presented peptides derived from HBV core and surface proteins. Bispecific antibodies (BsAbs) were developed by fuzing variable fragments of these TCR-like mAbs with an anti-CD3ϵ antibody. Our data demonstrate that the BsAbs could act as T cell engagers, effectively redirecting and activating T cells to target HBV-infected hepatocytes in vitro and in vivo. In HBV-persistent mice expressing human HLA-A2.1, two infusions of BsAbs induced marked and sustained suppression in serum HBsAg levels and also reduced the numbers of HBV-positive hepatocytes. These findings highlighted the therapeutic potential of TCR-like BsAbs as a new strategy to cure hepatitis B.

Preclinical Pharmacokinetics and in vitro Metabolism of FHND5071, a Novel Selective RET Kinase Inhibitor.

BACKGROUND AND OBJECTIVES: Rearranged during transfection (RET) is a transmembrane receptor tyrosine kinase that plays a crucial role in tumorigenesis. FHND5071, a potent and selective RET kinase inhibitor, could exert antitumor effects by inhibiting RET autophosphorylation. The present work aims to profile the pharmacokinetics of FHND5071 in in vivo and in vitro experiments as a ground work for further clinical research. METHODS: The absorption, distribution, metabolism, and excretion properties of FHND5071 were examined, along with metabolite production and cytochrome P450 (CYP) phenotyping assay. Additionally, plasma protein binding and pharmacokinetics in mice were investigated. RESULTS: Microsomal stability assay corroborated moderate to high clearance of FHND5071, and the use of UPLC-Q-TOF-MS identified a total of six metabolites and suggested a possible metabolic pathway involving oxidation, demethylation, and N-dealkylation. Primary contributors to the CYP-mediated metabolism of FHND5071 were found to be CYP2C8 and CYP3A4, and FHND5071 displayed low permeability and acted as a substrate for the P-glycoprotein (P-gp). FHND5071 had a moderate to high binding in plasma and exhibited a moderate absorption degree (absolute bioavailability > 60%) The distribution of FHND5071 in mouse tissues was rapid (mostly peaking at 1-4 h) and wide (detectable in almost all tissues and organs), with the highest exposure in the spleen. A small fraction of FHND5071 was excreted via the urine and feces, and a presumed metabolic pathway involving 20 metabolites in mice is proposed. CONCLUSION: Pharmacokinetic characteristics of FHND5071 were systemically profiled, which may lay the foundation for further clinical development as a drug candidate.

Mitochondria-Inspired Nanoparticles with Microenvironment-Adapting Capacities for On-Demand Drug Delivery after Ischemic Injury.

Stimuli-responsive nanoparticles (NPs), so-called "smart" NPs, possess great potentials in drug delivery. Presently, the intelligence of smart NPs is mainly based on their chemical or physical changes to stimuli, which are usually "mechanical" and fundamentally different from biological intelligence. Inspired by mitochondria (MT), a biosmart nanoparticle with microenvironment targeting and self-adaptive capacity (MTSNP) was fabricated for ischemic tissue repair. The nanoparticles were designed as shell@circular DNA@shell@core. The double shells were like the two-layered membranes of MT, the melatonin-loaded cores corresponded to the MT matrix, and the circular DNA corresponded to MTDNA. In function, melatonin-loaded cores simulated the cell-protective mechanism of MT, which naturally synthesized melatonin to resist ischemia, while circular DNA was constructed to mimic the biological oxygen-sensing mechanism, synthesizing VEGF for vascularization according to oxygen level, like the ATP supply by MT according to microenvironment demand. At the acute stage of ischemia, melatonin was rapidly released from MTSNP to scavenge reactive oxygen species and activated melatonin receptor I on MT to prevent cytochrome c release, which would activate apoptosis. During the chronic stage, circular DNA could sense hypoxia and actively secrete VEGF for revascularization as a response. Importantly, circular DNA could also receive feedback of revascularization and shut down VEGF secretion as an adverse response. Then, the therapeutic potentials of the MTSNP were verified in myocardial ischemia by the multimodality of the methods. Such nanoparticles may represent a promising intelligent nanodrug system.

Immunochromatographic assay for T-2 toxin based on luminescent quantum dot beads.

A quantum dot bead based immunochromatographic assay (QB-ICA) system was established for T-2 toxin (T-2), which widely occurs in agriculture and could be used as a potential biological warfare agent. After optimization, the dynamic linear detection range of T-2 calculated from a calibration curve was from 0.12 to 0.67 ng mL-1 and the limit of detection (LOD) was 0.08 ng mL-1, which is lower than those of the ICA based on colloidal gold nanoparticles or a fluorescent material or an antibody-based biochip in other reports. The performance and practicability of the established ICA system were validated with a commercial ELISA kit and the two methods were comparable. The proposed QB-ICA for T-2 could be an alternative for rapid, sensitive, and quantitative on-site detection of this toxin in biosafety monitoring in agriculture and for susceptibility testing of the potential release of this biological warfare agent.