Modelling the adsorption of phospholipid vesicles to a silicon dioxide surface using Langmuir kinetics

The rate constants and equilibrium constant for the adsorption and desorption of lipid vesicles from a SiO2 surface have been determined.

Polyethyleneimine-Based Lipopolyplexes as Carriers in Anticancer Gene Therapies

Recent years have witnessed rapidly growing interest in application of gene therapies for cancer treatment. However, this strategy requires nucleic acid carriers that are both effective and safe. In this context, non-viral vectors have advantages over their viral counterparts. In particular, lipopolyplexes—nanocomplexes consisting of nucleic acids condensed with polyvalent molecules and enclosed in lipid vesicles—currently offer great promise. In this article, we briefly review the major aspects of developing such non-viral vectors based on polyethyleneimine and outline their properties in light of anticancer therapeutic strategies. Finally, examples of current in vivo studies involving such lipopolyplexes and possibilities for their future development are presented.

Automated vitrification of cryo-EM samples with controllable sample thickness using suction and real-time optical inspection

Speed and efficiency of data collection and image processing in cryo electron microscopy have increased over the last decade. However, cryo specimen preparation techniques have lagged behind and faster, more reproducible specimen preparation devices are needed. Here we present a new vitrification device with highly automated sample handling, requiring only limited user interaction. Moreover, the device allows inspection of thin films using light microscopy, since excess liquid is removed through suction by tubes, not blotting paper. In combination with dew-point control, this enables thin film preparation in a controlled and reproducible manner. The advantage is that quality of the prepared cryo specimen is characterized prior to electron microscopy data acquisition. Practicality and performance of the device are illustrated by experimental results obtained by vitrification of protein suspensions, lipid vesicles, bacterial and human cells, followed by imaged using single particle analysis, cryo electron tomography and cryo correlated light and electron microscopy.

Investigation of Shape Transformations of Vesicles, Induced by Their Adhesion to Flat Substrates Characterized by Different Adhesion Strength

The adhesion of lipid vesicles to a rigid flat surface is investigated. We examine the influence of the membrane spontaneous curvature, adhesion strength, and the reduced volume on the stability and shape transformations of adhered vesicles. The minimal strength of the adhesion necessary to stabilize the shapes of adhered vesicles belonging to different shape classes is determined. It is shown that the budding of an adhered vesicle may be induced by the change of the adhesion strength. The importance of the free vesicle shape for its susceptibility to adhesion is discussed.

The Potential Therapeutic Role of Mesenchymal Stem Cells-Derived Exosomes in Osteoradionecrosis

As one of the most serious complications of radiotherapy, osteoradionecrosis (ORN) seriously affects the quality of life of patients and even leads to death. Vascular injury and immune disorders are the main causes of bone lesions. The traditional conservative treatment of ORN has a low cure rate and high recurrent. Exosomes are a type of extracellular bilayer lipid vesicles secreted by almost all cell types. It contains cytokines, proteins, mRNA, miRNA, and other bioactive cargos, which contribute to several distinct processes. The favorable biological functions of mesenchymal stem cells-derived exosomes (MSC exosomes) include angiogenesis, immunomodulation, bone regeneration, and ferroptosis regulation. Exploring the characteristic of ORN and MSC exosomes can promote bone regeneration therapies. In this review, we summarized the current knowledge of ORN and MSC exosomes and highlighted the potential application of MSC exosomes in ORN treatment.

The role of four cholesterol-recognition motifs localized between amino acid residues 400-550 in regulating translocation and lytic activity of Adenylate Cyclase Toxin

Adenylate Cyclase Toxin (ACT or CyaA) is an important virulence factor secreted by Bordetella pertussis, the bacterium causative of whooping cough, playing an essential role in the establishment of infection in the respiratory tract. ACT is a pore-forming cytolysin belonging to the RTX (Repeats in ToXin) family of leukotoxins, capable of permeabilizing several cell types and pure lipid vesicles. Besides, the toxin delivers its N-terminal adenylate cyclase domain into the target cytosol, where catalyzes the conversion of ATP into cAMP, which affects cell signalling. In this study we have made two major observations. First, we show that ACT binds free cholesterol, and identify in its sequence 38 potential cholesterol-recognition motifs. Second, we reveal that four of those motifs are real, functional cholesterol-binding sites. Mutations of the central phenylalanine residues in said motifs have an important impact on the ACT lytic and translocation activities, suggesting their direct intervention in cholesterol recognition and toxin functionality. From our data a likely transmembrane topology can be inferred for the ACT helices constituting the translocation and the hydrophobic regions. From this topology a simple and plausible mechanism emerges by which ACT could translocate its AC domain into target cells, challenging previous views in the field. Blocking the ACT-cholesterol interactions might thus be an effective approach for inhibiting ACT toxicity on cells, and this could help in mitigating the severity of pertussis disease in humans.