Maintenance and loss of endocytic organelle integrity: mechanisms and implications for antigen cross-presentation

The membranes of endosomes, phagosomes and macropinosomes can become damaged by the physical properties of internalized cargo, by active pathogenic invasion or by cellular processes, including endocytic maturation. Loss of membrane integrity is often deleterious and is, therefore, prevented by mitigation and repair mechanisms. However, it can occasionally be beneficial and actively induced by cells. Here, we summarize the mechanisms by which cells, in particular phagocytes, try to prevent membrane damage and how, when this fails, they repair or destroy damaged endocytic organelles. We also detail how one type of phagocyte, the dendritic cell, can deliberately trigger localized damage to endocytic organelles to allow for major histocompatibility complex class I presentation of exogenous antigens and initiation of CD8 + T-cell responses to viruses and tumours. Our review highlights mechanisms for the regulation of endocytic organelle membrane integrity at the intersection of cell biology and immunology that could be co-opted for improving vaccination and intracellular drug delivery.

Pulse Duration Dependent Asymmetry in Molecular Transmembrane Transport Due to Electroporation in H9c2 Rat Cardiac Myoblast Cells In Vitro

Electroporation (EP) is one of the successful physical methods for intracellular drug delivery, which temporarily permeabilizes plasma membrane by exposing cells to electric pulses. Orientation of cells in electric field is important for electroporation and, consequently, for transport of molecules through permeabilized plasma membrane. Uptake of molecules after electroporation are the greatest at poles of cells facing electrodes and is often asymmetrical. However, asymmetry reported was inconsistent and inconclusive—in different reports it was either preferentially anodal or cathodal. We investigated the asymmetry of polar uptake of calcium ions after electroporation with electric pulses of different durations, as the orientation of elongated cells affects electroporation to a different extent when using electric pulses of different durations in the range of 100 ns to 100 µs. The results show that with 1, 10, and 100 µs pulses, the uptake of calcium ions is greater at the pole closer to the cathode than at the pole closer to the anode. With shorter 100 ns pulses, the asymmetry is not observed. A different extent of electroporation at different parts of elongated cells, such as muscle or cardiac cells, may have an impact on electroporation-based treatments such as drug delivery, pulse-field ablation, and gene electrotransfection.

Anti-HER2 VHH Targeted Fluorescent Liposome as Bimodal Nanoparticle for Drug Delivery and Optical Imaging

Objective: The aim of this study was to formulate fluorescent-labeled targeted immunoliposome to visualize the delivery and distribution of drugs in real-time. Methods: In this study, fluorescent-labeled liposomes were decorated with anti-HER2 VHH or Herceptin to improve the monitoring of intracellular drug delivery and tumor cell tracking with minimal side effects. The conjugation efficiency of antibodies was analyzed by SDS-PAGE silver staining. In addition, the physicochemical characterization of liposomes was performed using DLS and TEM. Finally, confocal microscopy visualized nanoparticles in the target cells. Results: Quantitative and qualitative methods characterized the intracellular uptake of 110±10 nm particles with near 70% conjugation efficiency. In addition, live-cell trafficking during hours of incubation was monitored by wide-field microscopy imaging. The results show that the fluorescent-labeled nanoparticles can specifically bind to HER2-positive breast cancer with minimal off-target delivery. Conclusion: This kind of nanoparticles can have several applications in personalized medicine, especially drug delivery and real-time visualization of cancer therapy. Moreover, this method also can be applied in the targeted delivery of contrast agents in imaging and thermotherapy.