Cell bystander effect induced by radiofrequency electromagnetic fields and magnetic nanoparticles

Induced effects by direct exposure to ionizing radiation (IR) are a central issue in many fields like radiation protection, clinic diagnosis and oncological therapies. Direct irradiation at certain doses induce cell death, but similar effects can also occur in cells no directly exposed to IR, a mechanism known as bystander effect. Non-IR (radiofrequency waves) can induce the death of cells loaded with MNPs in a focused oncological therapy known as magnetic hyperthermia. Indirect mechanisms are also able to induce the death of unloaded MNPs cells. Using in vitro cell models, we found that colocalization of the MNPs at the lysosomes and the non-increase of the temperature induces bystander effect under non-IR. Our results provide a landscape in which bystander effects are a more general mechanism, up to now only observed and clinically used in the field of radiotherapy.Comment: 16 pages, 4 figures, submitted to International Journal of Radiation Biolog

Cell death induced by the application of alternating magnetic fields to nanoparticle-loaded dendritic cells

In this work, the capability of primary, monocyte-derived dendritic cells (DCs) to uptake iron oxide magnetic nanoparticles (MNPs) is assessed and a strategy to induce selective cell death in these MNP-loaded DCs using external alternating magnetic fields (AMFs) is reported. No significant decrease in the cell viability of MNP-loaded DCs, compared to the control samples, was observed after five days of culture. The amount of MNPs incorporated into the cytoplasm was measured by magnetometry, which confirmed that 1 to 5 pg of the particles were uploaded per cell. The intracellular distribution of these MNPs, assessed by transmission electron microscopy, was found to be primarily inside the endosomic structures. These cells were then subjected to an AMF for 30 min, and the viability of the blank DCs (i.e., without MNPs), which were used as control samples, remained essentially unaffected. However, a remarkable decrease of viability from approximately 90% to 2-5% of DCs previously loaded with MNPs was observed after the same 30 min exposure to an AMF. The same results were obtained using MNPs having either positive (NH2+) or negative (COOH-) surface functional groups. In spite of the massive cell death induced by application of AMF to MNP-loaded DCs, the amount of incorporated magnetic particles did not raise the temperature of the cell culture. Clear morphological changes at the cell structure after magnetic field application were observed using scanning electron microscopy. Therefore, local damage produced by the MNPs could be the main mechanism for the selective cell death of MNP-loaded DCs under an AMF. Based on the ability of these cells to evade the reticuloendothelial system, these complexes combined with an AMF should be considered as a potentially powerful tool for tumour therapy.Comment: In Press. 33 pages, 11 figure

Localization of androgen-binding protein in proliferating Sertoli cells in culture.

The peroxidase and immunofluorescent localization patterns of androgen-binding protein (ABP), a biological marker of Sertoli cell function, have been examined in cultured Sertoli cells isolated from 20- to 22-day-old rats. ABP immunoreactivity in the form of cytoplasmic granules of variable diameter was observed in Sertoli cells with characteristic lipid droplets and a colony-forming, epithelial-like growth pattern. Incubation of cultures with [3H]thymidine demonstrated that Sertoli cells continue to produce ABP while retaining their capability for synthesizing DNA and undergoing mitosis. A variable number of cultured Sertoli cells became morphologically transformed after exposure to follitropin (follicle-stimulating hormone) and pharmacological agents acting on cyclic nucleotide metabolism. The induced change in Sertoli cell shape coincided with a disappearance of ABP-containing granules from the cytoplasm. These observations demonstrate that localization of ABP by immunological techniques is a valuable tool for the characterization of structural and functional properties of Sertoli cell in culture

Type I Interferons Regulate Cytolytic Activity of Memory CD8+ T Cells in the Lung Airways during Respiratory Virus Challenge

SummaryMemory CD8+ T cells in the lung airways provide protection from secondary respiratory virus challenge by limiting early viral replication. Here, we demonstrate that although airway-resident memory CD8+ T cells were poorly cytolytic, memory CD8+ T cells recruited to the airways early during a recall response showed markedly enhanced cytolytic ability. This enhanced lytic activity did not require cognate antigen stimulation, but rather was dependent on STAT1 transcription factor signaling through the interferon-α receptor (Ifnar1), resulting in the antigen-independent expression of granzyme B protein in both murine and human virus-specific T cells. Signaling through Ifnar1 was required for the enhanced lytic activity and control of early viral replication by memory CD8+ T cells in the lung airways. These findings demonstrate that innate inflammatory signals act directly on memory T cells, enabling them to rapidly destroy infected host cells once they enter infected tissues