Dose-dependent 60Co γ-radiation Effects on Human Endothelial Cell Mechanical Properties

Photobiomodulation Therapy Affects the Elastic Modulus, Cytoskeletal Rearrangement and Migration Capability of Human Osteosarcoma Cells

Photobiomodulation (PBM) therapy utilizes low-power lasers to modulate the viability of living human cells and leads to changes in proliferation, differentiation, adhesion and gene expression, even though the rearrangement of cytoskeleton was not previously studied. The present study aims to evaluate the photobiological effects on the elastic behavior of human osteosarcoma cells (MG-63) and their morphological changes. Fluorescence staining, confocal imaging and atomic force microscopy (AFM) topography were performed to study the effects of PBM therapy with the exposure of 532 nm-25mW, 650 nm-3mW, 650 nm-150mW and 780 nm-70mW beams following the 5-min continuous irradiation. The area of each beam was 3.14cm² with a source-surface distance of 20 cm. Besides the cell proliferation assessment, the migratory potential of MG-63 was determined with the wound healing technique. The results indicated an increase in stiffness and shape index of radiation-induced cells 24 h after exposure along with the obvious F-actins changes. But, cell stiffening was not observed 72 h after 532 nm laser irradiation. Also, a decrease in the migration rate was seen in all of the groups after 72 h of irradiation except cells treated with 532 nm wavelength. However, 532 nm laser beams increase the migratory potential 24 h after exposure. Within 72 h after irradiation, the cell proliferation was only affected by applying 532 nm and 650 nm-150mW laser beams. It was concluded that applying photobiomodulation with wavelengths of 650 nm (at both utilized powers) and 780 nm alters the migration capability and provides a quantitative description of cytoskeletal changes. Moreover, membrane stiffening can be considered as the biological marker of PBM treatments.

Radioprotective Role of Vitamins C and E against the Gamma Ray-Induced Damage to the Chemical Structure of Bovine Serum Albumin

Radioprotective effects of vitamin C and vitamin E as a water-soluble and a lipid-soluble agent, respectively, were investigated at the molecular level during the imposition of gamma radiation-induced structural changes to bovine serum albumin (BSA) at the therapeutic dose of 3 Gy. Secondary and tertiary structural changes of control and irradiated BSA samples were investigated using circular dichroism and fluorescence spectroscopy. The preirradiation tests showed nonspecific and reversible binding of vitamins C and E to BSA. Secondary and tertiary structures of irradiated BSA considerably changed in the absence of the vitamins. Upon irradiation, α-helices of BSA transitioned to beta motifs and random coils, and the fluorescence emission intensity decreased relative to nonirradiated BSA. In the presence of the vitamins C or E, however, the irradiated BSA was protected from these structural changes caused by reactive oxygen species (ROS). The two vitamins exhibited different patterns of attachment to the protein surface, as inspected by blind docking, and their mechanisms of protection were different. The hydrophilicity of vitamin C resulted in the predominant scavenging of ROS in the solvent, whereas hydrophobic vitamin E localized on the nonpolar patches of the BSA surface, where it did not only form a barrier for diffusing ROS but also encountered them as an antioxidant and neutralized them thanks to the moderate BSA binding constant. Very low concentrations of vitamins C or E (0.005 mg/mL) appear to be sufficient to prevent the oxidative damage of BSA.

Assessing the short-term effects of radiotherapy on the shear modulus of the common carotid artery as a new biomarker of radiation-induced atherosclerosis

Purpose

The purpose of this study was to investigate the incidence of short-term atherosclerosis in the common carotid arteries following radiotherapy.

Methods

The mean radiation dose to the arteries was 49.30±15.83 Gy. A computational ultrasound method was introduced to investigate the elastic modulus. Ultrasonography was performed 2-3 cm inferior to the bifurcation region before and after radiotherapy, and sequential images were extracted from a video of each artery. Instantaneous movement of the arterial wall in the radial and longitudinal directions was extracted by implementing the maximum gradient and block matching algorithms, respectively.

Results

There was a significant change in systolic blood pressure after radiotherapy (P=0.008). Irradiated arteries had significantly smaller systolic and end-diastolic diameters than non-irradiated arteries (P<0.001). The shear modulus was significantly different between irradiated and non-irradiated arteries (3.10±2.03 kPa vs. 1.38±0.98 kPa, P<0.001). The shear and Young moduli of radiation-induced arteries were 2.25±1.50 and 1.57±0.59 times higher than those of the pre-irradiation arteries.

Conclusion

The arterial shear modulus can be considered as a new biomarker of radiation-induced atherosclerosis in the common carotid artery.

In vitro evaluation of simulated stereotactic radiotherapy for wet age-related macular degeneration on three different cell lines

Low energy stereotactic radiotherapy has been proposed for the treatment of neovascular age related macular degeneration. We investigated the in vitro effect of the radiotherapy on pericytes, retinal pigment epithelium and endothelial cells. Primary human retinal pigment epithelium cells, human umbilical vein endothelial cells and human pericytes from Placenta were cultivated. In a pairwise protocol, one plate was irradiated at a dose of 16 Gy, while the second plate served as a non-irradiated control. Thereafter, cells were cultivated either in serum-free (non-permissive) or serum-stimulated (permissive) conditions. A life/dead assay, an XTT and a BrdU assay were performed up to 7 days after irradiation. No cell death occurred at any timepoint in any cell line after treatment nor in the control. Compared to the unirradiated controls, cell viability and metabolic activity were significantly reduced in irradiated cells in the XTT assay, except for non-permissive RPE cells. In the BrdU assay, proliferation was inhibited. While no cell death was detected in vitro, viability and proliferative capacity of all cell lines were significantly reduced. Therefore, it seems that low energy stereotactic radiotherapy inhibits angiogenesis without a direct induction of apoptosis but influencing microvascular function and stability.