Cytoskeletal and Functional Changes in Bioreactor Assembled Thyroid Tissue Organoids Exposed to Gamma Radiation

Abstract

Fischer rat thyroid cells were grown under low-shear stress in a bioreactor to a stage of organization composed of integrated follicles resembling small thyroid glands prior to exposure to 3 Gray-gamma radiation. Bioreactor tissues and controls (both irradiated and non-irradiated) were harvested at 24, 48, 96 and 144 hours post-exposure. Tissue samples were fixed and fluorescently labeled for actin and microtubules. Tissues were assessed for changes in cytoskeletal components induced by radiation and quantified by laser scanning cytometry. ELISA's were used to quantify transforming growth factor-beta and thyroxin released from cells to the culture supernatant. Tissue architecture was disrupted by exposure to radiation with the structural organization of actin and loss of follicular content the most obviously affected. With time post-irradiation the actin appeared disordered and the levels of fluorescence associated with filamentous-actin and microtubules cycled in the tissue analogs, but not in the flask-grown cultures. Active transforming growth factor-beta was higher in supernatants from the irradiated bioreactor tissue. Thyroxin release paralleled cell survival in the bioreactors and control cultures. Thus, the engineered tissue responses to radiation differed from those of conventional tissue culture making it a potentially better mimic of the in vivo situation.

Early effects of gamma rays and protons on human melanoma cell viability and morphology

“…Many round-shaped melanoma cells, being probably pre-apoptotic, were detected 6 h after proton irradiation. Similar changes of cellular morphology were already reported for different cell lines such as Chinese hamster V79 and FRTL-5 cells, after being exposed to ionizing irradiations (Aoki et al, 2000;Green et al, 2002). All these morphological changes were followed by the significant reduction of the cell number.…”

Histological Study of Thyroid Gland after Experimental Exposure to Low Frequency Electromagnetic Fields in Adult Male Albino Rat and Possible Protective Role of Vitamin E

“…However, the partial recovery detected may be due to the short time left for the cell to regenerate. This had been demonstrated by Green et al [48] who reported regeneration of follicular cells immediately and may be more effective with Vit.E for two weeks after exposure.…”

Low Dose Gamma Irradiation Potentiates Secondary Exposure to Gamma Rays or Protons in Thyroid Tissue Analogs

“…The scan was analyzed (RIT-113 Image analysis software) and field uniformity determined to be 97.3%, and 100% within the 20x20 cm field used for typical exposure of tissue culture/bioreactor vessels. The dose was delivered as acute single fractions at a dose rate of approximately 50 cGy/minute (Green et al, 2002a(Green et al, & 2002b.…”

“…These procedures are/were performed according to standard methods (Green et al, 1995(Green et al, , 1997(Green et al, , 2001a(Green et al, , 2001b(Green et al, , 2002b. The bioreactor grown tissue was removed, covered with cryoprotectant and stored frozen.…”

“…For example, bioreactor technology allows for monitoring of assembled tissue analogs exposed to chronic radiation with continuous sampling of the tissue. This well characterized model (Green et al 2001a;2001b& 2002a, 2002b provides us the opportunity to investigate how a relatively normal tissue responds to ionizing radiation at multiple levels, including: cell-cell exchanges (bystander), signal transduction, functional changes and modulation of gene expression. We have significant preliminary data on structural, functional, signal transduction and gene expression from acute exposures at high doses and rates (50-100 cGy, at 1 Gy/minute) of gamma, protons and iron.…”