ABSTRACT
Objective To investigate the effect of 900MHz electromagnetic radiation on the ultrastructure of rat hippocampal neural stem cells (NSCs) in vitro in order to provide basic materials for studying the biological effects of electromagnetic wave on the central nervous system. Methods Rat NSCs were divided into sham group, Radi1 group and Radi2 group, and they were respectively exposed to 900 MHz electromagnetic wave at power density of 0, 1, and 3mW/cm2 in vitro. Cells in Radi1 group and Radi2 group were sub-grouped according to the way radiation was given: continuous irradiation, in which cells were exposed on the second day after culture for 2h per day for 6 consecutive days; single exposure to irradiation, in which cells were exposed for 12h on the sixth day after the culture. The ultrastructural changes on the surface of the cells were observed with atomic force microscope (AFM), whereas the ultrastructural changes in the cells were observed with transmission electron microscope (TEM). Results After 900 MHz electromagnetic radiation, when compared with the sham group (0mW/cm2), it was shown that the surface of neural stem cells in the exposure groups (1 and 3mW/cm2) became rough, and there were some changes such as "cavitation" and "fissure formation" in the membrane. The intracellular ultrastructure was found to have obviously disrupted in the exposure groups, such as homogenization of cytoplasm, obvious change organelle structure, morphological damage of structure of nucleus, nuclear membrane disappearance, and chromatin pyknosis, and the changes were more obvious in Radi2 group. Compared with the sham group, the surface roughness (Ra) of cells in the exposure group was significantly intensified (P<0.05), and it was higher in Radi2 group than that in Radi1 group (P<0.05). Conclusion A 900MHz electromagnetic radiation may cause injury changes in NSCs membrane and ultrastructure in vitro, and the extent of injury may be related to the dosage of microwave irradiation.
ABSTRACT
<p><b>OBJECTIVE</b>To establish the tridimensional culture method for tissue-engineered skin to observe the histomorphological change in human immortal KC strain (HacaT)cocultured with xenogenic acellular dermal matrix (ADM).</p><p><b>METHODS</b>The ADM was prepared from SD rats by a modified method. HaCaTs were cultured in defined KC-serum free medium. HaCaTs in log growth phase were inoculated on ADM at the cell density of 2 x 10(5)/cm(2). They were submergedly cultured for 5 days and then changed to air-liquid phase culture for another 5 days. ADM and growth of HaCaTs on day 1 and 5 after cocultured with ADM were observed with scanning electron microscope. The histological change in ADM and HaCaTs on day 1, 5, and 10 after cocultured with ADM were examined by HE staining.</p><p><b>RESULTS</b>The gross appearance of ADM was white with smooth and soft texture, and intact collagen bundles without cellular residue. HaCaTs adhered and stretched out pseudopodia on the surface of the ADM on day 1 after combined culture, and a monolayer of cells was formed on day 5, growing into 3-6 layers of cells on day 10 with a tendency to grow into ADM.</p><p><b>CONCLUSIONS</b>SD rats ADM is benefit for the adhesion of HaCaTs and the permeation of nutrient solution, from which an engineered multiple-layered human skin can be obtained within 10 days.</p>