A novel application of hectorite nanoclay for preparation of colorectal cancer spheroids with malignant potential.

Three-dimensional (3D) cell culture, which provides an in vivo-like environment in vitro unlike the conventional two-dimensional (2D) cell culture, has attracted much attention from researchers. Although various 3D cell culture methods have been developed, information on a method using inorganic nanoclay is scant. Here, we report that hectorite, an inorganic layered silicate, can be used as an auxiliary material for 3D cell culture. Human colon cancer cell lines cultured in a medium containing 0.01% synthetic hectorite spontaneously formed 3D spheroids in an adherent plate. Morphologically, these spheroids were more dispersed in all directions than control spheroids generated in an ultralow adherent plate. Microarray analysis showed that FGF19, TGM2, and SERPINA3, whose expression is reportedly increased in colon cancer tissues and is related to tumorigenesis or metastasis, were upregulated in HT-29 spheroids formed using synthetic hectorite compared with those in control spheroids. Gene ontology analysis revealed upregulation of genes associated with morphogenesis, cytoskeleton, extracellular matrix, cellular uptake and secretion, signaling pathways, and gene expression regulation. Moreover, fluorescence-labeled hectorite particles were localized in the cytoplasm of individual cells in spheroids. These results suggest that the synthetic hectorite modified the physiological state of and gene expression within the cells, triggering spheroid formation with malignant characteristics. Our findings highlight a novel application of synthetic hectorite for 3D cell culture.

Effect of hemoglobin vesicle, a cellular-type artificial oxygen carrier, on middle cerebral artery occlusion- and arachidonic acid-induced stroke models in rats.

Hemoglobin vesicle (HbV), which is also called liposome-encapsulated hemoglobin, functions as a hemoglobin-based oxygen carrier and is expected to be utilized in emergency situations including hemorrhagic shock and several kinds of ischemic diseases. In the present study, we evaluated the efficacy of HbV for improving stroke-related symptoms induced by middle cerebral artery (MCA) occlusion/reperfusion and an intra-internal carotid arterial injection of arachidonic acid (AA) in rats. When HbV (10 mL/kg, i.v.) was administered to rats immediately after the MCA occlusion, it reduced the cerebral infarct volumes of the cortex and total of the cortex plus sub-cortex significantly as compared with saline as a vehicle. In AA-induced stroke model, HbV (10 mL/kg, i.v.) improved the motor dysfunction score and inhibited the increase in cerebral water content suggesting it could suppress cerebral edema. These results strongly suggest that HbV would provide a novel beneficial option for the treatment of stroke, especially acute ischemic stroke.