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BACKGROUND: Spheroid culture of mesenchymal stem cells in bioreactors is an in vitro culture method to maintain their stemness properties and allow for large-scale expansion. Clarifying its effects on the immunoregulation effect of stem cells is beneficial for their clinical application. OBJECTIVE: To investigate the effects of spheroid culture in a rotating bioreactor on the secretion of inflammatory factors by human placenta-derived mesenchymal stem cells. METHODS: Placenta-derived mesenchymal stem cells isolated from human placenta tissue were cultured in two-dimensional culture or a rotating bioreactor culture. Cell morphology and proliferation ability were observed using inverted phase contrast microscopy, immunohistochemical staining, and CCK-8 assay. The gene expression and protein secretion of several inflammatory factors were detected by RT-qPCR and flow immunofluorescence assay. RESULTS AND CONCLUSION: (1) Mesenchymal stem cells cultured in a rotating bioreactor aggregated into multicellular spheroids, which gradually increased in number and volume. (2) The hematoxylin-eosin staining results showed that the mesenchymal stem cells cultured in the rotating bioreactor for 4 days were evenly distributed and had normal morphology in the spheroids. (3) Immunohistochemical staining results revealed many mesenchymal stem cells with Ki)67 positive in the spheroids. (4) The CCK-8 assay results exhibited that the viability of mesenchymal stem cells derived from spheroid culture was significantly higher than that of cells cultured in two-dimensional culture. (5) The results of RT-qPCR and flow immunofluorescence assay demonstrated that the gene expression and protein secretion (interleukin 1β, interleukin-4, interleukin-6, interleukin-8, interleukin-10, interleukin-17, tumor necrosis factor α and interferon α) of inflammatory factors derived from mesenchymal stem cells cultured in the rotating bioreactor were significantly higher than those in two-dimensional culture. (6) Our results indicate that spheroid culture in a rotating bioreactor can significantly elevate the secretion ability of various inflammatory factors by human placenta-derived mesenchymal stem cells, and enhance the immunoregulatory effect of human placenta-derived mesenchymal stem cells. [ABSTRACT FROM AUTHOR]

Orientation-averaged lidar linear depolarization ratios(LLDR) of spheroid dust aerosols are carried out based on discrete dipole approximation(DDA) for size parameters from 0.1 to 23(corresponding to effective radius from 0.01 to 2 μm at wavelength of 550 nm).The effects of the asphericity degree on the LLDRs for both monodisperse and polydisperse dust aerosols are performed by comparing LLDRs at different spheroid aspect ratios.For monodisperse spheroid,the dust LLDRs show strong dependences on aspect ratio and size parameter.For prolate spheroid dust particles,small LLDR values are found in the Rayleigh domain as opposed to large values in the Mie domain.Nevertheless,for oblate spheroid,large LLDR dust particles in the Mie domain can produce small LLDR values.For example,the dust LLDR has a value of about 0.1% at spheroid aspect ratio of 1/16 when the size parameter reaches 3.For monodisperse dust particles,the aspherical degree increases their LLDRs only at size parameters smaller than 0.5.However,for polydisperse aerosols,the degree of dust asphericity enhances their LLDRs. [ABSTRACT FROM AUTHOR]

Multicellular spheroids, which mimic the natural organ counterparts, allow the prospect of drug screening and regenerative medicine. However, their application is hampered by low processing efficiency or limited scale. This study introduces an efficient method to drive rapid multicellular spheroid formation by a cellulose nanofibril matrix. This matrix enables the facilitated growth of spheroids (within 48 h) through multiple cell assembly into size-controllable aggregates with well-organized physiological microstructure. The efficiency, dimension, and conformation of the as-formed spheroids depend on the concentration of extracellular nanofibrils, the number of assembled cells, and the heterogeneity of cell types. The above strategy allows the robust formation mechanism of compacted tumoroids and hepatocyte spheroids.

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