Live Imaging of Monocyte/Macrophage Differentiation with Cationized Gelatin Nanospheres Incorporating a Molecular Beacon.

As one imaging method to evaluate monocyte-macrophage differentiation, cationized gelatin nanospheres incorporating a molecular beacon (MB) (cGNSMB) were designed. Cationized gelatin nanospheres (cGNS) of different apparent sizes were prepared by the conventional coacervation method, and then the MB of CD204 was incorporated into cGNS to prepare cGNSMB. When three types of cGNSMB were cultured with human monocytoma (THP-1) cells, the cGNSMB with a 110 nm diameter showed the highest MB delivery efficiency. In addition, no influence on the monocyte-macrophage differentiation was observed in terms of CD204 gene expression and cell viability. After incubation with cGNS incorporating CD204 MB (cGNSCD204), THP-1 cells were stimulated by phorbol 12-myristate 13-acetate (PMA) for monocyte differentiation into macrophages. The fluorescence intensity of macrophages increased with the incubation time. In contrast, the fluorescence intensity of macrophages incubated with MB alone was not changed. On the other hand, there was no change in the fluorescence intensity of original THP-1 cells cultured with cGNSCD204. It is concluded that the cGNSCD204 are promising to trace the differentiation of THP-1 cells into macrophages in their live condition.