Figure 5 Specificity of the aptamer by immunohistochemical staining. After incubating the MMP2 aptamer with MMP2 protein in PBS at room temperature for 2 h, the immnohistochemical staining in gastric cancer tissues was significantly reduced. Scale bar, 100 μm. Finally, we used the aptamer for ex vivo imaging. To do this, the aptamer was conjugated to fluorescent nanoprobe using EDC (Figure 6). To induce atherosclerosis in mice, ApoE knockout mice were fed a high cholesterol Depsipeptide manufacturer diet for 4 months. After injecting the
aptamer-conjugated fluorescent nanoprobe into a tail vein, fluorescent see more signals from atherosclerotic plaques were observed. The presence of atherosclerotic plaques was confirmed by oilred O staining. The MMP2 aptamer-conjugated nanoprobe produced significantly stronger signals in atherosclerotic plaques than the control aptamer-conjugated probe (Figure 7). Figure 6 Construction of the MMP2 aptamer-conjugated LY2606368 price fluorescent nanoprobe. The MMP2 aptamer was conjugated into magnetic fluorescent nanoprobe using EDC. Figure 7 Ex vivo imaging of atherosclerotic plaques using the MMP2 aptamer-conjugated fluorescent nanoprobe. Atherosclerotic plaques were induced by feeding ApoE knockout mice a high
cholesterol diet for 4 months and were confirmed by oilred O staining (middle panels). Ex vivo imaging was performed 2 h after intravenously injecting mice with the MMP2 aptamer-conjugated fluorescent nanoprobe. The MMP2 aptamer (right panels) showed much stronger signals in atherosclerotic plaques than the control aptamer
(left panels). Many studies have tried to visualize MMP molecules. Small molecular MMP inhibitors attached to radioisotopes, such as123I, 99mTC, and 18 F have been used for the imaging of atherosclerotic lesions and myocardial infarctions [12–15]. Notably, a peptide substrate, which fluoresces when cleaved by MMPs, was used to visualize MMP activity L-gulonolactone oxidase [16–18]. However, considerable time is required for in vivo imaging using this peptide substrate. We considered that aptamers could overcome this problem because aptamers bind directly to target proteins. In addition, due to its small size and easy chemical modification, it can be easily applied to construct new nanoparticles as presented in this study (, Figure 6). The specificity of the MMP2 aptamer produced during the present study was confirmed in vitro and ex vivo. Precipitation and immunohistochemistry studies demonstrated specific protein binding by MMP2 aptamer, and in particular, immunohistochemical staining of MMP2 aptamer was blocked by MMP2 protein. Furthermore, ex vivo imaging demonstrated that whereas MMP2 aptamer visualized atherosclerotic plaques, control aptamer did not. These results suggest that the devised MMP2 aptamer has clinical merit. Conclusions We developed an aptamer targeting MMP2 protein using a modified DNA SELEX technique.