Browsing by Author "Schmithals, Christian"
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ItemBiodegradable human serum albumin nanoparticles as contrast agents for the detection of hepatocellular carcinoma by magnetic resonance imagingTumor visualization by magnetic resonance imaging (MRI) and nanoparticle-based contrast agents may improve the imaging of solid tumors such as hepatocellular carcinoma (HCC). In particular, human serum albumin (HSA) nanoparticles appear to be a suitable carrier due to their safety and feasibility of function- alization. In the present study HSA nanoparticles were conjugated with gadolinium diethylenetriamine- pentaacetic acid (Gd-DTPA) using carbodiimide chemistry. The nanoparticles had a uniform spherical shape and a diameter of 235 ± 19 nm. For better optical visualization in vitro and in vivo, the HSA-Gd nanoparticles were additionally labeled with rhodamine 123. As shown by confocal microscopy and ﬂow cytometry analysis, the ﬂuorescent nanoparticles were readily taken up by Huh-7 hepatocellular carci- noma cells. After 24 h incubation in blood serum, less than 5% of the Gd(III) was released from the par- ticles, which suggests that this nanoparticulate system may be stable in vivo and, therefore, may serve as potentially safe T1 MRI contrast agent for MRI of hepatocellular carcinoma.
ItemDetection of hepatocellular carcinoma in transgenic mice by Gd-DTPA- and rhodamine 123-conjugated human serum albumin nanoparticles in T1 magnetic resonance imagingNanoparticle (NP)-based contrast agents that enable high resolution anatomic T1-weighted magnetic resonance imaging (MRI) offer the prospect of improving differential diagnosis of liver tumors such as hepatocellular carci- noma (HCC). In the present study, we investigated the possibility of employing novel non-toxic human serum albumin nanoparticles conjugated with Gd-DTPA and rhodamine 123 (Gd-Rho-HSA-NPs) for the detection of HCC by T1-weighted MRI. In addition, the inﬂuence of surface coating of the NPs with poloxamine 908, which al- ters the absorptive behavior of NPs and changes their distribution between the liver and tumor was examined. MRI of transgenic mice with endogenously formed HCCs following intravenous injection of Gd-Rho-HSA-NPs revealed a strong negative contrast of the tumors. Contrasting of the HCCs by NP-enhanced MRI required less Gd as compared to gadolinium-ethoxybenzyl-diethylenetriaminepentaacetic acid-enhanced MRI, which current- ly provides the most sensitive detection of HCC in patients. Immunohistochemical analyses revealed that the Gd-Rho-HSA-NPs were localized to macrophages, which were – similar to HCC in patients – fewer in number in HCC as compared to the liver tissue, which is in agreement with the negative contrasting of HCC in Gd-Rho- HSA-NP-enhanced MRI. Poloxamine-coated NPs showed lower accumulation in the tumor macrophages and caused a longer lasting enhancement of the MRI signal. These data indicate that Gd-Rho-HSA-NPs enable sensi- tive detection of HCC by T1-weighted MRI in mice with endogenous HCC through their uptake by macrophages. Poloxamine coating of the NPs delayed the tumor localization of the NPs.