Ex Vivo Magnetic Resonance Imaging of Transplanted Hepatocytes in a Rat Model of Acute Liver Failure

Abstract

Hepatocyte transplantation is being evaluated as an alternative to liver transplantation. However, the fate of hepatocytes after transplantation is not well defined. The aims of the study were to improve hepatocyte labeling in vitro using superparamagnetic iron oxide nanoparticles (SPIOs) and to perform in vivo experiments on tracking labeled cells by magnetic resonance imaging (MRI). Human and rat hepatocytes were labeled in vitro for 16 h with clinically approved SPIOs (12.5 µg Fe/ml) and protamine sulfate (3 µg/ml) as a transfection agent. Increased cellular iron uptake was obtained, and cell viability and function were shown not to be affected by labeling. Labeled cells (2,000/µl) could be detected on T2-weighted images in vitro using a 7T MR scanner. In a rat model of acute liver failure (ALF), female recipients received intrasplenic transplantation of 2 × 10(7) male rat hepatocytes 28-30 h after intraperitoneal injection of d-galactosamine (1.2 g/kg). There were four groups (n = 4 each): vehicle injection, injection of freshly isolated cells labeled with CM-DiI, injection of cultured cells labeled with CM-DiI, and injection of cultured cells labeled with both SPIOs and CM-DiI. Ex vivo T2*-weighted gradient-echo images at 7T MRI were acquired at day 7 post-ALF induction. Six days after transplantation, SPIOs were detected in the rat liver as a decrease in the MRI signal intensity in the surviving animals. Histologically, most of the SPIOs were located in Kupffer cells, indicating clearance of labeled hepatocytes. Furthermore, labeled cells could not be detected in the liver by the fluorescent dye or by PCR for the Y-chromosome (Sry-2 gene). In conclusion, optimum conditions to label human hepatocytes with SPIOs were established and did not affect cell viability or metabolic function and were sufficient for in vitro MRI detection. However, the clearance of hepatocytes after transplantation limits the value of MRI for assessing long-term hepatocyte engraftment.

MR tracking of SPIO‐labeled mesenchymal stem cells in rats with liver fibrosis could not monitor the cells accurately

“…MR imaging has proven to be an effective technique to monitor transplanted cells labeled with magnetically visible contrast agents in vivo . In agreement with previous findings , our data demonstrated that SPIO‐labeled BMSCs can be tracked by MR imaging within a short period (<12 days) after transplantation into rats with liver fibrosis.…”

Biodistribution and Clearance of Stable Superparamagnetic Maghemite Iron Oxide Nanoparticles in Mice Following Intraperitoneal Administration

“…Over the last two decades there has been an increase in the use of magnetic particles and magnetic microspheres including iron oxide nanoparticles (IONPs) and superparamagnetic iron oxide nanoparticles (SPIONs) for bio-medical applications such as imaging, diagnostics, therapies and theranostics, but their suitability for these applications ultimately depends on their biodistribution and toxicity profiles [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]. The two main administration routes for IONPs into the body are intravenous (IV) injection and intraperitoneal (IP) injection.…”

Hepatocyte Transplantation Attenuates the Course of Acute Liver Failure Induced by Thioacetamide in Lewis Rats

“…We are aware that our current findings are limited only to the course of TAA-induced ALF, however recently hepatocyte Tx was successfully used in the treatment of another chemical models of ALF (e.g. D-galactosamine-induced ALF) (Puppi et al 2014) and therefore we believe that our present results should be reproducible in other models of ALF and such studies are necessary to be performed in future.…”

“…2 x 10 6 ) was transplanted. In accordance with these findings in liver-based metabolic diseases, also other investigators have recently started to use similar amount of cells for the treatment of ALF (Amano et al 2011, Fukumitsu et al 2011, Jitraruch et al 2014, Loukopoulos et al 2014, Puppi et al 2014. Untreated rats (without hepatocyte Tx) received 600 µl of physiological solution by the same route.…”