Utility of Hepatic Transporters as Multimodal Gene Reporters for Cell‐Based Medicine

Abstract

Hepatic transporters facilitate the uptake of xenobiotic compounds and confer immense potential as multimodality reporters, as they can uptake multitude of bioluminescent, fluorescence, near Infra-red (NIR), and magnetic resonance imaging (MRI) compounds. Here, it is aimed to identify the prospects of three human hepatocyte membrane proteins, organic anion transporters (OATP) 1B1, OATP1B3, and sodium-taurocholate cotransporting polypeptide in tracing the transplanted cells dynamics, by the uptake of clinically approved MRI compound, gadolinium ethoxybenzyl-diethylenetriaminepentaacetic acid (GD-EOB DTPA) or NIR fluorescent dye, Indocyanine Green (ICG). First, OATP1B1 is introduced as new MRI reporter which is the human orthologue of previously established rodent (Oatp1a1) reporter. Comparative sequential assays by assimilating MR image parameters reveal OATP1B3 as superior reporter on T1-weighted images and display highest contrast enhancement reported to-date when using a clinical 3T MR scanner (≈21-fold in vitro; ≈8-fold in vivo). Stably expressing these hepatic transporters have no effect on human adipose derived mesenchymal stem cells (hADSCs) characteristics. However, only OATP1B3 able to trace as few as 2 × 10 5 hADSCs intramuscular xenograft survival time on NIR and 3T MRI. These data suggest that OATP1B3 is relatively a robust Gd-EOB-DTPA/ICG-dependent multimodality reporter in visualizing dynamic processes for cell-based therapies.

Luminogenic D‐Luciferin Derivatives as OATP1B1 and 1B3 Substrates in No‐wash Assays†

“…By eliminating multiple steps required of conventional uptake transporter assays, our approach saves time, enables higher throughput, and would in principle reduce stepwise error accumulation. Our data is consistent with an understanding that D‐luciferin is a substrate for OATP1B1 and ‐1B3 (16, 17), TMQ derivatization blocks its activity with luciferase but does not generally prevent uptake, that free D‐luciferin is rapidly released from TMQ in the intracellular compartment of living cells, and it can be detected in a luciferin‐luciferase reaction (14). The latter two points made it necessary to design probes with negligible transporter‐independent uptake.…”

“…The objective of the present study was to develop no-wash addonly assays for detecting inhibitors or substrates acting as competitive inhibitors of OATP1B1 and -1B3 transport activity, and in this way enable a higher throughput approach. The assays would rely on derivatives of the OATP substrate D-luciferin (16,17). To confirm that human OATP1B1 and -1B3 transport D-luciferin and establish a model system for testing luciferin derivatives as uptake probes, we applied D-luciferin to human embryonal kidney cells (HEK293) with or without ectopic overexpression of recombinant human OATP1B1 or -1B3 (OATP1B1, OATP1B3 or Control cells).…”

“…This is a scalable approach since a targeting moiety can be selected from the list of all known substrates of any uptake transporter of interest. However, the recognition that D-luciferin itself is a substrate for rat Oatp1 and human OATP1B1 and -1B3 suggested a simplified probe design for at least OATP transporters, where a D-luciferin moiety would serve as both targeting moiety and optical leaving group (16,17). We hypothesized that this type of simplified probe would enable an effective transporter-dependent uptake of probe, potentially result in a highly sensitive and rapid homogeneous approach to detecting and characterizing OATP/NDE interactions, and thereby address some current transporter assay limitations.…”

Repurposing indocyanine green: exploring the potential of an old drug in modern medicine

“…Furthermore, most of the other studies have assembled or encapsulated MRI contrast agents and ICG into drug carriers, aiming to achieve multimodal imaging capabilities. 67,93–102 Fan et al self-assembled Fe 3+ and DOX molecules to synthesize a bioactive metal–organic framework (bio-MOF), and then wrapped another structure consisting of Gd 3+ and 1,3,5-benzenetricarboxylic acid (H 3 BTC) on the surface of the Fe-DOX nanoparticles, and then adsorbed ICG to form a Fe-DOX@Gd-MOF-ICG nanoplatform. 102,103 This nanoplatform enables combined MR/PA/PT multimodal imaging-guided chemotherapy, and photothermal and photodynamic therapy.…”

Near‐Infrared Fluorescence Imaging of miRNA Using a Transmembrane Polypeptide‐Based Genetic Reporter

“…Recently, a couple of studies indicated that the organic anion-transporting polypeptides (OATP) family proteins could mediate the uptake of ICG, thereby achieving near-infrared (NIR) fluorescence imaging. [17][18][19] Because of its clinical availability and deep tissue imaging capabilities, these OATP protein are considered as the potential reporter gene system with multiple biomedical applications.…”