Synthesis and evaluation of a tri-tyrosine decorated dextran MR contrast agent for vulnerable plaque detection

Recent Advances in Luminescence Imaging of Biological Systems Using Lanthanide(III) Luminescent Complexes

The use of luminescence in biological systems allows one to diagnose diseases and understand cellular processes. Molecular systems, particularly lanthanide(III) complexes, have emerged as an attractive system for application in cellular luminescence imaging due to their long emission lifetimes, high brightness, possibility of controlling the spectroscopic properties at the molecular level, and tailoring of the ligand structure that adds sensing and therapeutic capabilities. This review aims to provide a background in luminescence imaging and lanthanide spectroscopy and discuss selected examples from the recent literature on lanthanide(III) luminescent complexes in cellular luminescence imaging, published in the period 2016-2020. Finally, the challenges and future directions that are pointing for the development of compounds that are capable of executing multiple functions and the use of light in regions where tissues and cells have low absorption will be discussed.

A novel manganese chelated macromolecular MRI contrast agent based on O-carboxymethyl chitosan derivatives

Currently used Gd-based and Mn-based small molecular MRI contrast agents fail to meet the requirements for the long-term monitoring, and the potential safety risk under high administration dose or repeat dosing needs to be considered. In the present study, a biocompatible macromolecular magnetic resonance imaging (MRI) contrast agents based on O-carboxymethyl chitosan (CMCS), CMCS-(Mn-DTPA)_n was designed and synthesized. The relaxivity of CMCS-(Mn-DTPA)_n is approximately 3.5 and 5.5 times higher than that of Gd-DTPA and Mn-DPDP in aqueous solution, respectively. The MRI signal intensity in the kidney and liver of Sprague Dawley (SD) rats is significantly increased at a dose of 0.03 mM Mn/kg b.w. CMCS-(Mn-DTPA)_n accompanied by a long effective imaging window. According to in vitro studies, CMCS-(Mn-DTPA)_n exhibits good cellular and blood biocompatibility at the dose necessary for MRI imaging. Based on the results from in vivo studies, manganese (Mn) is completely excreted from SD rats within ten days after administration and does not exert a pathological effect on the liver. CMCS-(Mn-DTPA)_n represents a potentially novel MRI contrast agent due to its excellent relaxivity, long effective imaging window and good biocompatibility.

Gadolinium-Based Contrast Agents for Vessel Wall Magnetic Resonance Imaging (MRI) of Atherosclerosis

Cardiovascular disease due to atherosclerosis is the number one killer in the Western world, and threatens to become the major cause of morbidity and mortality worldwide. It is therefore paramount to develop non-invasive methods for the detection of high-risk, asymptomatic individuals before the onset of clinical symptoms or events. In the recent past, great strides have been made in the understanding of the pathological mechanisms involved in the atherosclerotic cascade down to the molecular details. This has allowed the development of contrast agents that can aid in the in vivo characterization of these processes. Gadolinium chelates are among the contrast media most commonly used in MR imaging. Originally used for MR angiography for the detection and quantification of vascular stenosis, more recently they have been applied to improve characterization of atherosclerotic plaques. In this manuscript, we will briefly review gadolinium-chelates (Gd) based contrast agents for non-invasive MR imaging of atherosclerosis. We will first describe Gd-based non-targeted FDA approved agents, used routinely in clinical practice for the evaluation of neovascularization in other diseases. Secondly, we will describe non-specific and specific targeted contrast agents, which have great potential for dissecting specific biological processes in the atherosclerotic cascade. Lastly, we will briefly compare Gd-based agents to others commonly used in MRI and to other imaging modalities.