Optical Molecular Imaging of Inflammatory Cells in Interventional Medicine-An Emerging Strategy

Beyond Anatomy: Fat-Suppressed MR and Molecular Imaging of Spinal Pain Generators

Spine pain is highly prevalent and costly, but evaluation with clinical features and anatomic imaging remain limited. Fat-suppressed MR imaging and molecular imaging (MI) may help identify inflammatory, lesional, and malignant causes. Numerous MI agents are available, each with advantages and disadvantages. Herein, FDG PET, prostate-specific membrane antigen (PSMA), bone radiotracers, and others are highlighted. No specific pain MI agents have been identified, but mechanisms of key agents are shown in video format, and the mechanism of PSMA as a theranostic agent is displayed. A multidisciplinary approach is needed to master this topic.

Detection of subcellular nitric oxide in mitochondria using a pyrylium probe: assays in cell cultures and peripheral blood

Fluorescent probes for the detection of intracellular nitric oxide (NO) are abundant, but those targeted to the mitochondria are scarce. Among those molecules targeting mitochondrial NO (mNO), the majority use a triphenylphosphonium (TPP) cation as a vector to reach such organelles. Here we describe a simple molecule (mtNOpy) based on the pyrylium structure, made in a few synthetic steps, capable of detecting selectively NO (aerated medium) over other reactive species. The calculated detection limit for mtNOpy is 88 nM. The main novelty of this probe is that it has a simple molecular architecture and can act both as a fluorogenic and as a mitochondriotropic agent, without using TPP. mtNOpy has been tested in two different scenarios: (a) in a controlled environment of cell line cultures (human colon carcinoma HT-29 cells and mouse macrophage RAW 264.7 cells), using confocal laser scanning microscopy, and (b) on a much more complex sample of peripheral blood, using flow cytometry. In the first context, mtNOpy has been found to be responsive (turn-on fluorescence) to exogenous and endogenous NO stimuli (via SNAP donor and LPS stimulation, respectively). In the second area, mtNOpy has been able to discriminate between NO-generating phagocytes (neutrophils and monocytes) from other leukocytes (NK, B and T cells).

Molecular and Nonmolecular Imaging of Macrophages in Atherosclerosis

Atherosclerosis is a major cause of ischemic heart disease, and the increasing medical burden associated with atherosclerotic cardiovascular disease has become a major public health concern worldwide. Macrophages play an important role in all stages of the dynamic progress of atherosclerosis, from its initiation and lesion expansion increasing the vulnerability of plaques, to the formation of unstable plaques and clinical manifestations. Early imaging can identify patients at risk of coronary atherosclerotic disease and its complications, enabling preventive measures to be initiated. Recent advances in molecular imaging have involved the noninvasive and semi-quantitative targeted imaging of macrophages and their related molecules in vivo, which can detect atheroma earlier and more accurately than conventional imaging. Multimodal imaging integrates vascular structure, function, and molecular imaging technology to achieve multi-dimensional imaging, which can be used to comprehensively evaluate blood vessels and obtain clinical information based on anatomical structure and molecular level. At the same time, the rapid development of nonmolecular imaging technologies, such as intravascular imaging, which have the unique advantages of having intuitive accuracy and providing rich information to identify macrophage inflammation and inform targeted personalized treatment, has also been seen. In this review, we highlight recent methods and research hotspots in molecular and nonmolecular imaging of macrophages in atherosclerosis that have enormous potential for rapid clinical application.

Molecular imaging of the urokinase plasminogen activator receptor: opportunities beyond cancer

The urokinase plasminogen activator receptor (uPAR) plays a multifaceted role in almost any process where migration of cells and tissue-remodeling is involved such as inflammation, but also in diseases as arthritis and cancer. Normally, uPAR is absent in healthy tissues. By its carefully orchestrated interaction with the protease urokinase plasminogen activator and its inhibitor (plasminogen activator inhibitor-1), uPAR localizes a cascade of proteolytic activities, enabling (patho)physiologic cell migration. Moreover, via the interaction with a broad range of cell membrane proteins, like vitronectin and various integrins, uPAR plays a significant, but not yet completely understood, role in differentiation and proliferation of cells, affecting also disease progression. The implications of these processes, either for diagnostics or therapeutics, have received much attention in oncology, but only limited beyond. Nonetheless, the role of uPAR in different diseases provides ample opportunity to exploit new applications for targeting. Especially in the fields of oncology, cardiology, rheumatology, neurology, and infectious diseases, uPAR-targeted molecular imaging could offer insights for new directions in diagnosis, surveillance, or treatment options.

Rapid differentiation between bacterial infections and cancer using a near-infrared fluorogenic probe

The reliable differentiation between bacterial infections and other pathologies is crucial for both diagnostics and therapeutic approaches. To accommodate such needs, we herein report the development of an activatable near-infrared fluorescent probe 1 that could be applied in the ultrafast, ultrasensitive and specific detection of nitroreductase (NTR) activity in bacterial pathogens both in vitro and in vivo. Upon reaction with NTR, the nitro-group of the para-nitro phenyl sulfonic moiety present in probe 1 was reduced to an amino-group, resulting in a near-infrared fluorescence turn-on of the latent cyanine 7 fluorophore. Probe 1 was capable of rapid and real-time quantitative detection of 0–150 ng mL⁻¹ NTR with a limit of detection as low as 0.67 ng mL⁻¹in vitro. In addition, probe 1 exhibited an outstanding performance of ultrafast measurements and suitable selectivity toward NTR to accurately sense intracellular basal NTR in ESKAPE bacterial pathogens. Most remarkably, probe 1 was capable of noninvasively identifying bacterial infection sites without showing any significantly increased signal of tumour sites in the same animal within 30 min.

A new nitroreductase-responsive near-infrared fluorogenic probe can specifically image live bacteria in mouse models and does not accumulate at sites of inflammation or tumor.