Non-invasive imaging and cellular tracking of pulmonary emboli by near-infrared fluorescence and positron-emission tomography

Abstract

Functional imaging of proteolytic activity is an emerging strategy to quantify disease and response to therapy at the molecular level. We present a new peptide-based imaging probe technology that advances these goals by exploiting enzymatic activity to deposit probes labelled with near-infrared (NIR) fluorophores or radioisotopes in cell membranes of disease-associated proteolysis. This strategy allows for non-invasive detection of protease activity in vivo and ex vivo by tracking deposited probes in tissues. We demonstrate non-invasive detection of thrombin generation in a murine model of pulmonary embolism using our protease-activated peptide probes in microscopic clots within the lungs with NIR fluorescence optical imaging and positron-emission tomography. Thrombin activity is imaged deep in tissue and tracked predominantly to platelets within the lumen of blood vessels. The modular design of our probes allows for facile investigation of other proteases, and their contributions to disease by tailoring the protease activation and cell-binding elements.

Global Identification of Biofilm-Specific Proteolysis in Candida albicans

“…We envision that fluorogenic peptide substrates with biofilm (or planktonic) selectivity could be used as ex vivo diagnostic tools through noninvasive blood sampling. The catalytic signal amplification by proteolytic activity ( 34 ) makes these probes particularly sensitive. Development of rapid and noninvasive approaches for detecting Candida biofilm formation would change current clinical practices by enabling the early identification of biofilms, well before they have had a chance to seed life-threatening disseminated infections.…”

Accurate Device-Free Tracking Using Inexpensive RFIDs

“…Target tracking systems generally adopt all kinds of techniques such as computer vision [ 2 ], infrared electromagnetic radiation [ 4 ], ultra-sound [ 3 ] and inertial sensors [ 30 ]. However, these techniques suffer from many limitations such as sensitivity to lighting, requiring line-of-sight communication between the target and the device, high installation and demanding extra sensors or devices to be worn or installed.…”

“…In real life, we envision target tracking as an essential means to support anti-intrusion protection. Existing approaches based on vision [ 2 ], ultra-sound [ 3 ] and infrared [ 4 ] have been applied in target tracking. While promising, these techniques have various limitations such as requiring line-of-sight, sensitivity to lighting, short communication distance, etc.…”

Peptide-based fibrin-targeting probes for thrombus imaging

“…Molecular probes that target the coagulation enzymes thrombin 52, 53 and factor XIII 54 have shown significant uptake in fresh thrombi, but have not shown any signal enhancement when used to image old thrombi. Such probes have, however, not been widely evaluated in patients and thus the natural history of thrombin and Factor XIII expression in thrombosis is unknown.…”