Near infrared thoracoscopy of tumoral protease activity for improved detection of peripheral lung cancer

Abstract

Improvement in tumor detection using ''smart'' probes in combination with microcatheter fluorescence thoracoscopy was evaluated in a mouse model. These imaging probes increase in fluorescence intensity after protease activation; cathepsin B is a major activator of the probes used in this study. Lewis lung carcinoma cells were orthotopically implanted in the subpleural lung parenchyma. Two activatable near infrared (NIR) probes with different excitation and emission wavelength were administered intravenously to determine whether wavelength would modulate target to background ratio (TBR). Mice were selectively intubated and thoracoscopy performed. A 0.8 mm outer diameter imaging catheter was used to record simultaneous white-light (anatomic) and NIR (protease expression) images. At both wavelength pairs evaluated (680/700 and 750/780 nm excitation/emission), the intrinsic luminosity differences between tumors and normal lung in uninjected animals was low (p > 0.3 and p 5 0.4, respectively and TBR near 1). In mice receiving protease probes IV, tumors were significantly more fluorescent than adjacent lung (p < 0.0005 for 680/700 and p < 0.006 for 750/780) and TBR increased to approximately 9-fold. Confirmatory fluorescence microscopy and immunohistochemistry were similar and revealed that normal lung had very low levels when compared to tumors of cathepsin B and probe fluorescence. In conclusion, protease sensitive imaging probes selective for cathepsin B, imaged with NIR microcatheters, significantly increase the TBR, making small peripheral lung tumors more readily apparent. Such an approach may be a useful adjunct in staging or restaging patients with lung cancer to find minimal disease in the pleural and subpleural space. ' 2005 Wiley-Liss, Inc.

Early photon tomography allows fluorescence detection of lung carcinomas and disease progression in mice in vivo

“…It has been shown previously that this model (20) as well as other lung tumor models (21) have markedly up-regulated levels of cysteine proteases during tumor growth. Therefore, in this study we used an activatable probe (Prosense-750; Visen Medical), which is nonfluorescent at base state but becomes fluorescent on interaction with cysteine proteases-primarily cathepsin B and to a lesser degree cathepsins S, L, and K (22).…”

“…A total of 15 female nu/nu mice (COX7, Massachusetts General Hospital, Boston, MA) aged 6 -10 weeks were used in the imaging studies. Lewis lung carcinoma (LLC) cells were grown at 37°C in 5% CO 2 in Dulbecco's modified Eagle's medium with 10% heat-inactivated FBS plus 1% glutamine, penicillin, and streptomycin (20). A 10-L aliquot of 10 6 LLC cells in suspension was injected into the right inferior lobe of the lung through a skin incision.…”

The use of fluorescent dyes and probes in surgical oncology

“…Three probes have been designed so far by one research group and they are all activated by protease Cathepsin B. [51][52][53][54][55][56] This protease is known to be up-regulated in areas of inflammation, necrosis, angiogenesis and focal invasion. 57 Being optically silent when injected, the probes have a low background signal which results in higher signal-to-background ratios when compared to nonspecific probes.…”

“…54 The tumoral protease activity was used to improve the detection of small peripheral lung cancer in the Lewis Lung Carcinoma model by use of a novel ProSense 750. 55 In this study, the imaging was performed by NIR microcatheters during thoracoscopy.…”

Quantitative Endovascular Fluorescence-based Molecular Imaging through Blood of Arterial Wall Inflammation

“…Proteases such as cathepsins and matrix metalloproteinases are commonly upregulated in-and therefore serve as useful biomarkers for-many inflammatory conditions. As such, protease-activatable probes function as molecular beacons for a number of disease states (7)(8)(9), including inflammatory activity in vascular disease (10). Performing direct endovascular imaging of these probes without first flushing away blood is of limited usefulness, however, as blood attenuates NIR fluorescence, rendering the probe's measured fluorescence difficult to determine without knowledge of the amount of blood through which the photons have traveled.…”