A Far-red Fluorescent Contrast Agent to Image Epidermal Growth Factor Receptor Expression

Abstract

Recent developments in optical technologies have the potential to improve the speed and accuracy of screening and diagnosis of curable precancerous lesions and early cancer, thereby decreasing the costs of detection and management of epithelial malignancies. The development of molecular-specific contrast agents for markers of early neoplastic transformation could improve the detection and molecular characterization of premalignant lesions. In the oral cavity, epidermal growth factor receptor (EGFR) overexpression has been identified in early stages of premalignant lesions of the oral squamous cell carcinoma; therefore, real-time assessment of EGFR expression could serve as a biomarker for oral neoplasia. The purpose of our study was to develop a molecular-specific optical contrast agent targeted against EGFR for in vivo assessment of epithelial neoplasia using a monoclonal antibody and the far-red fluorescent dye, Alexa FluorÒ 660 streptavidin. In addition to demonstrating the specificity of the contrast agent for EGFR in cell lines, we document the ability to achieve penetration through 500 lm thick epithelial layers using multilayer tissue constructs and permeability-enhancing agents. Finally, using the fluorescence intensity of the contrast agent on fresh oral cavity tissue sections, we were able to distinguish abnormal from normal oral tissue. This contrast agent should have important clinical applications for use in conjunction with fluorescence spectroscopy or imaging (or both) to facilitate tumor detection and demarcation.

In vivo confocal laser laparoscopy allows real time subsurface microscopy in animal models of liver disease

“…Imaging depth could be increased by integrating longer wavelength laser lines, e.g. near infrared [25], or by using non-linear imaging techniques, such as two-photon microscopy [26], for excitation of fluorophores well below the liver surface. This would potentially also ameliorate diagnosis of tissue fibrosis, which in the present study has only been observed at the liver surface and was therefore not quantified.…”

In-vivo confocal real-time mini-microscopy in animal models of human inflammatory and neoplastic diseases

“…Hav− ing established the feasibility of in−vivo molecular imaging in ro− dents in the present study, it is, however, tempting to speculate that translation of these findings into flexible endomicroscopy will soon offer the possibility of molecular imaging in humans in real time during endoscopy. Furthermore, exploitation of al− ternate laser lines and detection bands to achieve deeper tissue imaging [18] and co−localization of multiple fluorophores (mul− tichannel imaging) will extend the number of molecular biologi− cal and microarchitectural features that can be investigated in organs and cells in their natural environment. In−vivo confocal imaging with this new handheld probe could therefore contrib− ute to a deeper understanding of microarchitecture and cellular function and interactions in human diseases such as cancer and inflammation.…”

In Vivo Molecular Imaging of Somatostatin Receptors in Pancreatic Islet Cells and Neuroendocrine Tumors by Miniaturized Confocal Laser-Scanning Fluorescence Microscopy

“…In the future, however, imaging depth will be increased by integrating longer wavelength laser lines, e.g. near infrared, or using nonlinear imaging techniques such as two-photon microscopy (31,32). In analogy to pancreatic islet cells, confocal laser scan microscopy allowed visualization of sstr in tubular cells of the renal FIG.…”