Fluorescence lifetime imaging to differentiate bound from unbound ICG-cRGD both in vitro and in vivo

Conference paper (2015)

Authors

PL Stegehuis External organisation
MC Boonstra External organisation
AL Vahrmeijer External organisation
J. Dijkstra External organisation
M Giessen External organisation
KE de Rooij External organisation
FE Powolny External organisation
R Sinisi External organisation
HAR Homulle External organisation
Claudio Bruschini External organisation
E. Charbon-Iwasaki-Charbon Swiss Federal Institute of Technology
CJH van de Velde External organisation
B.P.F. Lelieveldt Leiden University Medical Center
Boudewijn P.F. Lelieveldt Leiden University Medical Center
Boudewijn Lelieveldt Leiden University Medical Center
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Published Date

2015

Language

English

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Abstract

 Excision of the whole tumor is crucial, but remains difficult for many tumor types. Fluorescence lifetime imaging could be helpful intraoperative to differentiate normal from tumor tissue. In this study we investigated the difference in fluorescence lifetime imaging of indocyanine green coupled to cyclic RGD free in solution/serum or bound to integrins e.g. in tumors. The U87-MG glioblastoma cell line, expressing high integrin levels, was cultured to use in vitro and to induce 4 subcutaneous tumors in a-thymic mice (n=4). Lifetimes of bound and unbound probe were measured with an experimental time-domain single-photon avalanche diode array (time resolution <100ps). In vivo measurements were taken 30-60 minutes after intravenous injection, and after 24 hours. The in vitro lifetime of the fluorophores was similar at different concentrations (20, 50 and 100μM) and showed a statistically significant higher lifetime (p<0.001) of bound probe compared to unbound probe. In vivo, lifetimes of the fluorophores in tumors were significantly higher (p<0.001) than at the control site (tail) at 30-60 minutes after probe injection. Lifetimes after 24 hours confirmed tumor-specific binding (also validated by fluorescence intensity images). Based on the difference in lifetime imaging, it can be concluded that it is feasible to separate between bound and unbound probes in vivo. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).