Integrin ¦Áv¦Â3 Receptor-targeted Ultrasound To Enhance The Imaging Assessment Of Experimental Hepatic Fibrosis In Rats

Objective:There is great interest in quantitative imaging of liver fibrosis. Established evidence clearly indicates that liver fibrosis is accompanied by hepatic angiogenesis. The integrinαvβ3 plays an important role in liver fibrogenesis and angiogenesis. The purpose of this study is to create a high affinitive and specific fibrogenesis molecular imaging methods using contrast ultrasound and microbubbles targeted toαvβ3, and to evaluate its effect for noninvasive quantification of liver fibrogenesis.Materials and Methods:A peptidomimetic small molecule ligand of the a vβ3 (cRGDyK) with low nanomolar affinity was modified by introducingαBiotin-PEG. This targeting ligand was attached to the micro-bubble using biotin-streptavidin coupling chemistry. Homologous competition with cRGDyK was performed on activated hepatic stellate cells (αvβ3 integrin positive) and HEK 293 (αvβ3 integrin negative) cell lines. Ultrasound contrast imaging was accomplished in 4 week-old and 9 week-old fibrogenic rats at a center frequency of 30 MHz, which provided lateral and axial resolutions of 55 and 115μm, respectively.Results:The Biotin-PEG-cRGDyK displayed a slightly decrease in affinity over the precursor (Bmax= 6×105 receptors) forαvβ3-positive hepatic stellate cells. Theαvβ3-based high-frequency ultrasound imaging agent showed a 4-to 7-fold enhanced retention in 4 week-old and 9 week-old fibrogenic liver as compared to age-matched controls after injection.Conclusion:It has demonstrated that molecular imaging ofαvβ3 expression with targeted micro-bubbles could potentially facilitate noninvasive assessment of liver fibrosis progression.