Hepatic fibrosis is the only chronic liver disease process that can be reversed. Developing non-invasive and effective methods to quantitatively assess the degree of liver fibrosis is of great clinical significance and remains a major challenge. The key factors in hepatic fibrosis pathogenesis are the activation and proliferation of hepatic stellate cells that subsequently express integrin αvβ3. An ultrasound (US) agent combined with a targeting peptide may be used for the early and non-invasive diagnosis of hepatic fibrosis. Herein, we report the synthesis of core-shell nanoparticles (NPs) successfully engineered by conjugation with cyclic arginine-glycine-aspartic acid (cRGD) octapeptide, allowing hepatic integrin αvβ3 targeting for liver fibrosis staging. This system consists of a perfluorooctyl bromide (PFOB) liquid in the core that is stabilized with a Poly (lactic-co-glycolic acid) (PLGA) polymer shell and modified with a cRGD. These core-shell NPs (cRGD-PLGA-PFOB NPs) exhibited useful US molecular imaging features including high imaging contrast among liver fibrotic stages and the adjacent tissues. Our results indicate that the cRGD-PLGA-PFOB NPs have significant potential to distinguish different liver fibrotic stages and could be used in clinical applications.

Liver fibrosis is a global health challenge with high morbidity and mortality rates, and diagnostic sensitivity of liver fibrosis tests can be increased using multimodal molecular agents. We designed cyclic arginine-glycine-aspartic acid (cRGD)-modified nanoparticles (NPs) using ultrasound (US)/computed tomography (CT)/magnetic resonance (MR) triple-modality imaging to evaluate liver fibrosis stages. In vitro and in vivo studies were conducted using primary hepatic stellate cells (HSCs) and a rat model of liver fibrosis induced by carbon tetrachloride (CCl4). Our results showed cRGD-poly(lactic-co-glycolic acid)-Fe3O4-perfluorocarbon bromide (cRGD-PLGA-Fe3O4-PFOB) NPs were preferentially internalised by activated HSCs (aHSCs). The main cell types expressing integrin αvβ3 during liver fibrogenesis were the aHSCs. The protein levels of αv and β3 expressed on aHSCs increased with the progression of liver fibrosis. After intravenous injection of cRGD-PLGA-Fe3O4-PFOB NPs, the echo intensity (EI) values, CT values, and T2 values of liver parenchyma correlated well with liver fibrosis severity. cRGD-PLGA-Fe3O4-PFOB NPs as multifunction contrast agents showed great potential to reflect the degree of HSC activation and distinguish among different liver fibrotic stages. The ligand-directed and integrin αvβ3-mediated accumulation provides active and passive targeting capabilities, permitting the targeted multimodal imaging of cRGD-PLGA-Fe3O4-PFOB NPs, which delivers accurate non-invasive diagnosis and real-time monitoring of liver fibrosis development.