Salvianolic Acid B-Loaded Albumin Nanoparticles Reduce Portal Hypertension in Cirrhotic Mice and Inhibit the Proliferation and Contraction of Hepatic Stellate Cells.

Introduction: Salvianolic acid B (SAB), as one of the major water-soluble compounds of Salvia miltiorrhiza, has proved to effectively reduce elevated portal pressure in cirrhotic rats. However, the short halflife and in vivo retention time of SAB affect its pharmacodynamics. Therefore, in this study, we prepared albumin nanoparticles loaded with SAB (SAB-ALB-NPs) to improve the in vivo retention time of the drug and enhance bioavailability.

Methods: We prepared and characterized SAB-ALB-NPs, including particle size, PDI, zeta potential, stability, EE, in-vitro release, and pharmacokinetics. Subsequently, we investigated the effects and potential mechanisms of SAB-ALB-NPs in CCl4-induced portal hypertension (PHT) mice models, and it was found that angiotensin- II (Ang-II) induced proliferation and contraction in hepatic stellate cells (HSCs). The CCl4 (0.3:1 in corn oil, 1mL/kg) was injected repeatedly, leading to the PHT mice model. The effect of SAB-ALB-NPs on PHT mice was evaluated by hematoxylin-eosin, Sirius red staining, immunohistochemistry, and western blot.

Results: We successfully prepared SAB-loaded albumin nanoparticles with smaller-sized particles, lower PDI and zeta potential with stable properties, and higher EE. Importantly, the SAB-ALB-NPs notably prolonged the in vitro release of SAB. SAB-ALB-NPs significantly reduced portal pressure, inhibited inflammation (decrease the concentration of TNF-α and IL-6) and hepatotoxicity of the liver (down-regulated the level of ALT and AST) against fibrous tissue hyperplasia, and reduced collagen deposition in the liver. Afterward, we used Ang-II to facilitate the proliferation of HSCs and induce HSC cell contraction. Cotreatment of SAB-ALB-NPs markedly inhibited Ang II-induced effects on cell proliferation and contraction and improved apoptosis. Importantly, SAB-ALB-NPs were preliminarily found to inhibit the expression of RhoA and ROCK II in Ang-II- treated HSC and CCl4-induced PHT mice, suggesting that SAB-ALB-NPs may participate in the regulation of RhoA/ROCK II pathway.

Conclusion: SAB-ALB-NPs improved portal hypertension by suppressing inflammation and inhibiting HSCs activation and proliferation to attenuate liver fibrosis. This therapeutic function of SAB-ALB-NPs may be owing to SAB-ALB-NPs regulating the RhoA/ROCK2 pathway, which may be one of its molecular mechanisms for reducing portal hypertension.