Enhanced Oral Absorption and Liver Distribution of Polymeric Nanoparticles through Traveling the Enterohepatic Circulation Pathways of Bile Acid

Oral targeted drug delivery to post-gastrointestinal sites

As an essential branch of targeted drug delivery, oral targeted delivery is attracting growing attention in recent years. In addition to site-specific delivery for the treatment of locoregional diseases in the gastrointestinal tract (GIT), oral targeted delivery to remote sites beyond the GIT emerges as a cutting-edge research topic. This review aims to provide an overview of the fundamental concepts and most recent advances in this field. Owing to the physiological barriers existing in the GIT, carrier systems should be transported across the enteric epithelia to target remote sites. Recently, pioneer investigations have validated the transport of intact micro- or nanocarriers across gastrointestinal barriers and subsequently to various distal organs and tissues. The microfold (M) cell pathway is the leading mechanism underlying the oral absorption of particulates, but the contribution of the transcellular and paracellular pathways should not be neglected either. In addition to well-acknowledged physicochemical and biological factors, the formation of a protein corona may also influence the biological fate of carrier systems. Although in an early stage of conceptualization, oral targeted delivery to remote diseases has demonstrated promising potential for the treatment of inflammation, tumors, and diseases inflicting the lymphatic and mononuclear phagocytosis systems.

Ursodeoxycholic Acid-Decorated Zwitterionic Nanoparticles for Orally Liver-Targeted Close-Looped Insulin Delivery

Oral insulin therapies targeting the liver and further simulating close-looped secretion face significant challenges due to multiple trans-epithelial barriers. Herein, ursodeoxycholic acid (UDCA)-decorated zwitterionic nanoparticles (NPs) (UC-CMs@ins) are designed to overcome these barriers, target the liver, and respond to glycemia, thereby achieving oral one-time-per-day therapy. UC-CMs@ins show excellent mucus permeability through the introduction of zwitterion (carboxy betaine, CB). Furthermore, UC-CMs@ins possess superior cellular internalization via proton-assisted amino acid transporter 1 (PAT1, CB-receptor) and apical sodium-dependent bile acid transporter (ASBT, UDCA-receptor) pathways. Moreover, UC-CMs@ins exhibit excellent endolysosomal escape ability and improve the basolateral release of insulin into the bloodstream via the ileal bile acid-binding protein and the heteromeric organic solute transporter (OSTα- OSTβ) routes compared with non-UDCA-decorated C-CMs@ins. Therefore, CB and UDCA jointly overcome mucus and intestinal barriers. Additionally, UC-CMs@ins prevent insulin degradation in the gastrointestinal tract for crosslinked structure, improve insulin accumulation in the liver for UDCA introduction, and effectively regulate glycemia for "closed-loop" glucose control. Surprisingly, oral ingestion of UC-CMs@ins shows a superior effect on glycemia (≈22 h, normoglycemia) and improves postprandial glycemic levels in diabetic mice, illustrating the enormous potential of the prepared NPs as a platform for oral insulin administration in diabetes treatment.

Hepatic-Accumulated Obeticholic Acid and Atorvastatin Self-Assembled Nanocrystals Potentiate Ameliorative Effects in Treatment of Metabolic-Associated Fatty Liver Disease

Exploration of medicines for efficient and safe management of metabolic-associated fatty liver disease (MAFLD) remains a challenge. Obeticholic acid (OCA), a selective farnesoid X receptor agonist, has been reported to ameliorate injury and inflammation in various liver diseases. However, its clinical application is mainly limited by poor solubility, low bioavailability, and potential side effects. Herein a hepatic-targeted nanodrugs composed of OCA and cholesterol-lowering atorvastatin (AHT) with an ideal active pharmaceutical ingredient (API) content for orally combined treatment of MAFLD is created. Such carrier-free nanocrystals (OCAHTs) are self-assembled, not only improving the stability in gastroenteric environments but also achieving hepatic accumulation through the bile acid transporter-mediated enterohepatic recycling process. Orally administrated OCAHT outperforms the simple combination of OCA and AHT in ameliorating of liver damage and inflammation in both acetaminophen-challenged mice and high-fat diet-induced MAFLD mice with less systematic toxicity. Importantly, OCAHT exerts profoundly reverse effects on MAFLD-associated molecular pathways, including impairing lipid metabolism, reducing inflammation, and enhancing the antioxidation response. This work not only provides a facile bile acid transporter-based strategy for hepatic-targeting drug delivery but also presents an efficient and safe full-API nanocrystal with which to facilitate the practical translation of nanomedicines against MAFLD.

Fabrication of a protein-dextran conjugates formed oral nanoemulsion and its application to deliver the essential oil from Alpinia zerumbet Fructus

The injury of vascular endothelial cells caused by high glucose (HG) is one of the driving factors of vascular complications of diabetes. Oral administration is the most common route of administration for the treatment of diabetes and its vascular complications. Essential oil extracts from Chinese medicine possess potential therapeutic effects on vascular endothelial injury. However, low solubility and volatility of essential oils generally result in poor oral absorption. Development of nanocarriers for essential oils is a promising strategy to overcome the physiological barriers of oral absorption. In this study, a nanoemulsion composed of bovine serum albumin (BSA)-dextran sulfate (DS) conjugate and sodium deoxycholate (SD) was constructed. The nanoemulsions were verified with promoted oral absorption and prolonged circulation time. After the primary evaluation of the nanoemulsion, essential oil from Alpinia zerumbet Fructus (EOFAZ)-loaded nanoemulsion (denoted as EOFAZ@BD5/S) was prepared and characterized. Compared to the free EOFAZ, EOFAZ@BD5/S increased the protective effects on HG-induced HUVEC injury in vitro and ameliorative effects on the vascular endothelium disorder and tunica media fibroelastosis in a T2DM mouse model. Collectively, this study provides a nanoemulsion for the oral delivery of essential oils, which holds strong promise in the treatment of diabetes-induced vascular endothelial injury.