Gentle palpating liver sinusoidal endothelial cells reveals the dynamic behavior and formation of fenestrae: A new window for biomedical research

Liver-targeted delivery based on prodrug: passive and active approaches

BACKGROUND

The liver, a central organ in human metabolism, is often the primary target for drugs. However, conditions such as viral hepatitis, cirrhosis, non-alcoholic fatty liver disease (NAFLD), and hepatocellular carcinoma (HCC) present substantial health challenges worldwide. Existing treatments, which suffer from the non-specific distribution of drugs, frequently fail to achieve desired efficacy and safety, risking unnecessary liver harm and systemic side effects.

PURPOSE

The aim of this review is to synthesise the latest progress in the design of liver-targeted prodrugs, with a focus on passive and active targeting strategies, providing new insights into the development of liver-targeted therapeutic approaches.

METHODS

This study conducted an extensive literature search through databases like Google Scholar, PubMed, Web of Science, and China National Knowledge Infrastructure (CNKI), systematically collecting and selecting recent research on liver-targeted prodrugs. The focus was on targeting mechanisms, including the Enhanced Permeability and Retention (EPR) effect, the unique microenvironment of liver cancer, and active targeting through specific transporters and receptors.

RESULTS

Active targeting strategies achieve precise drug delivery by binding specific ligands to liver surface receptors. Passive targeting takes advantage of the EPR effect and tumour characteristics to enrich drugs in liver tumours. The review details successful cases of using small molecule ligands, peptides, antibodies and nanoparticles as drug carriers.

CONCLUSION

Liver-targeted prodrug strategies show great potential in enhancing the efficacy of drug treatment and reducing side effects for liver diseases. Future research should balance the advantages and limitations of both targeting strategies, focusing on optimising drug design and targeting efficiency, especially for clinical application. In-depth research on liver-specific receptors and the development of innovative targeting molecules are crucial for advancing the field of liver-targeted prodrugs.

Effect of Curcumol on the Fenestrae of Liver Sinusoidal Endothelial Cells Based on NF-κB Signaling Pathway

OBJECTIVE

To study the effect of curcumol on liver sinusoidal endothelial cells (LSECs) and to analyze the mechanism of antihepatic fibrosis.

METHODS

The effects of drug intervention on cell proliferation rates were detected by MTT assay. The expression of NF-κB was detected by RT-PCR and WB. The NF-κB expression and entry into the nucleus were detected by immunofluorescence; scanning electron microscopy was used to observe the changes of LSECs fenestrae.

RESULTS

MTT results showed that the interference of cell proliferation in each group was small. RT-PCR showed that the expression of NF-κB in the curcumol intervention group was significantly lower than that in the positive control group (P < 0.05). The WB detection found that, in the curcumol intervention group, the expression of pNF-κB in the NF-κB signaling pathway was significantly lower than that in the positive control group (P < 0.05). Scanning electron microscopy showed that the LSEC fenestrae were significantly improved compared with the positive control group.

CONCLUSION

Curcumol may be one of the mechanisms of antihepatic fibrosis by inhibiting the activity of the NF-κB signaling pathway and increasing the fenestrae of LSECs.

LSEC Fenestrae Are Preserved Despite Pro-inflammatory Phenotype of Liver Sinusoidal Endothelial Cells in Mice on High Fat Diet

Healthy liver sinusoidal endothelial cells (LSECs) maintain liver homeostasis, while LSEC dysfunction was suggested to coincide with defenestration. Here, we have revisited the relationship between LSEC pro-inflammatory response, defenestration, and impairment of LSEC bioenergetics in non-alcoholic fatty liver disease (NAFLD) in mice. We characterized inflammatory response, morphology as well as bioenergetics of LSECs in early and late phases of high fat diet (HFD)-induced NAFLD. LSEC phenotype was evaluated at early (2-8 week) and late (15-20 week) stages of NAFLD progression induced by HFD in male C57Bl/6 mice. NAFLD progression was monitored by insulin resistance, liver steatosis and obesity. LSEC phenotype was determined in isolated, primary LSECs by immunocytochemistry, mRNA gene expression (qRT-PCR), secreted prostanoids (LC/MS/MS) and bioenergetics (Seahorse FX Analyzer). LSEC morphology was examined using SEM and AFM techniques. Early phase of NAFLD, characterized by significant liver steatosis and prominent insulin resistance, was related with LSEC pro-inflammatory phenotype as evidenced by elevated ICAM-1, E-selectin and PECAM-1 expression. Transiently impaired mitochondrial phosphorylation in LSECs was compensated by increased glycolysis. Late stage of NAFLD was featured by prominent activation of pro-inflammatory LSEC phenotype (ICAM-1, E-selectin, PECAM-1 expression, increased COX-2, IL-6, and NOX-2 mRNA expression), activation of pro-inflammatory prostaglandins release (PGE2 and PGF2α) and preserved LSEC bioenergetics. Neither in the early nor in the late phase of NAFLD, were LSEC fenestrae compromised. In the early and late phases of NAFLD, despite metabolic and pro-inflammatory burden linked to HFD, LSEC fenestrae and bioenergetics are functionally preserved. These results suggest prominent adaptive capacity of LSECs that might mitigate NAFLD progression.

Actin Depolymerization in Dedifferentiated Liver Sinusoidal Endothelial Cells Promotes Fenestrae Re-Formation

Liver sinusoidal endothelial cells (LSECs) possess fenestrae, which are key for the exchange between blood and hepatocytes. Alterations in their number or diameter have important implications for hepatic function in liver diseases. They are lost early in the development of hepatic fibrosis through a process called capillarization. In this study, we aimed to demonstrate whether in vitro dedifferentiated LSECs that have lost fenestrae are able to re-form these structures. Using stimulated emission depletion super-resolution microscopy in combination with transmission electron microscopy, we analyzed fenestrae formation in a model mimicking the capillarization process in vitro. Actin is known to be involved in fenestrae regulation in differentiated LSECs. Using cytochalasin D, an actin-depolymerizing agent, we demonstrated that dedifferentiated LSECs remain capable of forming fenestrae. Conclusion: We provide a new insight into the complex role of actin in fenestrae formation and in the control of their size and show that LSEC fenestrae re-formation is possible, suggesting that this process could be used during fibrosis regression to try to restore exchanges and hepatocyte functions.