Characterization, stability and in-vivo distribution of asialofetuin glycopeptide incorporating DSPC/CHOL liposomes prepared by mild cholate incubation

Silymarin loaded liposomes for hepatic targeting: in vitro evaluation and HepG2 drug uptake

Silymarin has hepatoprotective properties and is used in treatment of various liver diseases, but its bioavailability from oral products is very poor. In order to overcome its poor oral bioavailability we have prepared silymarin loaded hepatic targeting liposomes suitable for parenteral administration. The liposomal formulations were composed of hydrogenated soy phosphatidylcholine and cholesterol with or without distearoylphosphoethanolamine-(polyethyleneglycol)-2000 and various amounts of β-sitosterol β-D-glucoside (Sito-G) as the hepatic targeting moiety. Increasing the amount of Sito-G in the liposomes gradually decreased drug encapsulation efficiencies from ∼70% to ∼60%; still showing promising drug encapsulation efficiencies. Addition of Sito-G to non-PEGylated liposomes clearly affected their drug release profiles and plasma protein interactions, whereas no effect on these was seen for the PEGylated liposomes. Non-PEGylated liposomes with 0.17 M ratio of Sito-G exhibited the highest cellular drug uptake of 37.5% for all of the studied liposome formulations. The highest cellular drug uptake in the case of PEGylated liposomes was 18%, which was achieved with 0.17 and 0.33 M ratio of added Sito-G. The liposome formulations with the highest drug delivery efficacy in this study showed hemolytic activities around 12.7% and were stable for at least 2 months upon storage in 20 mM HEPES buffer (pH 7.4) containing 1.5% Polysorbate 80 at 4 °C and room temperature. These results suggest that the Sito-G containing liposomes prepared in this work have hepatic targeting capability and that they are promising candidates for delivering silymarin to the liver.

Liver-targeting of interferon-alpha with tissue-specific domain antibodies

Interferon alpha (IFNα) is used for the treatment of hepatitis C infection and whilst efficacious it is associated with multiple adverse events including reduced leukocyte, erythrocyte, and platelet counts, fatigue, and depression. These events are most likely caused by systemic exposure to interferon. We therefore hypothesise that targeting the therapeutic directly to the intended site of action in the liver would reduce exposure in blood and peripheral tissue and hence improve the safety and tolerability of IFNα therapy. We genetically fused IFN to a domain antibody (dAb) specific to a hepatocyte restricted antigen, asialoglycoprotein receptor (ASGPR). Our results show that the murine IFNα2 homolog (mIFNα2) fused to an ASGPR specific dAb, termed DOM26h-196-61, could be expressed in mammalian tissue culture systems and retains the desirable biophysical properties and activity of both fusion partners when measured in vitro. Furthermore a clear increase in in vivo targeting of the liver by mIFNα2-ASGPR dAb fusion protein, compared to that observed with either unfused mIFNα2 or mIFNα2 fused to an isotype control dAb V_HD2 (which does not bind ASGPR) was demonstrated using microSPECT imaging. We suggest that these findings may be applicable in the development of a liver-targeted human IFN molecule with improved safety and patient compliance in comparison to the current standard of care, which could ultimately be used as a treatment for human hepatitis virus infections.

Mechanisms of co-modified liver-targeting liposomes as gene delivery carriers based on cellular uptake and antigens inhibition effect

In order to deliver antisense oligonucleotides (asODN) into hepatocytes orientedly in the treatment of hepatitis B virus (HBV) infection, the liver-targeting cationic liposomes was developed as a gene carrier, which was co-modified with the ligand of the asialoglycoprotein receptor (ASGPR), beta-sitosterol-beta-d-glucoside (sito-G) and the nonionic surfactant, Brij 35. Flow cytometry (FCM) analysis and enzyme-linked immunosorbent assay (ELISA) showed that the asODN-encapsulating cationic liposomes exhibited high transfection efficiency and strong antigens inhibition effect in primary rat hepatocytes and HepG2.2.15 cells, respectively. With the help of several inhibitors acting on different steps during the targeting lipofection, the cellular uptake mechanisms of the co-modified liver-targeting cationic liposomes were investigated through antigens inhibition effect assay and confocal laser scanning microscopy (CLSM) analysis. The cellular uptake with high transfection efficiency seemed to involve both endocytosis and membrane fusion. The ligand sito-G was confirmed to be able to enhance ASGPR-mediated endocytosis, the nonionic surfactant Brij 35 seemed to be able to facilitate membrane fusion, and the co-modification resulted in the most efficient transfection but no enhanced cytotoxicity. These results suggested that the co-modified liver-targeting cationic liposomes would be a specific and effective carrier to transfer asODN into hepatocytes infected with HBV orientedly.

Effect of Amphiphilic Drugs on the Stability and Zeta-Potential of Their Liposome Formulations: A Study with Prednisolone, Diazepam, and Griseofulvin

Multilamellar liposomes consisting of phosphatidylcholine and incorporating prednisolone (PZ), diazepam (DZ), or griseofulvin (GF) were prepared and characterized. Liposome size, surface charge, and stability (in buffer and serum proteins) were measured for drug-incorporating liposomes and empty liposomes for comparison. The results reveal that for all drugs studied drug incorporation has a substantial effect on the vesicle zeta-potential and stability. Drug-incorporating liposomes have a negative surface charge, while their membrane integrity is significantly higher when compared with that of empty liposomes. Release of DZ from liposomes is induced by dilution. Summarizing, the results of this study demonstrate that the presence of PZ, DZ, or GF in liposome membranes has a significant effect on main vesicle properties and correlates well with those obtained previously for hydrochlorothiazide and chlorothiazide. Thereby, we may conclude that the previously demonstrated effects of the thiazides on liposome properties are not solely related to their structure.