Jitkasem Meewan. Effect of pegylation on the delivery of phospholipid-based liposomes into caco-2 cell. Master's Degree(Pharmaceutical Technology). Chulalongkorn University. Office of Academic Resources. : Chulalongkorn University, 2012.
Effect of pegylation on the delivery of phospholipid-based liposomes into caco-2 cell
Abstract:
This study was aimed to investigate the effects of PEGylation on cellular uptake of phospholipid-based liposomes into Caco-2 cells. The influence of liposome surface charge was also studied. The major mechanism in the delivery of PEGylated liposomes into Caco-2 cells was verified. Calcein and calcein acetoxymethyl ester (calcein AM) were used as models for hydrophilic compounds and lipophilic P-gp substrates, respectively. Calcein and calcein AM-loaded liposomes were prepared by either the film hydration or the dehydration-rehydration method, followed by size reduction to approximately 100 nm. The uptake of liposomes by Caco-2 cells was compared among liposomes with various compositions and with the solutions. The calcein uptake study showed that all types of conventional liposomes could enhance calcein uptake into Caco-2 cells. The calcein uptake from PEGylated liposomes was less efficient than that from conventional liposomes in all cases. Among the PEGylated liposomes, only those with positive surface charge showed better uptake efficiency than that of the calcein solution. For calcein AM, conventional neutral, PEG neutral, and PEG positively charged liposomes were successful in enhancing the uptake of the P-gp substrate by Caco-2 cells. PEGylation did not result in any changes in calcein AM uptake for both neutral and negatively charged liposomes. However, PEGylation markedly increased calcein AM uptake in positively charged liposomes. Furthermore, the use of fluorescence dequenching technique indicated that the major mechanism of PEGylated liposome uptake was likely to be endocytosis, similar to that of the conventional liposomes. This study indicated that liposome compositions including surface charge and PEGylation as well as the properties of the liposome contents would influence liposome-cell interaction, leading to the difference in liposome uptake. The overall results also indicated that PEGylated liposomes with the right composition could improve the delivery of hydrophilic compounds and lipophilic P-gp substrates into Caco-2 cells.