Intracellular delivery of liposome-encapsulated prolidase in cultured fibroblasts from prolidase-deficient patients

Prolidase is a cytosolic exopeptidase whose deficiency causes the development of a rare autosomal recessive disorder known
as Prolidase Deficiency (PD). The main manifestations of PD are intractable ulcerations of the skin, recurrent infections and
mental retardation. At this time only a hazardous and expensive chronic therapy based on blood transfusions is the suggested
treatment for PD. The aim of this work was to investigate the capability of utilizing liposomes as enzyme carriers: these
vesicular systems have been recently evaluated as protein carriers for their potential in terms of bin vivoQ localization, drug
release and for protein stabilization in biological fluids.
Liposomes were prepared, with a 1:1 PC:Col molar ratio with or without DSPE-PEG, by a thin-film hydration. Ex-vivo
experiments were performed, incubating prolidase loaded liposomes with cultured fibroblasts from PD patients and from
controls, to determine the amount of active enzyme delivered to cells. Evaluation of liposomes toxicity on cultured skin
fibroblasts showed that liposomes did not interfer with cellular growth. Results showed that all the active prolidase encapsulated
in the liposomes was completely vehiculated inside fibroblasts after 6 days incubation. SEM analysis suggests that prolidase is
vehiculated inside the cell through liposome endocytosis.