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 "in vivo" 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 interfere 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.