Am. Panico et al., LIPID VESICLES LOADED WITH THYMOPENTIN - CHARACTERIZATION AND IN-VITRO ACTIVITY ON TUMORAL CELLS, International journal of pharmaceutics, 98(1-3), 1993, pp. 19-28
The cytotoxic activity on tumoral cells of thymopentin (TP5), a synthe
tic pentapeptide corresponding to residues 32-36 of thymopoietin, was
evaluated after inclusion in multilamellar liposomes. These were made
by all neutral (zwitterionic) phospholipids as well as those containin
g positively (stearylamine, SA) OT negatively charged (DPPS) lipids. V
esicles were also prepared containing cholesterol, and were characteri
zed by tight scattering dimensional analysis and differential scanning
calorimetry. The effect of charged species and of the presence of cho
lesterol on TP5 incorporation was studied. For the different kinds of
liposomes, loaded with sodium fluoresceinate, the rate of interaction
after incubation with lymphocytes in a normal or tumoral (IM9 lymphobl
astoid cells) state was also evaluated. TP5-loaded vesicles were assay
ed on two tines of tumoral cells (IM9 and K562) to assess the ability
of liposomal carriers to potentiate the cell growth inhibitory activit
y of the drug. SA-containing positive liposomes appeared as the most e
fficacious, resulting in 87% inhibition on IM9 cells, with an amount o
f liposomes containing 100 ng of TP5.