In vitro evaluation of the activity of gemcitabine-loaded pegylated unilamellar liposomes against papillary thyroid cancer cells.

Papillary carcinoma is the most common form of malignant thyroid tumor. At present, a subset of these tumors are poorly responsive to the current treatment. Gemcitabine is a pyrimidine analog active against different types of solid tumors, but its use is limited by its short half-life. To improve the therapeutic effectiveness of this drug, gemcitabine-loaded unilamellar pegylated liposomes were prepared and investigated against two human papillary thyroid carcinoma cell lines, i.e. TPC-1 and B-CPAP cells. The pH gradient drug encapsulation followed by the membrane extrusion technique were used to achieve unilamellar liposomes characterized by a mean size of ~200 nm, a polydispersity index of 0.02 and a zeta potential of -1.7 mV. The gemcitabine was released from liposomes following a biphasic profile. The liposomal encapsulated gemcitabine showed an increased cytotoxic activity compared to the free drug against both thyroid carcinoma cell lines, as a consequence of the better drug internalization favored by the vesicular device. These findings demonstrate the advantage of channeling gemcitabine by liposomes suggesting a promising role for such a pharmaceutical formulation in the treatment of refractory papillary thyroid carcinoma.