Cytotoxicity of gemcitabine-loaded thermosensitive liposomes in pancreatic cancer cell lines

Gemcitabine (GEM) is currently the standard option for the treatment of pancreatic cancer but its short half-life and rapid metabolism has caused for new modality for delivery of GEM. The purpose of this study was to formulate GEM loaded PEGylated thermosensitive liposomal nanoparticles (GEM-TSLnps) to increase residence time and deliver high payload of GEM to pancreatic cancer cells using mild hyperthermia (mHT). The GEM-TSLnps were formulated by thin film hydration. The cytotoxic effects of GEM and GEM-TSLnps were evaluated against human pancreatic cancer cell lines. In vitro release of GEM by TSLnps was determined at temperatures from 26°C through to 50°C. Cell viability studies, clonogenic assay, flow cytometry and confocal imaging were performed on pancreatic cancer cell lines using GEM and GEM-TSLnps + mHT. The GEM-TSLnp size was determined to be 216.10 ± 0.57 nm with entrapment efficiency of 41.10 ± 2.0%. GEM release from TSLnps was sharply increased at 42°C (60%) than at 37°C (25%), (p<0.01). In vitro cytotoxicity of GEM-TSLnps + mHT treated pancreatic cancer cell lines was significantly higher than GEM treated. The IC50 values for PANC-1, MiaPaCa-2 and BxPC-3 cells GEM-TSLnps + mHT treated were 1.2 to 3.5 fold-higher than GEM treated. Among the cell lines, GEM-TSLnps + mHT treated PANC-1 and MiaPaCa-2 cells show significantly reduced reproductive viability compared with the GEM treated cells. Flow cytometric and confocal images revealed high Rho-TSLnps cellular uptake. Our findings suggest that GEMTSLnps+ mHT can significantly enhance cytotoxic effect of GEM and could serve as a new chemotherapy modality for delivering GEM.