Anti-tumour and immuno-modulation effects of triptolide-loaded polymeric micelles

Triptolide (TP) possesses both anti-tumour and immuno-suppressive activities. Its immuno-suppressive activity may be disadvantageous for the therapy of cancers. A novel polymeric micelle system containing TP (TP-PM) was constructed by the solvent evaporation method using methoxypolyethylene glycol-poly(d,l-lactic acid)-block copolymer as the carrier, and was characterised using photon correlation spectroscopy, transmission electron microscopy and high performance liquid chromatography. The anti-tumour and immuno-modulation effects of TP-PM were evaluated in sarcoma 180-bearing mice and A2780 cells. Results demonstrated that TP-PM had an average diameter of 78.9 nm, encapsulation efficiency of 66.7%, core-shell morphology and a long-term stability. TP-PM could significantly inhibit tumour growth via intravenous injections at the dose levels of 0.0375, 0.075 and 0.15 mg/kg, and their inhibition rates were 42.5%, 46.0% and 49.9%, respectively; they showed similar cytotoxicity against A2780 cells compared to that of TP. Simultaneously, TP-PM had no effect on the thymus index, spleen index, spleen lymphocyte proliferation and the TNF-alpha and IL-2 levels in serum as compared with TP. Therefore, TP encapsulated in polymeric micelles does not demonstrate immuno-suppressive activity but does not lose its anti-tumour effect. These results show that polymeric micelles are a promising carrier for cancer therapy using TP.