Abstract
Triptolide (TP) is an epoxy diterpene lactone compound isolated and purified from the traditional Chinese medicinal plant Tripterygium wilfordii Hook. f., which has been shown to inhibit the proliferation of hepatocellular carcinoma. However, due to problems with solubility, bioavailability, and adverse effects, the use and effectiveness of the drug are limited. In this study, a transferrin-modified TP liposome (TF-TP@LIP) was constructed for the delivery of TP. The thin-film hydration method was used to prepare TF-TP@LIP. The physicochemical properties, drug loading, particle size, polydispersity coefficient, and zeta potential of the liposomes were examined. The inhibitory effects of TF-TP@LIP on tumor cells in vitro were assessed using the HepG2 cell line. The biodistribution of TF-TP@LIP and its anti-tumor effects were investigated in tumor-bearing nude mice. The results showed that TF-TP@LIP was spherical, had a particle size of 130.33 ± 1.89 nm and zeta potential of -23.20 ± 0.90 mV, and was electronegative. Encapsulation and drug loading were 85.33 ± 0.41% and 9.96 ± 0.21%, respectively. The preparation was stable in serum over 24 h and showed biocompatibility and slow release of the drug. Flow cytometry and fluorescence microscopy showed that uptake of TF-TP@LIP was significantly higher than that of TP@LIP (p < 0.05), while MTT assays indicated mean median inhibition concentrations (IC50) of TP, TP@LIP, and TF-TP@ of 90.6 nM, 56.1 nM, and 42.3 nM, respectively, in HepG2 cell treated for 48 h. Real-time fluorescence imaging indicated a significant accumulation of DiR-labeled TF-TP@LIPs at tumor sites in nude mice, in contrast to DiR-only or DiR-labeled, indicating that modification with transferrin enhanced drug targeting to the tumor tissues. Compared with the TP and TP@LIP groups, the TF-TP@LIP group had a significant inhibitory effect on tumor growth. H&E staining results showed that TF-TP@LIP inhibited tumor growth and did not induce any significant pathological changes in the heart, liver, spleen, and kidneys of nude mice, with all liver and kidney indices within the normal range, with no significant differences compared with the control group, indicating the safety of the preparation. The findings indicated that modification by transferrin significantly enhanced the tumor-targeting ability of the liposomes and improved their anti-tumor effects in vivo. Reducing its distribution in normal tissues and decreasing its toxic effects suggest that the potential of TF-TP@LIP warrants further investigation for its clinical application.