Preparation and in vitro evaluation of platelet membrane biomimetic liposomes loaded with vincristine sulfate

[Objective] To prepare platelet membrane biomimetic liposomes loaded with vincristine sulfate (VCR) for targeted delivery to tumor. [Methods] Vincristine sulfate liposomes (LIPO) were prepared using the pH-gradient method, followed by the fusion of platelet membranes and subsequent drug loading to obtain platelet membrane biomimetic liposomes (PLM-LIPO). The particle size, polydispersity index (PDI), Zeta potential, and drug encapsulation efficiency (EE%) of both liposomes were characterized. The tumor-targeting capability was evaluated through in vitro cellular experiments and in vivo biodistribution studies. [Results] The optimal preparation conditions for LIPO were determined as follows: DPPC-to-cholesterol molar ratio of 1∶1, internal aqueous phase of 0.3 M pH 4.0 citrate buffer, external aqueous phase of 1 M Na2HPO4 solution, drug-to-lipid ratio of 1∶10, drug loading temperature of 60℃, and loading time of 10 minutes. The LIPO exhibited a mean particle size of (147.3±2.24) nm, PDI of 0.078±0.014, Zeta potential of (-3.54±0.75) mV, and EE% of 91.37±0.47. For PLM-LIPO, prepared via membrane fusion followed by drug loading, the mean particle size was (185.3±3.61) nm, PDI was 0.075±0.022, Zeta potential was (-18.91±1.54) mV, and EE% was 63.36±2.45. In the CD62P validation experiment, the fluorescence intensity of PLM-LIPO was five times higher than that of LIPO. In vitro cellular uptake experiments revealed that PLM-LIPO showed 1.3-fold and 1.2-fold higher uptake rates compared to LIPO at 6 h and 12 h, respectively. In vivo experiments demonstrated that 1h after administration, the accumulation of PLM-LIPO at tumor sites was 4-fold higher than that of LIPO and 6-7 times higher than that in healthy mice. [Conclusion] The platelet membrane biomimetic liposomes loaded with vincristine sulfate were successfully developed. Both cellular uptake and tissue distribution studies confirmed the PLM-LIPO enhanced tumor-targeting capability.