A Liposomal Platform Using a Microfluidic Mixing Method for Drug Delivery and Targeting of Metastatic Prostate Cancer

Abstract

Purpose: The success rate for the treatment of localized prostate cancer (PCa) is very high. However, the overall survival rate for patients with metastatic PCa drops to 28%. Bone is the primary metastatic site in 90% of PCa patients, which not only shortens survival, but also causes a significant decrease in the quality of life. The objective of the project is to develop a dual-targeted nanotherapeutic for bone metastatic PCa. We will engineer liposomes composed of two lipids, DOPE and DOTAP. A bone-targeting moiety with a high affinity to the Ca2+ in bone will be conjugated to the outside of the liposome. This liposome will be loaded with a cabazitaxel-ligand conjugate that has a high affinity for the receptors that are upregulated in 95% of PCa cells. Methods: In this formulation we have used a lipid ratio between 40% and 60%. Then the size and polydispersity were optimized by selecting the best Flow Ratio (FR) and Total Flow Rate (TFR) settings in the NanoAssemblr. We also measured the zeta potential (ZP). Cellular uptake studies were performed using the PC3 cell line and DID dye-loaded, DOPE-DOTAP liposomes, then imaged with a Zeiss LSM 510 confocal microscope. Additionally, liposomes were loaded with curcumin to determine their % drug loading (DL) and encapsulation efficiency (EE). Results: The liposomes were optimized with a 50:50 mol% ratio, a 1:1 FR, and a 6 ml/min TFR. Size (~150 nm) and polydispersity index (0.2), were measured and found to be consistent over a 7-day period to show stability. The ZP (~+40 mV) was also measured. The cellular uptake studies showed that the liposomes were increasingly taken up by the cells over time. The EE was ~93% and DL was ~5%. Conclusion: By finding a desirable ratio of lipids, FR and TFR, we have optimized our liposomal formulation based on size, PDI, and ZP. Also, we have demonstrated that our liposome can easily be taken up by cancer cells and have shown excellent DL and EE. As a result, we are prepared to continue with the next steps of the project. In the next step we will attach the bone-targeting moiety to the liposome, conjugate cabazitaxel with the targeting ligand, and load the liposomes with the cabazitaxel-ligand. Fully functional liposomes will be tested for in vitro and in vivo functionality.