Lipid Nanoparticle-based Co-delivery Of SiRNA And EPI For Enhanced Long-circulation And Reversing Multidrug Resistance

In the treatment of cancer,multidrug resistance is the main obstacle in the process of chemotherapy,which can reduce the accumulation of intracellular drug or enhance repair mechanisms of tumor cell DNA damage,leading to the decrease of the efficiency of single drug treatment of tumor.Gene drugs can inhibit the occurrence of multidrug resistance,but the delivery process is faced with many difficulties.The co-delivery of gene drugs and chemotherapeutic drugs has become a new strategy for the treatment of cancer.In the treatment,the key is to select the appropriate vector to co-deliver gene drugs and chemotherapeutic drugs to the tumor tissue,so as to exert the efficacy.We prepared and evaluated a p H-sensitive,reverse multidrug resistance and long-circulation multifunctional envelope type nano carrier（Multifunction Envelop-type Nano Device,MEND）for the co-delivery of si RNA and epirubicin（EPI）.MEND is an envelope type shell of nano microspheres with the advantages of both nano particles and liposomes,which encapsulated by liposome containing a functional ligand,the compressed DNA,si RNA and so on as the core.Polyethylene glycol（PEG）connected to the Distearoyl Phosphoethanolamine（DSPE）,forming a copolymer DSPE-PEG to achieve the long-circulation.Ketal containing poly（amino ester）（KPAE）with acid-sensitive properties,which is used for condensation of si RNA,can realize the intelligent release of si RNA in cells.Each component was identified by 1H NMR;the molecular weight of KPAE was determined by gel permeation chromatography;EPI was wrapped in the hydrophobic end of the phospholipid bilayer of the liposome membrane,and after the hydration by the KPAE/si RNA nanocomplexes solution,EPI/si RNA-MEND was obtained.The morphology and structure were observed by transmission electron microscope（TEM）;the particle size and potential were measured by Malvern Zetasizer Nano instrument;The entrapment efficiency of EPI and si RNA were determined by membrane filtration method and ultrafiltration centrifugation,respectively;MTT method was used to investigate the cytotoxicity of EPI/si BCL-2-MEND with Hep G₂ cells.The transfection efficiency of EPI/Cy5-si RNA-MEND to Hep G₂ cells was investigated by fluorescence labeling and flow cytometry;BCL-2 si RNA was chosen to investigate expression level of P-glycoprotein（P-gp）,it can reverse the occurrence of multidrug resistance in tumor cells,and it can be coordinated epirubicin in the treatment of tumor.Living animal imaging system was used to observe the in vivo distribution of MEND.The results showed that EPI/si RNA-MEND is spherical and has obvious lipid bimolecular layer structure with the fingerprint structure,which the average particle size is 121.6 nm and the average potential is + 41.5 m V;the encapsulation efficiency of EPI and si RNA are 86.13% and 97.07%,respectively.In the same concentration,the inhibition effect of EPI/si BCL-2-MEND is higher than that of individual drugs,and has high transfection efficiency.Western blot experiment indicated co-delivery of EPI/si BCL-2-MEND can significantly down-regulate the expression of P-gp,while free EPI and EPI-loaded liposomes up-regulated it.EPI/Cy5-si RNA-MEND is more likely to be concentrated in the liver than the individual drugs and has the characteristic of long-circulation.