To Investigate The Effects Of Different Species Of Polymer Nanoparticles And PLVAP On Tumor Tissue Accumulation

Nanotechnology has the potential to break the shackles of cancer treatment by delivering drugs to tumors more safely and effectively.Although nanodrug delivery systems are gradually overcoming the side effects of conventional chemotherapeutic drugs,their therapeutic effectiveness is still limited due to the limitations of solid tumor accumulation.The most widely used tumor-targeting strategy to solve this problem is the enhanced permeability and retention（EPR）effect based on tumor vascular endothelial permeability,shows that nanoparticles do not accumulate mainly through intercellular space.Instead,it is mediated by active transport cross-cellular structures including caveolae,fenestrations,and transendothelial channels,all of which contain a crucial structural and functional unit,Plasmalemmal vesicle-associated protein-1（PLVAP）.Endothelium-specific PLVAP is not only a major component of these transcellular membrane diaphragms,but it is also widely and highly expressed in solid tumor-associated endothelial cells,such as breast endothelial cells.In addition,although the study of PLVAP as a novel cancer therapeutic target is still in progress,the effectiveness of PLVAP as a marker of the tumor vascular endothelium has been demonstrated.Objective: The tumor tissue marker protein PLVAP was used to explore the effect of different nanoparticles on tumor tissue accumulation as a futural treatment aim.Molecular dynamics simulation was used to analyze the interactions between PLVAP and different nanoparticles at the microscopic level.Chitosan（CTS）and its derivatives,polylactic acid（PLA）and Poly（lactic-co-glycolic acid）（PLGA）,which are common drug delivery carriers in the biomedical field,were used to investigate the species of nanoparticles that are more conducive to the effective accumulation of tumor tissues through the transendothelial pathway mediated by PLVAP.Methods:（1）CTS and chitosan quaternary ammonium salt（HACC）nanoparticles were prepared via ionic crosslinking.PLA and PLGA nanoparticles were synthesized through emulsion-solvent evaporation.（2）The parameters of root-mean-square deviation,root-mean-square fluctuation,and conformational derivation of PLVAP and four kinds of nanoparticles were calculated in the molecular dynamics simulation phase,through which predicted the binding status of the system and the changes after binding,and the transport of PLVAP-mediated nanoparticles in tumor tissues was preliminarily measured.（3）The human breast cancer cell line MCF-7 was used to establish a tumor model,and the intratumoral transport and ultrastructure distribution of nanoparticles were observed by transmission electron microscope.The effect of nanoparticles entering tumor tissue through transendothelial pathway was determined by the endocytosis transport of nanoparticles through the interaction with tumor vascular endothelial cells.The intratumoral distribution of nanoparticles,combined with qualitative and quantitative analysis was observed by fluorescence microscope,to indirectly determine the entry of nanoparticles into the tumor through the PLVAPmediated transendothelial pathway.Two imaging analysis were used to demonstrate the PLVAP-mediated transendothelial entry of nanoparticles into tumors from different perspectives.Results: CTS was the least distributed in tumor tissues,accounting for 3.41±0.04%of fluorescence.PLA was the most widely distributed,accounting for 29.34±4.00%（P<0.05,vs.HACC;P<0.01,vs.CTS）,and the distribution was approximately 8.6 times that of CTS.The fluorescence ratio of PLGA in tumor tissue was 15.65±1.24%（P<0.05,vs.HACC and CTS）,approximately 6.2 times that of CTS distribution.The fluorescence ratio of HACC was 12.15±4.39%,approximately 2.5 times that of CTS distribution.Conclusions: Compared with CTS and HACC nanoparticles,PLA and PLGA nanoparticles are more suitable to be accumulated in tumors via the PLVAP-mediated transendothelial pathway.Due to there being minority studies on PLVAP to evaluate the accumulation of different nanoparticles in tumor tissues,molecular dynamics simulation was combined with two imaging analysis methods for tumor models to explore the research framework for EPR effects and efficient accumulation to tumor sites through PLVAP-mediated transcellular pathways.It is of vital significance to advise the preparation and delivery of nanomaterials in the future.