Construction And Antitumor Applications Of Biomimetic Camptothecin Crystal Pharmaceuticals

The insolubility of camptothecin and its derivatives has limited their wide applications in clinic.In order to enhance their water solubility,researchers have developed many camptothecin-based formulations,such as prodrug,liposome,micelle,polymer nanoparticles,but these formulations generally have showed low drug loading efficiency,poor tumor targeting and serious side effects.To solve these problems,this thesis designed and constructed two biomimetic hydroxycamptothecin nanocrystalline drug delivery systems using natural tumor cell membrane and erythrocyte cell membrane as carriers for of malignant tumor treatment.The main contents of this thesis are as follows1.Tumor cell membrane-based hydrocamptothecin nanocrystals were constructed and their specific tumor targeting and tumor killing effects at the cellular level were systematically evaluated.First,hydrocamptothecin nanocrystals(NCs)were prepared through the soft template induced method.Based on that,photosensitizer Indocyanine green(ICG)was absorbed to the prepared nanocrystals through intermolecular interactions.Then,cancer cell membrane fragments(CM)were decorated by physical extrusion to obtain cancer cell membrane coated and ICG loaded hydrocamptothecin nanocrystals(NCs/ICG/CM).Compared with other HCPT formulations,greater amount of HCPT uptake in 4T1 cells was achieved in NCs/ICG/CM group with the assistance of homologous targeting.In addition,NCs/ICG/CM could produce hyperthermia effect under laser irradiation,which induced the quick release of HCPT molecules from nanocrystals.Finally,under the combined chemo-photothermal effects,NCs/ICG/CM could trigger ideal tumor cell killing effect2.Two triple-negative breast cancer mouse models were constructed,and the antitumor and side effects of NCs/ICG/CM were comprehensively evaluated Compared with nanocrystal alone,NC/ICG/CM could significantly extend the in vivo circulation time of drug,effectively increase the intratumor HCPT concentration due to active targeting,and obviously improve the temperature of the tumors upon near infrared laser irradiation.With these advantages,NC/ICG/CM exhibited more effective tumor suppression and metastasis prevention,and greatly prolonged the survival time of mice.Besides,NCs/ICG/CM could significantly reduce side effects,such as tissue toxicity and blood toxicity,showing good biosafety3.A hydrocamptothecin nanocrystal-embedded erythrocyte vesicle system was constructed and systematically evaluated at 2D and 3D cell levels.First,HCPT sodium salt solution was loaded into RBC vesicles in the low osmotic pressure.Subsequently,by virtue of the'dissolve in alkaline solution and precipitate in acidic solution'property of HCPT,HCPT was crystallized in a confined way using RBC as a micro-reactor after injecting CO2,and finally hydrocamptothecin nanocrystal-embedded erythrocyte vesicle(RBC@HCPT)was obtained.The results showed that at the 2D cell level,RBC@HCPT could evade the clearance of macrophages,performing a good stealth effect.Meanwhile,for RBC@HCPT,HCPT uptake in 4T1 cells was significantly increased,and tumor cell inhibition was greatly improved.At 3D cell level,RBC@HCPT showed an extremely strong penetration ability of tumor cell spheroids and had a significant inhibitory effect on their proliferation and growth4.The in vivo distribution,antitumor and side effects of RBC@HCPT were investigated by mouse tumor models.Compared with the commercial formulation HCPT-Na,RBC@HCPT showed longer circulation time in vivo and more drug accumulation at tumor sites.Then,it achieved a better therapeutic effect and also extended the survival time of mice in three tumor-bearing mouse model(including 4T1 breast tumor model,orthotopic liver tumor model and patient-derived tumor xenografts model).RBC@HCPT could also inhibit lung and bone metastasis in 4T1 breast tumor model.In addition,RBC@HCPT was superior to HCPT-Na group in terms of tissue toxicity,blood toxicity and comprehensive toxicity,exhibiting low level of side effectsIn summary,this thesis selected HCPT as the model drug to construct two biomimetic camptothecin nanocrystal systems,which specifically solved the problems of low water solubility,poor targeting and serious toxicity and side effects of traditional camptothecin formulations and provided a new idea for the development of new camptothecin nano-formulations in the future.