Construction Of Targeted Drug Delivery System For High-risk Myelodysplastic Syndrome And The Research Of Its Mechanism In Vivo

OBJECTIVE:Myelodysplastic syndrome(MDS)is a heterogeneous bone marrow disease characterized by dysplasia and ineffective hematopoietic function.Chemotherapy is still the main treatment for high-risk MDS,but its remission rate is low and the prognosis is poor.At present,there is no targeted therapy for myelodysplastic syndrome(MDS).Many researches reported high expression of CD123 antigen on high-risk MDS cells,so we constructed a new drug delivery system of DNR-CdTe-CD123 by using CD123 antigen as target and polyethylene glycol(PEG)modified CdTe quantum dots as carrier carrying daunorubicin(DNR)and evaluated the therapeutic effect and toxicity in vivo.METHODS:The antiCD123 antibody was ligated with a polyethylene glycol-modified CdTe quantum dot using an amide bond,and then CdTe-CD123 constituted a DNR-CdTeCD123 targeting drug-loading system by electrostatically binding DNR.High-risk MDS tumor-bearing nude mice model was established using MUTZ-1 celIs(MDSRAEB transforming to AML cell line)and divided into Control,anti-CD123 mAb,CdTe,DNR,DNR-CdTe and DNR-CdTe-CD123 treatment groups to monitor the changes of tumor volume and body weight.In vivo imaging technology was used to evaluate the anti-tumor activity of DNR-CdTe-CD123 in vivo,fluorescence spectrophotometry was used to detect the tissue distribution of DNR in tumor-bearing mice.Hematoxylin–eosin(HE)staining was used to observe the histopathological changes of tumor tissues and important organs(heart,liver,spleen,lung and kidney)in nude mice of each treatment group.Immunofluorescence was used to detect the expression levels of P53,Bax,cleaved caspase-3 and cleaved caspase-9 protein in nude mice.RESULTS:(1)When the concentration of DNR was 0.2 mg/ml,the drug loading rate of DNR was 43.05±0.59% and the encapsulation efficiency was 74.32±1.59% in DNR-CdTeCD123 drug delivery system.(2)The tumor volume of DNR,DNR-CdTe,DNR-CdTe-CD123 group was significantly lower than that of Control group(P<0.05),and the tumor volume of DNRCdTe-CD123 group was the smallest at the end of treatment.(3)After 24 hours of treatment with DNR,DNR-CdTe,DNR-CdTe-CD123,in vivo imaging system detected the fluorescence intensity of DNR in tumor tissues of mice treated with DNR-CdTe-CD123 was obviously increased,which was significantly higher than that of mice treated with DNR and DNR-CdTe.(4)DNR concentration in heart tissue of mice treated with DNR-CdTe-CD123 was significantly lower than that of mice treated with free DNR(P<0.05),and DNR concentration in tumor tissue of mice treated with DNR-CdTe-CD123 was significantly higher than that of mice treated with free DNR(P<0.05).(5)HE staining to observe histopathological changes of tumors and important organs1)In DNR-CdTe-CD123 group,apoptotic morphology in tumor cells such as nuclear pyknosis and nuclear fragmentation increased.2)Typical DNR-induced myocardial damage was observed in DNR-treated mice.No significant histomorphological changes were observed in the heart,liver,spleen,lung and kidney of mice in the other groups.(6)The body weight of the mice treated with free DNR continued to decrease,and decreased to the lowest value on the 12 th day(18.17±0.26 g),which was significantly lower than that of the other groups(P<0.05),but the body weight of the DNR-CdTeCD123 group was not significantly different from that of the Control group.(7)Immunofluorescence staining showed that the green fluorescence intensity of P53,Cleaved-caspase 9,Bax and Cleaved-caspase3 gradually increased in the tumor tissues of DNR,DNR-CdTe and DNR-CdTe-CD123 groups.CONCLUSION:DNR-CdTe-CD123 targeting drug delivery system can effectively promote DNR to inhibit the tumor growth of MDS-bearing nude mice,reduce the side effects of DNR on myocardial cells,and up-regulate the expression of P53,Cleaved-caspase 9,Bax,Cleaved-caspase 3 protein in tumor tissues.