Bone-targeting nanoparticle to co-deliver decitabine and arsenic trioxide for effective therapy of myelodysplastic syndrome with low systemic toxicity

Abstract

Myelodysplastic syndromes (MDS) are a diverse group of bone marrow disorders and clonal hematopoietic stem cell disorders characterized by abnormal blood cells, or reduced peripheral blood cell count. Recent clinical studies on combination therapy of decitabine (DAC) and arsenic trioxide (ATO) have demonstrated synergy on MDS treatment, but the treatment can cause significant side effects to patients. In addition, both drugs have to be administered on a daily basis due to their short half-lives. In addressing key issues of reducing toxic side effects and improving pharmacokinetic profiles of the therapeutic agents, we have developed a new formulation by co-packaging DAC and ATO into alendronate-conjugated bone-targeting nanoparticles (BTNPs). Our pharmacokinetic studies revealed that intravenously administered BTNPs increased circulation time up to 3days. Biodistribution analysis showed that the BTNP facilitated DAC and ATO accumulation in the bone, which is 6.7 and 7.9 times more than untargeted NP. Finally, MDS mouse model treated with BTNPs showed better restoration of complete blood count to normal level, and significantly longer median survival as compared to free drugs or untargeted NPs treatment. Our results support bone-targeted co-delivery of DAC and ATO for effective treatment of MDS.

Keywords: Arsenic trioxide; Bone marrow; Decitabine; Delivery; Myelodysplastic syndrome; Nanoparticle.

Fig. 1

Design, preparation and characterization of bone-targeting nanoparticles (BTNPs). a, Schematic illustration of designed structure of BTNPs. b–d, Representative SEM, TEM and AFM image of BTNPs. e, Physiochemical characteristics of BTNPs. f–i, IVIS of whole-body mice to show BTNPs distribution compared with untargeted NPs, fluorescent control, and PBS (24-h time point, I.V. injection). j, Total fluorescence quantified in the region of interest of IVIS images from f–i.

Fig. 2

Cell growth inhibition and synergistic effects of BTNPs. a–c, Cell cytotoxicity were evaluated in MDS cells and WT cells. Data represent the mean ± SEM (n=5). d, Synergistic inhibitory effects of BTNPs was calculated based on IC50. Each CI score represents data from 7 different drug doses of single and paired-drug treatments with 5 biological replicates per condition.

Fig. 3

Apoptosis analysis of MDS cells induced by BTNPs. a, Representative CLSM images of apoptotic MDS cells after treatment with drugs at the concentration equivalent to ATO of 0.1 μg/mL. b–e, Flow cytometer analysis of apoptotic MDS cells treated with PBS, free dugs, untargeted NPs and BTNPs.

Fig. 4

Pharmacokinetics and biodistribution studies of BTNPs. a–b, Pharmacokinetic profiles of BTNPs after one dose in MDS model mouse. Data represent the mean ± SEM (n=4). c–d, Tissue biodistribution of BTNPs in MDS mouse after 12 hour of administration. Data represent the mean ± SEM (n=4).

Fig. 5

Therapeutic efficacy of BTNPs in MDS mouse model. a–c, Serial complete blood count measurements from MDS mice after treatment with DAC/ATO (Red line presents the threshold for normal WBC, PLT, and RBC count). Data represent the mean ± SEM (n=16). d, Survival curves showing progression to death in different treated group of mice. Data collected from 3 separate experiments. e–h, Representative peripheral blood smears from MDS mice after treatment.

Fig. 6

Inhibition of DNMT1 and apoptosis of MDS bone marrow cells (BM cells) after treatment with BTNPs. a. RT-PCR analysis of DNMT1 mRNA level in BM cells. b, Flow cytometer analysis of γH2AX expression in BM cells. c, Apoptosis percentage of BM cells after treatment. Data represent the mean ± SEM (n=5); d–g. Representative H&E staining show apoptotic liver cell from MDS mouse after treatment.