Anti-glioblastoma efficacy and safety of paclitaxel-loading Angiopep-conjugated dual targeting PEG-PCL nanoparticles
Introduction
At present, glioblastoma multiforme (GBM) is the most frequent primary central nervous system tumor in human. Although the advances in other solid tumor therapy have improved the survival of patients, GBM prognosis is still poor, with a 14-month median survival time despite interventions [1]. Because GBM is different from other cancers by its diffuse invasion of the surrounding normal brain tissue, it is impossible to make the complete removal of glioma by conventional surgery and the chances of glioma recurrence from residual tumors are very high [2]. Therefore, chemotherapy is indispensable for glioma treatment after the surgery [3]. Unfortunately, the GMB treatment by chemotherapy is very limited due to the rare blood brain barrier (BBB) penetration and poor glioma targeting of the chemotherapeutics [4]. Although compromised endothelial barrier which facilitates molecular transport under glioma condition exists [5], [6], BBB still plays important role in the infiltrating margin of glioma and should be considered for glioma treatment and diagnosis [7]. Paclitaxel (PTX) is a new class of microtubule stabilizing agents with perfect anti-glioma activity [8], [9]. However, the activity of commercial PTX preparation against glioblastoma has been disappointing in clinical study because of drug-resistance and poor penetration across the BBB [10], [11]. Accordingly, it is impending to develop a targeted drug delivery system with high BBB penetration and glioma targeting abilities.
To overcome BBB and blood tumor barrier (BTB) [12], [13], dual targeting drug delivery systems based on receptor-mediated endocytosis were developed to deliver chemotherapeutic agent across BBB and simultaneously target brain tumor [14]. The most common dual targeting strategy is based on modification of nanocarriers with two kinds of ligands, one of which can target to BBB, the other can target to glioma cancerous cells [15], [16]. It has been reported that low density lipoprotein receptor related protein (LRP) is not only over-expressed on BBB but also on glioma cancerous cells. Thus, another dual targeting strategy was developed to decorate the surface of nanocarriers with one single ligand [17]. In our previous study, Angiopep-2, a specific ligand of LRP receptor, was used to modify poly(ethylene glycol)-co-poly(ε-caprolactone) (PEG-PCL) copolymer nanoparticles to develop a dual targeting drug delivery system (ANG-PEG-NP) for PTX delivery [17]. The glioma dual targeting strategy of PTX loading Angiopep-conjugated PEG-PCL nanoparticles (ANG-PEG-NP-PTX) was shown as Fig. 1, which denoted that Angiopep-2 mediated transcytosis of ANG-PEG-NP-PTX across BBB through LRP as grade І targeting, followed by endocytosis of ANG-PEG-NP-PTX via recognition of LRP on the surface of glioma cells as grade ІІ targeting. The in vitro and in vivo brain targeting mechanism [18] and enhancement of cytotoxicity to U87 MG glioma cells [17] of ANG-PEG-NP were also confirmed in our previous studies. However, there are still several challenges need to be addressed: firstly, since the solid tumor microenvironment which contains clusters of tumor cells, nonuniform leaky vasculature and a dense interstitial structure differs from in vitro cancerous cells by its structural heterogeneity [19], so can ANG-PEG-NP enhance the penetration, distribution, and accumulation of chemotherapeutic agent in the solid tumor in vivo? Secondly, what will be the difference between targeted and non-targeted nanoparticles in anti-glioblastoma efficacy assessment using intracranial glioma mice model? Thirdly, considering part of ANG-PEG-NP will accumulate in the brain parenchyma and other organ tissues, can this accumulation of dual targeting nanoparticles induce functional disorder and other toxicities?
In this study, we used ex vivo 3D glioma tumor spheroids and intracranial glioma mice model to evaluate the penetration, distribution, and accumulation of ANG-PEG-NP into brain tumor. The in vivo anti-glioblastoma efficacy of ANG-PEG-NP was investigated by intracranial glioma mice model as well. The safety of ANG-PEG-NP following intravenous injection was carried out using healthy mice.
Section snippets
Materials
Methoxyl poly(ethylene glycol)-co-poly(ε-caprolactone) copolymer (Me-PEG–PCL, 12 KDa) and Maleimidyl-poly(ethylene glycol)-co-poly(ε-caprolactone) copolymer (Maleimide-PEG-PCL, 14 KDa) were synthesized by the ring opening polymerization as described before [17]. Rhodamine B isothiocyanate (RBITC), Propidium Iodide (PI), MTT were purchased from Sigma (St. Louis, MO, USA). Low melting-point agarose was obtained from Yixin Biotechnology Co., Ltd. (Shanghai, China). Angiopep (TFFYGGSRGKRNNFKTEEYC)
Preparation and characterization of ANG-PEG-NP
In the process of nanoparticle fabrication, about 10% Me-PEG-PCL copolymer was replaced by Maleimide-PEG-PCL copolymer which can specifically react with the thiol group of Angiopep. The average particle size of ANG-PEG-NP was about 90 nm, which may accumulate more readily in tumor due to the Enhanced Permeability and Retention (EPR) effect [26], [27]. The PTX loading coefficient and encapsulation ratio of ANG-PEG-NP were about 7% and 86%, respectively. To trace the nanoparticles qualitatively,
Conclusion
We proposed ANG-PEG-NP as a dual targeting drug delivery system for glioma treatment. In this study, we evaluated the availability and safety of ANG-PEG-NP for glioma treatment. The penetration, distribution, and accumulation into 3D glioma tumor spheroid and in vivo glioma region of ANG-PEG-NP were much higher than those of plain PEG-NP. The anti-glioblastoma efficacy of ANG-PEG-NP was significantly enhanced in comparison with that of Taxol and PEG-NP. Preliminary safety tests showed no acute
Acknowledgments
The authors acknowledge Prof. Yalin, Huang, Institutes of Biomedical Sciences (IBS), Fudan University, China, for her great help with the use of confocal microscopy. We are grateful for the financial supports from the National Basic Research Program of China 973 program (2007CB935802); National Natural Science Foundation of China (30901862); National Science and Technology Major Project (2009ZX09310-006) and Science and Technology Development Foundation of Nanjing Medical University (2011NJMU271
References (35)
- et al.
Paclitaxel delivery from PLGA foams for controlled release in post-surgical chemotherapy against glioblastoma multiforme
Biomaterials
(2009) - et al.
Gene and doxorubicin co-delivery system for targeting therapy of glioma
Biomaterials
(2012) - et al.
Targeted delivery of liposomal nanocontainers to the peritumoral zone of glioma by means of monoclonal antibodies against GFAP and the extracellular loop of Cx43
Nanomedicine
(2012) - et al.
Cytotoxicity and apoptosis enhancement in brain tumor cells upon coadministration of paclitaxel and ceramide in nanoemulsion formulations
J Pharm Sci
(2008) - et al.
A phase ІІ study of paclitaxel in chemonaive patients with recurrent high-grade
Ann Oncol
(2000) - et al.
A dual-targeting nanocarrier based on poly(amidoamine) dendrimers conjugated with transferrin and tamoxifen for treating brain gliomas
Biomaterials
(2012) - et al.
Precise glioma targeting of and penetration by aptamer and peptide dual-functioned nanoparticles
Biomaterials
(2012) - et al.
Angiopep-conjugated poly(ethylene glycol)-co-poly(ε-caprolactone) nanoparticles as dual-targeted drug delivery system for brain glioma
Biomaterials
(2011) - et al.
The brain targeting mechanism of Angiopep-conjugated poly(ethylene glycol)-co-poly(ε-caprolactone) nanoparticles
Biomaterials
(2012) - et al.
Enhanced anti-glioblastoma efficacy by PTX-loaded PEGylated poly (ε-caprolactone) nanoparticles: in vitro and in vivo evaluation
Int J Pharm
(2010)