Doxorubicin-loaded PLGA nanoparticles for the chemotherapy of glioblastoma: Towards the pharmaceutical development.

Brain delivery of drugs by nanoparticles is a promising strategy that could open up new possibilities for the chemotherapy of brain tumors. As demonstrated in previous studies, the loading of doxorubicin in poly(lactide-co-glycolide) nanoparticles coated with poloxamer 188 (Dox-PLGA) enabled the brain delivery of this cytostatic that normally cannot penetrate across the blood-brain barrier in free form. The Dox-PLGA nanoparticles produced a very considerable anti-tumor effect against the intracranial 101.8 glioblastoma in rats, thus representing a promising candidate for the chemotherapy of brain tumors that warrants clinical evaluation. The objective of the present study, therefore, was the optimization of the Dox-PLGA formulation and the development of a pilot scale manufacturing process. Optimization of the preparation procedure involved the alteration of the technological parameters such as replacement of the particle stabilizer PVA 30-70 kDa with a presumably safer low molecular mass PVA 9-10 kDa as well as the modification of the external emulsion medium and the homogenization conditions. The optimized procedure enabled an increase of the encapsulation efficiency from 66% to >90% and reduction of the nanoparticle size from 250 nm to 110 nm thus enabling the sterilization by membrane filtration. The pilot scale process was characterized by an excellent reproducibility with very low inter-batch variations. The in vitro hematotoxicity of the nanoparticles was negligible at therapeutically relevant concentrations. The anti-tumor efficacy of the optimized formulation and the ability of the nanoparticles to penetrate into the intracranial tumor and normal brain tissue were confirmed by in vivo experiments.

Treatment of glioma by cisplatin-loaded nanogels conjugated with monoclonal antibodies against Cx43 and BSAT1.

Targeted drug delivery for brain tumor treatment is one of the important objectives in nanomedicine. Human glioblastoma is the most frequent and aggressive type of brain tumors. The preferential expression of membrane protein connexin 43 (Cx43) and brain-specific anion transporter (BSAT1) in the tumor and peritumoral area is a key component for targeted drug delivery. The purpose of this study was to design cisplatin-loaded nanogels conjugated with monoclonal antibodies to Cx43 and BSAT1 for treatment of intracranial gliomas 101/8. MRI volumetric analysis of tumor-bearing rats indicated significantly reduced tumor volume with cisplatin-loaded targeted-nanogel treatment compared to other formulations. The median survival of rats treated with targeted nanogels conjugated with specific mAbs against extracellular loops of Cx43 and BSAT1 were 27 and 26.6 days higher than that in control group, respectively. For the first time we demonstrated the efficiency of mAb-targeted cisplatin-loaded nanogels in the experimental model of glioma 101/8. This approach could facilitate the development of new drug delivery systems for the treatment of gliomas.

Treatment of glioblastoma with poly(isohexyl cyanoacrylate) nanoparticles.

Glioblastomas belong to the most devastating cancer diseases. For this reason, polysorbate 80 (Tween 80)-coated poly(isohexyl cyanoacrylate) (PIHCA) (Monorex) nanoparticles loaded with doxorubicin were developed and tested for their use for the treatment of glioblastomas. The preparation of the nanoparticles resulted in spherical particles with high doxorubicin loading. The physico-chemical properties and the release of doxorubicin from the PIHCA-nanoparticles were analysed, and the influence on cell viability of the rat glioblastoma 101/8-cell line was investigated. In vitro, the empty nanoparticles did not show any toxicity, and the anti-cancer effects of the drug-loaded nanoparticles were increased in comparison to doxorubicin solution, represented by IC(50) values. The in vivo efficacy was then tested in intracranially glioblastoma 101/8-bearing rats. Rats were treated with 3 × 1.5mg/kg doxorubicin and were sacrificed 18 days after tumour transplantation. Histological and immunohistochemical analyses were carried out to assess the efficacy of the nanoparticles. Tumour size, proliferation activity, vessel density, necrotic areas, and expression of glial fibrillary acidic protein demonstrated that doxorubicin-loaded PIHCA-nanoparticles were much more efficient than the free drug. The results suggest that poly(isohexyl cyanoacrylate) nanoparticles hold great promise for the non-invasive therapy of human glioblastomas.

Kinetics of transport of doxorubicin bound to nanoparticles across the blood-brain barrier.

Drug delivery to the brain is restricted due to the blood-brain barrier (BBB). Previously, it has been shown that surfactant-coated doxorubicin-loaded nanoparticles were successful in overcoming the BBB and were effective in the treatment of rat brain tumours. However, drug distribution in brain tissue after crossing the BBB was never determined. To distinguish between the amounts of drug in the whole brain and the fraction of drug in the brain parenchyma after crossing the BBB a capillary depletion technique was employed. For this purpose rats were intravenously treated with a doxorubicin solution in 1% polysorbate 80, or doxorubicin-loaded poly-(n-butyl cyanoacrylate) (PBCA) nanoparticles without and with 1% polysorbate 80 coating, respectively. The dosage of doxorubicin was 5 mg per kg of rat body weight. At 30 min, 2 h, and 4 h following intravenous injection into the tail vein, the rats were sacrificed and their brains removed. Homogenates of the brains were prepared. In addition, one part of the homogenate was separated by centrifugation into a pellet (vascular elements) and supernatant (parenchyma) using a well established capillary depletion technique. The time-dependent distribution of doxorubicin in these brain fractions was studied. Clinically effective concentrations in all investigated brain fractions could only be detected in rats treated with surfactant-coated nanoparticles, indicating a significant transcytosis across the BBB. Only low concentrations were observed after 0.5 and 2 h with the uncoated nanoparticles. No uptake of doxorubicin into the brain was observable after administration of drug solution alone. These observations demonstrate the great potential of surface-coated PBCA nanoparticles for the delivery of drugs to the central nervous system.

Efficient chemotherapy of rat glioblastoma using doxorubicin-loaded PLGA nanoparticles with different stabilizers.

BACKGROUND: Chemotherapy of glioblastoma is largely ineffective as the blood-brain barrier (BBB) prevents entry of most anticancer agents into the brain. For an efficient treatment of glioblastomas it is necessary to deliver anti-cancer drugs across the intact BBB. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles coated with poloxamer 188 hold great promise as drug carriers for brain delivery after their intravenous injection. In the present study the anti-tumour efficacy of the surfactant-coated doxorubicin-loaded PLGA nanoparticles against rat glioblastoma 101/8 was investigated using histological and immunohistochemical methods. METHODOLOGY: The particles were prepared by a high-pressure solvent evaporation technique using 1% polyvinylalcohol (PLGA/PVA) or human serum albumin (PLGA/HSA) as stabilizers. Additionally, lecithin-containing PLGA/HSA particles (Dox-Lecithin-PLGA/HSA) were prepared. For evaluation of the antitumour efficacy the glioblastoma-bearing rats were treated intravenously with the doxorubicin-loaded nanoparticles coated with poloxamer 188 using the following treatment regimen: 3 × 2.5 mg/kg on day 2, 5 and 8 after tumour implantation; doxorubicin and poloxamer 188 solutions were used as controls. On day 18, the rats were sacrificed and the antitumour effect was determined by measurement of tumour size, necrotic areas, proliferation index, and expression of GFAP and VEGF as well as Isolectin B4, a marker for the vessel density. CONCLUSION: The results reveal a considerable anti-tumour effect of the doxorubicin-loaded nanoparticles. The overall best results were observed for Dox-Lecithin-PLGA/HSA. These data demonstrate that the poloxamer 188-coated PLGA nanoparticles enable delivery of doxorubicin across the blood-brain barrier in the therapeutically effective concentrations.

Drug delivery to the brain using surfactant-coated poly(lactide-co-glycolide) nanoparticles: influence of the formulation parameters.

Poly(lactide-co-glycolide) (PLGA) nanoparticles coated with poloxamer 188 (Pluronic((R)) F-68) or polysorbate 80 (Tween((R)) 80) enable an efficient brain delivery of the drugs after intravenous injection. This ability was evidenced by two different pharmacological test systems employing as model drugs the anti-tumour antibiotic doxorubicin and the agonist of opioid receptors loperamide, which being P-gp substrates can cross the blood-brain barrier (BBB) only in pharmacologically insignificant amounts: binding of doxorubicin to the surfactant-coated PLGA nanoparticles, however, enabled a high anti-tumour effect against an intracranial 101/8 glioblastoma in rats, and the penetration of nanoparticle-bound loperamide into the brain was demonstrated by the induction of central analgesic effects in mice. Both pharmacological tests could demonstrate that therapeutic amounts of the drugs were delivered to the sites of action in the brain and showed the high efficiency of the surfactant-coated PLGA nanoparticles for brain delivery. The results of the study also demonstrated that the efficacy of brain delivery by nanoparticles not only is influenced by the coating surfactants but also by other formulation parameters such as core polymer, drug, and stabilizer.

Influence of surfactants, polymer and doxorubicin loading on the anti-tumour effect of poly(butyl cyanoacrylate) nanoparticles in a rat glioma model.

Poly(n-butyl cyanoacrylate) nanoparticles coated with polysorbate-80 can enable the transport of bound drugs across the blood-brain barrier (BBB) after i.v. injection. In the present study the influence of different formulation parameters on the anti-tumoural effects of doxorubicin nanoparticles against glioblastoma 101/8 was investigated. The manufacturing parameters of poly(alkyl cyanoacrylate) doxorubicin-loaded nanoparticles were optimized concerning drug loading. The nanoparticles were coated with different surfactants and injected intravenously on days 2, 5 and 8 after intra-cranial implantation of glioblastoma 101/8 to rats. The survival times of all doxorubicin containing preparations, including a doxorubicin solution, increased the survival times significantly compared to untreated tumour-bearing rats. The most pronounced increase in survival was obtained with the poly(n-butyl cyanoacrylate) doxorubicin-loaded nanoparticles coated with polysorbate 80 and 35% of these animals survived for over 180 days (termination of the experiments). The other nanoparticle preparations yielded lower survival times. Poly(n-butyl cyanoacrylate) doxorubicin-loaded nanoparticles coated with polysorbate 80-coated proved to be very efficient against glioblastoma 101/8. The data suggest that the interaction of nanoparticles with the blood after injection as well as the enhanced permeability and retention effect (EPR effect) contributed differently to the anti-tumoural efficacy depending on nanoparticle formulation and surface properties.

Biodistribution of polysorbate 80-coated doxorubicin-loaded [14C]-poly(butyl cyanoacrylate) nanoparticles after intravenous administration to glioblastoma-bearing rats.

It was recently shown that doxorubicin (DOX) bound to polysorbate-coated nanoparticles (NP) crossed the intact blood-brain barrier (BBB), and thus reached therapeutic concentrations in the brain. Here, we investigated the biodistribution in the brain and in the body of poly(butyl-2-cyano[3-(14)C]acrylate) NP ([(14)C]-PBCA NP), polysorbate 80 (PS 80)-coated [(14)C]-PBCA NP, DOX-loaded [(14)C]-PBCA NP in glioblastoma 101/8-bearing rats after i.v. injection. The biodistribution profiles and brain concentrations of radiolabeled NP were determined by radioactivity counting after i.v. administration in rats. Changes in BBB permeability after tumour inoculation were assessed by i.v. injection of Evans Blue solution. The accumulation of NP in the tumour site and in the contralateral hemisphere in glioblastoma bearing-rats probably was augmented by the enhanced permeability and retention effect (EPR effect) that may have been becoming instrumental due to the impaired BBB on the NP delivery into the brain. The uptake of the NP by the organs of the reticuloendothelial system (RES) was reduced after PS 80-coating, but the addition of DOX increased again the concentration of NP in the RES.

Chemotherapy of glioblastoma in rats using doxorubicin-loaded nanoparticles.

Glioblastomas belong to the most aggressive human cancers with short survival times. Due to the blood-brain barrier, they are mostly inaccessible to traditional chemotherapy. We have recently shown that doxorubicin bound to polysorbate-coated nanoparticles crossed the intact blood-brain barrier, thus reaching therapeutic concentrations in the brain. Here, we investigated the therapeutic potential of this formulation of doxorubicin in vivo using an animal model created by implantation of 101/8 glioblastoma tumor in rat brains. Groups of 5-8 glioblastoma-bearing rats (total n = 151) were subjected to 3 cycles of 1.5-2.5 mg/kg body weight of doxorubicin in different formulations, including doxorubicin bound to polysorbate-coated nanoparticles. The animals were analyzed for survival (% median increase of survival time, Kaplan-Meier). Preliminary histology including immunocytochemistry (glial fibrillary acidic protein, ezrin, proliferation and apoptosis) was also performed. Rats treated with doxorubicin bound to polysorbate-coated nanoparticles had significantly higher survival times compared with all other groups. Over 20% of the animals in this group showed a long-term remission. Preliminary histology confirmed lower tumor sizes and lower values for proliferation and apoptosis in this group. All groups of animals treated with polysorbate-containing formulations also had a slight inflammatory reaction to the tumor. There was no indication of neurotoxicity. Additionally, binding to nanoparticles may reduce the systemic toxicity of doxorubicin. This study showed that therapy with doxorubicin bound to nanoparticles offers a therapeutic potential for the treatment of human glioblastoma.