Experimental cystic echinococcosis therapy: In vitro and in vivo combined 5-fluorouracil/albendazole treatment.

Human cystic echinococcosis is a zoonosis caused by the larval stage of the tapeworm Echinococcus granulosus sensu lato (s. l.). Although benzimidazole compounds such as albendazole (ABZ) and mebendazole have been the cornerstone of chemotherapy for the disease, there is often no complete recovery after treatment. Hence, new strategies are required to improve treatment of human cystic echinococcosis. The goals of the current study were as follows: (i) to evaluate the in vitro efficacy of the 5-fluorouracil (5-FU) and ABZ combination against E. granulosus s. l. protoscoleces and cysts, (ii) to compare the clinical efficacy of 5-FU alone or in combination with ABZ in infected mice. The combination of 5-FU+ABZ had a stronger in vitro effect against larval stage than that did both drugs alone. Even at the lowest concentration of 5-FU+ABZ combination (1µg/ml), the reduction of the viability of protoscoleces and cysts was greater than that observed with drugs alone at 10µg/ml. The results were confirmed at the ultrastructural level by scanning electron microscopy. These data helped to justify the in vivo investigations assessing the therapeutic potential of the combination of 5-FU and ABZ suspension in CF-1 mice infected with E. granulosus sensu stricto (s. s.) metacestodes. Treatment with 5-FU (10mg/kg) or 5-FU (10mg/kg) + ABZ suspension (5mg/kg) reduced the weight of cysts recovered from mice compared with control groups. Interestingly, the effect of 5-FU given weekly for 5 consecutive weeks was comparable to that observed with ABZ suspension under a daily schedule during 30days. Co-administration of 5-FU with ABZ did not enhance the in vivo efficacy of drugs alone calculated in relation to cysts weights. However, the combination provoked greater ultrastructural alterations compared to the monotherapy. In conclusion, we demonstrated the efficacy of 5-FU either alone or co-administrated with ABZ against murine experimental cystic echinococcosis. Since 5-FU treatments did not cause toxic effect in mice, further in vivo studies will be performed by adjusting the dosage and the frequency of treatments.

Ivermectin-loaded lipid nanocapsules: toward the development of a new antiparasitic delivery system for veterinary applications.

Ivermectin (IVM) is probably one of the most widely used antiparasitic drugs worldwide, and its efficacy is well established. However, slight differences in formulation may change the plasma kinetics, the biodistribution, and in consequence, the efficacy of this compound. The present study focuses on the development of a novel nanocarrier for the delivery of lipophilic drugs such as IVM and its potential application in antiparasitic control. Lipid nanocapsules (LNC) were prepared by a new phase inversion procedure and characterized in terms of size, surface potential, encapsulation efficiency, and physical stability. A complement activation assay (CH50) and uptake experiments by THP-1 macrophage cells were used to assess the stealth properties of this nanocarrier in vitro. Finally, a pharmacokinetics and biodistribution study was carried out as a proof of concept after subcutaneous (SC) injection in a rat model. The final IVM-LNC suspension displayed a narrow size distribution and an encapsulation rate higher than 90 % constant over the evaluated time (60 days). Through flow cytometry and blood permanence measurements, it was possible to confirm the ability of these particles to avoid the macrophage uptake. Moreover, the systemic disposition of IVM in the LNC administered by the SC route was higher (p < 0.05) (1367 ng h/ml) compared to treatment with a commercial formulation (CF) (1193 ng.h/ml), but no significant differences in the biodistribution pattern were found. In conclusion, this new carrier seems to be a promising therapeutic approach in antiparasitic control and to delay the appearance of resistance.

In vivo evaluation of paclitaxel-loaded lipid nanocapsules after intravenous and oral administration on resistant tumor.

AIM & METHODS: The aim of the present work was to encapsulate paclitaxel (Ptx) in various lipid nanocapsules (LNCs) formulations and then to compare their pharmacokinetics and efficacy on a subcutaneous isograft model in rats. RESULTS: Three different Ptx formulations were obtained. Drug payloads ranged from 1.32 to 3.62 mg Ptx/g of formulation. After oral administration the area under concentration-time curve was higher (p < 0.05) if Ptx was encapsulated, (1,2 Distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(PEG)] (DSPE-PEG-NH2)) LNCs displaying the highest area under concentration-time curve (p < 0.05). Efficacy was better than control for standard LNCs after oral administration (p < 0.05) and for (DSPE-PEG-NH2) LNCs after intravenous administration. Despite good absorption, (DSPE-PEG-NH2) LNCs failed to remain efficient after oral route. CONCLUSION: This study highlights the importance of efficacy studies paired to pharmacokinetic studies for nanomedicines.

In vitro effect of 5-fluorouracil and paclitaxel on Echinococcus granulosus larvae and cells.

Human cystic echinococcosis is a zoonosis caused by the metacestode stage of the tapeworm Echinococcus granulosus. Although benzimidazole compounds such as albendazole and mebendazole have been the cornerstone of chemotherapy for the disease, there is often no complete recovery after treatment. Hence, in searching for novel treatment options, we examined the in vitro efficacies of 5-fluorouracil (5-FU) and paclitaxel (PTX) against E. granulosus germinal cells, protoscoleces and cysts. 5-FU or PTX inhibited the growth of E. granulosus cells in a time dependent manner. Although both treatments had a protoscolicidal effect, 5-FU had a considerably stronger effect than PTX. 5-FU produced a dose- and time-dependent effect, provoking the complete loss of viability after 24 days of incubation. Moreover, cysts did not develop following the inoculation of treated protoscoleces into mice. The loss of viability was slower in PTX treated protoscoleces, reaching to approximately 60% after 30 days. The results of the in vitro treatment with 5-FU and PTX were similar in secondary murine cysts. The employment of SEM and TEM allowed us to examine, at an ultrastructural level, the effects induced by 5-FU and PTX on E. granulosus germinal cells, protoscoleces and murine cysts. In conclusion, the data obtained clearly demonstrated that 5-FU and PTX at clinically achievable concentrations inhibit the survival of larval cells, protoscoleces and metacestodes. In vivo studies to test the antiparasitic activities of 5-FU and PTX are currently being undertaken on the murine model of cystic echinococcosis.

Lipid nanocapsule functionalization by lipopeptides derived from human papillomavirus type-16 capsid for nucleic acid delivery into cancer cells.

Plasmid DNA (pDNA) and small interfering RNAs (siRNAs) are very useful tools for the treatment of cancer. However, pDNA and siRNAs efficacy is restricted by their negative charge and susceptibility to degradation by endonucleases that prevent them penetrating tissue and cellular barriers such as the plasma and endolysosomal membranes. Viral vectors have some advantages but their use is largely limited by their immunogenicity. On the other hand, synthetic nanoparticles have advantage of being relatively non-immunogenic but their ability to deliver nucleic acids remains less efficient than their viral counterparts. The present study is focussed on the development and evaluation of biomimetic lipid nanocapsules (LNCs) functionalized with a L1 papillomavirus type-16 capsid-derived lipopeptide on their surface, for transfection of U87MG glioma cells and Caco-2 colorectal adenocarcinoma cells with pDNA or siRNAs. Since the L1-peptide has been described as a nuclear localization signal able to complex with nucleic acids and bind to heparan sulfate on the cell surface, the structure and function of L1-peptide bound to LNCs (L1-LNCs) were investigated. Although L1-LNCs were shown to complex with both pDNA and siRNAs, the pDNA-L1-LNC complexes showed only weak transfection efficiency. In contrast, siRNA-L1-LNC complexes appeared as effective repressors of targeted messengers.

Perfluorocarbon-loaded lipid nanocapsules as oxygen sensors for tumor tissue pO2 assessment.

The assessment of tumor oxygenation is a crucial factor in cancer therapy and may be carried out using fluorine MRI once fluorine probes have been distributed within the tumor. However, the deposit of those highly fluorinated compounds often jeopardizes anatomical image quality and requires emulsification of the probes. Due to the high density and the high lipophilicity of perfluorocarbons, nanoemulsion of these molecules usually requires high-energy processes. In the present work, we discuss the synthesis and the physico-chemical characterization of perfluorocarbon nanocapsules using a low-energy phase-inversion process. The nanocapsules were tested on a mouse tumor brain model to assess oxygenation.

Smart nanocarriers for pH-triggered targeting and release of hydrophobic drugs.

The use of hybrid pH-sensitive micelles based mainly on the (PEO)(129)(P2VP)(43)(PCL)(17) ABC miktoarm star copolymer as potential triggered drug delivery systems was investigated. Co-micellization of this star copolymer with a second copolymer labeled by a targeting ligand, i.e. biotin, on the pH sensitive block (poly-2-vinylpyridine) is considered here in order to impart possible active targeting of the tumor cells. Two architectures were studied for these labeled copolymers, i.e. a miktoarm star or a linear ABC terpolymer, and the respective hybrid micelles are compared in terms of cytotoxicity (cells viability) and cellular uptake (using fluorescent dye loaded micelles). Finally, the triggered drug release in the cytosol of tumor cells was investigated by studying, on the one hand, the lysosomal integrity after internalization and, on the other hand, the release profile in function of the pH.

Development and characterization of immuno-nanocarriers targeting the cancer stem cell marker AC133.

In the context of targeted therapy, we addressed the possibility of developing a drug delivery nanocarrier capable to specifically reach cancer cells that express the most prominent marker associated with cancer stem cell (CSC) phenotype, AC133. For this purpose, 100nm lipid nanocapsules (LNCs) were functionalized with a monoclonal antibody (mAb) directed against AC133 according to two distinct methods: firstly, post-insertion within 100nm LNCs of a lipid poly(ethylene glycol) functionalized with reactive-sulfhydryl maleimide groups (DSPE-PEG(2000)-maleimide) followed by thiolated mAb coupling, and, secondly, creation of a thiolated lipo-immunoglobulin between DSPE-PEG(2000)-maleimide and AC133, then post-inserted within LNCs. Due to the reduced number of purification steps, lower amounts of DSPE-PEG(2000)-maleimide that were necessary as well as lower number of free maleimide functions present onto the surface of immuno-LNC, the second method was found to be more appropriate. Thus, 126nm AC133-LNC with a zeta potential of -22mV while keeping a narrow distribution were developed. Use of the IgG1κ isotype control-immunoglobulins produced similar control IgG1-LNCs. Micro-Bradford colorimetric assay indicated a fixation of about 40 immunoglobulins per LNC. Use of human Caco-2 cells that constitutively express AC133 (Caco-2-AC133(high)) allowed addressing the behavior of the newly functionalized immuno-LNCs. siRNA knockown strategy permitted to obtain Caco-2-AC133(low) for comparison. Immunofluorescence-combined flow cytometry analysis demonstrated that the epitope-recognition function of AC133 antibody was preserved when present on immuno-LNCs. Although grafting of immunoglobulins onto the surface of LNCs repressed their internalization within Caco-2 cells as evaluated by flow cytometry, AC133-specific cellular binding was obtained with AC133-LNC as assessed by computer-assisted fluorescence microscopy. In conclusion, interest of AC133-LNCs as niche carriers is discussed toward the development of CSC targeted chemo- or radio-nanomedicines.

Stealth properties of poly(ethylene oxide)-based triblock copolymer micelles: a prerequisite for a pH-triggered targeting system.

Evaluation of the biocompatibility of pH-triggered targeting micelles was performed with the goal of studying the effect of a poly(ethylene oxide) (PEO) coating on micelle stealth properties. Upon protonation under acidic conditions, pH-sensitive poly(2-vinylpyridine) (P2VP) blocks were stretched, exhibiting positive charges at the periphery of the micelles as well as being a model targeting unit. The polymer micelles were based on two different macromolecular architectures, an ABC miktoarm star terpolymer and an ABC linear triblock copolymer, which combined three different polymer blocks, i.e. hydrophobic poly(ε-caprolactone), PEO and P2VP. Neutral polymer micelles were formed at physiological pH. These systems were tested for their ability to avoid macrophage uptake, their complement activation and their pharmacological behavior after systemic injection in mice, as a function of their conformation (neutral or protonated). After protonation, complement activation and macrophage uptake were up to twofold higher than for neutral systems. By contrast, when P2VP blocks and the targeting unit were buried by the PEO shell at physiological pH, micelle stealth properties were improved, allowing their future systemic injection with an expected long circulation in blood. Smart systems responsive to pH were thus developed which therefore hold great promise for targeted drug delivery to an acidic tumoral environment.

Mitochondrial targeting by use of lipid nanocapsules loaded with SV30, an analogue of the small-molecule Bcl-2 inhibitor HA14-1.

Taking advantage from the development of SV30, a new analogue of the pro-apoptotic molecule HA14-1, the aim of this study was to functionally evaluate SV30 and to develop safe nanocarriers for its administration. By using an inversion phase process, 57nm organic solvent-free lipid nanocapsules loaded with SV30 (SV30-LNCs) were formulated. Biological performance of SV30 and SV30-LNCs were evaluated on F98 cells that express Bax and Bcl-2, through survival assays, HPLC, flow cytometry, confocal microscopy and spectral imaging. We observed that SV30 alone or in combination with paclitaxel, etoposide or beam radiation could trigger cell death in a similar fashion to HA14-1. Although partially blocked by Z-VAD-fmk, this effect was coincident to caspase-3 activation. Hence, we established that SV30-LNCs improved SV30 biological activity together with a potentiation of the mitochondrial membrane potential decrease. Interestingly, flow cytometry and confocal analysis indicated that SV30 itself conferred to LNCs improved mitochondrial targeting skills that may present a great interest toward the development of mitochondria targeted nanomedicines.

Local implantation of doxorubicin drug eluting beads in rat glioma.

We evaluated the safety and the efficacy of doxorubicin drug eluting beads "CM-BC1" when used locally in a 9L glioma model. Twenty microlitres of 1mg/ml CM-BC1 (4µg/rat), 10mg/ml CM-BC1 (40µg/rat) or unloaded beads were injected into the brain of 27 rats which was analyzed on day 8, month 3 or month 6. Then, after tumor implantation, rats were treated locally: (1) control group; (2) a group receiving 20µl of unloaded beads, (3) a group "3×6Gy whole-brain irradiation" (WBI), (4) a group receiving 20µl of 1mg/ml CM-BC1 and (5) a group receiving 20µl of 1mg/ml CM-BC1 followed by a WBI. Both the unloaded beads and the lower dose of 1mg/ml CM-BC1 were well tolerated with no early deaths in opposite to 10mg/ml CM-BC1. Medians of survival for the "1mg/ml CM-BC1" group and the combination group are respectively 28.9 and 64.4 days. These results were significant compared to the "unloaded beads" group. The rat's survival was not significantly improved in comparison with the radiotherapy group. This preliminary evidence suggests that 1mg/ml CM-BC1 could be interesting for recurrent high-grade gliomas. Further work is necessary to improve this seducing tool.

Reciprocal competition between lipid nanocapsules and P-gp for paclitaxel transport across Caco-2 cells.

Lipid nanocapsules (LNCs) have been shown to improve paclitaxel (Ptx) bioavailability and transport across an intestinal barrier model. In the present study, the interaction between P-glycoprotein (P-gp) and LNC transport across Caco-2 cells are investigated. Transport experiments have been performed on Caco-2 cells displaying different P-gp activities (early and later cell passages). The permeability of Ptx encapsulated in LNCs has been studied in the presence of P-gp inhibitors (verapamil and vinblastin) or unloaded LNCs. The uptake of dye-labelled LNCs was also observed in the presence of the same inhibitors. It was found that the permeability of Ptx varied depending on the passages with later ones showing higher absolute values (5.74+/-1.21 cms(-1) vs 133.41+/-5.74 cms(-1)). P-gp inhibition obtained with verapamil or vinblastin improved Ptx transport up to 98%. LNCs have also demonstrated their capacity to increase their own transport. Experiments performed with dye-labelled LNCs demonstrated an enhancement of the uptake of dye (Nile red), only in the presence of verapamil. These results demonstrated an effect of P-gp on the transport of Ptx when loaded in LNCs and support a direct effect of P-gp on their endocytosis in Caco-2 cells. These finding may assist in the development of new nanomedicine for oral administration.

Lipid nanocarriers improve paclitaxel transport throughout human intestinal epithelial cells by using vesicle-mediated transcytosis.

The use of lipid nanocapsules (LNCs) has enabled an improvement of the oral bioavailability of paclitaxel (Ptx). However, mechanisms that support this recent observation are not yet understood. By focusing on the well defined in vitro Caco-2 model, the purpose of this study was to evaluate the transport of LNCs across a model intestinal barrier. Firstly, four sizes of paclitaxel or dye (Nile Red)-loaded LNCs were formulated and LNCs with sizes between 26.3+/-2.7 nm and 132.7+/-5.5 nm were obtained. Different transport and uptake experiments were then performed across a Caco-2 cells culture model using these LNCs. Paclitaxel-loaded LNCs improved permeability of Ptx across intestinal epithelium compared with free Ptx or Taxol by a factor of 3.5. At 37 degrees C particle size did not influence transport efficiency. However, at 4 degrees C a decrease in Ptx transport was observed with increasing size of LNCs. Thus, with LNCs of 25 nm size, the apparent permeability coefficient (P(app)) was 5.3+/-1.1 cm s(-1) at 37 degrees C and 2.2+/-0.4 cm s(-1) at 4 degrees C. In comparison in LNCs of 130 nm size, the P(app) decreased from 5.8+/-0.8 cm s(-1) at 37 degrees C to 0.5+/-0.1 cm s(-1) at 4 degrees C. The uptake of LNCs by Caco-2 cells and the incapacity of LNCs to open tight junctions were also demonstrated. Furthermore, experiment transports were performed in the presence of different inhibitors of endocytosis. Findings indicated a reduction of Ptx transport of 30+/-6% when cell cholesterol was depleted, 65+/-12% when caveolae-mediated endocytosis was inhibited and 20+/-8% when clathrin-mediated endocytosis was inhibited. Finally, transmission electronic microscopy showed the presence of nano-objects on the basolateral side of the Caco-2 cell monolayers when LNCs were applied on the apical side.

Lipid nanocapsules: a new platform for nanomedicine.

Nanomedicine, an emerging new field created by the fusion of nanotechnology and medicine, is one of the most promising pathways for the development of effective targeted therapies with oncology being the earlier and the most notable beneficiary to date. Indeed, drug-loaded nanoparticles provide an ideal solution to overcome the low selectivity of the anticancer drugs towards the cancer cells in regards to normal cells and the induced severe side-effects, thanks to their passive and/or active targeting to cancer tissues. Liposome-based systems encapsulating drugs are already used in some cancer therapies (e.g. Myocet, Daunoxome, Doxil). But liposomes have some important drawbacks: they have a low capacity to encapsulate lipophilic drugs (even though it exists), they are manufactured through processes involving organic solvents, and they are leaky, unstable in biological fluids and more generally in aqueous solutions for being commercialized as such. We have developed new nano-cargos, the lipid nanocapsules, with sizes below the endothelium fenestration (phi<100 nm), that solve these disadvantages. They are prepared according to a solvent-free process and they are stable for at least one year in suspension ready for injection, which should reduce considerably the cost and convenience for treatment. Moreover, these new nano-cargos have the ability to encapsulate efficiently lipophilic drugs, offering a pharmaceutical solution for their intravenous administration. The lipid nanocapsules (LNCs) have been prepared according to an original method based on a phase-inversion temperature process recently developed and patented. Their structure is a hybrid between polymeric nanocapsules and liposomes because of their oily core which is surrounded by a tensioactive rigid membrane. They have a lipoprotein-like structure. Their size can be adjusted below 100 nm with a narrow distribution. Importantly, these properties confer great stability to the structure (physical stability>18 months). Blank or drug-loaded LNCs can be prepared, with or without PEG (polyethyleneglycol)ylation that is a key parameter that affects the vascular residence time of the nano-cargos. Other hydrophilic tails can also be grafted. Different anticancer drugs (paclitaxel, docetaxel, etoposide, hydroxytamoxifen, doxorubicin, etc.) have been encapsulated. They all are released according to a sustained pattern. Preclinical studies on cell cultures and animal models of tumors have been performed, showing promising results.

The adaptation of lipid nanocapsule formulations for blood administration in animals.

In many cell-culture and animal models, the therapeutic effects of the entrapped drugs in lipid nanocapsules (LNCs) were preserved with low toxicity. These results allow foreseeing further preclinical efficiency and toxicity studies in animals. In this article, preliminary studies were performed to check the genetically modified organism (GMO) status of the LNCs components and to determine the effects of the acidity of the LNCs dispersions in acid-base balance in rats. Then, several freezing protocols to store paclitaxel-loaded LNCs dispersions for a 6-month period were compared. Results indicate that the Lipoïd S75-3 could not be certified GMO-free. The same soya bean lecithin certified to be GMO-free permitted to produce LNCs with expected characteristics. The blood administration of blank LNCs dispersions in rats induced no modifications of blood acidity, but a significant decrease of the base excess was observed. Injections of LNCs dispersions in animals might induce iatrogenic acidosis. We finally demonstrated that the best protocol to store LNCs dispersion for a 6-month period is by freezing in liquid nitrogen. This protocol minimized the characteristics modifications and interrupted the drug-release phenomenon. These original data are expected to prepare of LNCs dispersions well adapted for i.v. administration in animals.

Dose effect activity of ferrocifen-loaded lipid nanocapsules on a 9L-glioma model.

Ferrociphenol (Fc-diOH) is a new molecule belonging to the fast-growing family of organometallic anti-cancer drugs. In a previous study, we showed promising in vivo results obtained after the intratumoural subcutaneous administration of the new drug-carrier system Fc-diOH-LNCs on a 9L-glioma model. To further increase the dose of this lipophilic entity, we have created a series of prodrugs of Fc-diOH. The phenol groups were protected by either an acetyl (Fc-diAc) or by the long fatty-acid chain of a palmitate (Fc-diPal). LNCs loaded with Fc-diOH prodrugs have to be activated in situ by enzymatic hydrolysis. We show here that the protection of diphenol groups with palmitoyl results in the loss of Fc-diOH in vitro activity, probably due to a lack of in situ hydrolysis. On the contrary, protection with an acetate group does not affect the strong, in vitro, antiproliferative effect of ferrocifen-loaded-LNCs neither the reduction of tumour volume observed on an ectopic model, confirming that acetate is easily cleaved by cell hydrolases. Moreover, the cytostatic activity of Fc-diOH-LNCs is confirmed on an orthotopic glioma model since the difference in survival time between the infusion of 0.36 mg/rat Fc-diOH-LNCs and blank LNCs is statistically significant. By using LNCs or Labrafac to carry the drug, a dose-effect ranging from 0.005 to 2.5mg of Fc-diOH per animal can be evidenced.

[Local chemotherapy of malignant glioma: from syringe injections to nanotechnology]. / Chimiothérapie locale dans les gliomes malins: de l'injection à la seringue aux nanotechnologies.

Many arguments support the development of local therapies for malignant gliomas. Simple injections of antimitotic agents into the surgical cavity has been replaced by more sophisticated systems. Tissues can be infused with complex prolonged-release polymeric or lipidic systems with macroscopic, microscopic and now even nanometric particles. But, as for any drug, the developments of these new agents has been long and only very few reach the stage of the clinic trials.

188Re-loaded lipid nanocapsules as a promising radiopharmaceutical carrier for internal radiotherapy of malignant gliomas.

PURPOSE: Lipid nanocapsules (LNC) entrapping lipophilic complexes of (188)Re ((188)Re(S(3)CPh)(2)(S(2)CPh) [(188)Re-SSS]) were investigated as a novel radiopharmaceutical carrier for internal radiation therapy of malignant gliomas. The present study was designed to evaluate the efficacy of intra-cerebral administration of (188)Re-SSS LNC by means of convection-enhanced delivery (CED) on a 9L rat brain tumour model. METHODS: Female Fischer rats with 9L glioma were treated with a single injection of (188)Re-SSS LNC by CED 6 days after cell implantation. Rats were put into random groups according to the dose infused: 12, 10, 8 and 3 Gy in comparison with blank LNC, perrhenate solution (4 Gy) and non-treated animals. The radionuclide brain retention level was evaluated by measuring (188)Re elimination in faeces and urine over 72 h after the CED injection. The therapeutic effect of (188)Re-SSS LNC was assessed based on animal survival. RESULTS: CED of (188)Re perrhenate solution resulted in rapid drug clearance with a brain T (1/2) of 7h. In contrast, when administered in LNC, (188)Re tissue retention was greatly prolonged, with only 10% of the injected dose being eliminated at 72 h. Rat median survival was significantly improved for the group treated with 8 Gy (188)Re-SSS LNC compared to the control group and blank LNC-treated animals. The increase in the median survival time was about 80% compared to the control group; 33% of the animals were long-term survivors. The dose of 8 Gy proved to be a very effective dose, between toxic (10-12 Gy) and ineffective (3-4 Gy) doses. CONCLUSIONS: These findings show that CED of (188)Re-loaded LNC is a safe and potent anti-tumour system for treating malignant gliomas. Our data are the first to show the in vivo efficacy of (188)Re internal radiotherapy for the treatment of brain malignancy.

In vivo evaluation of lipid nanocapsules as a promising colloidal carrier for paclitaxel.

Paclitaxel-loaded lipid nanocapsules (PX-LNC) exhibit interesting in vitro characteristics with improved antitumoral activity compared with free PX formulation. Biodistribution studies were realized with the use of (14)C-trimyristin ((14)C-TM) or (14)C-phosphatidylcholine ((14)C-PC) whereas antitumoral activity of PX-LNC formulations was based on the animal survival in a chemically induced hepatocellular carcinoma (HCC) model in Wistar rats. Blood concentration-time profiles for both labeled (14)C-TM-LNC and (14)C-PC-LNC were similar; the t(1/2) and MRT values (over 2h and close to 3h, respectively, for both formulations) indicated the long circulating properties of the LNC carrier with a slow distribution and elimination phase. Survival curves of paclitaxel treated groups showed a statistical significant difference compared to the control survival curve (P=0.0036 and 0.0408). Animals treated with 4x 70 mg/m(2) of PX-LNC showed the most significant increase in mean survival times compared to the controls (IST(mean) 72%) and cases of long-term survivors were preferentially observed in the PX-LNC treated group (37.5%; 3/8). These results demonstrate the great interest to use LNC as drug delivery system for paclitaxel, permitting with an equivalent therapeutic efficiency to avoid the use of excipients such as polyoxyethylated castor oil for its formulation.

Radiolabeling and targeting of lipidic nanocapsules for applications in radioimmunotherapy.

AIM: Radioimmunotherapy is limited in some cases by the low radioactive doses delivered to tumor cells by antibodies or pretargeted haptens. In order to increase this dose, lipidic nanocapsules (LNC) with a hydrophobic core are proposed as radionuclide vectors that could be targeted to cancer cells by a bispecific anti-tumor x anti-hapten antibody after incorporation of different haptens in the nanocapsule membrane. METHODS: To bind different radionuclides to the nanocapsules, several bifunctional chelating agents (BCA) were used to form stable complexes with the radionuclides. Some of them are hydrophilic for LNC shell while others are lipophilic to radiolabel the core. Poly(ethylene glycols) (PEG) were used to increase the residence time in blood. Since PEG can modify haptens recognition by the bispecific antibody and radiolabeling efficiency, haptens, BCA or Bolton-Hunter reagent (BH) were attached to the PEG extremity to optimize accessibility. Specific constructs (DSPE-PEG-haptens, DSPE-PEG-BCA, and DSPE-PEG-BH) were synthesized to develop these new radiolabeled vector formulations. Large amounts of PEG have been introduced by a postinsertion method without important change in nanocapsule size and properties. The nanocapsule core was radiolabeled with a lipophilic [(99m)Tc]SSS complex. RESULTS: Serum stability studies showed that this (99m)Tc-labeling method was efficient for at least 20 h. Concerning the nanocapsule surface, several methods have been performed for (111)In-labeling by using DSPE-PEG-DTPA and for (125)I-labeling with DSPE-PEG-BH. CONCLUSIONS: The nanocapsules labeling feasibility with a variety of radionuclides and their stability were demonstrated in this paper.