Professor Elias Fattal, Director of Institut Galien Paris-Sud
UMR CNRS,  University of Paris-Sud, School of Pharmacy, Châtenay-Malabry, France

Tailoring Nanomaterials for Personalized Drug Delivery: Safety and Efficacy

Poly(lactide-co-glycolide) (PLGA) nanoparticles has been widely applied to the delivery of several drugs among which antiinfective drugs systemically and by pulmonary administration and anticancer drugs mainly by systemic administration. In this latest case, the potentialities of nanoparticles have mainly been based on the observation that the endothelium surrounding solid tumours are permeable to colloidal carriers which could use this pathway to extravasate from blood to tumour tissues. This so-called enhanced penetration and retention (EPR) mechanism is highly discussed today since there are a lot of inter-individual physiological differences in each patient regarding extravasation and diffusion across the extracellular matrix. To circumvent this problem, we are developing a strategy that combine imaging and drug delivery which should, by ultrasound imaging or MRI, allow following the fate of nanoparticles and helping in the decision of pursuing the treatment or not (1,2). Moreover, before getting into clinics, nanoparticles need to be clearly demonstrated as safe. One tissue very sensitive to nanotoxicity is lungs. We have investigated the impact of biodegradable nanoparticles on this specific organ (3).

PLGA-PEG nanocapsules containing a liquid core of perfluorooctyl bromide were synthesized by an emulsion-evaporation process and designed as contrast agents for 19F MRI (4, 5, 6). Physico-chemical properties of plain and PEGylated nanocapsules were compared. The encapsulation efficiency of PFOB, estimated by 19F NMR spectroscopy, is enhanced when using PLGA-PEG instead of PLGA. PLGA-PEG nanocapsule diameter, measured by Dynamic Light Scattering is around 120nm, in agreement with Transmission Electron microscopy (TEM) observations. TEM and Scanning Electron Microscopy (SEM) reveal that spherical core-shell morphology is preserved. PEGylation is further confirmed by Zeta potential measurements and X-ray Photoelectron Spectroscopy. In vitro, stealthiness of the PEGylated nanocapsules is evidenced by weak complement activation. Accumulation kinetics in the liver and the spleen was performed by 19F MRI in mice, during the first 90 minutes after intravenous injection. In the liver, plain nanocapsules accumulate faster than their PEGylated counteparts. We observe PEGylated nanocapsule accumulation in CT26 xenograft tumor 7 hours after administration to mice, whereas plain nanocapsules remain undetectable, using 19F MRI. Our results validate the use of diblock copolymers for PEGylation to increase the residence time of nanocapsules in the blood stream and to reach tumors by the Enhanced Permeation and Retention (EPR) effect.

The same nanocapsules were loaded with paclitaxel. The loading was high and likely to be limited to the shell of the nanocapsules. Pharmacokinetics and biodistribution show that drug loaded nanocapsules follow the same profile obseved in imaging experiments.

Modifying nanoparticle surface has large impact on toxicity. Whereas PLA nanoparticles induce the secretion of acute phase protein after iv administration (7). This is not the case for PLA-PEG nanoparticles. Moreover, we have shown no toxicity on Calu-3 or A549 cells of PLGA nanoparticles (7, 8, 9). To extend the toxicity studies to other organ such as lungs, we have developed a co-culture model of THP-1/A549 cells to evaluate the toxicity of the PLGA NPs.  This model was shown to be relevant for in vitro pulmonary nanotoxicology studies. It was possible to detect a mild inflammatory response to PLGA nanoparticles stabilized by three different hydrophilic polymers PVA, CS and PF68, but very limited compared to well-known inflammatory compounds.

Our results validate the use of diblock copolymers for PEGylation to increase the residence time of nanocapsules in the blood stream and to reach tumors by the Enhanced Permeation and Retention (EPR) effect. This added to a low toxicity should support the optimisation of PLGA nanoparticles for drug delivery.

REFERENCES

1. Diou O., N. Tsapis, E. Fattal Targeted nanotheranostics for personalized cancer therapy. Exp. Op. Drug Deliv., 2012; 9:1475-1487.
2. Diaz-Lopez R., N. Tsapis, E. Fattal Liquid Perfluorocarbons as Contrast Agents for Ultrasonography and 19F-MRI. Pharm. Res., 2010; 27:1-16.
3. Fattal E.,  Grabowski N., Mura S., Vergnaud J., Tsapis N., Hillaireau H. Lung toxicity of biodegradable nanoparticles. Journal of Biomedical Nanotechnology (in press 2014).
4. Pisani E., C. Ringard, V. Nicolas, E. Raphaël, V. Rosilio, L. Moine, E. Fattal, N. Tsapis Tuning microcapsules surface morphology using blends of homo and copolymers of PLGA and PLGA-PEG. Soft Mat., 2009; 5, 3054–3060.
5. Pisani E., N. Tsapis, B.Galaz, M.Santin, R.Berti, N.Taulier, E. Kurtisovski, O. Lucidarme, M. Ourevitch, B. Thuy Doan, J-C. Beloeil, B. Gillet, W. Urbach, L. Bridal, E. Fattal - Perfluorooctyl bromide polymeric capsules as dual contrast agents for ultrasonography and magnetic resonance imaging. Adv. Funct.Mat., 2008; 18: 2963–297.
6. O. Diou, N. Tsapis, C.  Giraudeau, J. Valette, C. Gueutin, F. Bourasset, S. Zanna, C.Vauthier, E. Fattal. Long-circulating perfluorooctyl bromide nanocapsules for tumor imaging by 19F-MRI. Biomaterials, 2012; 33:5593-602.
7. Fernandez-Urrusuno R., E. Fattal, D. Porquet, J. Feger, P. Couvreur Influence of the surface properties on the inflammatory response to polymeric nanoparticles. Pharm. Res., 1995; 12:1385-1387.
8. Mura S., Hillaireau H., Nicolas J., Kerdine-Römer S., Le Droumaguet B., Deloménie C., Nicolas V., Pallardy M., Tsapis N., Fattal E. Biodegradable nanoparticles meet the bronchial airway barrier: how surface properties affect their interaction with mucus and epithelial cells. Biomacromolecules, 12(11), 4136-4143, (2011).
9. Mura S., Hillaireau H., Nicolas J., Le Droumaguet B., Gueutin C., Zanna S. Tsapis N., Fattal E. Influence of surface charge on the potential toxicity of PLGA nanoparticles towards Calu-3 cells. Int. J. Nanomed., 2011; 6:2591-2605.
10. Grabowski N, Hillaireau H, Vergnaud J, Santiago La, Kerdine-Romer S, Pallardy M, Tsapis N, Fattal E. Toxicity of surface-modified PLGA nanoparticles towards lung alveolar epithelial cells. Int. J. Pharm. 2013; 454:686-694.