Long-circulating DNA lipid nanocapsules as new vector for passive tumor targeting

Abstract

Systemic gene delivery systems are needed for therapeutic application to organs that are inaccessible by percutaneous injection. Currently, the main objective is the development of a stable and non-toxic vector that can encapsulate and deliver foreign genetic material to target cells. To this end, DNA, complexed with cationic lipids i.e DOTAP/DOPE, was encapsulated into lipid nanocapsules (LNCs) leading to the formation of stable nanocarriers (DNA LNCs) with a size inferior to 130nm. Amphiphilic and flexible poly (ethylene glycol) (PEG) polymer coatings [PEG lipid derivative (DSPE-mPEG 2000 ) orF108 poloxamer] at different concentrations were selected to make DNA LNCs stealthy. Some of these coated lipid nanocapsules were able to inhibit complement activation and were not phagocytised in vitro by macrophagic THP-1 cells whereas uncoated DNA LNCs accumulated in the vacuolar compartment of THP-1 cells. These results correlated with a significant increase of in vivo circulation time in mice especially for DSPE-mPEG 2000 10mM and an early half-life time (t 1/2 of distribution) 5-fold greater than for non-coated DNA LNCs (7.1h vs 1.4h). Finally, a tumor accumulation assessed by in vivo fluorescence imaging system was evidenced for these coated LNCs as a passive targeting without causing any hepatic damage. Furthermore, when injected intravenously, colloidal carriers are rapidly cleared by the mononuclear phagocyte system (MPS) mainly represented by Kupffer cells in the liver and spleen macrophages. The recognition of the carriers by macrophages usually occurs through specific recognition by cellular receptors specific for plasma proteins that have been adsorbed at the vector surface. Among them, the C3 protein of the complement system plays a major role in the immune system's recognition of foreign particles [2]. The concept of modifying the surface of vectors has therefore been applied in order to decrease the opsonisation process and the specific or non-specific recognition by MPS and blood components [3]. Heurtault et al.[4] developed lipid nanocapsules synthesised by a solvent-free method and covered by PEG 660 at high density, leading to really weak complement activation and low macrophage uptake [3,5]. In a previous work, the formulation of these nanocapsules was adapted to obtain DNA nanocapsules (DNA LNCs) [6]. Thanks to the use of oleic Plurol ® instead of Lipoid ® in their formulation, the lipid core allowed the entrapment of plasmid DNA molecules via the formation of lipoplexes (cationic liposomes of DOTAP:DOPE complexed with plasmid DNA). DNA LNCs were small (117 ± 10nm), suitable for an intravenous injection, but in vivo stability and blood half-life remained low and were ill-adapted to efficient in vivo transfection [6].To allow an extended circulation time, and consequently a higher tumor selectivity by passive accumulation through the EPR (enhanced permeability and retention) effect [7], we chose to modify the surface of our gene delivery systems, by inserting longer PEG chains at the sur...

Tumour targeting of lipid nanocapsules grafted with cRGD peptides

“…As reported earlier, encapsulation of 99m Tc or DiI did not change these characteristics of the blank LNC (data not shown) as also reported earlier [19,20]. On the contrary, peptide grafting increased the size of LNC by 11-14 nm while PdIs remained relatively low indicating slightly negative whereas the peptide grafting decreased the ζ-potential to about -45 mV.…”

“…Because of their structure which includes a semi-rigid shell, LNC can be further modified by insertion of amphiphilic molecules. This kind of post-insertion allows several benefits like improvement of biodistribution profile [20] or creation of templates for further attachment of active targeting ligands [21,22].…”

Efficient delivery of ursolic acid by poly(N-vinylpyrrolidone)-block-poly (ε-caprolactone) nanoparticles for inhibiting the growth of hepatocellular carcinoma in vitro and in vivo

“…First, the enhanced permeability and retention (EPR) effect enables the accumulation of drug-loaded nanoparticles in the tumor site during the circulation when administered systemically -which is also called passive targeting. 29 Moreover, as to the cellular uptake, drug-loaded nanoparticles can …”

Development and in vitro evaluations of new decitabine nanocarriers for the treatment of acute myeloid leukemia

“…[12][13][14][15][16][17] Hydrophilic drugs, such as fondaparinux 18 or DNA and siRNA, 19,20 have also been encapsulated, and reverse micelles associated with LNCs containing doxorubicin hydrochloride or erlotinib hydrochloride have been developed. 21,22 Encapsulation into LNCs has modified the pharmacokinetic parameters of DNA when encapsulated in stealth LNCs, 20 or of miltefosine, an antischistosomal drug, by increasing its time to reach the maximal concentration and increasing its activity against Shistosoma mansoni.…”

“…Accuracy of the method was assessed by making nine determinations of three concentrations (5,20, and 40 µg/mL) three times a day, for 3 days. Accuracy was determined as the difference between the mean measured value and the accepted true value.…”