4. Conclusion We successfully developed PVA/DNA nanoparticles encapsulating HAps by using simple high hydrostatic pressure technology. They could enhance the transfection efficiency without any significant cytotoxicity in vitro and in vivo hydrodynamic injection. Consequently, the potential use of HAp could be expected as an enhancer of gene transfer activity of PVA/DNA nanoparticles.

Acknowledgments Inhibitors,research,lifescience,medical This work was partly supported by grants from the Ministry of Health, Labor and Welfare, the Ministry of Education, Culture, Sports, Science and Technology, and Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology Agency (JST). We thank Kuraray, Co., Ltd., for supplying Inhibitors,research,lifescience,medical the poly(vinyl alcohol).
In the drug-delivery field, several nanocarriers have been proposed to improve

the therapeutic index of various biologically active molecules such as peptides. Indeed, in vivo administration of peptides is still limited by their poor bioavailability and Akt inhibitor susceptibility to cleavage by proteases. In order to obtain a satisfactory therapeutic effect, the peptide has to be frequently administrated at high doses leading to unwanted toxic effects, such as induction of immune response. Consequently, peptide encapsulation into site-specific delivery systems can offer solutions to the above-mentioned problems. Indeed, the nanocarriers Inhibitors,research,lifescience,medical can (i) enhance drug solubility, (ii) control drug release thus avoiding toxic side effects, (iii) improve drug biodistribution, (iv) and, if appropriate molecule is grafted on the nanocarrier surface, target a specific Inhibitors,research,lifescience,medical site

of action. Several nanovectors have been used to encapsulate various therapeutic peptides such as liposomes, nanoparticles, and nano- or microgels [1–8]. Among these nanocarriers, Inhibitors,research,lifescience,medical liposomes are of great importance because of their relatively large carrying capacity and the possibility to entrap either hydrophilic, hydrophobic, or amphiphilic drugs. Moreover, a good knowledge of such vectors has been acquired since the first discovery of liposomes by Bangham and Horne [9] attested by commercially available anticancer liposomial formulations such as Doxil [10, 11]. However, despite encouraging results, a major limitation to the development of liposomes as drug carriers is their instability, especially during their transit to the site of action [12]. Attempts to improve their these stability, either by incorporation of high amount of cholesterol or by coating the liposome surface with poly(ethylene glycol), have led to limited success. Within this context, archaeosomes, made with one or more of either the ether lipids found in Archaea bacteria or synthetic archaeal lipids, constitute a novel family of liposomes exhibiting higher stabilities in several conditions, such as high temperature, alkaline or acidic pH, presence of phospholipases, bile salts, and serum media [13, 14].