In vitro and in vivo activities of verteporfin-loaded nanoparticles

Nanoparticles in photodynamic therapy: an emerging paradigm

Photodynamic therapy (PDT) has emerged as one of the important therapeutic options in management of cancer and other diseases [M. Triesscheijn, P. Baas, J.H. Schellens, F.A. Stewart, Photodynamic therapy in oncology, Oncologist 11 (2006) 1034-1044]. Most photosensitizers are highly hydrophobic and require delivery systems. Previous classification of delivery systems was based on presence or absence of a targeting molecule on the surface [Y.N. Konan, R. Gurny, E. Allemann, State of the art in the delivery of photosensitizers for photodynamic therapy, J. Photochem. Photobiol., B 66 (2002) 89-106]. Recent reports have described carrier nanoparticles with additional active complementary and supplementary roles in PDT. We introduce a functional classification for nanoparticles in PDT to divide them into passive carriers and active participants in photosensitizer excitation. Active nanoparticles are distinguished from non-biodegradable carriers with extraneous functions, and sub-classified mechanistically into photosensitizer nanoparticles, [A.C. Samia, X. Chen, C. Burda, Semiconductor quantum dots for photodynamic therapy, J. Am. Chem. Soc. 125 (2003) 15736-15737, R. Bakalova, H. Ohba, Z. Zhelev, M. Ishikawa, Y. Baba, Quantum dots as photosensitizers? Nat. Biotechnol. 22 (2004) 1360-1361] self-illuminating nanoparticles [W. Chen, J. Zhang, Using nanoparticles to enable simultaneous radiation and photodynamic therapies for cancer treatment, J. Nanosci. Nanotechnology 6 (2006) 1159-1166] and upconverting nanoparticles [P. Zhang, W. Steelant, M. Kumar, M. Scholfield, Versatile photosensitizers for photodynamic therapy at infrared excitation, J. Am. Chem. Soc. 129 (2007) 4526-4527]. Although several challenges remain before they can be adopted for clinical use, these active or second-generation PDT nanoparticles probably offer the best hope for extending the reach of PDT to regions deep in the body.

Naringenin-loaded nanoparticles improve the physicochemical properties and the hepatoprotective effects of naringenin in orally-administered rats with CCl(4)-induced acute liver failure

PURPOSE

A novel naringenin-loaded nanoparticles system (NARN) was developed to resolve the restricted bioavailability of naringenin (NAR) and to enhance its hepatoprotective effects in vivo on oral administration.

MATERIALS AND METHODS

Physicochemical characterizations of NARN included assessment of particle size and morphology, powder X-ray diffraction, fourier transform infrared spectroscopy, and dissolution study. In addition, to evaluate its bioactivities and its oral treatment potential against liver injuries, we compared the hepatoprotective, antioxidant, and antiapoptotic effects of NARN and NAR on carbon tetrachloride (CCl(4))-induced hepatotoxicity in rats.

RESULTS

NARN had a significantly higher release rate than NAR and improved its solubility. NARN also exhibited more liver-protective effects compared to NAR with considerable reduction in liver function index and lipid peroxidation, in conjunction to a substantial increase in the levels of the antioxidant enzymes (P < 0.05). Moreover, NARN was able to significantly inhibit the activation of caspase-3, -8, and -9 signaling, whereas NAR only markedly inhibited caspase-3 and -9 (P < 0.05).

CONCLUSION

NARN effectively improved the release of NAR which resulted in more hepatoprotective effects mediated by its antioxidant and antiapoptotic properties. These observations also suggest that nanoformulation can improve the free drug's bioactivity on oral administration.

Nanoparticles as vehicles for delivery of photodynamic therapy agents

Photodynamic therapy (PDT) in cancer treatment involves the uptake of a photosensitizer by cancer tissue followed by photoirradiation. The use of nanoparticles as carriers of photosensitizers is a very promising approach because these nanomaterials can satisfy all the requirements for an ideal PDT agent. This review describes and compares the different individual types of nanoparticles that are currently in use for PDT applications. Recent advances in the use of nanoparticles, including inorganic oxide-, metallic-, ceramic-, and biodegradable polymer-based nanomaterials as carriers of photosensitizing agents, are highlighted. We describe the nanoparticles in terms of stability, photocytotoxic efficiency, biodistribution and therapeutic efficiency. Finally, we summarize exciting new results concerning the improvement of the photophysical properties of nanoparticles by means of biphotonic absorption and upconversion.

Hydrolysable core-crosslinked thermosensitive polymeric micelles: synthesis, characterisation and in vivo studies

In this study, core-crosslinked (CCL) biodegradable thermosensitive micelles based on mPEG(5000) and N-(2-hydroxyethyl)methacrylamide)-oligolactates (mPEG-b-p(HEMAm-Lac(n))) were synthesised and their properties investigated. Rapidly heating aqueous solutions of partially methacrylated block copolymers to above their critical micelle temperature (CMT), followed by illumination in presence of a photoinitiator yielded almost monodisperse CCL micelles with a size of 68+/-7 nm. Either below the CMT or after addition of sodium dodecyl sulphate, the non-crosslinked (NCL) micelles rapidly disintegrated whereas the CCL micelles kept their integrity. NCL micelles fell apart after 5h in pH 7.4 at 37 degrees C as a result of the hydrolysis of lactate side chains, whereas the CCL micelles had a much higher stability and only degraded after cleavage of the ester bonds in the crosslinks. The circulation kinetics and biodistribution of CCL micelles were considerably better than those of NCL micelles, i.e., 58% of the injected dose (ID) of CCL versus 6% of NCL micelles was recovered in the circulation 4h post-injection. Furthermore, the liver uptake of the CCL micelles (10% ID) was much lower than that of the NCL micelles (24% ID) 4h after administration, while tumour accumulation was almost 6 times higher for the CCL micelles. Likely, NCL micelles dissociated after i.v. administration and/or were opsonised and captured by macrophages while the dense PEG shell of CCL micelles made them less prone towards opsonisation. The excellent physical stability of these degradable CCL micelles and very favourable biodistribution profile renders them very suitable for drug targeting purposes.

Effect of nanoparticle size on the extravasation and the photothrombic activity of meso(p-tetracarboxyphenyl)porphyrin

Particle size should be optimized to achieve targeted and extended drug delivery to the affected tissues. We describe here the effects of the mean particle size on the pharmacokinetics and photothrombic activity of meso-tetra(carboxyphenyl)porphyrin (TCPP), which is encapsulated into biodegradable nanoparticles based on poly(d,l-lactic acid). Four batches of nanoparticles with different mean sizes ranging from 121 to 343 nm, were prepared using the emulsification-diffusion technique. The extravasations of each TCPP-loaded nanoparticle formulation from blood vessels were measured, as well as the extent of photochemically induced vascular occlusion. These preclinical tests were carried out in the chorioallantoic membrane (CAM) of the chicken's embryo. Fluorescence microscopy showed that both the effective leakage of TCPP from the CAM blood vessels and its photothrombic efficiency were dependent on the size of the nanoparticle drug carrier. Indeed, the TCPP fluorescence contrast between the blood vessels and the surrounding tissue increased at the applied conditions, when the particle size decreased. This suggests that large nanoparticles are more rapidly eliminated from the bloodstream. In addition, after injection of a drug dose of 1mg/kg body weight and a drug-light application interval of 1 min, irradiation with a fluence of 10J/cm(2) showed that the extent of vascular damage gradually decreased when the particle size increased. The highest photothrombic efficiency was observed when using the TCPP-loaded nanoparticles batch with a mean diameter of 121 nm. Thus, in this range of applied conditions, for the treatment of for instance a disease like choroidal neovascularization (CNV) associated with age-related macular degeneration (AMD), these experiments suggest that the smallest nanoparticles may be considered as the optimal formulation since they exhibited the greatest extent of vascular thrombosis as well as the lowest extravasation.

Polyion complex micelles for photodynamic therapy: Incorporation of dendritic photosensitizer excitable at long wavelength relevant to improved tissue-penetrating property

A polymeric micelle (DPcZn/m) system, which is formed via an electrostatic interaction of anionic dendrimer phthalocyanine (DPcZn) and poly(ethylene glycol)-poly(l-lysine) block copolymers (PEG-b-PLL), was prepared for use as an effective photosensitizer for photodynamic therapy. DPcZn/m exhibited strong Q band absorption around 650 nm, a useful wavelength for high tissue penetration. Dynamic light scattering studies indicated that the DPcZn/m system has a relevant size of 50 nm for intravenous administration. Under light irradiation, either DPcZn or DPcZn/m exhibited efficient consumption of dissolved oxygen in a medium to generate reactive oxygen species and an irradiation-time-dependent increase in photocytotoxicity. The photodynamic efficacy of the DPcZn was drastically improved by the incorporation into the polymeric micelles, typically exhibiting more than two orders of magnitude higher photocytotoxicity compared with the free DPcZn at 60-min photoirradiation.

Cellular and Antitumor Activity of a New Diethylene Glycol Benzoporphyrin Derivative (Lemuteporfin)†

A newly synthesized diethylene glycol functionalized chlorin-type photosensitizer, lemuteporfin, was characterized for use in photodynamic therapy (PDT) in a panel of in vitro and in vivo test systems. The photosensitizer was highly potent, killing cells at low nanomolar concentrations upon exposure to activating light. The cellular uptake of lemuteporfin was rapid, with maximum levels reached within 20 min. Mitogen-activated lymphoid cells accumulated more of the lemuteporfin than their quiescent equivalents, supporting selectivity. Photosensitizer fluorescence in the skin increased rapidly within the first few minutes following intravenous administration to mice, then decreased over the next 24 h. Skin photosensitivity reactions indicated rapid clearance of the photosensitizer. Intravenous doses as low as 1.4 micromol/kg combined with exposure to 50 J/cm2 red light suppressed tumor growth in a mouse model. In conclusion, this new benzoporphyrin was found to be an effective photosensitizer, showing rapid uptake and clearance both in vitro and in vivo. This rapid photosensitization of tumors could be useful in therapies requiring a potent, rapidly accumulating photosensitizer, while minimizing the potential for skin photosensitivity reactions to sunlight following treatment.

Monomolecular DNA nanoparticles for intravenous delivery of genes

Delivery is the major obstacle to success of nucleic-acid-based therapies. We have neutralized DNA with a cationic detergent (C12CCP) obtained by amide bond formation between dodecanoic acid, cysteinyl-cysteine, and diaminopropane. Subsequent detergent polymerization by formation of intermolecular disulfide bonds within the condensed plasmid DNA leads to 32-nm-large neutral particles. (C12CCP)n/DNA complexes are more stable than those formed with other gene delivery agents toward exchange with extracellular polyanions such as glycosaminoglycans. Yet exposure to phosphatidylserine, an ubiquitous intracellular anionic lipid, still releases DNA from the complexes for transcription of the carried gene. Pharmacokinetics and biodistribution in mice showed that 25% of the complexes were still circulating after 30 min (2% for other cationic lipid vectors) in a form essentially not bound to blood cells. Altogether, straightforward control over size and surface charge, stability toward aggregation or exchange, and favorable pharmacokinetics make these complexes attractive vehicles for reaching tumor metastases after injection in the blood circulation.