Showing papers by "Lina Bezdetnaya published in 2012"

Interaction of liposomal formulations of meta-tetra(hydroxyphenyl)chlorin (temoporfin) with serum proteins: protein binding and liposome destruction.

Abstract: mTHPC is a non polar photosensitizer used in photodynamic therapy. To improve its solubility and pharmacokinetic properties, liposomes were proposed as drug carriers. Binding of liposomal mTHPC to serum proteins and stability of drug carriers in serum are of major importance for PDT efficacy; however, neither was reported before. We studied drug binding to human serum proteins using size-exclusion chromatography. Liposomes destruction in human serum was measured by nanoparticle tracking analysis (NTA). Inclusion of mTHPC into conventional (Foslip(®)) and PEGylated (Fospeg(®)) liposomes does not affect equilibrium serum protein binding compared with solvent-based mTHPC. At short incubation times the redistribution of mTHPC from Foslip(®) and Fospeg(®) proceeds by both drug release and liposomes destruction. At longer incubation times, the drug redistributes only by release. The release of mTHPC from PEGylated vesicles is delayed compared with conventional liposomes, alongside with greatly decreased liposomes destruction. Thus, for long-circulation times the pharmacokinetic behavior of Fospeg(®) could be influenced by a combination of protein- and liposome-bound drug. The study highlights the modes of interaction of photosensitizer-loaded nanovesicles in serum to predict optimal drug delivery and behavior in vivo in preclinical models, as well as the novel application of NTA to assess the destruction of liposomes.

Visualisation of sentinel lymph node with indium-based near infrared emitting Quantum Dots in a murine metastatic breast cancer model.

Abstract: Due to its non-invasiveness, high temporal resolution and lower cost, fluorescence imaging is an interesting alternative to the current method (blue dye and radiocolloid) of sentinel lymph node (SLN) mapping in breast cancer. Near-infrared (NIR) emitting cadmium-based Quantum Dots (QDs) could be used for this purpose; however, their wide application is limited because of the toxicity of heavy metals composing the core. Our recent work demonstrated that indium-based QDs exhibit a weak acute local toxicity in vivo compared to their cadmium-based counterparts. In the present study we confirmed the weak toxicity of CuInS2/ZnS QDs in different in vitro models. Further in vivo studies in healthy mice showed that In-based QDs could be visualised in SLN in a few minutes after administration with a progressive increase in fluorescence until 8 h. The quantity of indium was assessed in selected organs and tissues by inductively coupled plasma – mass spectroscopy (ICP-MS) as a function of post-injection time. QD levels decrease rapidly at the injection point in the first hours after administration with a parallel increase in the lymph nodes and to a lesser extent in the liver and spleen. In addition, we observed that 3.5% of the injected indium dose was excreted in faeces in the first 4 days, with only trace quantities in the urine. Metastatic spread to the lymph nodes may hamper its visualisation. Therefore, we further performed non-invasive fluorescence measurement of QDs in SLN in tumour-bearing mice. Metastatic status was assessed by immunohistology and molecular techniques and revealed the utmost metastatic invasion of 36% of SLN. Fluorescence signal was the same irrespective of SLN status. Thus, near-infrared emitting cadmium-free QDs could be an excellent SLN tracer.

Aptamers as remarkable diagnostic and therapeutic agents in cancer treatment.

Abstract: Nucleic acid aptamers are molecules that are being used in a large number of biomedical applications. Aptamers have the properties to bind to a wide range of molecules with high specificity and affinity for their target. These properties together with their small size and their ease of synthesis make them very attractive and promising for targeting diseases and therapeutic applications. Aptamers can serve as cancer diagnostic tools by detecting specific biomarkers, circulating cancer cells or imaging diseased tissue. On the other hand, aptamers can be used as therapeutic agents due to their potential antagonist activity, or as targeting agents. Therefore, they can be designed to deliver antitumor molecules such as chemotherapeutic drugs, siRNA or photodynamic therapy sensitizers to diseased tissues. Attempts are also made to synthesize aptamers-targeted nanoplatforms capable to ferry cargo and load onto them both imaging and therapeutic functions creating so called nanotheragnostics agents. In the future, its seems likely that aptamers will play an important role in diagnosis and treatment of several pathologies including cancer.

Fluorescence diagnosis of bladder cancer: a novel in vivo approach using 5-aminolevulinic acid (ALA) dendrimers.

Abstract: What's known on the subject? and What does the study add? Fluorescence cystoscopy with hexylaminolevulinate (h-ALA, Hexvix®) is known to improve tumour detection in non-muscle-invasive bladder cancer. However, specificity is relatively low and the intensity of the observed fluorescence signal decreases over time due to protoporphyrin IX (PpIX) efflux. This study evaluates in an in vivo model the use of a dendritic 5-aminolevulinic acid compound for fluorescence diagnosis. Fluorescence ratios between tumour and urothelium as well as muscle were significantly better as compared with h-ALA. Sustained synthesis of PpIX accounts for preservation of fluorescence for >24 h. OBJECTIVE • To overcome the relative lack of tumour selectivity of fluorescence-guided cystoscopy using 5-aminolevulinic acid (ALA) or its ester derivative (e.g. hexylaminolevulinate, h-ALA; Hexvix®), we evaluated the use of dendrimers bearing different ALA loads in rats bearing orthotopic bladder tumours. MATERIALS AND METHODS • Rat bladders were instilled with h-ALA or ALA dendrimers and fluorescence ratio between tumour and normal urothelium, as well as tumour and muscle and depth of fluorescence were determined with Image J software. • Quantification of ALA and/or esters systemic reabsorption was evaluated by high-performance liquid chromatography. RESULTS • Slow hydrolysis of ALA from dendrimers as observed in vitro implies a higher initial ALA load and longer resting times in vivo. Sustained synthesis of protoporphyrin IX (PpIX) explains persistence of fluorescence for >24 h. • There were significantly better fluorescence ratios with dendrimers, as well as higher penetration depths and absence of systemic reabsorption. CONCLUSION • The prolonged and sustained PpIX synthesis, the improved tumour selectivity with a deeper penetration and the absence of systemic reabsorption are primary indicators that ALA dendrimers could be an alternative to h-ALA in fluorescence-guided cystoscopy.

Animal models for photodiagnosis and photodynamic therapy

Abstract: A prerequisite for starting a clinical trial is evidence of a positive impact of the technique or drug used in animals. The choice of the animal models is thus very important and should mimic as closely as possible the human situation. A variety of animal models has been validated for pharmaceutical trials. The situation in phototheranostics however is not fully clear. This is due to the very complex interplay of various elements such as vascularisation, oxygenation, drug availability and biodistributrion, light absorption and scattering etc. The present paper will give general information on aspects of animal models that have to be considered in phototheranostics as well as highlight some typical animal models that are useful for the investigation of light tissue interactions.

Contrasting facets of nanoparticles-based phototherapy : photo-damage and photo-regeneration

Abstract: The present review describes two different applications of the phototherapy. The first one referred as Photodynamic Therapy (PDT) is widely used for pathologically proliferated tissues, including cancer. PDT is based on the combined action of three parameters: photosensitizer, light and oxygen, resulting in the production of toxic reactive oxygen species. To improve the selectivity of phosensitizers for pathological tissues the liposomal photosensitizers formulations have been proposed favoring tumor targeting. The comprehension of the mechanisms that govern the drug release processes of photosensitizers in liposomal nanostructures and as such their pharmacokinetics behavior is essential and is addressed in the present review. Another facet of nanoparticles-based photoinduced therapy is related to tissue regeneration. Complex mechanisms of photoinduced wound healing and repair will be considered, including the role of different cell types, growth factors and antimicrobial action. In conclusion, PDT offers two contrasting strategies either to eradicate pathological tissues or to stimulate tissue repair. In fine, consideration of all parameters involved in this kind of phototherapy is required to obtain a desired effect and optimize clinical protocols.

Biodistribution of near-infrared emitting CuInS2/ZnS Quantum Dots by mass spectroscopy and fluorescence imaging of sentinel lymph node in mice

Abstract: Background: The biopsy of the sentinel lymph nodes in breast cancer patients is now strongly recommended for the definition of the further therapeutic strategy. Although this approach has strong advantages, it has its own limitations (manipulation of radioactive products and possible anaphylactic reactions to the dye). As recently proposed, these limitations could in principle be by-passed if semiconductor nanoparticles (quantum dots or QDs) were used as fluorescent contrast agents for the in vivo imaging of sentinel lymph nodes [1]. QDs are fluorescent nanoparticles with unique optical properties like strong resistance to photobleaching, size dependent emission wavelength, large molar extinction coefficient and good quantum yield [2]. Most synthesized QDs are composed of toxic heavy metals (Cd, Te, Se,...) and as such could not be used in the clinical context. Recently, we have demonstrated excellent imaging properties of Cd-free QDs for in vivo lymph nodes detection along with the greatly diminished acute inflammation in healthy rodents [3, 4]. Far before the clinical settings could be envisaged, the study on biodistribution of CuInS2/ZnS QDs in pre-clinical models and the possibility of visualization of lymph nodes upon metastatic dissemination is mandatory. Material and Methods: In vitro studies: The toxicity of CuInS2/ZnS core/shell QD on red blood cells has been tested using the haemolysis test. Red blood cells were incubated during 2h with different concentration of QDs and the release of haemoglobin was measured by spectrophotometry. In vivo studies: Healthy or tumor-bearing mice received 20 μL of 1 μM CuInS2/ZnS core/shell QD solution subcutaneously in the right anterior paw. Right axillary lymph nodes (RALN) were visualized using a near-infrared imaging system (Fluobeam™) and healthy animals were sacrificed at different time points after QDs injection. Organs, blood and excretions were collected and their indium content was measured by ICP-MS. The sentinel lymph node of tumor-bearing mice was imaged by fluorescence and the metastatic involvement of lymph nodes was assessed by the measurement of cytokeratin 19 by RT-qPCR or immunohistochemistry. Results and Discussion: In vitro assessed toxicity: No haemolysis of red blood cells was detected in the range of concentrations of CuInS2/ZnS QDs from 25 to 150 nM, while Cd-based QDs induced 50% of hemolysis with already 56.3 nM (data not shown). In vivo studies: CuInS2/ZnS QDs were observed in RALN as soon as 5 min (Fig. 1) and up to 7 days after the subcutaneous injection of QD in the right anterior paw by in vivo NIR fluorescence imaging.