Unleashing the potential of 5-Aminolevulinic acid: Unveiling a promising target for cancer diagnosis and treatment beyond photodynamic therapy

The therapeutic properties of 5-aminolevulinic acid (5-ALA) have been extensively studied for cancer detection and treatment using photodynamic therapy (PDT). When administered externally, 5-ALA is converted to protoporphyrin IX (PpIX) in cancer cells, which generates reactive oxygen species (ROS) upon exposure to light. This process enables targeted cell death induction and cancer detection. Given the highly conserved nature of heme biosynthesis over billions of years, we hypothesized that natural mechanisms might exist to prevent excessive accumulation of PpIX or heme resulting from 5-ALA overload. Therefore, we anticipated alterations in protein expression profiles upon exogenous administration of 5-ALA. To understand cellular responses to 5-ALA, we investigated protein expression changes and identified OR1B1 as a promising target in bladder, prostate, lung, and cervical cancer cells. OR1B1 expression was observed only with 5-ALA and ferrous chloride, highlighting the central role of heme in this discovery. Immunofluorescence and electron microscopy confirmed OR1B1's sub-cellular localization. These findings suggest that 5-ALA transformation in cancer cells and OR1B1 expression have potential for enhancing cancer detection and developing alternative treatments, including immunotherapy. This approach overcomes the limitations of PDT and opens new avenues for effective and targeted cancer interventions.

A step ahead to enhancing routine breast cancer resection: Spheroid and hen's egg chorioallantoic membrane models to assess the photodynamic diagnosis efficiency of ALA and PSI-ALA-hex

Aminolevulinic acid (ALA) and its derivatives have been used in the diagnosis of several diseases through topical, intravesical, and oral administration. However, their intravenous use for the theranostics of cancers has not raised interest despite its potential advantages. In this study, we compared the efficacy of ALA, its hexyl ester ALA-Hex, and our new derivative PSI-ALA-Hex to induce a fluorescent protoporphyrin IX (PpIX) overproduction in breast cancers. First, we tested the drugs on four subtypes of breast cancer spheroids in vitro. Our results demonstrated the capacity of ALA-Hex and PSI-ALA-Hex to produce PpIX in all breast spheroids, although ALA struggled in half of the models. We applied the chick embryo in vivo model to investigate the intravenous administration route of ALA and PSI-ALA-Hex, ALA-Hex being toxic. We engrafted breast cancer nodules having various hormonal profiles onto the chorioallantoic membrane of the eggs. They were all detected by fluorescence imaging with mild efficacy using PSI-ALA-Hex, which displayed a maximum selectivity of 2.2 to 2.9, whereas ALA showed a higher selectivity from 3.2 to 5.1 at 300 μmol/kg. PSI-ALA-Hex was less appropriate for the diagnosis of breast cancer by intravenous administration. We show for the first time, to the best of our knowledge, the photodetection and imaging of a wide range of breast tumors in vivo upon intravenous treatment with ALA.

Modulation and proteomic changes on the heme pathway following treatment with 5-aminolevulinic acid

5-ALA-mediated photodynamic therapy (PDT) has been developed around the heme biosynthesis physiological pathway. It is based on the external supplementation of 5 aminolevulinic acid (5-ALA), increasing the activity of the heme pathway and leading to a significant protoporphyrin IX (PpIX) accumulation. Interestingly, this metbolite accumulation is predominant in cancer cells, induced by a highly active metabolism, therefore limiting off-target side effects and increasing therapy specificity. Nevertheless, the intrinsic mechanism responsible of PpIX accumulation on cells following PDT is still unknown, limiting clinical therapy translation. In order to further understand the mechanisms behind 5-ALA-induced PDT, in this study we aimed to evaluate the proteome changes reported on the physiological heme pathway, in response to an external 5-ALA supplementation. We studied two different scenarios following 5-ALA treatment, 5-ALA accumulation (5-ALA metabolization into the heme pathway blocked with inhibitors) and accumulation of PpIX (normal heme pathway with 5-ALA supplementation). Therefore, we were able to characterize enzymatic changes and to describe bottlenecks in the pathway. Following mass spectrometry analysis, we reported significant differences between 5-ALA and PpIX effects on heme biosynthesis and regulation of degradation. 5-ALA accumulation significantly decreased porphobilinogen deaminase (HMBS) expression, while phorphyrins accumulation (PpIX) upregulated heme synthesis, specifically HMBS and uroporphyrinogen decarboxylase (UROD), and enhanced the enzymatic level of the heme degradation pathway, including Heme oxygenase 1 (HMOX1) and biliverdin reductase A (BLVRA). Interestingly, porphyrins induced a significant downregulation effect on oxygen-dependent coproporphyrinogen-III oxidase (CPOX). In conclusion, in this study we demonstrated that porphyrins play the most relevant role in heme biosynthesis modulation, while 5-ALA alone (PDT substrate) is not responsible of the main changes observed in this pathway during PDT treatment. Understanding heme enzyme modulation would help to design a more rational approach for patient treatment in the clinic. AIM: Effect of 5-ALA and porphyrins on the different Heme biosynthesis and degradation enzymes.

A Recap of Heme Metabolism towards Understanding Protoporphyrin IX Selectivity in Cancer Cells

Mitochondria are essential organelles of mammalian cells, often emphasized for their function in energy production, iron metabolism and apoptosis as well as heme synthesis. The heme is an iron-loaded porphyrin behaving as a prosthetic group by its interactions with a wide variety of proteins. These complexes are termed hemoproteins and are usually vital to the whole cell comportment, such as the proteins hemoglobin, myoglobin or cytochromes, but also enzymes such as catalase and peroxidases. The building block of porphyrins is the 5-aminolevulinic acid, whose exogenous administration is able to stimulate the entire heme biosynthesis route. In neoplastic cells, this methodology repeatedly demonstrated an accumulation of the ultimate heme precursor, the fluorescent protoporphyrin IX photosensitizer, rather than in healthy tissues. While manifold players have been proposed, numerous discrepancies between research studies still dispute the mechanisms underlying this selective phenomenon that yet requires intensive investigations. In particular, we wonder what are the respective involvements of enzymes and transporters in protoporphyrin IX accretion. Is this mainly due to a boost in protoporphyrin IX anabolism along with a drop of its catabolism, or are its transporters deregulated? Additionally, can we truly expect to find a universal model to explain this selectivity? In this report, we aim to provide our peers with an overview of the currently known mitochondrial heme metabolism and approaches that could explain, at least partly, the mechanism of protoporphyrin IX selectivity towards cancer cells.

Definition of Local Spatial Densities in Hadrons

We show that the matrix element of a local operator between hadronic states can be used to unambiguously define the associated spatial density. As an explicit example, we consider the charge density of a spinless particle and clarify its relationship to the electric form factor. Our results lead to an unconventional interpretation of the spatial densities of local operators and their moments.

Cathepsin B-Cleavable Polymeric Photosensitizer Prodrug for Selective Photodynamic Therapy: In Vitro Studies

Cathepsin B is a lysosomal cysteine protease that plays an important role in cancer, atherosclerosis, and other inflammatory diseases. The suppression of cathepsin B can inhibit tumor growth. The overexpression of cathepsin B can be used for the imaging and photodynamic therapy (PDT) of cancer. PDT targeting of cathepsin B may have a significant potential for selective destruction of cells with high cathepsin B activity. We synthesized a cathepsin B-cleavable polymeric photosensitizer prodrug (CTSB-PPP) that releases pheophorbide a (Pha), an efficient photosensitizer upon activation with cathepsin B. We determined the concentration dependant uptake in vitro, the safety, and subsequent PDT-induced toxicity of CTSB-PPP, and ROS production. CTSB-PPP was cleaved in bone marrow cells (BMCs), which express a high cathepsin B level. We showed that the intracellular fluorescence of Pha increased with increasing doses (3-48 µM) and exerted significant dark toxicity above 12 µM, as assessed by MTT assay. However, 6 µM showed no toxicity on cell viability and ex vivo vascular function. Time-dependent studies revealed that cellular accumulation of CTSB-PPP (6 µM) peaked at 60 min of treatment. PDT (light dose: 0-100 J/cm2, fluence rate: 100 mW/cm2) was applied after CTSB-PPP treatment (6 µM for 60 min) using a special frontal light diffuser coupled to a diode laser (671 nm). PDT resulted in a light dose-dependent reduction in the viability of BMCs and was associated with an increased intracellular ROS generation. Fluorescence and ROS generation was significantly reduced when the BMCs were pre-treated with E64-d, a cysteine protease inhibitor. In conclusion, we provide evidence that CTSB-PPP showed no dark toxicity at low concentrations. This probe could be utilized as a potential imaging agent to identify cells or tissues with cathepsin B activity. CTSB-PPP-based PDT results in effective cytotoxicity and thus, holds great promise as a therapeutic agent for achieving the selective destruction of cells with high cathepsin B activity.

Cathepsin B-Cleavable Cyclopeptidic Chemotherapeutic Prodrugs

Cyclopeptidic chemotherapeutic prodrugs (cPCPs) are macromolecular protease-sensitive doxorubicin (DOX) prodrugs synthesized from a cyclodecapeptidic scaffold, termed Regioselectively Addressable Functionalized Template (RAFT). In order to increase the chemotherapeutic potential of DOX and limit its toxicity, we used a Cathepsin B (Cat B)-sensitive prodrug concept for its targeted release since this enzyme is frequently overexpressed in cancer cells. Copper-free “click” chemistry was used to synthesize cPCPs containing up to four DOX moieties tethered to the upper face of the scaffold through a Cat B-cleavable peptidic linker (GAGRRAAG). On the lower part, PEG 5, 10 and 20 kDa and a fifth peptidyl DOX moiety were grafted in order to improve the solubility, bioavailability and pharmacokinetic profiles of the compound. In vitro results on HT1080 human fibrosarcoma cells showed that cPCPs display a delayed action that consists of a cell cycle arrest in the G2 phase comparable to DOX alone, and increased cell membrane permeability.

c(RGDfK)- and ZnTriMPyP-Bound Polymeric Nanocarriers for Tumor-Targeted Photodynamic Therapy

Active targeting strategies are currently being extensively investigated in order to enhance the selectivity of photodynamic therapy. The aim of the present research was to evaluate whether the external decoration of nanopolymeric carriers with targeting peptides could add more value to a photosensitizer formulation and increase antitumor therapeutic efficacy and selectivity. To this end, we assessed PLGA-PLA-PEG nanoparticles (NPs) covalently attached to a hydrophilic photosensitizer 5-[4-azidophenyl]-10,15,20-tri-(N-methyl-4-pyridinium)porphyrinato zinc (II) trichloride (ZnTriMPyP) and also to c(RGDfK) peptides, in order to target α_v β₃ integrin-expressing cells. In vitro phototoxicity investigations showed that the ZnTriMPyP-PLGA-PLA-PEG-c(RGDfK) nanosystem is effective at submicromolar concentrations, is devoid of dark toxicity, successfully targets α_v β₃ integrin-expressing cells and is 10-fold more potent than related nanosystems where the PS is occluded instead of covalently bound.

Correction: Cyclopeptidic photosensitizer prodrugs as proteolytically triggered drug delivery systems of pheophorbide A: part I - self-quenched prodrugs

Correction for 'Cyclopeptidic photosensitizer prodrugs as proteolytically triggered drug delivery systems of pheophorbide A: part I - self-quenched prodrugs' by Jordan Bouilloux et al., Photochem. Photobiol. Sci., 2018, 17, 1728-1738.

Correction: Cyclopeptidic photosensitizer prodrugs as proteolytically triggered drug delivery systems of pheophorbide A: part II - co-loading of pheophorbide A and black hole quencher

Correction for 'Cyclopeptidic photosensitizer prodrugs as proteolytically triggered drug delivery systems of pheophorbide A: part II - co-loading of pheophorbide A and black hole quencher' by Jordan Bouilloux et al., Photochem. Photobiol. Sci., 2018, 17, 1739-1748.

Cyclopeptidic photosensitizer prodrugs as proteolytically triggered drug delivery systems of pheophorbide A: part II - co-loading of pheophorbide A and black hole quencher

Previously, we have shown that the use of a cyclopeptidic carrier could be of great interest for the design of fully characterized prodrugs for further use in photodynamic therapy. In order to further optimize the design, we decided to modify the highly quenched conjugate uPA-cPPP_4/5 by co-loading a long-distance fluorescence quencher. For this purpose we tethered two black hole quenchers (BHQ3) together with two pheophorbide A moities onto the same PEGylated backbone and assessed the modified photophysical properties. In addition, to prove the reliability of our concept, we designed two analogues, uPA-cPPQ_2+2/5 and CathB-cPPQ_2+2/5, by using two different peptidic linkers as substrates for uPA and cathepsin B, respectively. These two conjugates proved to be much more water-soluble than their analogues bearing only Phas. These conjugates are not only highly quenched in their native state with regard to their fluorescence emission (up to 850 ± 287 times less fluorescent for CathB-cPPQ_2+2/5 as compared to the unquenched monosubstituted reference uPA-cPPP_1/5), but also prevent singlet oxygen production (with a total quenching of the emission when the quenchers are co-loaded with photosensitizers) when the photosentistizers are excited. After proteolytic activation, these conjugates recover their photophysical properties in the same way as occurred for uPA-cPPP_4/5, with up to a 120-fold increase in fluorescence emission for uPA-cPPQ_2+2/5 after two hours of incubation with uPA.

Squalene-PEG-Exendin as High-Affinity Constructs for Pancreatic Beta-Cells

Novel drug delivery systems targeting native, transplanted, or cancerous beta-cells are of utmost importance. Herein, we present new exendin-4 derivatives with modified unnatural amino acids at strategic positions within the polypeptide sequence. The modified peptides allowed modular orthogonal chemical modifications to attach imaging agents and amphiphilic squalene-PEG groups. The resulting conjugates, SQ-PEG-ExC₁-Cy5 and SQ-PEG-ExC₄₀-Cy5 fluorescence probes, display low nanomolar affinity to GLP-1R in fluorescence-based binding assays with EC₅₀ at 1.1 ± 0.2 and 0.8 ± 0.2 nM, respectively. Naturally expressing GLP-1R MIN6 cells and recombinantly transfected CHL-GLP-1R positive cells were specifically targeted by all of the new beta-cell probes in vitro. Specific islet targeting was observed after i.v. injection of SQ-PEG-ExC₁-Cy5 with SQ-PEG in normoglycemic mice ex vivo. Semiquantitative biodistribution analysis by epifluorescence indicated prolonged blood half-life (3.8 h) for the amphiphilic Ex conjugate. Liver and pancreas were identified as main biodistribution organs for SQ-PEG-ExC₁-Cy5.

5-Aminolevulinic Acid-Squalene Nanoassemblies for Tumor Photodetection and Therapy: In Vitro Studies

Protoporphyrin IX (PpIX) as natural photosensitizer derived from administration of 5-aminolevulinic acid (5-ALA) has found clinical use for photodiagnosis and photodynamic therapy of several cancers. However, broader use of 5-ALA in oncology is hampered by its charge and polarity that result in its reduced capacity for passing biological barriers and reaching the tumor tissue. Advanced drug delivery platforms are needed to improve the biodistribution of 5-ALA. Here, we report a new approach for the delivery of 5-ALA. Squalenoylation strategy was used to covalently conjugate 5-ALA to squalene, a natural precursor of cholesterol. 5-ALA-SQ nanoassemblies were formed by self-assembly in water. The nanoassemblies were monodisperse with average size of 70 nm, polydispersity index of 0.12, and ζ-potential of + 36 mV. They showed good stability over several weeks. The drug loading of 5-ALA was very high at 26%. In human prostate cancer cells PC3 and human glioblastoma cells U87MG, PpIX production was monitored in vitro upon the incubation with nanoassemblies. They were more efficient in generating PpIX-induced fluorescence in cancer cells compared to 5-ALA-Hex at 1.0 to 3.3 mM at short and long incubation times. Compared to 5-ALA, they showed superior fluorescence performance at 4 h which was diminished at 24 h. 5-ALA-SQ presents a novel nano-delivery platform with great potential for the systemic administration of 5-ALA.

Cyclopeptidic photosensitizer prodrugs as proteolytically triggered drug delivery systems of pheophorbide A: part I – self-quenched prodrugs

RAFTs bearing multiple copies of pheophorbide A allow perfectly defined photosensitizer prodrugs.

Multivariate characterization of white matter heterogeneity in autism spectrum disorder

The complexity and heterogeneity of neuroimaging findings in individuals with autism spectrum disorder has suggested that many of the underlying alterations are subtle and involve many brain regions and networks. The ability to account for multivariate brain features and identify neuroimaging measures that can be used to characterize individual variation have thus become increasingly important for interpreting and understanding the neurobiological mechanisms of autism. In the present study, we utilize the Mahalanobis distance, a multidimensional counterpart of the Euclidean distance, as an informative index to characterize individual brain variation and deviation in autism. Longitudinal diffusion tensor imaging data from 149 participants (92 diagnosed with autism spectrum disorder and 57 typically developing controls) between 3.1 and 36.83 years of age were acquired over a roughly 10-year period and used to construct the Mahalanobis distance from regional measures of white matter microstructure. Mahalanobis distances were significantly greater and more variable in the autistic individuals as compared to control participants, demonstrating increased atypicalities and variation in the group of individuals diagnosed with autism spectrum disorder. Distributions of multivariate measures were also found to provide greater discrimination and more sensitive delineation between autistic and typically developing individuals than conventional univariate measures, while also being significantly associated with observed traits of the autism group. These results help substantiate autism as a truly heterogeneous neurodevelopmental disorder, while also suggesting that collectively considering neuroimaging measures from multiple brain regions provides improved insight into the diversity of brain measures in autism that is not observed when considering the same regions separately. Distinguishing multidimensional brain relationships may thus be informative for identifying neuroimaging-based phenotypes, as well as help elucidate underlying neural mechanisms of brain variation in autism spectrum disorders.

Time-resolved singlet-oxygen luminescence detection with an efficient and practical semiconductor single-photon detector

In clinical applications, such as PhotoDynamic Therapy, direct singlet-oxygen detection through its luminescence in the near-infrared range (1270 nm) has been a challenging task due to its low emission probability and the lack of suitable single-photon detectors. Here, we propose a practical setup based on a negative-feedback avalanche diode detector that is a viable alternative to the current state-of-the art for different clinical scenarios, especially where geometric collection efficiency is limited (e.g. fiber-based systems, confocal microscopy, scanning systems etc.). The proposed setup is characterized with Rose Bengal as a standard photosensitizer and it is used to measure the singlet-oxygen quantum yield of a new set of photosensitizers for site-selective photodynamic therapy.

Multivalent glibenclamide to generate islet specific imaging probes

The monitoring of diabetes mellitus, as it develops and becomes clinically evident, remains a major challenge for diagnostic imaging in clinical practice. Here we present a novel approach to beta-cell imaging by targeting the sulphonylurea receptor subtype 1 (SUR1), using multivalent derivatives of the anti-diabetic drug glibenclamide. Since glibenclamide has a high affinity for SUR1 but does not contain a suitable functional group to be linked to an imaging probe, we have synthesized 11 glibenclamide derivatives and evaluated their affinity to SUR1 in MIN6 cells. The most promising compound has been used to obtain multivalent glibenclamide-polyamidoamine (PAMAM) derivatives, containing up to 15 sulphonylurea moieties per dendrimer. The remaining functional groups on the dendrimers can consecutively be used for labeling with reporter groups for different imaging modalities, thus allowing for multifunctional imaging, and for the modification of pharmacokinetic properties. We synthesized fluorochrome-labeled multivalent probes, that demonstrate in cellular assays affinities to SUR1 in the nanomolar range, superior to native glibenclamide. The probes specifically label MIN6 cells, but not HeLa or PANC-1 cells which do not express SUR1. A very low cytotoxicity of the multivalent probes is demonstrated by the persistent release of insulin from MIN6 cells exposed to high glucose concentrations. Furthermore, the probes display positive labeling of beta-cells of primary mouse and human islet-cells ex vivo and of islets of Langerhans in vivo. The data document that multivalent probes based on glibenclamide derivatives provide a suitable platform for further developments of cell-specific probes, and can be adapted for multiple imaging modalities, including those that are now used in the clinics.

Repeated exposures to blue light-activated eosin Y enhance inactivation of E. faecalis biofilms, in vitro

BACKGROUND

In dentistry, antibacterial photodynamic therapy (a-PDT) has shown promising results for inactivating bacterial biofilms causing carious, endodontic and periodontal diseases. In the current study, we assessed the ability of eosin Y exposed to 3 irradiation protocols at inactivating Enterococcus faecalis biofilms, in vitro.

METHODS

E. faecalis biofilms formed on hydroxyapatite disks were incubated with eosin Y (10-80μM), then activated with blue light using different irradiation protocols. Biofilms exposed to continuous exposure were incubated for 40min before being light-activated for 960 s. For the intermittent exposure, biofilms were exposed 4 times to the light/photosensitizer combination (960 s total) without renewing the photosensitizer. For repeated a-PDT, the same light dose was delivered in a series of 4 irradiation periods separated by dark periods; fresh photosensitizer was added between each light irradiation. After treatment, bacteria were immediately labeled with LIVE/DEAD BacLight Bacterial Viability kit and viability was assessed by flow cytometry (FCM). Results were statistically analyzed using one-way ANOVA and Tukey multiple comparison intervals (α=0.05).

RESULTS

The viability of E. faecalis biofilms exposed to 10μM eosin Y, was significantly reduced compared to controls (light only-eosin Y only). After a second exposure to blue light-activated eosin Y, viability significantly decreased from 58% to 12% whereas 6.5% of the bacterial biofilm remained live after a third exposure (p<0.05). Only 3.5% of the bacterial population survived after the fourth exposure.

CONCLUSIONS

The results of this study indicate that blue light-activated eosin Y can photoinactivate E. faecalis biofilms grown on hydroxyapatite disks. Also, repeated exposures to blue light-activated eosin Y were shown to significantly improve efficacy. Further studies seem warranted to optimize the antibacterial activity of blue light-activated eosin Y on major oral pathogens.

Targeting GLP-1 receptors for repeated magnetic resonance imaging differentiates graded losses of pancreatic beta cells in mice

AIMS/HYPOTHESIS

Non-invasive imaging of beta cells is a much-needed development but is one that faces significant biological and technological hurdles. A relevant imaging method should at least allow for an evaluation over time of the mass of beta cells under physiological and pathological conditions, and for an assessment of novel therapies. We, therefore, investigated the ability of a new MRI probe to repeatedly measure the loss of beta cells in a rodent model.

METHODS

We developed an innovative nanoparticle probe that targets the glucagon-like peptide 1 receptor, and can be used for both fluorescence imaging and MRI. Using fluorescence, we characterised the specificity and biodistribution of the probe. Using 1.5 T MRI, we longitudinally imaged the changes in insulin content in male and female mice of the RIP-DTr strain, which mimic the changes expected in type 1 and type 2 diabetes, respectively.

RESULTS

We showed that this probe selectively labelled beta cells in situ, imaged in vivo native pancreatic islets and evaluated their loss after diphtheria toxin administration, in a model of graded beta cell deletion. Thus, using clinical MRI, the probe quantitatively differentiates, in the same mouse strain, between female animals featuring a 50% loss of beta cells and the males featuring an almost complete loss of beta cells.

CONCLUSIONS/INTERPRETATION

The approach addresses several of the hurdles that have so far limited the non-invasive imaging of beta cells, including the potential to repeatedly monitor the very same animals using clinically available equipment, and to differentiate graded losses of beta cells.

Protoporphyrin (PPIX) efflux by the MacAB-TolC pump in Escherichia coli

In most organisms, heme biosynthesis is strictly controlled so as to avoid heme and heme precursor accumulation, which is toxic. Escherichia coli regulates heme biosynthesis by a feedback loop involving heme-induced proteolytic cleavage of HemA, glutamyl-tRNA reductase, which is the first enzyme in the heme biosynthetic pathway. We show here that heme homeostasis can be disrupted by overproduction of YfeX, a cytoplasmic protein that captures iron from heme that we named deferrochelatase. We also show that it is disrupted by iron chelation, which reduces the intracellular iron concentration necessary for loading iron into protoporphyrin IX (PPIX, the immediate heme precursor). In both cases, we established that there is an increased PPIX concentration and we demonstrate that this compound is expelled by the MacAB-TolC pump, an efflux pump involved in E. coli and Salmonella for macrolide efflux. The E. coli macAB and tolC mutants accumulate PPIX and are sensitive to photo-inactivation. The MacAB-TolC pump is required for Salmonella typhimurium survival in macrophages. We propose that PPIX is an endogenous substrate of the MacAB-TolC pump in E. coli and S. typhimurium and that this compound is produced inside bacteria when natural heme homeostasis is disrupted by iron shortage, as happens when bacteria invade the mammalian host.

Pharmaceutical technology at the service of targeted drug delivery

Research in pharmaceutical technology has drifted from formulation of systems with improved drug absorption and bioavailability to systems targeting molecular sites of diseases. The research unit of Pharmaceutical Technology from the University of Geneva focuses on the development of systems for both diagnostic and therapeutic purposes. Three types of constructs for targeting are reviewed. With a fine-tuning of size and surface composition, polymeric nanoparticles are developed to improve detection of micrometastasis by fluorescence imaging. Furthermore, surface coating with specific antibodies increase the therapeutic efficiency of the encapsulated chemotherapeutic agent for tumor treatment in animal models. Constructs that are activated by remote sources of energy are investigated in the unit. For instance, microbubbles bearing specific antibody fragments at their surface are useful contrast agents for ultrasound molecular imaging. Microbubbles, if combined with a thrombolytic drug and ultrasound, improve clot lysis, which is promising for stroke treatments. Enzymatically activated prodrug scaffolds are also under development. With this approach, intrinsic enzymatic activity of a diseased tissue activates the formulations. This concept led to the development of theranostic agents that can be used for both diagnostic and therapeutic purposes.

Matrix mediated fluorescence enhancement — why nanoparticles and PPIX make a friendly couple

The hexyl ester of 5-aminolevulinic acid (HAL) is an efficient inducer of the endogenous photosensitizer protoporphyrin IX (PPIX) in neoplastic tissue and approved for the fluorescence photodetection of bladder cancer. It is, however, limited to topical application due to unsuitable pharmacokinetic and pharmacodynamic properties following systemic administration. In this study we sought to prepare HAL laden polymeric nanoparticles made from polylactic acid (PLA) as possible means to improve the systemic bioavailability of HAL. Nanoparticles were prepared by nanoprecipitation. Particle size and morphology of freshly prepared and dehydrated nanoparticles were assessed and the ability to generate PPIX fluorescence was tested on a T24 human bladder carcinoma cell line. Fluorescence intensities of cells incubated with nanoencapsulated HAL were significantly higher than in presence of free HAL. Interestingly, the effect was — at least partly — provoked by the direct interaction of exogenously induced PPIX with the nanoparticles.

Enhanced prostate cancer targeting by modified protease sensitive photosensitizer prodrugs

Prodrugs combining macromolecular delivery systems with site-selective drug release represent a powerful strategy to increase selectivity of anticancer agents. We have adapted this strategy to develop new polymeric photosensitizer prodrugs (PPP) sensitive to urokinase-like plasminogen activator (uPA). In these compounds (to be referred to as uPA-PPPs) multiple copies of pheophorbide a are attached to a polymeric carrier via peptide linkers that can be cleaved by uPA, a protease overexpressed in prostate cancer (PCa). uPA-PPPs are non-phototoxic in their native state but become fluorescent and produce singlet oxygen after uPA-mediated activation. In the present work, we studied the influence of side-chain modifications, molecular weight, and overall charge on the photoactivity and pharmacokinetics of uPA-PPPs. An in vitro promising candidate with convertible phototoxicity was then further investigated in vivo. Systemic administration resulted in a selective accumulation and activation of the prodrug in luciferase transfected PC-3 xenografts, resulting in a 4-fold increase in fluorescence emission over time. Irradiation of fluorescent tumors induced immediate tumor cell eradication as shown by whole animal bioluminescence imaging. PDT with uPA-PPP could therefore provide a more selective treatment of localized PCa and reduce side effects associated with current radical treatments.

Like a bolt from the blue: phthalocyanines in biomedical optics

The purpose of this review is to compile preclinical and clinical results on phthalocyanines (Pcs) as photosensitizers (PS) for Photodynamic Therapy (PDT) and contrast agents for fluorescence imaging. Indeed, Pcs are excellent candidates in these fields due to their strong absorbance in the NIR region and high chemical and photo-stability. In particular, this is mostly relevant for their in vivo activation in deeper tissular regions. However, most Pcs present two major limitations, i.e., a strong tendency to aggregate and a low water-solubility. In order to overcome these issues, both chemical tuning and pharmaceutical formulation combined with tumor targeting strategies were applied. These aspects will be developed in this review for the most extensively studied Pcs during the last 25 years, i.e., aluminium-, zinc- and silicon-based Pcs.

Retigabine, a K(V)7 (KCNQ) potassium channel opener, attenuates L-DOPA-induced dyskinesias in 6-OHDA-lesioned rats

L-DOPA-induced dyskinesias (LID) represent a severe complication of long-time pharmacotherapy in Parkinson's disease that necessitates novel therapeutics. The acute and chronic effects of K(V)7.2-7.5 channel openers (retigabine, flupirtine) on the severity of LID and parkinsonian signs were examined in comparison to the glutamate receptor antagonist amantadine (positive control) in a rat model of LID. Acute treatment with retigabine (2.5, 5 mg/kg i.p.) and flupirtine (5, 10 mg/kg i.p.) significantly reduced the severity of abnormal involuntary movements (AIM) to a comparable extent as amantadine (20, 40 mg/kg s.c.), but flupirtine delayed the disappearance of AIM. Chronic treatment with retigabine (daily 5 mg/kg i.p. over 19 days combined with l-DOPA 10 mg i.p.) did not prevent or delay the development of LID, but reduced the severity of AIM, while antidyskinetic effects of amantadine (40 mg/kg i.p.) were restricted to the first day of treatment. Retigabine caused sedation and ataxia which declined during the chronic treatment, but did not reduce the antiparkinsonian effects of l-DOPA in these experiments. Acute co-injections of retigabine (5 mg) together with l-DOPA (10 mg/kg) neither reduced the motor performance in the rotarod test nor exerted negative effects on the antiparkinsonian efficacy of l-DOPA in the block and stepping test. Nevertheless, the sedative effects of retigabine may limit its therapeutic potential for the treatment of LID. The present data indicate that K(V)7 channels deserve attention in the research of the pathophysiology of dyskinesias. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.

Exercise-induced adaptations of cardiac redox homeostasis and remodeling in heterozygous SOD2-knockout mice

A reduced expression of the manganese-dependent superoxide dismutase (SOD2) is characterized by increased cardiac oxidative stress. Oxidative stress has also been described in situations of physical exercise. We investigated the influence of physical exercise (EX; treadmill 1 h/day at 15 m/min, 5 days/wk, at an angle of 5° for a duration of 8 wk) on cardiac function [heart frequency (HF), echocardiography, morphometry], oxidative stress [reactive oxygen species (ROS)], and antioxidative defence capacity (peroxiredoxin 1–6) in male SOD2-knockout (SOD2_EX) and wild-type mice (WT_EX) compared with untrained age-matched animals (WT_CON; SOD2_CON). In SOD2_CON, heart weight, cardiomyocyte diameter, and cardiac ROS were significantly larger and peroxiredoxin isoforms 4–6 lower than in WT_CON. The vessel-to-cardiomyocyte ratio, cardiac VEGF-concentration, and cardiac function were similar in SOD2_CON and WT_CON. Both groups tolerated the exercise protocol well. In WT, exercise significantly increased vessel-to-cardiomyocyte ratio and ROS-generation and downregulated peroxiredoxin isoforms 4–6 and VEGF generation. The vessel-to-cardiomyocyte ratio, cardiac VEGF concentration, and cardiac ROS were not altered in SOD2_EX compared with SOD2_CON, but a significant upregulation of cardiac peroxiredoxin 1 and 4 was observed. Similar to the result observed in WT_EX, peroxiredoxin 3 was upregulated in SOD2_EX. Chronic exercise shifted the (mal)adaptive hypertrophic into a compensated dilated cardiac phenotype in SOD2_EX. In conclusion, downregulation of SOD2 induces a maladaptive cardiac hypertrophy. In this situation, physical exercise results in a further deterioration of cardiac remodeling despite an upregulation of the antioxidative defense system.

It is all about proteases: from drug delivery to in vivo imaging and photomedicine

Clinical studies provide overwhelming evidence for the importance of proteolytic imbalance and the upregulation of diverse protease classes in diseases such as cancer and arthritis. While the complex nature of proteolytic networks has hampered the development of protease inhibitors for these indications, aberrant enzyme activity could be successfully exploited for the development of proteasesensitive drug delivery systems and fluorescent in vivo imaging agents. More recently, these concepts have also been translated into photomedical applications to develop dual modality prodrugs for the simultaneous treatment and imaging of disease. After an introductory overview of proteases and their role in cancer, we present and discuss different strategies to exploit upregulated protease activity for the development of drug delivery systems, fluorescent in vivo reporter probes, and photosensitizer-prodrugs with respect to their potential and limitations. The main approaches used for targeting proteases in all three areas can be roughly divided into peptide-based and macromolecular strategies. Both involve the use of a short, peptide-based protease substrate, which is either directly tagged to the therapeutic agent or dye/quencher pair, or alternatively, serves as a linker between the polymeric carrier and a functional unit. In the latter case, the pharmacokinetic properties of peptide-based protease-sensitive prodrugs and imaging probes can be further ameliorated by the passive targeting capacity of macromolecular drug delivery systems for neoplastic and inflammatory lesions.

Stimulation of anti-tumor immunity by photodynamic therapy

Photodynamic therapy (PDT) is a rapidly developing cancer treatment that utilizes the combination of nontoxic dyes and harmless visible light to destroy tumors by generating reactive oxygen species. PDT produces tumor-cell destruction in the context of acute inflammation that acts as a 'danger signal' to the innate immune system. Activation of the innate immune system increases the priming of tumor-specific T lymphocytes that have the ability to recognize and destroy distant tumor cells and, in addition, lead to the development of an immune memory that can combat recurrence of the cancer at a later point in time. PDT may be also successfully combined with immunomodulating strategies that are capable of overcoming or bypassing the escape mechanisms employed by the progressing tumor to evade immune attack. This article will cover the role of the immune response in PDT anti-tumor effectiveness. It will highlight the milestones in the development of PDT-mediated anti-tumor immunity and emphasize the combination strategies that may improve this therapy.

Production of reactive oxygen species from photosensitizers activated with visible light sources available in dental offices

OBJECTIVES

The aim of this study was to assess the ability of commonly available red- or blue-light dental sources to generate reactive oxygen species (ROS) from photosensitive chemicals that might be useful for photodynamic antimicrobial chemotherapy (PACT).

BACKGROUND

Although the use of red diode lasers is well documented, there is limited information on how useful blue-light sources might be for PACT in dental contexts.

MATERIALS AND METHODS

A diode laser (Periowave; see Table 1 for material and equipment sources) emitting red light (660-675 nm) was used to activate toluidine blue; riboflavin and pheophorbide-a polylysine (pheophorbide-a-PLL) were photoactivated using an Optilux 501 curing unit emitting blue light (380-500 nm). Ozone gas (generated by OzoTop, Tip Top Tips, Rolle, Switzerland), sodium hypochlorite, and hydrogen peroxide were used for comparison. ROS production was estimated using an iodine-triiodide colorimetric assay, and ROS levels were plotted versus concentration of chemicals to determine each chemical's efficiency in ROS production. One-way ANOVA with Tukey post hoc analysis (alpha = 0.05) was used to compare the efficiencies of ROS production for the various chemicals.

RESULTS

Sodium hypochlorite, hydrogen peroxide, and ozone gas produced ROS spontaneously, whereas pheophorbide-a-PLL, riboflavin, and toluidine blue required light exposure. The efficiency of ROS production was higher for pheophorbide-a-PLL and toluidine blue than for ozone gas or riboflavin (p < 0.05). Hydrogen peroxide was the least efficient ROS producer.

CONCLUSIONS

The results of the current study support the use of blue- or red-light-absorbing photosensitizers as candidates to produce ROS for clinical applications. Blue-light photosensitizers were as efficient as red-light photosensitizers in producing ROS and more efficient than the oxidant chemicals currently used for dental disinfection.

Benefit of anti-HER2-coated paclitaxel-loaded immuno-nanoparticles in the treatment of disseminated ovarian cancer: Therapeutic efficacy and biodistribution in mice

The benefit of polymeric immuno-nanoparticles (NPs-Tx-HER), consisting of paclitaxel (Tx)-loaded nanoparticles coated with anti-HER2 monoclonal antibodies (Herceptin, trastuzumab), in cancer treatment was assessed in a disseminated xenograft ovarian cancer model induced by intraperitoneal inoculation of SKOV-3 cells overexpressing HER2 antigens. The study was focused on the evaluation of therapeutic efficacy and biodistribution of NPs-Tx-HER compared to other Tx formulations. The therapeutic efficacy was determined by two methods: bioluminescence imaging and survival rate. The treatment regimen consisted in an initial dose of 20mg/kg Tx administered as 10mg/kg intravenously (IV) and 10mg/kg intraperitonealy (IP), followed by five alternative IP and IV injections of 10mg/kg Tx every 3 days. The bioluminescence study has clearly shown the superior anti-tumor activity of NPs-Tx-HER compared to free Tx. As a confirmation of these results, a significantly longer survival of mice was observed for NPs-Tx-HER treatment compared to free Tx, Tx-loaded nanoparticles coated with an irrelevant mAb (Mabthera, rituximab) or Herceptin alone, indicating the potential of immuno-nanoparticles in cancer treatment. The biodistribution pattern of Tx was assessed on healthy and tumor bearing mice after IV or IP administration. An equivalent biodistribution profile was observed in healthy mice for Tx encapsulated either in uncoated nanoparticles (NPs-Tx) or in NPs-Tx-HER. No significant difference in Tx biodistribution was observed after IV or IP injection, except for a lower accumulation in the lungs when NPs were administered by IP. Encapsulated Tx accumulated in the organs of the reticulo-endothelial system (RES) such as the liver and spleen, whereas free Tx had a non-specific distribution in all tested organs. Compared to free Tx, the single dose injection (IV or IP) of encapsulated Tx in mice bearing tumors induced a higher tumor accumulation. However, no difference in overall tumor accumulation between NPs-Tx-HER and NPs-Tx was observed. In conclusion, the encapsulation of Tx into NPs-Tx-HER immuno-nanoparticles resulted in an improved efficacy of drug in the treatment of disseminated ovarian cancer overexpressing HER2 receptors.

Decreased left posterior insular activity during auditory language in autism

BACKGROUND AND PURPOSE

Individuals with autism spectrum disorders often exhibit atypical language patterns, including delay of speech onset, literal speech interpretation, and poor recognition of social and emotional cues in speech. We acquired functional MR images during an auditory language task to evaluate systematic differences in language-network activation between control and high-functioning autistic populations.

MATERIALS AND METHODS

Forty-one right-handed male subjects (26 high-functioning autistic subjects, 15 controls) were studied by using an auditory phrase-recognition task, and areas of differential activation between groups were identified. Hand preference, verbal intelligence quotient (IQ), age, and language-function testing were included as covariables in the analysis.

RESULTS

Control and autistic subjects showed similar language-activation networks, with 2 notable differences. Control subjects showed significantly increased activation in the left posterior insula compared with autistic subjects (P < .05, false discovery rate), and autistic subjects showed increased bilaterality of receptive language compared with control subjects. Higher receptive-language scores on standardized testing were associated with greater activation of the posterior aspect of the left Wernicke area. A higher verbal IQ was associated with greater activation of the bilateral Broca area and involvement of the prefrontal cortex and lateral premotor cortex.

CONCLUSIONS

Control subjects showed greater activation of the posterior insula during receptive language, which may correlate with impaired emotive processing of language in autism. Subjects with autism showed greater bilateral activation of receptive-language areas, which was out of proportion to the differences in hand preference in autism and control populations.