Improved pharmacokinetic and lymphatic uptake of Rose Bengal after transfersome intradermal deposition using hollow microneedles.

The lymphatic system is active in several processes that regulate human diseases, among which cancer progression stands out. Thus, various drug delivery systems have been investigated to promote lymphatic drug targeting for cancer therapy; mainly, nanosized particles in the 10-150 nm range quickly achieve lymphatic vessels after an interstitial administration. Herein, a strategy to boost the lymphotropic delivery of Rose Bengal (RB), a hydrosoluble chemotherapeutic, is proposed, and it is based on the loading into Transfersomes (RBTF) and their intradermal deposition in vivo by microneedles. RBTF of 96.27 ± 13.96 nm (PDI = 0.29 ± 0.02) were prepared by a green reverse-phase evaporation technique, and they showed an RB encapsulation efficiency of 98.54 ± 0.09%. In vitro, RBTF remained physically stable under physiological conditions and avoided the release of RB. In vivo, intravenous injection of RBTF prolonged RB half-life of 50 min in healthy rats compared to RB intravenous injection; the RB half-life in rat body was further increased after intradermal injection reaching 24 h, regardless of the formulation used. Regarding lymphatic targeting, RBTF administered intravenously provided an RB accumulation in the lymph nodes of 12.3 ± 0.14 ng/mL after 2 h, whereas no RB accumulation was observed after RB intravenous injection. Intradermally administered RBTF resulted in the highest RB amount detected in lymph nodes after 2 h from the injection (84.2 ± 25.10 ng/mL), which was even visible to the naked eye based on the pink colouration of the drug. In the case of intradermally administered RB, RB in lymph node was detected only at 24 h (13.3 ± 1.41 ng/mL). In conclusion, RBTF proved an efficient carrier for RB delivery, enhancing its pharmacokinetics and promoting lymph-targeted delivery. Thus, RBTF represents a promising nanomedicine product for potentially facing the medical need for novel strategies for cancer therapy.

Improving Dermal Delivery of Rose Bengal by Deformable Lipid Nanovesicles for Topical Treatment of Melanoma.

Cutaneous melanoma is one of the most aggressive and metastatic forms of skin cancer. However, current therapeutic options present several limitations, and the annual death rate due to melanoma increases every year. Dermal delivery of nanomedicines can effectively eradicate primary melanoma lesions, avoid the metastatic process, and improve survival. Rose Bengal (RB) is a sono-photosensitizer drug with intrinsic cytotoxicity toward melanoma without external stimuli but the biopharmaceutical profile limits its clinical use. Here, we propose deformable lipid nanovesicles, also known as transfersomes (TF), for the targeted dermal delivery of RB to melanoma lesions to eradicate them in the absence of external stimuli. Considering RB's poor ability to cross the stratum corneum and its photosensitizer nature, transfersomal carriers were selected simultaneously to enhance RB penetration to the deepest skin layers and protect RB from undesired photodegradation. RB-loaded TF dispersion (RB-TF), prepared by a modified reverse-phase evaporation method, were nanosized with a ζ-potential value below -30 mV. The spectrophotometric and fluorimetric analysis revealed that RB efficiently interacted with the lipid phase. The morphological investigations (transmission electron microscopy and small-angle X-ray scattering) proved that RB intercalated within the phospholipid bilayer of TF originating unilamellar and deformable vesicles, in contrast to the rigid multilamellar unloaded ones. Such outcomes agree with the results of the in vitro permeation study, where the lack of a burst RB permeation peak for RB-TF, observed instead for the free drug, suggests that a significant amount of RB interacted with lipid nanovesicles. Also, RB-TF proved to protect RB from undesired photodegradation over 24 h of direct light exposure. The ex vivo epidermis permeation study proved that RB-TF significantly increased RB's amount permeating the epidermis compared to the free drug (78.31 vs 38.31%). Finally, the antiproliferative assays on melanoma cells suggested that RB-TF effectively reduced cell growth compared to free RB at the concentrations tested (25 and 50 µM). RB-TF could potentially increase selectivity toward cancer cells. Considering the outcomes of the characterization and cytotoxicity studies performed on RB-TF, we conclude that RB-TF represents a valid potential alternative tool to fight against primary melanoma lesions via dermal delivery in the absence of light.

Exploiting a Rose Bengal-bearing, oxygen-producing nanoparticle for SDT and associated immune-mediated therapeutic effects in the treatment of pancreatic cancer.

Sonodynamic therapy (SDT) is an emerging stimulus-responsive approach for the targeted treatment of solid tumours. However, its ability to generate stimulus-responsive cytotoxic reactive oxygen species (ROS), is compromised by tumour hypoxia. Here we describe a robust means of preparing a pH-sensitive polymethacrylate-coated CaO2 nanoparticle that is capable of transiently alleviating tumour hypoxia. Systemic administration of particles to animals bearing human xenograft BxPC3 pancreatic tumours increases oxygen partial pressures (PO2) to 20-50 mmHg for over 40 min. RT-qPCR analysis of expression of selected tumour marker genes in treated animals suggests that the transient production of oxygen is sufficient to elicit effects at a molecular genetic level. Using particles labelled with the near infra-red (nIR) fluorescent dye, indocyanine green, selective uptake of particles by tumours was observed. Systemic administration of particles containing Rose Bengal (RB) at concentrations of 0.1 mg/mg of particles are capable of eliciting nanoparticle-induced, SDT-mediated antitumour effects using the BxPC3 human pancreatic tumour model in immuno-compromised mice. Additionally, a potent abscopal effect was observed in off-target tumours in a syngeneic murine bilateral tumour model for pancreatic cancer and an increase in tumour cytotoxic T cells (CD8+) and a decrease in immunosuppressive tumour regulatory T cells [Treg (CD4+, FoxP3+)] was observed in both target and off-target tumours in SDT treated animals. We suggest that this approach offers significant potential in the treatment of both focal and disseminated (metastatic) pancreatic cancer.

pH-Sensitive mesoporous silica nanoparticles for chemo-photodynamic combination therapy.

In order to optimize the chemotherapeutic efficacy of doxorubicin (DOX) and improve the photodynamic therapeutic effectiveness of rose bengal (RB), a mesoporous silica nanoparticle system was designed as the carrier of RB and DOX for chemo-photodynamic combination therapy. A pH-sensitive strategy has been exploited to enhance the delivery efficiency. Our results suggested that the production of singlet oxygen was independent of the release of RB while strongly influenced by the external DOX layer. This method showed several benefits, including accelerating cellular uptake of the payloads and enabling chemo-photodynamic combination therapy for synergistic cancer treatment. Our study provides a new way for co-delivery of chemotherapy agents and photosensitizers.

Release of membrane-associated mucins from ocular surface epithelia.

PURPOSE: Three membrane-associated mucins (MAMs)--MUC1, MUC4, and MUC16--are expressed at the ocular surface epithelium. Soluble forms of MAMs are detected in human tears, but the mechanisms of their release from the apical cells are unknown. The purpose of this study was to identify physiologic agents that induce ocular surface MAM release. METHODS: An immortalized human corneal-limbal epithelial cell line (HCLE) expressing the same MAMs as native tissue was used. An antibody specific to the MUC16 cytoplasmic tail was developed to confirm that only the extracellular domain is released into the tear fluid or culture media. Effects of agents that have been shown to be present in tears or are implicated in the release or shedding of MAMs in other epithelia (neutrophil elastase, tumor necrosis factor [TNF]), TNF-alpha-converting enzyme, and matrix metalloproteinase-7 and -9) were assessed on HCLE cells. HCLE cell surface proteins were biotinylated to measure the efficiency of induced MAM release and surface restoration. Effects of induced release on surface barrier function were measured by rose bengal dye penetrance. RESULTS: MUC16 in tears and in HCLE-conditioned medium lacked the cytoplasmic tail. TNF induced the release of MUC1, MUC4, and MUC16 from the HCLE surface. Matrix metalloproteinase-7 and neutrophil elastase induced the release of MUC16 but not of MUC1 or MUC4. Neutrophil elastase removed 68% of MUC16, 78% of which was restored to the HCLE cell surface 24 hours after release. Neutrophil elastase-treated HCLE cells showed significantly reduced rose bengal dye exclusion. CONCLUSIONS: Results suggest that the extracellular domains of MUC1, MUC4, and MUC16 can be released from the ocular surface by agents in tears. Neutrophil elastase and TNF, present in higher amounts in the tears of patients with dry eye, may cause MAM release, allowing rose bengal staining.

Synthesis of amphiphilic derivatives of rose bengal and their tumor accumulation.

It is known that the combination of laser light and its sensitizer is effective for noninvasive tumor treatment, referred to as photodynamic therapy. Using the combination of ultrasound and its sensitizer has also been suggested for a similar kind of tumor treatment, referred to as sonodynamic therapy. The purpose of this paper is to obtain such sensitizers accumulating selectively in tumors. Amphiphilic derivatives of rose bengal (RB) were synthesized to add a tumor-accumulating property to RB. One type of the synthesized RB derivatives (RBD3), having an alkyl chain with a branching carboxyl group, was found to be superior in amphiphilicity to the other types. Tumor tissue distribution of the synthesized derivatives in mice bearing colon 26 carcinoma was evaluated. It was found that RBD3s with carbon chain lengths of 12, 14, and 16 had higher concentrations in the tumor tissue than RB by more than 1 order of magnitude, several hours after administration. The concentrations correlated well with their water/1-octanol partition coefficients. Since RB is known to induce in vitro cell damage in combination with either laser light or ultrasound, the newly synthesized amphiphilic RB derivatives may be potentially useful as a tumor-selective sensitizer for both light and ultrasound.

Firefly luciferin-activated rose bengal: in vitro photodynamic therapy by intracellular chemiluminescence in transgenic NIH 3T3 cells.

Photodynamic therapy (PDT) of cancer (1, 2) is a well-established treatment modality that uses light excitation of a photosensitive substance to produce oxygen-related cytotoxic intermediates, such as singlet oxygen or free radicals (3, 4). Although PDT is advantageous over other forms of cancer treatments because of its limited side effects, its main disadvantage is the poor accessibility of light to more deeply lying malignancies. External light sources such as lasers or lamps can be applied either noninvasively to reach tumors that lie well within the penetration depth of the light or in a minimally invasive fashion (interstitial treatments) in which optical fibers are placed intratumorally through needles. Even with the second approach, light distribution over the tumor is not homogeneous and nonidentified metastatic disease is left untreated. CL, the chemical production of light, is exemplified by firefly light emission mediated by the enzymatic (luciferase + ATP) oxidation of D-luciferin to oxyluciferin (5). This mobile light source is a targetable alternative to external sources of illumination. Here we show the in vitro photodynamic effect of rose bengal activated by intracellular generation of light, in luciferase-transfected NIH 3T3 murine fibroblasts.

Topical rose bengal: pre-clinical evaluation of pharmacokinetics and safety.

BACKGROUND AND OBJECTIVES: Rose bengal (RB) is a potent photosensitizer that has largely been overlooked as a potential photodynamic therapy (PDT) agent. In this study, the feasibility of topical delivery of RB to the epidermis has been evaluated. STUDY DESIGN/MATERIALS AND METHODS: Topical formulations of RB were assessed on murine and rabbit skin for pharmacokinetic properties, cutaneous toxicity, and photosensitization. RESULTS: Hydrophilic formulations (

Site-directed photochemical disruption of the actin cytoskeleton by actin-binding Rose Bengal-conjugates.

The in situ light-induced, non-enzymatic digestion of cytoskeletal actin by a xanthene dye conjugated to heavy meromyosin, anti-actin antibodies and/or anti-myosin antibodies is reported. The dye Rose Bengal was conjugated to either anti-actin antibodies, anti-myosin antibodies or heavy meromyosin. Under our experimental conditions, visible light induced the non-enzymatic breakdown of cytoskeletal actin when mammalian tissue culture cells were probed either with Rose Bengal-conjugated anti-actin and/or anti-myosin antibodies. Similar results were obtained when tissue culture cells were probed with Rose Bengal-conjugated heavy meromyosin before irradiation with visible light. The in situ photochemical reaction depended on the presence of actin-binding Rose Bengal-conjugates.

Localization of rose bengal, aluminum phthalocyanine tetrasulfonate, and chlorin e6 in the rabbit eye.

PURPOSE: The localization and site of action of photosensitizers in the eye may be important for photodynamic therapy for fundus disorders but remain poorly understood for most agents. We investigated the intraocular localization of xanthene, phthalocyanine, and chlorin photosensitizers by using fluorescence microscopy and digital fundus fluorescence angiography. METHODS: Rose bengal (40 mg/kg), aluminum phthalocyanine tetrasulfonate (CASPc) (5 mg/kg), or chlorin e6 (2 mg/kg) was intravenously administered to albino rabbits. The eyes were enucleated and examined by means of fluorescence microscopy 5, 20, 60, and 120 minutes and 24 hours after dye injection. In vivo digital fundus fluorescence angiography with use of rose bengal (2-4 mg/kg), CASPc (2 mg/kg), and chlorin e6 (2 mg/kg) was performed. RESULTS: For all agents studied pathologically, there was moderate fluorescence from the choroid and retinal pigment epithelium 5 minutes after dye injection. Mild fluorescence detected from the photoreceptor outer segments at 5 minutes was increased at 20 minutes. Angiographic studies with use of rose bengal, CASPc, and chlorin e6 revealed differences in the pattern and rate of photosensitizer accumulation. CONCLUSIONS: Rose bengal, CASPc, and chlorin e6 accumulate rapidly in the choroid and retinal pigment epithelium and less rapidly in the outer retina. Differences in ocular localization of these photosensitizers were demonstrated. The significance of these findings for potential photodynamic therapy with these agents requires further investigation.

Photosensitizer accumulation in spontaneous multidrug resistant cells: a comparative study with Rhodamine 123, Rose Bengal acetate and Photofrine.

The influence both of overexpression of multidrug transporter proteins and of phenotype changes occurring in cells developing spontaneous resistance on the accumulation of photosensitizer molecules was studied on two tumor-derived cell lines (B16, A2780) expressing the MDR-1 phenotype. Rhodamine 123, Rose Bengal acetate (a fluorogenic substrate that is restored to the native active molecule by specific enzyme activity inside cells) and Photofrin were considered. The two resistant variants accumulate Rhodamine 123 to a lesser extent than the respective wild types. Treatment with verapamil markedly enhances Rhodamine 123 accumulation in resistant cells, blocking the drug's extrusion. The amount of Rose Bengal is larger in resistant cells than in wild type cells. Verapamil does not affect drug accumulation, although it significantly impairs the efflux process. The results are explained by the enhancement of both membrane traffic and esterase activity resulting in intracellular Rose Bengal production that counterbalances the increased ability in the outward transport of resistant cells. Photofrin is accumulated to a lower degree in resistant than in wild type cells. Verapamil does not alter the drug accumulation, although the release process is somewhat affected. Different intracellular turnovers of Photofrin take place in the cell variants, and the release of the monomeric fluorescent fractions is greater in resistant than in wild type cells.

Hepatobiliary excretion of bile acids and rose bengal in streptozotocin-induced and genetic diabetic rats.

Divergent opinions regarding the effect of streptozotocin- (STZ) induced diabetes on bile flow rate may be due to the differing lengths of time after STZ administration at which bile flow was measured. Also, the biliary excretion of bile acids can influence the canalicular transport of several organic anions. Therefore, the hepatic clearance of the bile acid-dependent organic anion rose bengal was studied over a 30-day period in STZ-induced insulin-dependent Sprague-Dawley diabetic rats with elevated bile acid pools and in fatty noninsulin-dependent diabetic and lean Wistar rats. Excretion of total bile acids and rose bengal was higher in diabetic rats than in Sprague-Dawley control or lean or fatty Wistar rats. Depletion of bile acids for 10 hr in the 30-day STZ rat prevented the increased excretion of rose bengal. Bile flow rates in fatty and lean Wistar rats were similar to that in Sprague-Dawley controls. Increased bile acid excretion 7 and 14 days after STZ was not accompanied by the expected significant increase in bile flow, reflecting decreased bile acid-independent bile flow, regardless of method of calculation of bile flow (per g liver or per kg body weight). By 30 days, there were significant increases in bile acid excretion and bile flow. The increased clearance of rose bengal 7 days after STZ indicates that pathophysiological changes in the hepatocyte begin soon after the initiation of diabetes. Studies of taurocholate uptake into liver plasma membrane vesicles indicated that the maximal velocity of transport across the basolateral membrane was increased with no change in Km. This change was not observed in vesicles from insulin-treated diabetic rats. Therefore, studies employing STZ need to allow time for STZ toxicity to be overcome and for the pathology of diabetes to become established, to accurately reflect the diabetic condition.

Chronic voluntary exercise may alter hepatobiliary clearance of endogenous and exogenous chemicals in rats.

A chronic voluntary exercise paradigm, which mimics the exercise pattern of many humans, influences the hepatic clearance of several organic anions and a bile acid, whereas a neutral organic compound is seemingly unaffected. To extend these observations, the present work has evaluated in female Sprague-Dawley rats the effect of 6 weeks of voluntary running on the hepatobiliary elimination of endogenous bile acids and glutathione and exogenously injected rose bengal, digoxin, and acetaminophen. Inactive rats had mobility limited to their cages, whereas exercised rats had free access to a 44-in running wheel. In comparison to weight-matched sedentary rats, the exercised rats ran 4.3 +/- 0.3 miles/day, consumed 45% more food daily, had slightly greater liver/body weight ratios, and slightly elevated basal bile flow rates. Biliary excretion of endogenous bile acids was increased significantly, and excretion of reduced and oxidized glutathione was increased in exercised rats by 190% and 173% of sedentary levels, respectively. Total clearance, biliary clearance, and maximal biliary excretion of the injected organic anion rose bengal (60 mumol/kg) were elevated in exercised rats by 86%, 440%, and 85%, respectively. In contrast, there were no observed differences in pharmacokinetic parameters, serum elimination, or biliary excretion for the clinically important cardiac glycoside digoxin (dose of 100 nmol/kg). Finally, study of the analgesic acetaminophen (330 mumol/kg) revealed that total and biliary clearances were increased by 37% and 42%, respectively, in exercised rats, whereas steady-state volume of distribution and elimination half-life were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)

Biliary excretion of cholephilic organic dyes in glutathione-depleted rats.

Sprague-Dawley rats were treated with a combination of buthionine sulfoximine (2.5 mmol/kg body wt) and diethyl maleate (6.2 mmol/kg). After 4 h, the hepatic glutathione was depleted to 0.02 +/- 0.01 mumol/g liver (mean +/- SD, n = 6) (4.73 +/- 0.29 mumol/g in controls (n = 6), p < 0.005). The bile flow rate was lower in treated animals than in controls (39.0 +/- 11.2 vs. 73.7 +/- 13.7 microliters.kg-1.min-1, p < 0.005). Bile concentrations of bile acids, phospholipids, and cholesterol were not changed compared to controls, while glutathione was virtually absent from the bile. A bolus of indocyanine green (6.5 mumol/kg), rose bengal (6.5 mumol/kg), or sulfobromophthalein-glutathione conjugate (20 mumol/kg) was injected i.v. and the biliary excretion was monitored. In glutathione-depleted rats, the excretion of indocyanine green was delayed, and the cumulative excretion in 90 min was 36 +/- 8% (n = 6) of the injected dose (79 +/- 18% in controls (n = 7), p < 0.005). The bile concentration of indocyanine green was lower in the glutathione-depleted rats than in controls, while the other dyes increased. The plasma disappearance curve of indocyanine green was not significantly altered by the treatment, whereas the hepatic retention of indocyanine green 90 min after the injection was significantly increased (58 +/- 12% of the injected dose vs. 8 +/- 2% in controls, p < 0.005). The results indicate that depletion of hepatic glutathione inhibits biliary excretion of indocyanine green.