Patent Application
20130336889
1. Field of the Invention
The present application relates to a nanoparticle, and more particularly relates to a nanoparticle for detection and treatment of a tumor.
2. Description of Related Art
Photothermal therapy (PTT) destroys cancer cells by generating heat within a tumor by absorbing specific light sources. A major challenge of thermal therapies is to selectively injure the targeted tissue without damaging the normal tissue Minimally invasive cancer treatments are currently being investigated, such as radiofrequency ablation, magnetic thermal ablation, focused ultrasound ablation and laser-based PTT. The effectiveness of such treatments is limited by nonspecific heating of targeted tissue, which often injures healthy tissue.
Exogenous chromophores are known to increase heat generation within targets by increasing the light sensitivity of targeted tissue. Therefore, exogenous chromophores that strongly absorb light in the near-infrared (NIR) region (650-900 nm) have been widely studied because they produce localized cytotoxic heat upon NIR irradiation. Since the tissue absorption of NIR light is minimal, it can penetrate deep into the tissue.
Polymethine cyanine dyes such as indocyanine green (ICG) are suitable contrast agents for clinical and experimental NIR imaging. ICG also exhibits unique optical properties due to its strong absorption at NIR wavelengths, which causes photothermal effects that can trigger thermal injury and cell death both in vitro and in vivo.
For hydrophobic dyes, not like ICG, polymeric nanoparticles have shown great promise in drug delivery due to their good biocompatibility, high stability both in vitro and in vivo, and successful encapsulation of various poorly soluble agents. An additional benefit of nanosized carriers is that they slowly accumulate in pathological sites, including tumors, through the enhanced permeability and retention (EPR) effect, which is known as a passive targeting. Many tumor tissues are supplied by a leaky neovasculature with an incomplete endothelial barrier and poor lymphatic drainage. The EPR phenomenon provides an opportunity for nanosized carriers to reach their target site.
However, a multifunctional nanoparticle for optical and nuclear imaging as well as for PTT is not yet available.
A nanoparticle having biodegradability and biocompatibility comprising a plurality of polymer backbones and at least one first detectable substance for detecting or treating a tumor is provided, wherein each of the plurality of polymer backbones includes a hydrophobic region, a hydrophilic region, and a chelating region, and the first detectable substance is bound to the chelating region of the polymer backbone. In one embodiment, the hydrophobic regions of the polymer backbones form a core block, and the hydrophilic regions of the polymer backbones form a shell block surrounding the core block.
In one embodiment, the hydrophilic region comprises at least one of polyethylene glycol and polypropylene glycol, and the hydrophobic region comprises at least one of polycaprolactone, polybutyrolactone and polyvalerolactone. In one embodiment, the polymer backbones form a micelle. In one embodiment, the nanoparticle further comprises crosslinkages between the polymer backbones.
In one embodiment, the first detectable substance is a radionuclide selected from the group consisting of Fluorine-18, Copper-64, Technetium-99m, Indium-111, Iodine-123, Iodine-131, Holmium-166, Rhenium-188, Gold-198, and a combination thereof, wherein Rhenium-188 is used for detecting or treating liver cancer, colon cancer, breast cancer, lung cancer and a combination thereof, and Iodine-131 is used for detecting or treating liver cancer, thyroid cancer, neuroblastoma, glioblastoma, lymphoma, myeloma, and a combination thereof.
In one embodiment, the nanoparticle further comprises a second detectable substance bound to the hydrophobic region or the hydrophilic region of the polymer backbone, wherein the second detectable substance is a visible or near infrared detectable substance selected from the group consisting of fluorescein, fluorescein isothiocyanate (FITC), rhodamine, Texas Red, cyanine dye, cy3, cy5, cy5.5, cy7, cy7.5, Alexa fluor dye, heptamethycyanine, indocyanine green (ICG), IR-780, IR-783, ADS7800H, NIR-797 isothiocynate, and a combination thereof.
In one embodiment, the polymer backbones bound with a first detectable substance or a second detectable substance is between 1% wt and 100% wt, preferably between 5% wt and 100% wt, and more preferably between 10% wt and 100% wt. In one embodiment, the molecular weight of the nanoparticle is between 200 and 30000.
In one embodiment, the nanoparticle further comprises an anti-cancer drug, wherein the anti-cancer drug is selected from the group consisting of 7-ethyl-10-hydroxycamptothecin (SN-38), camptothecin (CPT), paclitaxel, doxorubin, 17-(Allylamino)-17-demethoxygeldanamycin (17-AAG), celecoxib, capecitabine, docetaxel, epothilone B, Erlotinib, Etoposide, GDC-0941, Gefitinib, Geldanamycin, Imatinib, Intedanib, lapatinib, Neratinib, NVP-AUY922, NVP-BEZ235, Panobinostat, Pazopanib, Ruxolitinib, Saracatinib, Selumetinib, Sorafenib, Sunitinib, Tandutinib, Temsirolimus, Tipifarnib, Tivozanib, Topotecan, Tozasertib, Vandetanib, Vatalanib, Vemurafenib, Vinorelbine, Vismodegib, Vorinostat, ZSTK474 and a combination thereof.
In another embodiment, a method for detecting or treating a tumor is provided. The method comprises administering a nanoparticle to a subject in need thereof, wherein the nanoparticle comprises a plurality of polymer backbones, each including a hydrophobic region, a hydrophilic region and a chelating region, and at least one first detectable substance bound to the chelating region of the polymer backbone. The hydrophobic regions of the polymer backbones form a core block, and the hydrophilic regions of the polymer backbones form a shell block surrounding the core block. In one embodiment, the nanoparticle further comprises a second detectable substance bound to the hydrophobic region or the hydrophilic region of the polymer backbone.
In one embodiment, the method further comprises detecting the first or second detectable substance by single-photon emission computed tomography (SPECT), positron emission tomography (PET), a radiation image system or a fluorescent image system.
In another embodiment, a composition for detecting and treating a tumor, comprising the nanoparticle and a pharmaceutical acceptable excipient thereof is provided.
Various specific details are herein provided to provide a more thorough understanding of the invention.
εe-Caprolactone, stannous octoate, and methoxy poly(ethylene glycol) (mPEG, MW=5000) were from Fluka (Milwaukee, Wis., USA), and fluorenylmethyloxycarbonyl-amino-poly(ethylene glycol) (Fmoc-NH-PEG-OH, Mn=5000 Da) was from Laysan Bio Inc. (Arab, Ala., USA). Before polymerization, mPEG was vacuum-dried at room temperature for 24 hours. All other HPLC grade solvents, including methanol, ethanol, n-hexane, dichloromethane (DCM), acetone, dimethyl sulfoxide (DMSO), acetonitrile, and tetrahydrofuran (THF) were from Tedia Inc. (Fairfield, Ohio, USA). Both DCM and THF were dried over calcium hydride (CaH2) and distilled before use. Stannous (II) octoate (SnOct), 3-caprolactone (CL), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), diethylenetriaminepentaacetic acid dianhydride (DTPA dianhydride), calcein-AM, ropidium iodide (PI), and cyanine dye IR-780 iodine were from Sigma Aldrich (Milwaukee, Wis., USA).
Synthesis of mPEG-b-PCL and DTPA-PEG-b-PCL
Methoxy poly-(ethylene glycol)-block-poly(ε-caprolactone) (mPEG-b-PCL) and fluorenylmethyloxycarbonyl-amino-poly(ethylene glycol)-block-poly(ε-caprolactone) (Fmoc-NH-PEG-b-PCL) amphiphilic block copolymers were synthesized by ring-opening polymerization of ε-caprolactone at 140° C. overnight in the presence of mPEGOH (MW=5000) and Fmoc-NH-PEG-OH (MW=5000) as a macroinitiator under stannous octoate (SnOct) catalysis (
PEG-b-PCL and Fmoc-NH-PEG-b-PCL were synthesized by a ring-opening polymerization of ε-caprolactone in the presence of either mPEG-OH or Fmoc-NH-PEG-OH, respectively (
aTheoretical molecular weight based on feed ratio.
bCalculated from 1H NMR data.
cDetermined by GPC.
dCMC indicates critical micelle concentration.
eAs determined by DLS.
The characteristic resonances of both PCL (δMe=1.37 ppm, δHd=1.65 ppm, δHc=2.28 ppm, δHf=4.07 ppm) and mPEG (δHa=3.39 ppm and δHb=3.65 ppm) were observed, suggesting the coexistence of two blocks. The molecular weight (Mn,NMR) of PCL was determined by comparing the peak intensities of the methylene protons of the oxyethylene units (δMb) of mPEG to the methylene protons (δHd) of PCL (
The 1H NMR spectrum of Fmoc-NH-PEG-b-PCL exhibited distinct resonance signals of Fmoc moieties at 7.30-7.76 ppm, which were not present in the spectrum of mPEG-b-PCL (
Amino-terminated PEG-b-PCL (H2N-PEG-b-PCL) copolymers were prepared via deprotection of the Fmoc-NH-PEG-b-PCL that was accomplished by stifling Fmoc-NH-PEG-b-PCL with 20% piperidine in DMF. The NH2-PEG-b-PCL copolymers were then purified by dialysis before being lyophilized to dryness. The DTPA-PEG-b-PCL was prepared by conjugating the DTPA dianhydride with the amino group of N2H-PEG-b-PCL. The conjugation efficiency of DTPA dianhydride to NH2-PEG-b-PCL was evaluated by ITLC that analyzed the efficiency of the 188Re labeling of DTPA-PEG-b-PCL. It revealed that 76.8% of the radioactivity remaining at the origin corresponded to 188Re-DTPA-PEG-b-PCL (
IR-780 micelles and IR-780-loaded/DTPA micelles (IR-780/DTPA micelles) were prepared by the cosolvent evaporation method. Briefly, a mixture of 10-40 mg of mPEG-b-PCL was dissolved in acetone with 2 mg of IR-780 iodide dye (D/P=1/5-1/20), or 36 mg of mPEG-b-PCL and 4 mg of DTPA-PEG-b-PCL in a ratio of 9:1 were dissolved in acetone with 2 mg of IR-780 dye (D/P was 1:20). These mixtures were added to saline while stirring with a rotor-stator device (Variomag Poly 15, H+P Labortechnik GmbH, Munich, Germany) at a speed of 550 rpm. The organic solvent was evaporated, while the solution was stirred overnight. Then, the solution was filtered through a 0.45 μm sterile filter (Millex GS, Millipore, Bedford, Mass., USA) to remove non-incorporated drug crystals and copolymer aggregates. The IR-780 micelles were lyophilized and then dissolved with DMSO. The concentration of IR-780 iodide was determined with a spectrophotometer using a quartz cell with a 1 cm path length at 786 nm. The drug encapsulation efficiency is the amount of drug encapsulated divided by the amount of drug added multiplied by 100%.
The IR-780-loaded micelles, as observed by TEM, had a spherical morphology with particle sizes in agreement with DLS (
For example, the number of IR-780 iodide dye loaded into each micelle (Ndye) was calculated using the equation Ndye=Wdye/Mn, in which Wdye is the weight of IR-780 iodide dye loading per micelles and Mn is the molar mass of the IR-780 iodide dye (Mn=667). The IR-780 iodide dye loaded micelles with a D:P ratio of 1:20 were employed, which had an encapsulation efficiency of 93.8%. The weight average molecular weight of these micelles (Mw, micelle), obtained from static light scattering (SLS) using a Zetasizer Nano ZS90 apparatus (Malvern Instruments, Worcestershire, UK), was (77.0±7.7)×106 g/mol as shown in
The micelles with a D/P ratio of 1:5 or 1:10 had larger particle sizes and lower encapsulation efficiencies than those with a D/P ratio of 1:20 (Table 2). Drug encapsulation efficiency is a crucial factor in developing micelles or other drug delivery vesicles. Moreover, since a drug solution will be distributed all over the body, the EPR effect may preferentially distribute nanoparticles of 100-300 nm to the tumor, while the reticuloendothelial system will readily scavenge drug carriers with a diameter larger than 200 nm. The IR-780 micelle with a D/P ratio of 1:20, which exhibited efficient drug encapsulation and an ideal size suitable for future medical applications, was chosen as the drug carrier for further study.
aD/P ratio = weight of IR-780 iodide/weight of polymer.
bIR-780 iodide encapsulation efficiency (%) = (weight of IR-780 iodide in the micelles/weight of the feeding IR-780 iodide) × 100%.
cIR-780 iodide drug content (%) = (weight of IR-780 iodide)/(weight of IR-780 iodide t weight of polymer) × 100%.
dAs determined by DLS.
The IR-780 cyanine dye diluted in THF and IR-780 micelles in PBS strongly absorbed in the NIR region with a maximum wavelength (λmax) at about 795 nm (
The 188Re with DTPA micelles were labeled by reacting a mixture of 1 mL of DTPA micelles, 100 μL of 188Re-perrhenate (188ReO4, about 37 MBq), and 5 mg of stannous chloride for 2 h at 37° C. The radiolabeling yields of 188Re-DTPA micelles were determined by ITLC using silica gel as the stationary phase and normal saline as the mobile phase. The chromatograms were analyzed by a radio thin layer chromatography imaging scanner (AR2000, Bioscan, Washington, D.C., USA).
The IR-780 iodide-loaded DTPA micelles (IR-780/DTPA micelles) were labeled with 188Re by reacting IR-780/DTPA micelles, 188Re-perrhenate, and stannous chloride for 2 h at 37° C. The 188Re-labeled IR-780/DTPA micelles had high radioactivity and radiochemical purity (about 90%) as analyzed by ITLC (
The mean diameter and polydispersity index (PDI) of the micelles were characterized with a Delsa Nano Particle Analyzer (Beckman Coulter, Fullerton, Calif.). The morphology of the micelles was observed by H-7650 transmission electron microscopy (TEM, Hitachi Ltd., Tokyo, Japan). The absorptions of the IR-780 iodide dissolved in 0.15 M NaCl buffer and of IR-780 micelles dispersed in phosphate buffer saline (PBS) were measured on a UV-vis spectrophotometer (BioMate 3S, Thermo Electron Corporation, Hudson, N.H., USA) with a quartz thermostatted cell with a 1 cm path length. The temperature profile of the IR-780 micelles during NIR irradiation was analyzed in a 24-well plate with a thermocouple needle. A total of 1 mL of about 100 μg/mL IR-780 micelles was added to one of the wells, the well was irradiated by the NIR laser at 1.8 W/cm2, and the temperature of the well was measured continuously over 5 min
The HCT116 human colon cancer cells were maintained in a humidified 5% CO2 incubator at 37° C. in DMEM (Gibco BRL, Gaithersburg, Md., USA) supplemented with 10% heat-activated fetal bovine serum (FBS) and 1% antibiotics (antibiotic-antimycotic; Gibco). The HCT-116 cells were seeded onto 6-well plates at a density of 1×106 cells per well and cultured.
The HCT-116 cells were incubated in media containing different concentrations of IR-780 micelles for 3 h and washed with PBS. Next, the cells were treated for 10 min with a laser diode with a wavelength of 808 nm at a power density of 0.6 W/cm2. After the irradiation, the cells were stained for 30 min with 2 μM calcein-AM and 2 μM propidium idodide (PI) prior to imaging. Cell viability was visually determined with an X51 Olympus fluorescence microscope (Olympus Optical Co., Tokyo, Japan).
The cytotoxicity of treating HCT-116 cells with IR-780 micelles and NIR irradiation was additionally determined The HCT-116 cells were first seeded onto 96-well plates at a density of 10,000 cells per well and cultured. After 24 h, the cells were incubated in media with different concentrations of IR-780 micelles for 3 h and then washed with PBS. Next, the cells were treated with a laser diode with a wavelength of 808 nm at a power density of 0.6 W/cm2 for 10 or 20 min. Cell viability was determined with the MTT assay and a scanning multiwell ELISA reader (Microplate Autoreader EL311, Bio-Tek Instruments Inc., Winooski, Vt., USA). The fraction of live cells was calculated by dividing the mean optical density obtained from treated cells by the mean optical density from untreated control cells.
HCT-116 cells were used to evaluate the cytotoxicity of HCT-116 treated with IR-780 micelles plus NIR irradiation. The cells were treated with IR-780 micelles and NIR irradiation, and then live cells were stained with calcein AM, a nonfluorescent cell-permeating compound that is hydrolyzed by intracellular esterases in live cells into intensely fluorescent calcein, and dead cells with PI (
The cytotoxicity of IR-780 micelles and free IR-780 iodide in HCT-116 cells without or with NIR irradiation was also determined by the MTT assay. Treatment of the cells with only NIR irradiation for 10 or 20 min did not cause observation cell death (
The HCT-116 cells treated with 2.5 μg/mL of IR-780 micelles and NIR irradiation (excess 14.4 and 53.5% of cells killed for 10 and 20 min of irradiation, respectively) significantly accelerates cell killing than that treated with 2.5 μg/mL of free IR-780 iodide and NIR irradiation (excess 0.3 and 26.8% of cells killed for 10 and 20 min of irradiation, respectively). The observation may be due to the aggregation of lipophilic IR-780 iodide in the aqueous medium, which reduces their photocytotoxicity and cellular uptake. The aggregation of lipophilic IR-780 iodide shows a broad and blue-shifted absorbance spectrum with a peak at λhd max=775 nm (as shown in
After PTT mediated by the IR-780 micelles plus NIR irradiation, the cells were incubated in media for three hours, and then stained for 30 minutes with 2 μM calcein-AM and 2 μM propidium idodide (PI) prior to imaging. The calcein-AM (excitation at 495 nm and emission at 515 nm) stained live cells green, and the PI (excitation at 535 nm and emission at 617 nm) stained dead cells red. Cell viability was visually determined with an X51 Olympus fluorescence microscope (Olympus Optical Co., Tokyo, Japan).
The images were acquired with a microSPECT/CT scanner system (XSPECT, Gamma Medica, Northridge, Calif., USA). The SPECT images used a low-energy, high-resolution collimator and were taken 1, 4, and 24 hours after the micelles were intravenously injected. During the imaging, the mice were kept still by inhaling anesthetic isoflurane (ABBOTT, Kent, England). The SPECT imaging was followed by acquiring CT images using a 50 kV, 0.4 mA X-ray source with 256 projections while the animal was in the exact same position. The CT images were reconstructed with COBRA_Exxim software (Exxim Computing Corporation, Pleasanton, Calif., USA) and the SPECT images with LumaGEM software (Segami, Columbia, Md., USA). The SPECT/CT images were fused with IDL 6.0 software (RSI Inc, Boulder, Colo., USA).
Female BALB/c athymic (nut/nut) mice that were 5-6 weeks old were purchased from the National Laboratory Animal Center (Taipei, Taiwan). Tumors were initially established by subcutaneously injecting a mixture of 1×106 HCT-116 cells, matrigel, and DMEM. Tumor sizes and body weights were measured every 3 days for the duration of the experiment. Tumor volume was calculated as π/6ab2, where “a” is the length and “b” is the width of the tumor.
Mice received an intravenous injection of 188Re-labeled IR-780 micelles, equivalent to 22 MBq of 188Re, when the tumors reached a volume of 150 to 200 mm3 The distribution of 188Relabeled IR-780 micelles in the mice bearing HCT-116 tumors was evaluated by microSPECT/CT images at 1, 4, and 24 h after the micelles were intravenously injected.
The mice were sacrificed by cervical vertebra dislocation at 24 and 96 h after the intravenous administration of 188Relabeled IR-780 micelles. The plasma, tumor, and normal tissue were collected, and the uptake of radioactivity was measured by a γ counter. The distribution data were expressed as the percentage of injected dose (ID). The biodistribution of IR-780 iodide was studied by injecting 1.25 mg/kg IR-780 micelles intravenously through a tail vein of mice bearing HCT-116 tumors and was imaged 1, 4, 24, 48, and 96 h after the injection with an IVIS imaging system (Xenogen, Alameda, Calif., USA). The mice were anesthetized with a mixture of oxygen and isoflurane, and were placed on a 37° C. animal plate. The near-infrared fluorescence (NIRF) data were collected with a two second exposure time and an ICG filter set with excitation at 710-760 nm and emission at 810-875 nm. All data were calculated using the region-of interest (ROI) function of the Living Image® software (Caliper Life Sciences Inc, Hopkinton, Mass., USA). Dye accumulation and retention in tumors was evaluated by calculating the contrast index (CI) values. The CI was measured according to the formula CI=(Ftumor−Fauto)/(Fnorm−Fauto). The Ftumor value is the fluorescence mean intensity of the tumor region, and the Fnorm value is that of the normal region. The Fauto value is the autofluorescence from the corresponding region measured before injection. The tumor-bearing mice were sacrificed 48 h after the IR-780 micelles were injected, and then the tumor, heart, liver, spleen, lung, kidneys, and intestine were harvested for isolated organ imaging to estimate the tissue distribution of IR-780 micelles.
The biodistribution of 188Re-labeled IR-780 micelles was evaluated in tumor and normal tissues of mice bearing HCT-116 human colon cancer xenografts. Images obtained by microSPECT/CT revealed that radioactivity accumulated in the spleen, liver, and tumor at 24 h after the injection of 188Re-labeled IR-780 micelles, and that the tumors were targeted by the radioactivity (
The in vivo real-time biodistribution of IR-780 iodide in HCT-116 tumor-bearing mice that were injected intravenously with 188Re-labeled IR-780 micelles is characterized through NIR fluorescence imaging with an IVIS imaging system. The IR-780 iodide had a time-dependent biodistribution and tumor accumulation in mice bearing HCT-116 tumors (
The intratumoral temperature increases upon NIR irradiation were determined by injecting 1.25 mg/kg IR-780 micelles through a tail vein into mice bearing HCT-116 tumors. Control mice were injected with 100 μL of empty micelles (equivalent to 25 mg/kg). The temperatures of the tumor tissues during NIR irradiation were measured 96 h after the injections with thermocouple needles (127 μm diameter, T-type, copper-constantan thermocouple, Omega Engineering, Stamford, Conn.) connected to a data acquisition system (TC-2190, National Instruments, Austin, Tex.). First, the 23 gauge needles intratumorally injected into the center of tumor about 3-4 mm in depth. Next, the thermocouples were inserted into the tumor through the 23 gauge needles, while the tumor region was exposed to 1.8 W/cm2 NIR light for 5 min with a laser diode (λ=808 nm). All data were analyzed with Matlab (Mathworks, Natick, Mass., USA). The distribution of tumoral temperature after NIR irradiation was examined with an IR thermographic camera (F30s, NEC Avio Infrared Technologies Co., Ltd., Tokyo, Japan) in the mice treated with the IR-780 micelles.
The intratumoral temperature profiles were measured during PTT mediated by IR-780 micelles (
The spatial distribution of temperatures in the tumors of mice treated with PTT mediated by IR-780 micelles was observed with a thermal imaging camera (Thermo Shot F30, NEC Avio Infrared Technologies Co., Ltd.) (
Treatments were started when the tumors reached a volume of 100 to 150 mm3. The mice were divided into groups of five mice each that were treated with the PBS control, the NIR irradiation alone, the IR-780 micelles, or the combination of IR-780 micelles and NIR irradiation. The IR-780 micelles were administered via tail vein injections at doses equivalent to 1.25 mg/kg of IR-780 iodide, and 96 h after the micelles were administered was designated as day 0. On day 0, the tumors were exposed to the NIR laser with a spot size of 5 mm at 1.8 W/cm2 for 5 min. The tumor size and change in body weight of each mouse were recorded. The percentage of tumor growth inhibition (TGI) was calculated from the relative tumor volume on day 27 and is presented as percent reduction in the mean tumor volume in experimental groups compared with saline-treated control groups.
It was investigated how effectively PTT using IR-780 micelles on HCT-116 tumors in nude mice reduced tumor growth in vivo (
After the mice were sacrificed, the tumors were excised and fixed in formalin and embedded in paraffin for immunohistochemical staining and for hematoxylin and eosin staining. The tumor blocks, which were paraffin-embedded and 5 mm thick, were analyzed by immunohistochemical staining for proliferating cell nuclear antigen (PCNA), heat shock protein 70 (HSP70), and heat shock protein 90 (HSP90). Edogenous peroxidase activity was quenched with 3% hydrogen peroxide for 15 minutes, and then tumor blocks were blocked with 10% normal goat serum for 15 minutes and rinsed three times with PBS for two minutes. Consecutive blocks were incubated overnight at 4° C. with antibodies specific for HSP70 (rabbit anti-human, diluted 1:50, Cell Signaling Technology Inc., Danvers, Mass., USA), HSP90 (rabbit anti-human, diluted 1:50, Cell Signaling), and PCNA (mouse anti-PCNA, clone PC 10, Sigma). The blocks were again rinsed with PBS, and then incubated at room temperature with biotinylated secondary antibodies for 30 minutes. Finally, an avidin-biotin complex was applied and visualized with 3, 30-diaminobenzidine tetrahydrochloride chromogen. The immunostaining was applied and visualized by using Histostain-Plus kits (Zymed Laboratories, Inc., San Francisco, Calif., USA). The terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was carried out with the DeadEnd Colorimetric TUNEL System (Promega, Fitchburg, Wis., USA). The NADPH-diaphorase staining was carried out to demonstrate necrosis. Tissue viability was analyzed by reacting the samples for 20 min at room temperature with NADPH-diaphorase reaction solution (10 mL of 10 mmol/L phosphate buffered saline, pH 7.4, containing 10 mg NADPH, and 5 mg nitroblue tetrazolium).
Body weight loss was used as a measure of treatments-induced toxicity (
To further determine the effect of IR-780 micelle-mediated photothermal therapy in vivo, subcutaneously, tumors underwent immunohistochemical analysis (
Proliferating cell nuclear antigen (PCNA) immunolocalization can be used as an index of cell proliferation and may define the extent of departure from normal growth control. The PBS control tumors had a mean of 151.5±11.3 PCNA positive cells, and the tumors treated only with the NIR irradiation had a mean of 135.7±5.8 (
Apoptotic cells in each treatment were identified by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method. TUNEL is a method for detecting DNA fragmentation, which results from apoptotic signaling cascades, by labeling the terminal end of nucleic acids. The PBS control group tumors had a mean of 9.3±2.6 apoptotic cells, and those tumors treated only with NIR irradiation had a mean of 14.6±3.2. The viable, non-necrotic regions in tumors treated with PTT mediated by IR-780 micelles plus NIR irradiation had more apoptotic tumor cells (mean±SD=98.2±10.8) than either control group (for both, P<0.01).
Since HSPs are induced by temperatures above 43° C., they serve as endogenous markers of thermal stress. Tumors treated only with PBS had minimal expression of HSPs, while those treated with only NIR irradiation had more HSP90 expression induced in the viable, non-necrotic regions of tumors, which were close to the incident laser (
All data are expressed as mean±standard deviation. The significance of difference in this study between groups was analyzed by the t-test. A value of P<0.05 was considered statistically significant.
In one embodiment of the present invention, IR-780 iodide-loaded micelles, which both acted as NIR contrast agents for optical imaging and were labeled with the radionuclide rhenium-188 (188Re) for nuclear imaging, have been prepared and characterized. It has been demonstrated that the NIR dye, IR-780 iodide, could serve as a photosensitizing agent for photothermal therapy of cancer since using IR-780 micelles to generate heat upon NIR irradiation resulted in thermal destruction of colon cancer both in vitro and in vivo. Measurements of the viable regions around necrotic regions of tumors found that these treatments decreased the cell proliferation as measured by PCNA expression, increased apoptotic cells as measured by TUNEL, and increased the expression of HSPs. These results indicate that irreversible tissue damage was induced by PTT mediated by the IR-780 micelles plus NIR irradiation in treated tumors. This platform permits image-guided drug delivery. The tumor accumulation, intratumoral distribution, and kinetics of the drug can be monitored in real-time. This platform allows diagnosis and therapeutics to be combined in optical/nuclear imaging and PTT. The 188Re-labeled IR-780 micelles potentially offer multifunctional modalities for the near-infrared (NIR) fluorescence and nuclear imaging and for photothermal therapy of cancer.
In another embodiment of the present invention, multifunctional micelles for optical and nuclear imaging and for PTT were prepared. Two imageable components were incorporated into this micelle, a NIR dye and a radionuclide, which created a multifunctional drug delivery system that permitted image-guided drug delivery and real-time monitoring of the accumulation of the drug in the tumor, the intratumoral distribution, and the kinetics of drug release. It has been demonstrated that IR-780 iodide-loaded micelles (IR-780 micelles), which were labeled with the radionuclide rhenium-188 (188Re), can combine the modalities of targeting, imaging, and drug delivery on one nanocarrier. This multifunctional micelle presents simultaneous optical and nuclear imaging and treatment capacities in one delivery system, using NIR fluorescence imaging, microSPECT/CT imaging, and photothermal cancer ablation. The size and morphology of IR-780 micelles were determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM), and their encapsulation efficiency and optical properties were also analyzed. Cellular cytotoxicity by the IR-780 micelles upon NIR irradiation was evaluated in human colon cancer HCT-116 cells, and a xenograft model of these cells investigated the biodistribution, SPECT imaging, generation of heat, and photothermal cancer ablation of IR-780 micelles.
