Dose ranging, expanded acute toxicity and safety pharmacology studies for intravenously administered functionalized graphene nanoparticle formulations

Graphene nanoparticle dispersions show immense potential as multifunctional agents for in vivo biomedical applications. Herein, we follow regulatory guidelines for pharmaceuticals that recommend safety pharmacology assessment at least 10-100 times higher than the projected therapeutic dose, and present comprehensive single dose response, expanded acute toxicology, toxicokinetics, and respiratory/cardiovascular safety pharmacology results for intravenously administered dextran-coated graphene oxide nanoplatelet (GNP-Dex) formulations to rats at doses between 1 and 500 mg/kg. Our results indicate that the maximum tolerable dose (MTD) of GNP-Dex is between 50 mg/kg ≤ MTD < 125 mg/kg, blood half-life < 30 min, and majority of nanoparticles excreted within 24 h through feces. Histopathology changes were noted at ≥250 mg/kg in the heart, liver, lung, spleen, and kidney; we found no changes in the brain and no GNP-Dex related effects in the cardiovascular parameters or hematological factors (blood, lipid, and metabolic panels) at doses < 125 mg/kg. The results open avenues for pivotal preclinical single and repeat dose safety studies following good laboratory practices (GLP) as required by regulatory agencies for investigational new drug (IND) application.

Can TiC nanoparticles produce toxicity in oral administration to rats?

BACKGROUND

Titanium carbide (TiC) is used for ceramic metal composites in several industries and is regarded as a nanomaterial for catalyst and battery applications. However, there are very few studies in regard to the toxicological potential of TiC nanoparticles (NPs).

OBJECTIVE

To study the toxicodynamics and toxicokinetics of TiC NPs in Sprague Dawley rats in acute (24 h) and subacute (28 days) oral administrations. The acute doses were 0.5, 5, 50, 300 and 1000 mg kg-1; the subacute doses were 0.5 and 50 mg kg-1.

RESULTS

Organ histopathological examination (esophagus, stomach, intestines, spleen, liver, and kidneys) indicates the absence of damage at all applied doses, in both assessments. In the acute administration, alkaline phosphatases increased (5, 300 and 1000 mg kg-1), ASAT increased (1000 mg kg-1) and bile salts decreased (0.5 mg kg-1). No alterations in urine parameters (sodium, potassium, osmolarity) were found. Acute administration of TiC caused mineral changes in organs (liver, spleen, kidneys). TiC was mostly cleared by feces excretion 24 h after administration, in subacute administration causing variations in mineral absorption (Mg, Al, P, S, Ca, Zn). TiC could pass the intestinal barrier as TiC traces were detected in urine.

CONCLUSION

No sign of toxicity was found after oral administration. TiC was excreted mostly in feces producing mineral absorption alterations. Low traces were retrieved in urine, indicating that TiC can cross the intestinal barrier.

Pharmacoscintigraphic evaluation of potential of lipid nanocarriers for nose-to-brain delivery of antidepressant drug

Efficacy of antidepressants relies upon their continued presence at the site of action (brain) over a prolonged period of time. The BBB restricts the access of antidepressants to the brain on oral as well as intravenous administration. Direct delivery (by-passing the BBB) of antidepressant drugs can increase the CSF concentration with concomitant reduction in dose and side effects. Intranasal administration of nanostructured lipid carriers (NLC) containing antidepressant drug circumvent the BBB and maintain the prolonged release at the site of action. The aim of the present study was to evaluate the enhancement in brain uptake of NLC containing duloxetine (DLX) after intranasal administration. Duloxetine loaded NLC (DLX-NLC) was evaluated pharmacoscintigraphically for drug targeting potential (DTP), drug targeting efficiency (DTE) and biodistribution studies in different organs including brain. The radiolabeling efficiency of DLX and DLX-NLC was found to be 98.41 ± 0.96 and 98.87 ± 0.82 after 30 min, respectively. The biodistribution studies exhibited higher percentage of radioactivity/g for DLX-NLC formulations in brain as compared with the DLX. The higher DTP (86.80%) and DTE (757.74%) suggested that DLX-NLC formulation has a better brain targeting efficiency than DLX solution (DTP=65.12%; DTE=287.34%) when administered intranasally. Moreover, the intranasal administration exhibited about 8-times higher concentration of DLX in brain when compared with the intravenous administration of DLX solution. The intranasal NLC containing DLX can be employed as an effective method for the treatment of depression.

¹⁸F-DOPA PET/computed tomography imaging

18F-DOPA is a radiopharmaceutical with interesting clinical applications and promising performances in the evaluation of the integrity of dopaminergic pathways, brain tumors, NETs (especially MTCs, paragangliomas, and pheochromocytomas), and congenital hyperinsulinism. 18F-DOPA traces a very specific metabolic pathway and has a very precise biodistribution pattern. As for any radiopharmaceutical, the knowledge of the normal distribution of 18F-DOPA, its physiologic variants, and its possible pitfalls is essential for the correct interpretation of PET scans. Moreover, it is important to be aware of the potential false-positive and false-negative episodes that can occur in the various clinical settings.

Improving drug accumulation and photothermal efficacy in tumor depending on size of ICG loaded lipid-polymer nanoparticles

A key challenge to strengthen anti-tumor efficacy is to improve drug accumulation in tumors through size control. To explore the biodistribution and tumor accumulation of nanoparticles, we developed indocyanine green (ICG) loaded poly (lactic-co-glycolic acid) (PLGA) -lecithin-polyethylene glycol (PEG) core-shell nanoparticles (INPs) with 39 nm, 68 nm and 116 nm via single-step nanoprecipitation. These INPs exhibited good monodispersity, excellent fluorescence and size stability, and enhanced temperature response after laser irradiation. Through cell uptake and photothermal efficiency in vitro, we demonstrated that 39 nm INPs were more easily be absorbed by pancreatic carcinoma tumor cells (BxPC-3) and showed better photothermal damage than that of 68 nm and 116 nm size of INPs. Simultaneously, the fluorescence of INPs offered a real-time imaging monitor for subcellular locating and in vivo metabolic distribution. Near-infrared imaging in vivo and photothermal therapy illustrated that 68 nm INPs showed the strongest efficiency to suppress tumor growth due to abundant accumulation in BxPC-3 xenograft tumor model. The findings revealed that a nontoxic, size-dependent, theranostic INPs model was built for in vivo cancer imaging and photothermal therapy without adverse effect.

Biodistribution of P-selectin targeted microbubbles

PURPOSE

To evaluate binding of P-selectin targeted microbubbles (MB) in tumor vasculature; a whole-body imaging and biodistribution study was performed in a tumor bearing mouse model.

METHODS

Antibodies were radiolabeled with Tc-99 m using the HYNIC method. Tc-99 m labeled anti-P-selectin antibodies were avidin-bound to lipid-shelled, perfluorocarbon gas-filled MB and intravenously injected into mice bearing MDA-MB-231 breast tumors. Whole-body biodistribution was performed at 5 min (n = 12) and 60 min (n = 4) using a gamma counter. Tc-99 m-labeled IgG bound IgG-control-MB group (n = 12 at 5 min; n = 4 at 60 min), Tc-99 m-labeled IgG-control-Ab group (n = 5 at 5 min; n = 3 at 60 min) and Tc-99 m-labeled anti P-selectin-Ab group (n = 5 at 5 min; n = 3 at 60 min) were also evaluated. Planar gamma camera imaging was also performed at each time point.

RESULTS

Targeted-MB retention in tumor (60 min: 1.8 ± 0.3% ID/g) was significantly greater (p = 0.01) than targeted-MB levels in adjacent skeletal muscle at both time points (5 min: 0.7 ± 0.2% ID/g; 60 min: 0.2 ± 0.1% ID/g) while there was no significant difference (p = 0.17) between muscle and tumor retention for the IgG-control-MB group at 5 min.

CONCLUSIONS

P-selectin targeted MBs were significantly higher in tumor tissue, as compared with adjacent skeletal tissue or tumor retention of IgG-control-MB.

Paramagnetic hollow silica nanospheres for in vivo targeted ultrasound and magnetic resonance imaging

A series of hollow silica nanospheres (HSNSs) with sizes ranging from 100 to 400 nm were synthesized and used for primary ultrasound imaging (US) efficiency assessment. The 400 nm HSNSs were chosen as platform for conjugation with Gd-DTPA and cyclo-arginine-glycine-aspartic acid c(RGD) peptide to construct US and magnetic resonance imaging (MRI) dual-modal contrast agents (CAs): [HSNSs@(DTPA-Gd)-RGD]. The obtained CAs displayed good physiological stability, low cytotoxicity and negligible hemolytic activity in vitro. Furthermore, the passive accumulation and active-targeting of the HSNSs in the tumor site of mice was demonstrated by US and MR imaging, respectively. The qualitative and quantitative biodistribution of the HSNSs showed that they mainly accumulated in the tissues of liver, lung, tumor after intravenous administration and then be excreted from feces. In addition, histological, hematological, blood and biochemical analysis were used to further study toxicity of the HSNSs, and all results indicated that there were no covert toxicity of HSNSs in mice after long exposure times. Findings from this study indicated that the silica-based paramagnetic HSNSs can be used as a platform for long-term targeted imaging and therapy studies safely in vivo.

Combination of MIDGE-Th1 DNA vaccines with the cationic lipid SAINT-18: studies on formulation, biodistribution and vector clearance

We have previously shown that the combination of MIDGE-Th1 DNA vectors with the cationic lipid SAINT-18 increases the immune response to the encoded antigen in mice. Here, we report on experiments to further optimize and characterize this approach. We evaluated different formulations of MIDGE-Th1 vectors with SAINT-18 by assessing their influence on the transfection efficiency in cell culture and on the immune response in mice. We found that high amounts of SAINT-18 in formulations with a w/w ratio MIDGE Th1/SAINT-18 of 1:4.8 are beneficial for cell transfection in vitro. In contrast, the formulation of HBsAg-encoding MIDGE-Th1 DNA vectors with the lowest amount of SAINT-18 (w/w ratio MIDGE Th1/SAINT-18 of 1:0.5) resulted in the highest serum IgG1 and IgG2a levels after intradermal immunization of mice. Consequently, latter formulation was selected for a comparative biodistribution study in rats. Following intradermal administration of both naked and formulated MIDGE-Th1 DNA, the vectors localized primarily at the site of injection. Vector DNA levels decreased substantially over the two months duration of the study. When administered in combination with SAINT-18, the vectors were found in significantly higher amounts in draining lymph nodes in comparison to administration of naked MIDGE-Th1 DNA. We propose that the high immune responses induced by MIDGE-Th1/SAINT-18 lipoplexes are mediated by enhanced transfection of cells in vivo, resulting in stronger antigen expression and presentation. Importantly, the combination of MIDGE-Th1 vectors with SAINT-18 was well tolerated in mice and rats and is expected to be safe in human clinical applications.

Biodistribution of locally or systemically transplantedosteoblast-like cells

Objectives

In order to ensure safety of the cell-based therapy for bone regeneration, we examined in vivo biodistribution of locally or systemically transplanted osteoblast-like cells generated from bone marrow (BM) derived mononuclear cells.

Methods

BM cells obtained from a total of 13 Sprague-Dawley (SD) green fluorescent protein transgenic (GFP-Tg) rats were culture-expanded in an osteogenic differentiation medium for three weeks. Osteoblast-like cells were then locally transplanted with collagen scaffolds to the rat model of segmental bone defect. Donor cells were also intravenously infused to the normal Sprague-Dawley (SD) rats for systemic biodistribution. The flow cytometric and histological analyses were performed for cellular tracking after transplantation.

Results

Locally transplanted donor cells remained within the vicinity of the transplantation site without migrating to other organs. Systemically administered large amounts of osteoblast-like cells were cleared from various organ tissues within three days of transplantation and did not show any adverse effects in the transplanted rats.

Conclusions

We demonstrated a precise assessment of donor cell biodistribution that further augments prospective utility of regenerative cell therapy.

Fetal uptake of intra-amniotically delivered dendrimers in a mouse model of intrauterine inflammation and preterm birth

Intrauterine inflammation is associated with preterm birth and can lead to fetal neuroinflammation and neurobehavioral disorders in newborns. Dendrimers can intrinsically target and deliver drugs for the treatment of neuroinflammation. We explore whether hydroxyl polyamidoamine (PAMAM) dendrimer (G4-OH)-based nanomedicines can be delivered to the fetus by intra-amniotic administration, in a mouse model of intrauterine inflammation. The time-dependent accumulation of G4-OH-fluorophore conjugate was quantified by fluorescence. These studies suggest that, after intra-amniotic administration, there is significant accumulation of dendrimer in the fetus gut and brain. In addition, there is some fetal-maternal transport of the dendrimer. Confocal microscopy confirmed the presence of G4-OH in the fetal brain, with a large accumulation in the brain blood vessels and the brain parenchyma, and some microglial uptake. We believe that intra-amniotic administration of G4-OH-drug nanomedicines may enable the treatment of diseases related to intrauterine inflammation and fetal neuroinflammation.

FROM THE CLINICAL EDITOR

Using a mouse model of intrauterin inflammation leading to neuroinflammation in the fetus, these investigators demonstrate that intra-amniotic delivery of hydroxyl polyamidoamine (PAMAM) dendrimer (G4-OH)-based nanomedicines may provide an effective method in preventing this complication.

Whole-body biodistribution and dosimetry estimates of a novel radiotracer for imaging of serotonin 4 receptors in brain: [¹⁸F]MNI-698

INTRODUCTION

A new radiotracer for imaging the serotonin 4 receptors (5-HT4) in brain, [¹⁸F]MNI-698, was recently developed by our group. Evaluation in nonhuman primates indicates the novel radiotracer holds promise as an imaging agent of 5-HT4 in brain. This paper aims to describe the whole-body biodistribution and dosimetry estimates of [¹⁸F]MNI-698.

METHODS

Whole-body positron emission tomography (PET) images were acquired over 240 minutes after intravenous bolus injection of [¹⁸F]MNI-698 in adult rhesus monkeys. Different models were investigated for quantification of radiation absorbed and effective doses using OLINDA/EXM 1.0 software.

RESULTS

The radiotracer main elimination route was found to be urinary and the critical organ was the urinary bladder. Modeling of the urinary bladder voiding interval had a considerable effect on the estimated effective dose. Normalization of rhesus monkeys' organs and whole-body masses to human equivalent reduced the calculated dosimetry values. The effective dose ranged between 0.017 and 0.027 mSv/MBq.

CONCLUSION

The dosimetry estimates, obtained when normalizing organ and whole-body weights and applying the urinary bladder model, indicate that the radiation doses from [¹⁸F]MNI-698 comply with limits and guidelines recommended by key regulatory authorities that govern the translation of radiotracers to human clinical trials. The timing of urinary bladder emptying should be considered when designing future clinical protocols with [¹⁸F]MNI-698, in order to minimize the subject absorbed doses.

Bioconcentration and distribution of silver nanoparticles in Japanese medaka (Oryzias latipes)

The study of the bioconcentration of silver nanoparticles (AgNPs) is important to fully understand their hazard potential in the aquatic environment. We synthesized AgNPs radiolabeled with silver isotopes ((110m)Ag) to quantify the bioconcentration of AgNPs coated with citrate (AgNPs-CIT) and polyvinylpyrrolidone (AgNPs-PVP) in Japanese medaka, and to investigate the biodistribution of silver in organs, which were compared with (110m)AgNO3. BCF values were determined to be 39.8±7.4, 42.5±5.1 and 116.4±6.1Lkg(-1) for AgNPs-CIT, AgNPs-PVP and AgNO3, respectively. The release of more silver ions in AgNPs-PVP contributed to a different kinetic uptake pattern with AgNPs-CIT, which was similar to that of AgNO3. Bioconcentrated AgNPs in medaka were not observed to be eliminated, independent of surface coating differences, similarly to AgNO3. There was no difference in biodistribution in each organ before and after depuration in two types of AgNPs and AgNO3, all of which were mainly concentrated in the liver. This study quantified the bioconcentration and distribution of AgNPs and AgNO3 more precisely by utilizing a silver isotope, which is helpful in monitoring the toxicity of AgNPs to Japanese medaka.

Improved tumor targetability of Tat-conjugated PAMAM dendrimers as a novel nanosized anti-tumor drug carrier

The generation 4-poly-amidoamine-dendrimers (PAMAM G4 dendrimer, P) was conjugated to Tat peptide (Tat, T), a cell-penetrating peptide, in search of an efficient anti-tumor drug delivery vehicle for cancer therapy. In this study, we synthesized BODIPY-labeled Tat-Conjugated PAMAM dendrimers (BPTs) as a novel nanosized anticancer drug carriers and systemically investigated their biodistribution and the tumor accumulation in Sarcoma 180-bearing mice. In addition, the uptake and the cytotoxicity to S180 cells of BPTs thereof were evaluated. The unmodified dendrimer (BP) showed a soon clearance from the blood stream and nonspecific accumulation in tumor. In contrast, the Tat-modified dendrimer, BPT(64) with appropriate particle size showed a better retention in blood and could be accumulated effectively in tumor tissue via the enhanced permeability and retention (EPR) effect. Moreover, BPTs with a high Tat modification rate was accumulated more effectively in tumor tissue. In vitro experiments, these BPTs displayed low cytotoxicity on S180 cells and high uptake to S180 cells. These findings indicate that the nanoparticulate system on the basis of Tat-conjugated PAMAM dendrimers is safer and effective in the concentration range (below 20 μg/ml) to be used as a carrier of anti-tumor drugs for tumor targeting by intravenous administration.

Novel PEG-grafted nanostructured lipid carrier for systematic delivery of a poorly soluble anti-leukemia agent Tamibarotene: characterization and evaluation

Tamibarotene (Am80), a poorly water-soluble drug for the treatment of acute promyelocytic leukemia (APL), loaded nanostructured lipid carrier (Am80-NLC) was developed and characterized previously. The purpose of the present work was to develop PEGylated nanostructured lipid carrier (PEG-NLC) for intravenous delivery of Am80, with the aim to further extend the circulation in blood and decrease the adverse events. Am80-loaded PEG-NLC (Am80-PEG-NLC) modified with PEG-40 stearate (PEG40-SA, molecular weight 2000 Da) was formulated by the method of melt-emulsification and low temperature-solidification technique. Am80-NLC was developed as well as control. Based on the optimized results of single-factor screening experiment, the average drug entrapment efficiency, the mean particle size, and zeta potential of Am80-NLC and Am80-PEG-NLC were found to be 89.8-94.3%, 178.9-201.6 nm, and -37.74 to -20.1 mV, respectively. In vitro drug release of Am80-NLC and Am80-PEG-NLC possessed a sustained release characteristic and their release behavior was in accordance with the Ritger-Peppas equation. In vivo, after intravenous (i.v.) injection to rats, the mean residence time (MRT) of Am80-PEG-NLC group was significantly prolonged and the AUC value was improved as well compared with the Am80-NLC group. Furthermore, the biodistribution in mice showed that Am80-PEG-NLC preferentially decreased the accumulation of Am80 in kidney and increased the drug concentration in brain after i.v. injection. In conclusion, Am80-PEG-NLC may be a potential delivery system for Am80 in the treatment of APL.

Glutathione PEGylated liposomes: pharmacokinetics and delivery of cargo across the blood-brain barrier in rats

Partly due to poor blood–brain barrier drug penetration the treatment options for many brain diseases are limited. To safely enhance drug delivery to the brain, glutathione PEGylated liposomes (G-Technology®) were developed. In this study, in rats, we compared the pharmacokinetics and organ distribution of GSH-PEG liposomes using an autoquenched fluorescent tracer after intraperitoneal administration and intravenous administration. Although the appearance of liposomes in the circulation was much slower after intraperitoneal administration, comparable maximum levels of long circulating liposomes were found between 4 and 24 h after injection. Furthermore, 24 h after injection a similar tissue distribution was found. To investigate the effect of GSH coating on brain delivery in vitro uptake studies in rat brain endothelial cells (RBE4) and an in vivo brain microdialysis study in rats were used. Significantly more fluorescent tracer was found in RBE4 cell homogenates incubated with GSH-PEG liposomes compared to non-targeted PEG liposomes (1.8-fold, p < 0.001). In the microdialysis study 4-fold higher (p < 0.001) brain levels of fluorescent tracer were found after intravenous injection of GSH-PEG liposomes compared with PEG control liposomes. The results support further investigation into the versatility of GSH-PEG liposomes for enhanced drug delivery to the brain within a tolerable therapeutic window.

Biodistribution and lymph node retention of polysaccharide-based immunostimulating nanocapsules

The adjuvant properties of polyglucosamine/squalene-based nanocapsules (PG-nanocapsules) associated with different subunit antigens has been previously reported. Thus, the aim of the present study was to monitor the biodistribution of PG-nanocapsules and their affinity for the draining lymph nodes after subcutaneous (s.c.) injection. The nanocapsules were efficiently radiolabeled with indium-111 ((111)In) (labeling efficiency of 98%). The diameter and zeta potential values of the unlabeled nanocapsules was preserved after the radiolabeling process and only 20% of the (111)In dissociated from the nanocapsules after 48h of incubation in serum. The radiolabeled nanocapsules and the control (111)InCl3 in saline solution (18.5MBq (500μCi) in 100μL) were injected s.c. in New Zealand White rabbits. The γ-scintigraphy imaging analysis revealed a slow clearance of the nanocapsules from the injection site and their progressive accumulation in the popliteal lymph node over time (3.8%±1.2 of the injected dose at 48h). Indeed, the clearance rate of the nanocapsules from the injection site was significantly slower than that of the control (free (111)InCl3), which rapidly drained into systemic circulation and accumulated mainly in excretion organs (i.e. kidneys and liver). In contrast, the biodistribution of nanocapsules was preferably limited to the lymphatic circulation. These results suggest that the immune potentiating effect previously observed for PG-nanocapsules is mainly due to the formation of a depot at the injection site, which was followed by a slow drainage into the lymphatic system and a prolonged retention in the lymph nodes.

The fate of inhaled (14)C-labeled PCB11 and its metabolites in vivo

BACKGROUND

The production ban of polychlorinated biphenyl (PCB) technical mixtures has left the erroneous impression that PCBs exist only as legacy pollutants. Some lower-chlorinated PCBs are still being produced and contaminate both indoor and ambient air.

OBJECTIVES

To inform PCB risk assessment, we characterized lung uptake, distribution, metabolism and excretion of PCB11 as a signature compound for these airborne non-legacy PCBs.

METHODS

After delivering [(14)C]PCB11 to the lungs of male rats, radioactivity in 34 major tissues and 5 digestive matter compartments was measured at 12, 25, 50, 100, 200 and 720min postexposure, during which time the excreta and exhaled air were also collected. [(14)C]PCB11 and metabolites in lung, liver, blood, digestive matter, urine, feces, and adipose tissues were extracted separately to establish the metabolic profile of the disposition.

RESULTS

[(14)C]PCB11 was distributed rapidly to all tissues after 99.8% pulmonary uptake and quickly underwent extensive metabolism. The major tissue deposition of [(14)C]PCB11 and metabolites translocated from liver, blood and muscle to skin and adipose tissue 200min postexposure, while over 50% of administered dose was discharged via urine and feces within 12h. Elimination of the [(14)C]PCB11 and metabolites consisted of an initial fast phase (t½=9-33min) and a slower clearance phase to low concentrations. Phase II metabolites dominated in liver blood and excreta after 25min postexposure.

CONCLUSIONS

This study shows that PCB11 is completely absorbed after inhalation exposure and is rapidly eliminated from most tissues. Phase II metabolites dominated with a slower elimination rate than the PCB11 or phase I metabolites and thus can best serve as urine biomarkers of exposure.

In vivo biodistribution of platinum-based drugs encapsulated into multi-walled carbon nanotubes

Carbon nanotubes (CNTs) are promising drug delivery systems due to their external functionalizable surface and their hollowed cavity that can encapsulate several bioactive molecules. In this study, the chemotherapeutic drug cisplatin or an inert platinum(IV) complex were entrapped inside functionalized-multi-walled-CNTs and intravenously injected into mice to investigate the influence of CNTs on the biodistribution of Pt-based molecules. The platinum levels in vital organs suggested that functionalized-CNTs did not affect cisplatin distribution, while they significantly enhanced the accumulation of Pt(IV) sample in some tissues (e.g. in the lungs, suggesting their potential application in lung cancer therapy) and reduced both kidney and liver accumulation (thus decreasing eventual nephrotoxicity, a typical side effect of cisplatin). Concurrently, CNTs did not induce any intrinsic abnormal immune response or inflammation, as confirmed by normal cytokine levels and histological evaluations. Therefore, functionalized nanotubes represent an efficient nano-carrier to improve accumulation of Pt species in targeted tissues/organs. From the clinical editor: In this preclinical study functionalized carbon nanotubes are reported to be safe and efficient for targeted delivery of platinum-containing compounds in rodents. Approaches like this may improve the treatment of specific cancers, since platinum based chemotherapies are commonly used, yet limited by toxicity and relatively poor target tissue concentration.

Novel ubiquitin-derived high affinity binding proteins with tumor targeting properties

Targeting effector molecules to tumor cells is a promising mode of action for cancer therapy and diagnostics. Binding proteins with high affinity and specificity for a tumor target that carry effector molecules such as toxins, cytokines, or radiolabels to their intended site of action are required for these applications. In order to yield high tumor accumulation while maintaining low levels in healthy tissues and blood, the half-life of such conjugates needs to be in an optimal range. Scaffold-based binding molecules are small proteins with high affinity and short systemic circulation. Due to their low molecular complexity, they are well suited for combination with effector molecules as well as half-life extension technologies yielding therapeutics with half-lives adapted to the specific therapy. We have identified ubiquitin as an ideal scaffold protein due to its outstanding biophysical and biochemical properties. Based on a dimeric ubiquitin library, high affinity and specific binding molecules, so-called Affilin® molecules, have been selected against the extradomain B of fibronectin, a target almost exclusively expressed in tumor tissues. Extradomain B-binding molecules feature high thermal and serum stability as well as strong in vitro target binding and in vivo tumor accumulation. Application of several half-life extension technologies results in molecules of largely unaffected affinity but significantly prolonged in vivo half-life and tumor retention. Our results demonstrate the utility of ubiquitin as a scaffold for the generation of high affinity binders in a modular fashion, which can be combined with effector molecules and half-life extension technologies.

Blood protein coating of gold nanoparticles as potential tool for organ targeting

Nanoparticles (NP) and nanoparticulated drug delivery promise to be the breakthrough for therapy in medicine but raise concerns in terms of nanotoxicity. We present quantitative murine biokinetics assays using polyelectrolyte-multilayer-coated gold NP (AuNP, core diameter 15 and 80 nm; (198)Au radio-labeled). Those were stably conjugated either with human serum albumin (alb-AuNP) or apolipoprotein E (apoE-AuNP), prior to intravenous injection. We compare the biokinetics of protein-AuNP-conjugates with citrate-stabilized AuNP (cit-AuNP). Biokinetics was complemented with histology in organs with high AuNP content using 15 nm double fluorescently-labeled alb-AuNP-conjugates. Protein conjugation massively reduced liver retention (alb-AuNP: 52%, apoE-AuNP: 72%, cit-AuNP: >95%, at 19 h and 48 h) when compared to cit-AuNP. The protein conjugates were retained in lungs (alb-AuNP (18%) and spleen (alb-AuNP (16%), apoE-AuNP (21%) at 19 h. Alb-AuNP show significantly increased fractions in lungs (factors: 60 (30 min); 111 (19 h); 235 (48 h) and brain (factors: 70 (30 min); 90 (19 h); >200 (48 h) compared to cit-AuNP (control) - or even to apoE-AuNP. The influence of protein conjugation on the biodistribution disappears for 80 nm AuNP comparing to control. Histologically, the 15 nm alb-AuNP are mainly located in the endothelium of brain, lungs, liver and kidneys after 30 min, while at 19 h they moved deeper into the parenchyma e.g. in hippocampus. Our study clearly suggests that stable conjugation of AuNP with albumin and apoE prior to intravenous administration increases specificity and efficiency of NP in diseased target-organs thus suggesting a potential role in nanomedicine and nanopharmacology.

Biodistribution of adult derived human liver stem cells following intraportal infusion in a 17-year-old patient with glycogenosis type 1A

INTRODUCTION

Current treatment of inherited liver inborn errors of metabolism in children consists in appropriate diet and drugs and, for unstable patients, final orthotopic liver transplantation. Unfortunately, liver transplantation remains not easily available because of organ shortage and imposes inherent risks and lifelong immunosuppressive therapy. Therefore alternative treatments are required. Hepatocytes transplantation and its limitations led to consider innovative alternative such as transplantation of adult derived human liver stem cells (ADLHSC). These cells present high proliferative capacity, good resistance to cryopreservation and ability to differentiate into hepatocyte-like cells displaying mature hepatocyte functions.

AIM

Biodistribution of ADHLSC had never been assessed after infusion through the portal vein in patients. This information is required to determine the safety of the method.

METHODS

ADHLSC were efficiently labelled with 111-Indium DTPA radiotracer and SPECT imaging was used for the acquisition of whole body imaging to document short term biodistribution of ADHLSC.

RESULTS

Following infusion through the portal vein, ADHLSC diffused homogenously throughout the liver and remained strictly within the targeted organ. Images were acquired until 5 days after infusion. At that time, no signal was observed in any other organs except the liver. Urinary excretion of 111-Indium DTPA was also monitored.

CONCLUSION

For the first time, we documented the short term biodistribution of ADHLSC within the liver after infusion through the portal vein.

Foliar exposure of the crop Lactuca sativa to silver nanoparticles: evidence for internalization and changes in Ag speciation

The impact of engineered nanomaterials on plants, which act as a major point of entry of contaminants into trophic chains, is little documented. The foliar pathway is even less known than the soil-root pathway. However, significant inputs of nanoparticles (NPs) on plant foliage may be expected due to deposition of atmospheric particles or application of NP-containing pesticides. The uptake of Ag-NPs in the crop species Lactuca sativa after foliar exposure and their possible biotransformation and phytotoxic effects were studied. In addition to chemical analyses and ecotoxicological tests, micro X-ray fluorescence, micro X-ray absorption spectroscopy, time of flight secondary ion mass spectrometry and electron microscopy were used to localize and determine the speciation of Ag at sub-micrometer resolution. Although no sign of phytotoxicity was observed, Ag was effectively trapped on lettuce leaves and a thorough washing did not decrease Ag content significantly. We provide first evidence for the entrapment of Ag-NPs by the cuticle and penetration in the leaf tissue through stomata, for the diffusion of Ag in leaf tissues, and oxidation of Ag-NPs and complexation of Ag(+) by thiol-containing molecules. Such type of information is crucial for better assessing the risk associated to Ag-NP containing products.

Long-term biodistribution in vivo and toxicity of radioactive/magnetic hydroxyapatite nanorods

Although nanoscale hydroxyapatite [Ca10(PO4)6(OH)2; HA] has been widely investigated as a carrier in the delivery of drugs, genes, or siRNA, the in vivo toxicity of nanoscale HA is not clear and the long-term dynamic distribution in vivo has not hitherto been visualized. In this work, gadolinium-doped HA nanorods (HA:Gd) with an r1 value of 5.49 s(-1) (mm)(-1) have been prepared by a hydrothermal method. Samarium-153 ((153)Sm) was then effectively post-labeled onto the HA:Gd ((153)Sm-HA:Gd) with a labeling rate of ∼100% and a radio-labeling stability in vitro of ∼100% over 48 h. The product could serve as a new dual-modality probe for SPECT and MR imaging in vivo. By means of SPECT and MRI, the HA:Gd nanorods were found to be quickly taken up by the mononuclear phagocyte system, especially the liver and spleen. The nanorods in the liver and lung tended to be eliminated within 24 h, but nanorods in the spleen behaved differently and proved difficult to excrete. In vitro studies by cell transmission electron microscopy (TEM) and methyl thiazolyl tetrazolium (MTT) assay showed good biocompatibility of the HA:Gd nanorods with HeLa cells, even at a high concentration. The indicators of body weight, histology, and serology demonstrated that the HA:Gd nanorods exhibited excellent biocompatibility in vivo for at least 61 days. Therefore, (153)Sm-HA:Gd nanorods with excellent relaxivity, γ-emission, and biosafety offer clear advantages and potential for bioapplications.

Influence of polyethylene glycol density and surface lipid on pharmacokinetics and biodistribution of lipid-calcium-phosphate nanoparticles

The pharmacokinetics (PK) and biodistribution of nanoparticles (NPs) are controlled by a complex array of interrelated, physicochemical and biological factors of NPs. The lipid-bilayer core structure of the Lipid-Calcium-Phosphate (LCP) NPs allows us to examine the effects of the density of polyethylene glycol (PEG) and the incorporation of various lipids onto the surface on their fate in vivo. Fluorescence quantification estimated that up to 20% (molar percent of outer leaflet lipids) could be grafted on the surface of LCP NPs. Contrary to the common belief that high level of PEGylation could prevent the uptake of NPs by the reticuloendothelial system (RES) organs such as liver and spleen, a significant amount of the injected dose was observed in the liver. Confocal microscopy revealed that LCP NPs were largely localized in hepatocytes not Kupffer cells. It was further demonstrated that the delivery to hepatocytes was dependent on both the concentration of PEG and the surface lipids. LCP NPs could be directed from hepatocytes to Kupffer cells by decreasing PEG concentration on the particle surface. In addition, LCP NPs with 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) exhibited higher accumulation in the hepatocytes than LCP NPs with dioleoylphosphatidylcholine (DOPC). Analysis of the proteins bound to NPs suggested that apolipoprotein E (apoE) might serve as an endogenous targeting ligand for LCP-DOTAP NPs, but not LCP-DOPC NPs. The significant uptake of NPs by the hepatocytes is of great interest to formulation design for oncologic and hepatic drug deliveries.

Effect of Intra-Medullar and Intra-Venous Infusions of Mesenchymal Stem Cells on Cell Engraftment by In-Vivo Cell Tracking and Osteoinductivity in Rabbit Long Bones: A Pilot Study

OBJECTIVE

Stem cell therapy can be an efficacious treatment option for bone fragility disorders (eg, osteogenesis imperfecta, disuse osteopenia, and osteoporosis), and successful cell therapy application may be dependent on optimal cell engraftment in target bones. The objective of this study was to compare the efficiency of intra-medullar and intra-venous delivery of mesenchymal stem cells (MSC) to improve cell engraftment rate, bone mineral density, and micro-architecture.

METHODS

By using six healthy juvenile New Zealand White rabbits, MSC were isolated from cancellous bone harvests and confirmed to have osteogenic capacity by inducing ectopic bone formation. The MSC were cultured, transduced by foamy viral vectors with marker genes for in vivo cell tracking, and expanded. All rabbits had one randomly selected limb receive intra-medullar infusion of 3×10⁷ to 1×10⁸ autologous MSC in the distal femur or the distal femur and proximal tibia. Two of six rabbits also received an intra-venous MSC infusion. At 28 days, MSC bone engraftment was assessed by PCR and the bone density and microstructure assessed by computed tomography and histomorphometry.

RESULTS

The intra-medullar-infused MSC were detected in epiphysis or diaphysis of the distal femurs and/or proximal tibiae. Infused MSC comprised 0.01 to 0.3% of all cells in the bone tissues. The intra-venous-infused MSC were not detected in any location. Neither intra-medullar nor intra-venous MSC infusion altered bone volume, bone mineral density, or cortical bone porosity/thickness. Systemic biodistribution of intra-medullar-infused MSC was not evident.

CONCLUSIONS

Our results indicated that intra-medullar infusion can be an effective cell delivery route for stem cell therapy potentially for orthopedic disorders, in preference to systemic administration. Further research is warranted to demonstrate an efficacy of intra-medullar MSC infusion on bone density and micro-architecture using animal models of bone disorders.

Development of (111)In-labeled porphyrins for SPECT imaging

OBJECTIVES

The aim of this research was the development of (111)In-labeled porphyrins as possible radiopharmaceuticals for the imaging of tumors.

METHODS

Ligands, 5, 10, 15, 20-tetrakis (3, 5-dihydroxyphenyl) porphyrin) (TDHPP), 5, 10, 15, 20-tetrakis (4-hydroxyphenyl) porphyrin (THPP) and 5, 10, 15, 20-tetrakis (3,4-dimethoxyphenyl) porphyrin) (TDMPP) were labeled with (111)InCl3 (produced from proton bombardment of natCd target) in 60 min at 80 ºC. Quality control of labeled compounds was performed via RTLC and HPLC followed by stability studies in final formulation and presence of human serum at 37 ºC for 48 h as well as partition coefficient determination. The biodistribution studies performed using tissue dissection and SPECT imaging up to 24h.

RESULTS

The complexes were prepared with more than 99% radiochemical purity (HPLC and RTLC) and high stability to 48 h. Partition coefficients (calculated as log P) for (111)In-TDHPP, (111)In-THPP and (111)In-TDMPP were 0.88, 0.8 and 1.63 respectively.

CONCLUSION

Due to urinary excretion with fast clearance for (111)In-TDMPP, this complex is probably a suitable candidate for considering as a possible tumor imaging agent.

Intervention in cyclophosphamide induced oxidative stress and DNA damage by a flavonyl-thiazolidinedione based organoselenocyanate and evaluation of its efficacy during adjuvant therapy in tumor bearing mice

A novel flavonyl-thiazolidinedione based organoselenocyanate compound was synthesized and established as nontoxic at the doses of 2.5 and 5 mg/kg b.w. in mice. Oral administration of the compound in combination with cyclophosphamide (CP) resulted in an improved therapeutic efficacy which was mostly evidenced in terms of tumor burden and protection of normal cells. The adjuvant therapy was proved to be immensely significant in increasing the mean survivability of the tumor bearing hosts. Reduction in the tumor volume was manifested through the induction of apoptosis and generation of ROS in transformed cells. Moreover, the organoselenium compound could efficiently suppress CP-induced DNA damage, chromosomal aberration, hepatic damage and enhanced the activities of various antioxidant enzymes in normal cells.

Influence of charge on encapsulation and release behavior of small molecules in self-assembled layer-by-layer microcapsules

The objective of this study is to investigate the influence of charge of model small molecules on their encapsulation and release behavior in layer-by-layer microcapsules (LbL-MC). Poly(styrene sulfonate) and poly(ethylene imine) were sequentially adsorbed on calcium carbonate sacrificial templates to prepare LbL-MC. Model molecules with varying charge, anionic - ascorbic acid, cationic - imatinib mesylate (IM) and neutral - 5-fluorouracil were encapsulated in LbL-MC. Free and encapsulated LbL-MC were characterized using zetasizer, FTIR spectroscope and differential scanning calorimeter. The influence of IM-loaded LbL-MC on cell viability was studied in B16F10 murine melanoma cells. Furthermore, biodistribution of IM-loaded LbL-MC with and without PEGylation was studied in BALB/c mice. Results showed spherical LbL-MC of 3.0 ± 0.4 μm diameter. Encapsulation efficiency of LbL-MC increased linearly (R(2 )= 0.89-0.99) with the increase in solute concentration. Increase in pH from 2 to 6 increased the encapsulation of charged molecules in LbL-MC. Charged molecules showed greater encapsulation efficiency in LbL-MC compared with neutral molecule. In vitro release kinetics showed Fickian and non-Fickian diffusion of small molecules, depending on the nature of molecular interactions with LbL-MC. At 50 μM concentration, free IM showed significantly (p < 0.05) more cytotoxicity compared with IM-loaded LbL-MC. Biodistribution studies showed that PEGylation of LbL-MC decreased the liver and spleen uptake of IM-encapsulated LbL-MC. In conclusion, LbL-MC can be developed as a potential carrier for small molecules depending on their physical and chemical properties.

Biodistribution, pharmacokinetics, and blood compatibility of native and PEGylated tobacco mosaic virus nano-rods and -spheres in mice

Understanding the pharmacokinetics, blood compatibility, biodistribution and clearance properties of nanoparticles is of great importance to their translation to clinical application. In this paper we report the biodistribution and pharmacokinetic properties of tobacco mosaic virus (TMV) in the forms of 300×18nm(2) rods and 54nm-sized spheres. The availability of rods and spheres made of the same protein provides a unique scaffold to study the effect of nanoparticle shape on in vivo fate. For enhanced biocompatibility, we also considered a PEGylated formulation. Overall, the versions of nanoparticles exhibited comparable in vivo profiles; a few differences were noted: data indicate that rods circulate longer than spheres, illustrating the effect that shape plays on circulation. Also, PEGylation increased circulation times. We found that macrophages in the liver and spleen cleared the TMV rods and spheres from circulation. In the spleen, the viral nanoparticles trafficked through the marginal zone before eventually co-localizing in B-cell follicles. TMV rods and spheres were cleared from the liver and spleen within days with no apparent changes in histology, it was noted that spheres are more rapidly cleared from tissues compared to rods. Further, blood biocompatibility was supported, as none of the formulations induced clotting or hemolysis. This work lays the foundation for further application and tailoring of TMV for biomedical applications.

Enhanced tumor uptake, biodistribution and pharmacokinetics of etoposide loaded nanoparticles in Dalton's lymphoma tumor bearing mice

BACKGROUND

Nanotechnology plays a remarkable role in the field of the treatment of Lymphomas associated with tumor.

OBJECTIVE

The purpose of this study is to determine and to compare the tumor uptake, biodistribution and pharmacokinetics of radiolabeled etoposide and etoposide loaded nanoparticles in Dalton's Lymphoma tumor bearing mice and healthy mice.

MATERIALS AND METHODS

Etoposide loaded nanoparticles were prepared by nanoprecipitation technique using the poly (lactic-co-glycolic) acid (PLGA) in the presence of Pluronic F 68 (F 68) as a stabilizer and characterized by particle size analyzer, zeta potential and transmission electron microscope. Etoposide and etoposide loaded nanoparticles were labeled with Technetium-99m (Tc-99m) by the direct method and various quality control tests were carried out. The labeling parameters like labeling efficiency, stability, etc., were optimized to get high labeling efficiency as well as stability of the labeled formulations. Tc-99m labeled formulations were administered intravenously in Balb C mice and their biodistribution and pharmacokinetics were determined.

RESULTS

Mean size of the etoposide loaded PLGA nanoparticles was found to be 105.1 nm. The concentration of both free etoposide and nanoparticles increased with time and showed higher tumor concentrations of both free etoposide and nanoparticles increased with time and showed higher retention, indicating their applicability in effective and prolonged tumor therapy. Nuclear scintigraphic images confirm the presence of labeled complexes at the site of tumor for 24 h at higher concentration than in the normal muscles.

CONCLUSION

This study indicated higher tumor affinity and targeting properties of etoposide loaded nanoparticles than free etoposide.

Pharmacology of carbon nanotubes: toxicokinetics, excretion and tissue accumulation

Carbon nanotubes (CNT) are increasingly being investigated for their use in biomedical applications and nanomedicine. An emergent need for the understanding of their in vivo biodistribution and pharmacokinetics is therefore needed to establish the essential properties and criteria for their further development as targeted CNT delivery systems to specific tissues for diagnostics and therapeutic purposes. Until their biodistribution and toxicoketic profiles are fully understood, their translation into the clinic will be hindered. This review will highlight the important factors affecting the biodistribution and pharmacokinetic profile of CNT and address their toxicokinetics following systemic, pulmonary and dermal exposure.

Dynamic in vivo imaging of dual-triggered microspheres for sustained release applications: synthesis, characterization and cytotoxicity study

This paper deals with the synthesis, characterization and property evaluation of drug-loaded magnetic microspheres with pH-responsive cross-linked polymer shell. The synthetic procedure consists of 3 steps, of which the first two comprise the synthesis of a poly methyl methacrylate (PMMA) template and the synthesis of a shell by using acrylic acid (AA) and methyl methacrylate (MMA) as monomers, and divinyl benzene (DVB) as cross-linker. The third step of the procedure refers to the formation of magnetic nanoparticles on the microsphere's surface. AA that attaches pH-sensitivity in the microspheres and magnetic nanoparticles in the inner and the outer surface of the microspheres, enhance the efficacy of this intelligent drug delivery system (DDS), which constitutes a promising approach toward cancer therapy. A number of experimental techniques were used to characterize the resulting microspheres. In order to investigate the in vitro controlled release behavior of the synthesized microspheres, we studied the Dox release percentage under different pH conditions and under external magnetic field. Hyperthermia caused by an alternating magnetic field (AFM) is used in order to study the doxorubicin (Dox) release behavior from microspheres with pH functionality. The in vivo fate of these hybrid-microspheres was tracked by labeling them with the γ-emitting radioisotope (99m)Tc after being intravenously injected in normal mice. According to our results, microsphere present a pH depending and a magnetic heating, release behavior. As expected, labeled microspheres were mainly found in the mononuclear phagocyte system (MPS). The highlights of the current research are: (i) to illustrate the advantages of controlled release by combining hyperthermia and pH-sensitivity and (ii) to provide noninvasive, in vivo information on the spatiotemporal biodistribution of these microsphere by dynamic γ-imaging.

Characterization and biodistribution in vivo of quercetin-loaded cationic nanostructured lipid carriers

Nanobiotechnology has been recently viewed as a promising strategy to improve therapy efficacy by promoting the accumulation of hydrophobic bioactive compounds in tissues. The aim of present study was to formulate a novel quercetin-loaded cationic nanostructured lipid carriers (QR-CNLC) and to evaluate its biodistribution in vivo after oral administration. QR-CNLC were prepared by emulsifying at high temperature and subsequent solidifying at low temperature using various functional ingredients, and its characteristics, including physical index, release profile in vitro, and tissue distribution in vivo, were investigated. The results demonstrated that QR-CNLC exhibited an average particle size 126.6 nm, a zeta potential of 40.5 mV and 89.3% entrapment efficiency. QR-CNLC performed slower release compared with quercetin solution in vitro. QR-CNLC showed higher AUC (area under tissue concentration-time curve) value and higher Cmax value in lung, liver and kidney compared with control group. The value of relative intake rate (re) for lung, liver and kidney was 1.57, 1.51 and 1.68, respectively, which revealed that quercetin can be significantly accumulated in lung, kidney and liver after oral administration of QR-CNLC compared with quercetin suspension. In conclusion, cationic nanostructured lipid carriers may be an attractive nanocarrier system for oral delivery of hydrophobic functional components.

The influence of lipid composition and surface charge on biodistribution of intact liposomes releasing from hydrogel-embedded vesicles

Mixed drug delivery systems possess advantages over discrete systems, and can be used as a strategy to design more effective formulations. They are more valuable if the embedded particles perform well, rather than using drugs that have been affected by the surrounding vehicle. In order to address this concept, different liposomes have been incorporated into hydrogel to evaluate the potential effect on the controlled release of liposomes. Radiolabeled liposomes, with respect to different acyl chain lengths (DMPC, DPPC, or DSPC) and charges (neutral, negative [DSPG], or positive [DOTAP]) were integrated into chitosan-glycerophosphate. The results obtained from the biodistribution showed that the DSPC liposomes had the highest area under the curve (AUC) values, both in the blood (206.5%ID/gh(-1)) and peritoneum (622.3%ID/gh(-1)), when compared to the DPPC and DMPC formulations, whether in liposomal hydrogel or dispersion. Interesting results were observed in that the hydrogel could reverse the peritoneal retention of negatively charged liposomes, increasing to 8 times its AUC value, to attain the highest amount among all formulations. The interactions between the liposomes and chitosan-glycerophosphate, confirmed by the Fourier transform infrared (FTIR) spectra as shifted characteristic peaks, were observed in the combined systems. Overall, the hydrogel could control the release of intact liposomes, which could be manipulated by both the liposome type and interactions between the two vehicles.

[In vitro comparative study of plasma protein binding of 99mTc-DTPA used in renal scintigraphy]

The radiopharmaceutical (99m)Tc-DTPA (diethylene-triamine-pentaacetic acid) is a tracer widely used in renal scintigraphy to assess glomerular filtration rate. The estimation of protein binding is very important due to its impact on clinical parameters biodistribution since only the free fraction is filtered by the kidney. A number of laboratory techniques have been developed to study protein binding. Precipitation and ultrafiltration are the mostly used techniques in pharmacology for studies of the binding between proteins and small molecules. The aim of this work is to apply and compare those two analytical methods in (99m)Tc-DTPA protein binding determination in vitro before in vivo application. The results obtained by precipitation with trichloroacetic acid are not enough reproducible, while those obtained by ultrafiltration seem more consistent and reproducible.

In vitro and in vivo studies of an aqueous extract of Matricaria recutita (German chamomile) on the radiolabeling of blood constituents, on the morphology of red blood cells and on the biodistribution of the radiopharmaceutical sodium pertechnetate

Background:

Natural products might alter the labeling of blood constituents with technetium-99m (^99mTc) and these results may be correlated with modifications of the shape of the red blood cells (RBC). The biodistribution of radiopharmaceuticals can be also altered.

Objective:

This investigation aimed to determine biological effects of an aqueous extract of chamomile (CE).

Materials and Methods:

To study the effect of the CE on the labeling of blood constituents with ^99mTc, in vitro and in vivo assays were performed. The effect of the CE on the morphology of RBC was observed under light microscope. The images were acquired, processed, and the perimeter/area ratio of the RBC determined. To analyze the effect of the CE on biodistribution of the sodium pertechnetate (Na^99mTcO₄) in Wistar rats, these animals were treated or not with a CE. Na^99mTcO₄ was injected, the rats were sacrificed, the organs were removed, weighted and percentage of radioactivity/gram calculated.

Result:

In the in vitro experiment, the radioactivity on blood cells compartment and on insoluble fractions of plasma was diminished. The shape and the perimeter/area ratio of the RBC were altered in in vitro assays. An increase of the percentage of radioactivity of Na^99mTcO₄ was observed in stomach after in vivo treatment.

Conclusion:

These results could be due to substances of the CE or by the products of the metabolism of this extract in the animal organism. These findings are examples of drug interaction with a radiopharmaceutical, which could lead to misdiagnosis in clinical practice with unexpected consequences.

Comparison between two labeled agents in mice using a coinjection-ratio approach in contrast to a conventional group approach

INTRODUCTION

The differences between two agents often need to be accurately defined in vivo. Usually they are injected respectively into two groups of subjects. However, if the two agents do not interact with each other in vivo, a coinjection would serve the same purpose. We believe some individual differences in biodistribution may be circumvented through this approach by calculating organ level ratios.

METHODS

A model system of MORF/cMORF pretargeting (MORF/cMORF is a complementary pair of DNA analogues) was employed in connection with an on-going tumor therapeutic project. Human LS174T cells were implanted into the flank of severely immuno-compromised NOD-scid IL2rg(null) mice. The tumor was confirmed to express TAG-72 antigens. At 16 days post tumor inoculation, mice received IV 60 μg of MORF-conjugated CC49 (an antiTAG-72 antibody), followed 2 days later by a low-mass-dose IV coinjection containing 2.5 μg of (90)Y-cMORF and 2.5 μg of (99m)Tc-cMORF. At 3 h post radioactivity injection, the distribution of (99m)Tc was imaged on a SPECT/CT camera and then organs were excised and counted for (90)Y and (99m)Tc. Because the two labeled cMORFs do not react or interact with each other in vivo, the two groups of (90)Y and (99m)Tc data enabled a conventional group comparison. In a new effort, (90)Y/(99m)Tc ratios were calculated. Student's t-test and retrospective power analysis were performed for both approaches. In the new approach, the ratios were set at 1 as the null hypothesis.

RESULTS

The Student's t-test in the conventional group approach indicated that the two labeled cMORFs distributed similarly, but significant differences were observed in salivary gland and large intestines. The coinjection-ratio approach certainly did not subvert the results of the conventional approach but revealed subtler differences. The P values were reduced, the powers were increased in most organs, and more significant differences were observed. The increased sensitivity was due to the reduced CV%s (SD/average*100%) of the (90)Y/(99m)Tc ratios. Therefore, some individual differences were circumvented and notably the ratio approach differentiated individual differences into ratio-correctable and ratio-uncorrectable.

CONCLUSIONS

Although the conventional approach is reliable, the coinjection-ratio approach using organ level ratios is more sensitive and therefore is recommended whenever possible. In addition, it differentiates individual differences into "coinjection correctable" and "coinjection uncorrectable".

Gold nanoparticle mediated cancer immunotherapy

Significant progress has been made in the field of cancer immunotherapy, where the goal is to activate or modulate the body's immune response against cancer. However, current immunotherapy approaches exhibit limitations of safety and efficacy due to systemic delivery. In this context, the use of nanotechnology for the delivery of cancer vaccines and immune adjuvants presents a number of advantages such as targeted delivery to immune cells, enhanced therapeutic effect, and reduced adverse outcomes. Recently, gold nanoparticles (AuNP) have been explored as immunotherapy carriers, creating new AuNP applications that merit a critical overview. This review highlights recent advances in the development of AuNP mediated immunotherapies that harness AuNP biodistribution, optical properties and their ability to deliver macromolecules such as peptides and oligonucleotides. It has been demonstrated that the use of AuNP carriers can improve the delivery and safety of immunotherapy agents, and that AuNP immunotherapies are well suited for synergistic combination therapy with existing cancer therapies like photothermal ablation.

FROM THE CLINICAL EDITOR

Cancer immunotherapy approaches are rapidly evolving and are some of the most promising avenues to approach malignancies. This review summarizes the role of gold nanoparticles in immunotherapy agent delivery, and in the development of synergistic therapies such as photothermal ablation.

In vivo pharmacokinetics, biodistribution and antitumor effect of amphiphilic poly(L-amino acids) micelles loaded with a novel all-trans retinoic acid derivative

Poly(amino acid)s are well-known as biodegradable and environmentally acceptable materials. In this study, a series of poly(L-aspartic acid)-b-poly(L-phenylalanine) (PAA-PPA) compounds with different degrees of polymerization were used to prepare copolymer micelles for a poorly water-soluble drug 4-amino-2-trifluoromethyl-phenyl retinate (ATPR, a novel all-trans retinoic acid derivative) and in vivo pharmacokinetics, biodistribution and antitumor efficacy of ATPR delivered by PAA-PPA micelles were evaluated. The area under the plasma concentration time curve AUC0→∞ of ATPR-loaded PAA20PPA20 micelles was 2.23 and 1.97 times higher than that of ATPR solution and ATPR CrmEL solution, respectively; In addition, the mean residence time (MRT) was increased 1.67 and 1.97-fold, respectively and the total body clearance (CL) was reduced 2.25 and 1.98-fold, respectively. The biodistribution study indicated that most of the ATPR in the ATPR-M group was distributed in the liver and there was delayed liver aggregation compared with the ATPR solution and ATPR CrmEL solution groups. Furthermore, the antitumor efficacy of ATPR-loaded PAA20PPA20 micelles was demonstrated in in vivo antitumor models involving mice inoculated with the human gastric cancer cell line SGC-7901. At the same dose of 7mg/kg, the ATPR-loaded micelles group demonstrated a better tumor growth inhibition and induced differentiation than the groups given ATPR solution and ATPR CrmEL solution. Therefore, the ATPR-loaded PAA-PPA micelles appear to be a potentially useful drug delivery system for ATPR and suitable for the chemotherapy of gastric cancer.

Factors controlling the pharmacokinetics, biodistribution and intratumoral penetration of nanoparticles

Nanoparticle drug delivery to the tumor is impacted by multiple factors: nanoparticles must evade clearance by renal filtration and the reticuloendothelial system, extravasate through the enlarged endothelial gaps in tumors, penetrate through dense stroma in the tumor microenvironment to reach the tumor cells, remain in the tumor tissue for a prolonged period of time, and finally release the active agent to induce pharmacological effect. The physicochemical properties of nanoparticles such as size, shape, surface charge, surface chemistry (PEGylation, ligand conjugation) and composition affect the pharmacokinetics, biodistribution, intratumoral penetration and tumor bioavailability. On the other hand, tumor biology (blood flow, perfusion, permeability, interstitial fluid pressure and stroma content) and patient characteristics (age, gender, tumor type, tumor location, body composition and prior treatments) also have impact on drug delivery by nanoparticles. It is now believed that both nanoparticles and the tumor microenvironment have to be optimized or adjusted for optimal delivery. This review provides a comprehensive summary of how these nanoparticle and biological factors impact nanoparticle delivery to tumors, with discussion on how the tumor microenvironment can be adjusted and how patients can be stratified by imaging methods to receive the maximal benefit of nanomedicine. Perspectives and future directions are also provided.

In vivo biodistribution and synergistic toxicity of silica nanoparticles and cadmium chloride in mice

Silica nanoparticles (SiNPs) are now in daily use due to their low intrinsic toxicity. Cadmium is a ubiquitous environmental pollutant. In spite of real risk of humans' co-exposure to SiNPs and cadmium, their synergistic toxicity is still unclear. Here, we report the synergistic effects of SiNPs and CdCl₂ on their biodistribution and subacute toxicity in mice. The biodistributions, histopathological changes, serum biochemical parameters and oxidative stress responses were determined after intraperitoneal injection of SiNPs and/or CdCl₂ to mice. SiNPs and CdCl₂ have a positive synergistic toxicity in mice. Although SiNPs were low toxic to mice, co-exposure of SiNPs and CdCl₂ significantly enhanced CdCl₂-induced oxidative damage in the liver as indicated by the severe liver dysfunction and histopathological abnormalities. Co-exposure to SiNPs and CdCl₂ markedly increased the cadmium accumulation in the liver, which induced significant hepatic oxidative stress. In vitro binding assays indicated that serum albumin and Cd(2+) mutually enhanced the binding of each other to SiNPs via the interaction of serum albumin and Cd(2+). The uptake of serum albumin- and Cd(2+)-bound SiNPs by the macrophages significantly increased cadmium accumulation in mice. These results demonstrate that serum albumins play an important role in the positive synergistic toxicity of SiNPs and CdCl₂.

Synthesis and Evaluation of [(67)Ga]-AMD3100: A Novel Imaging Agent for Targeting the Chemokine Receptor CXCR4

In order to develop a possible C-X-C chemokine receptor type 4 (CXCR4) imaging agent for oncological scintigraphy, [⁶⁷Ga]-labeled 1,1′-[1,4-Phenylene-bis(methylene)]bis(1,4,8,11-tetraazacyclotetradecane) ([⁶⁷Ga]-AMD3100) was prepared by using [⁶⁷Ga]GaCl₃ and AMD-3100 for 2 h at 50 °C (radiochemical purity: >95% ITLC, >99% HPLC, specific activity: 1800–2000 TBq/mmol) in acetate buffer. The stability of the complex was checked in the presence of human serum (37 °C) and in the final formulation for four days. The biodistribution of the labeled compound in the vital organs of wild type Sprague-Dawley rats was determined and compared with that of the free Ga³⁺ cation up to 48 h. Considering the spleen as the target organ, the best target:non target ratios were obtained 48 h post-injection (spleen:blood ratio; 14.5 and spleen:muscle ratio; 88.4). Initial SPECT images and biodistribution results in the wild type rats matched each other and demonstrated rapid washout of the tracer from the urinary tract. SPECT images in human breast carcinoma-bearing mice demonstrated a detectable tumor uptake in 48 h post-injection.

In vivo lung deposition and sub-acute inhalation toxicity studies of nano-sized alendronate sodium as an antidote for inhaled toxic substances in Sprague Dawley rats

INTRODUCTION

Alendronate sodium is a bisphosphonate agent used for the treatment of osteoporosis and other bone diseases. It has a strong chelating property to bind or, to some extent, counteract the effects of substances, such as magnesium, calcium citrate, ferrous fumarate, carbonyl iron, as well as the zinc gluconate, sulfate and acetate salts. The objective of the present study was to evaluate lung deposition and sub-acute inhalation toxicity of the alendronate sodium respiratory formulation.

METHODS

Particle dimension of aerosols of alendronate was measured using a particle size analyzer. Alendronate was radiolabeled using Technetium-99m for in vitro and in vivo biodistribution studies. Alendronate at doses, 0.5%, 1.0%, and 1.5% in ethanol-saline respiratory formulation was inhaled twice a day up to 5 weeks for inhalation toxicity investigations. Hematological, biochemical and lung toxicity biomarkers in bronchoalveolar lavage (BAL) fluid were determined at the end of the experiment. Histopathological analysis of lung tissues was carried out to observe any microscopic changes

RESULTS

Particle size analysis revealed the size within 300-500nm. Anderson cascade impactor results showed that the particles exhibited higher respirable fraction (55.52%) with MMAD of 4.66μm. Hematology, serum biochemistry and lung toxicity biomarkers in BAL fluid performed in the sub-acute toxicity studies indicated no adverse effects of alendronate sodium inhalation except for a significant increase in cholesterol levels and marginal increase in BAL fluid protein. At autopsy, no histopathological changes in major organs were observed.

CONCLUSIONS

The lung deposition and safety evaluation data observed from these studies suggested that aerosolized nanosized alendronate sodium by the inhalation route could be a new and promising route of administration as an antidote to radioactive substances through an increase in the bioavailability of the drug as well as a decrease in side effects on systemic delivery.

Preparation, characterization, biodistribution and antitumor efficacy of hydroxycamptothecin nanosuspensions

Hydroxycamptothecin (HCPT) has shown activity against a broad spectrum of cancers, but its therapeutic efficacy is impaired by its poor solubility and delivery challenges. In this study, HCPT nanosuspensions were prepared with precipitation-combined ultrasonication and characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The HCPT nanosuspensions were spherical with a smooth surface and a small size of 150-200 nm. The lyophilized powders for the HCPT nanosuspensions were amorphous and displayed sustained release in vitro. Compared to commercial HCPT injection, in vivo experiments with HCPT nanosuspensions showed significantly increased HCPT concentrations in the blood and all tissues of the tested as well as improved tumor targetability and liver targetability. Meanwhile, nanosuspensions displayed better anticancer efficacy than injection on H22 bearing mice (81.20% vs. 56.39%, in tumor inhibition rate). Therefore, HCPT nanosuspensions seem very promising for the treatment of hepatic cancer.

Biodistribution and bioimaging studies of hybrid paclitaxel nanocrystals: lessons learned of the EPR effect and image-guided drug delivery

Paclitaxel (PTX) nanocrystals (200 nm) were produced by crystallization from a solution. Antitumor efficacy and toxicity were examined through a survival study in a human HT-29 colon cancer xenograft murine model. The antitumor activity of the nanocrystal treatments was comparable with that by the conventional solubilization formulation (Taxol®), but yielded less toxicity as indicated by the result of a survival study. Tritium-labeled PTX nanocrystals were further produced with a near infrared (NIR) fluorescent dye physically integrated in the crystal lattice. Biodistribution and tumor accumulation of the tritium-labeled PTX nanocrystals were determined immediately after intravenous administration and up to 48 h by scintillation counting. Whole-body optical imaging of animals was concurrently carried out; fluorescent intensities were also measured from excised tumors and major organs of euthanized animals. It was found that drug accumulation in the tumor was less than 1% of 20mg/kg intravenous dose. Qualitatively correlation was identified between the biodistribution determined by using tritium-labeled particles and that using optical imaging, but quantitative divergence existed. The divergent results suggest possible ways to improve the design of hybrid nanocrystals for cancer therapy and diagnosis. The study also raises questions of the general role of the enhanced permeability and retention (EPR) effect in tumor targeting and the effectiveness of bioimaging, specifically for theranostics, in tracking drug distribution and pharmacokinetics.

Complex interactions between dietary and genetic factors impact lycopene metabolism and distribution

Intake of lycopene, a red, tetraterpene carotenoid found in tomatoes is epidemiologically associated with a decreased risk of chronic disease processes, and lycopene has demonstrated bioactivity in numerous in vitro and animal models. However, our understanding of absorption, tissue distribution, and biological impact in humans remains very limited. Lycopene absorption is strongly impacted by dietary composition, especially the amount of fat. Concentrations of circulating lycopene in lipoproteins may be further influenced by a number of variations in genes related to lipid absorption and metabolism. Lycopene is not uniformly distributed among tissues, with adipose, liver, and blood being the major body pools, while the testes, adrenals, and liver have the greatest concentrations compared to other organs. Tissue concentrations of lycopene are likely dictated by expression of and genetic variation in lipoprotein receptors, cholesterol transporters, and carotenoid metabolizing enzymes, thus impacting lycopene accumulation at target sites of action. The novel application of genetic evaluation in concert with lycopene tracers will allow determination of which genes and polymorphisms define individual lycopene metabolic phenotypes, response to dietary variables, and ultimately determine biological and clinical outcomes. A better understanding of the relationship between diet, genetics, and lycopene distribution will provide necessary information to interpret epidemiological findings more accurately and to design effective, personalized clinical nutritional interventions addressing hypotheses regarding health outcomes.

Pharmacokinetics and biodistribution of negatively charged pectin nanoparticles encapsulating paclitaxel

Pectin, a naturally occurring biopolymer has been found to have increasing applications in the pharmaceutical and biotechnology industry. Sugars with their three-dimensional structures are important for many biological functions. We report preparation of negatively charged pectin nanoparticles encapsulating paclitaxel, a broad-spectrum anticancer drug for possible therapeutic applications. The mean diameter of the nanoparticles was ~300–350 nm with an encapsulation efficiency ~17 %. The TEM studies indicated that the particles were spherical in shape and their sizes are in unison with the DLS size spectra. The surface charge of pectin polymer was −5 mV and of nanoparticles were ~ −32 mV. The enhanced surface charge shows greater stability. The high electrophoretic mobility of ~3.5 to 1.5 μmcm/Vs confirmed the nano-size of particles. We compared the cytotoxic effect of paclitaxel (Pax) per se, pectin nanoparticles (PPN), and pectin chains on Hep G2, hepatic carcinoma cell line. Dose-dependent cytotoxicity was observed, wherein ~21.7 ± 3.2 % cytotoxicity was observed by PPN, but Pax per se showed ~55.6 ± 3.5 % cytotoxicity in a 72-h assay. The pharmacokinetics and biodistribution studies on Balb/c mice indicated that the nanoparticles had prolonged plasma retention of the drug with major accumulation in liver tissue after an i.v. tail vein injection of 20 mg/kg drug. The rank order of concentration are as follows, i.e., liver > kidney > lung > spleen for the PPN and spleen > liver > kidney ≥ lung for Pax per se. The in vitro studies clearly indicated that the efficacy of the drug was not compromised by encapsulation, making it a good candidate to deliver biopharmaceuticals. Nanoparticles produced free radicals in the free cell system and this ability caused oxidative stress, which may give rise to inflammation, cell destruction, and genotoxicity. Thus, the results obtained in this study holds great promise for pectin nanoparticles to be exploited for passive delivery of paclitaxel to tumor tissues, in particular, liver cancers.

Rapid clearance of intranasally administered DNA from rat tissues

The cold-adapted (ca) live attenuated influenza vaccine (LAIV) strains are manufactured in embryonated hens' eggs. Recently, a clonal isolate from Madin Darby Canine Kidney (MDCK) cells was derived and characterized to assess its utility as a potential cell substrate for the manufacturing of LAIV [1]. Since MDCK cells are a transformed continuous cell line [2], and low levels of residual cellular components (DNA and protein) are found in the intermediates and final filled vaccine, we sought to characterize the uptake and clearance of MDCK DNA from tissues in order to assess theoretical risks associated with manufacturing LAIV in MDCK cell culture. In order to address this concern, MDCK DNA uptake and clearance studies were performed in Sprague Dawley rats. DNA extracted from MDCK Master Cell Bank (MCB) cells was administered via an intranasal (IN) or intramuscular (IM) route. Tissue distribution and clearance of MDCK DNA were then examined in fourteen selected tissue types at selected time points post-administration using a quantitative PCR assay specific for canine (SINE) DNA. Results from these studies demonstrate that the uptake and clearance of MDCK DNA from tissues vary depending on the route of administration. When DNA was administered intranasally, as compared to intramuscularly, detectable DNA levels were lower at all time points. Thus, the intranasal route of vaccine administration appears to reduce potential risk associated with residual host cell DNA that may be present in cell culture produced final vaccine products.

Production, Quality Control and Biological Evaluation of (166)Ho-PDTMP as a Possible Bone Palliation Agent

OBJECTIVE(S)

In this study, (166)Ho-1,2-propylene di-amino tetra(methy1enephosphonicAcid) ((166)Ho-PDTMP) complex was prepared as a bone palliation agent.

MATERIALS AND METHODS

The complex was successfully prepared using an in-house synthesized EDTMP ligand and (166)HoCl3. Ho-166 chloride was obtained by thermal neutron irradiation (1 × 1013 n.cm-2.s-1) of natural Ho(NO3)3 samples followed by radiolabeling and stability studies. Biodistribution in wild type rats was also peformed.

RESULTS

The complex was prepared with the specific activity of 278 GBq/mg and high radiochemical purity (>99%, checked by ITLC). (166)Ho-PDTMP complex was stabilized in the final preparation and in the presence of human serum (>90%) up to 72 hr. The biodistribution of (166)Ho-PDTMP in wild-type rats demonstrated significant bone uptake was up to 48 hr compared to (166)HoCl3.

CONCLUSION

The produced (166)Ho-PDTMP properties suggest a possible new bone palliative therapeutic to overcome the metastatic bone pains.

Development of (177)Lu-phytate Complex for Radiosynovectomy

OBJECTIVE(S)

In this work a new possible agent for radiosynovectomy has been targeted for articular pain palliation.

MATERIALS AND METHODS

Lu-177 of 2.6-3 GBq/mg specific activity was obtained by irradiation of natural Lu2O3 sample with thermal neutron flux of 4 × 10(13) n.cm(-2).s(-1). The product was converted into chloride form which was further used for labeling of (177)Lu-phytate complex and checked using ITLC (MeOH: H2O: acetic acid, 4: 4: 2, as mobile phase). The complex stability and viscosity were checked in the final solution up to seven days. The prepared complex solution (100 µCi/100 µl) was injected intra-articularly to male rat knee joint. Leakage of radioactivity from injection site and its distribution in organs were investigated up to seven days.

RESULTS

The complex was successfully prepared with high radiochemical purity (>99.9 %). Approximately, the whole injected dose has remained in injection site seven days after injection.

CONCLUSION

The complex was proved to be a feasible agent for cavital radiotherapy in oncology and rheumatology.