enhanced brain delivery of deferasirox–lactoferrin conjugates for iron chelation therapy in...

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Article

Enhanced brain delivery of deferasirox-lactoferrin conjugates for ironchelation therapy in neurodegenerative disorders: in vitro and in vivo studies

Golnaz Kamalinia, Fariba Khodagholi, Fatemeh Atyabi, Mohsen Amini,Fatemeh Shaerzadeh, Mohammad Sharifzadeh, and Rassoul Dinarvand

Mol. Pharmaceutics, Just Accepted Manuscript • DOI: 10.1021/mp4002014 • Publication Date (Web): 24 Sep 2013

Downloaded from http://pubs.acs.org on September 30, 2013

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Enhanced brain delivery of deferasirox-lactoferrin conjugates for iron chelation therapy in

neurodegenerative disorders: in vitro and in vivo studies1

Golnaz Kamalinia1,2; Fariba Khodagholi3; Fatemeh Atyabi1,4; Mohsen Amini5; Fatemeh

Shaerzadeh3; Mohammad Sharifzadeh6; Rassoul Dinarvand1,4,*

1 Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences,

Tehran1417614411, Iran

2 Nano Alvand Co., Avicenna Tech Park, Tehran University of Medical Sciences,


3 Neuroscience Research Center, Shahid Beheshti University of Medical Sciences,


4 Nanotechnology Research Centre, Faculty of Pharmacy, Tehran University of Medical Sciences,

Tehran 1417614411, Iran

5 Department of Medicinal Chemistry, Faculty of Pharmacy, Tehran University of Medical Sciences,


6 Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tehran University of Medical

Sciences, Tehran 141556451, Iran

* Corresponding author:

Fax: +98 21 66959096, Email: [email protected]

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Table of contents:

Abbreviations

Abstract

Keywords

1. Introduction

2. Experimental

2.1. Materials

2.2. Deferasirox activation and conjugation to Lf

2.3. Determination of conjugation ratio

2.4. Characterization of conjugates

2.4.1. Gel permeation chromatography and gel electrophoresis

2.4.2. Size and Size Distribution

2.5. In vitro cell culture studies in PC12 cell line

2.5.1. PC12 differentiation and cell culture

2.5.2. Determination of cell viability and morphological analysis

2.5.3. Cellular uptake studies

2.5.4. Hoechst staining

2.5.5. Acridine orange and monodansylcadaverine staining

2.5.6. Western blot analysis

2.6. In vivo animal studies

2.6.1. Animals

2.6.2. Beta amyloid (1-42) preparation and fiber formation

2.6.3. Surgery

2.6.4. In vivo drug treatment

2.6.5. Behavioral training and testing

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2.7. Data analysis

3. Results

3.1. Lf-deferasirox conjugates characterization and quantification

3.2. In vitro effects of Lf conjugates in PC12 cell line

3.2.1. Evaluation of neuroprotective effects of Lf conjugates on PC12 cell viability against

H2O2 induced cell death

3.2.2. Cellular uptake in PC12 cells

3.2.3. Morphological evaluation of apoptosis

3.2.4. Effect of Lf conjugates on Bax/Bcl-2 ratio in H2O2 exposed PC12 cells

3.2.5. Effect of Lf conjugates on caspase-3 and PARP cleavage in H2O2 exposed PC12 cells

3.2.6. Morphological evaluation of autophagy

3.2.7. Effect of Lf conjugates on autophagy factors in H2O2 exposed PC12 cells

3.3. In vivo animal tests results

4. Discussion

5. Conclusions

Acknowledgement

References

Tables

Figures

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Graphical abstract

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Abbreviations

AD: Alzheimer’s disease, AO: acridine orange, Aβ: beta amyloid, Bax: Bcl-2 associated X protein,

BBB: blood brain barrier, Bcl-2: B Cell Lymphoma-2, DL10: lactoferrin-deferasirox conjugates with

10 times molar excess of deferasirox, DL15: lactoferrin-deferasirox conjugates with 15 times

molar excess of deferasirox, DL20: lactoferrin-deferasirox conjugates with 20 times molar excess

of deferasirox, DMEM: Dulbecco’s modified Eagle’s medium, DMSO: dimethylsulfoxide, ECL:

enhanced electrochemiluminescence, EDC: 1-(3-dimethylaminopropyl) ethyl carbodiimide, EPR:

enhanced permeation and retention, FITC: fluorescein Isothiocyanate, GPC: gel permeation

chromatography, H2O2: hydrogen peroxide, i.p.: intraperitoneal, Lf: lactoferrin, MDC:

monodansylcadaverine, MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide,

MWM: Morris water maze, NGF: nerve growth factor, PARP: Poly (ADP-ribose) polymerase, PBS:

phosphate buffered saline, PDI: poly dispersity index, PVDF: polyvinylidenefluoride, RMT:

receptor mediated transcytosis, ROS: reactive oxygen species, SDS-PAGE: sodium dodecyl sulfate

polyacrylamide gel electrophoresis, SEM: standard error of mean, SNHS: N-hydroxy-3-sulfo-

succinimde

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Abstract

Oxidative stress associated cell damage is one of the key factors in neurodegeneration

development and is highly related to the presence of transition metal ions including iron. Herein,

deferasirox, a high affinity iron chelator was conjugated to lactoferrin molecules by carbodiimide

mediated coupling reaction to create a novel drug delivery system with higher brain permeability

through receptor mediated transcytosis. Each lactoferrin molecule was averagely attached to 4 to

6 deferasirox molecules resulting in water soluble conjugated nanostructures which were purified

and characterized. Neuroprotective effects of lactoferrin conjugated nanostructures and their

cellular uptake were evaluated in differentiated PC12 cell line and the molecular mechanisms

involved in such neuroprotection were elucidated. Lactoferrin conjugates were able to interfere in

apoptotic caspase cascade by affecting the expression level of capsase-3, PARP, Bax and Bcl-2.

Furthermore, an elevation in the expression level of autophagy markers including Atg7, Atg12-

Atg5 and LC3-II/LC3-I ratio was observed. Intraperitoneal injection of lactoferrin conjugates was

able to significantly attenuate learning deficits induced by beta amyloid injection in a rat model of

Alzheimer’s disease which further confirms a potential neuroprotective effect for lactoferrin

conjugated deferasirox in neurodegenerative disorders management through metal chelation

therapy.

Keywords: Brain drug delivery; Conjugated nanostructures; Lactoferrin; Deferasirox; Metal

chelation; Oxidative stress; Neurodegenerative disorders

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1. Introduction

Oxidative stress associated cell damage has been considered as one of the main etiological factors

in a wide variety of neurodegenerative disorders including Alzheimer’s disease (AD). The

involvement of apoptotic cell death and its main attributes including DNA fragmentation and

nuclear body formation in oxidative stress induced neurodegeneration is proposed by various

biochemical, molecular and morphological evidences1. In contrast, the catabolic process of

autophagy which contributes in degradation of unwanted or dysfunctional cell components, may

act as a protective mechanism in neurodegeneration progression. Therefore, an enhancement in

autophagy cascade may result in a better outcome in neurodegeneration control2.

Oxidative stress is strongly mediated by reactive oxygen species (ROS) and is highly related to the

presence of transition metal ions including iron. Although iron is amongst the essential metals

which mediate various biological functions, it has been found to be associated with

neurodegenerative disorders etiopathology. An elevation in brain iron concentration has been

found in patients suffering from AD where iron localization mostly occurs in neurofibrillary

tangles and senile plaques as the two main features of AD. Moreover, iron is implicated in Beta

amyloid (Aβ) self-assembly and aggregation as one of the major components of senile plaques3.

The special role of metal ions in neurodegenerative disorders development and progression has

raised an interest toward metal chelation therapy. Metal chelators are among the potential agents

that may be used to prevent or even reverse neurodegeneration progress. Their use is however

limited due to the presence of tight junctions in blood brain barrier (BBB) which is meant to

protect central nervous system but deprives it from the beneficial effects of neuro-therapeutics.

Clioquinol, a hydrophobic brain permeable metal chelating agent was successfully used to hinder

neurodegeneration and has markedly lowered Aβ levels but was withdrawn from market due to a

neuropathic side effect4. Therefore, the concept of using safer chelating agents and their brain

delivery by novel systems has gained growing attention during the recent years5. In this regard,

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molecular modification approach is one of the proposed strategies to circumvent BBB and

improve brain permeability and is strongly based on molecular structure and lipophilicity of drug

molecules. In this approach, drug molecules are targeted through some molecular alteration and

are enzymatically activated after brain permeation. However this method suffers from the limited

number of drugs which can be subjected to such kind of modification. Alternatively polymeric

nanoparticles and in particular poly(alkylcyanoacrylate) nanoparticles represent promising

carriers for brain drug delivery which are capable of opening tight junctions and facilitate drug

molecules transportation through BBB.6 These carriers are usually surface modified by

polysorbate 80 coating which results in apo-lipoproteins adsorption on nanoparticles surface and

facilitates their brain delivery through low density lipoproteins selective transporters. However a

moderate inhibition of p-glycoproteins by polysorbate 80 has limited their therapeutic

application.7

Another useful strategy in developing potential brain permeable delivery systems is drug

conjugation to certain protein carriers which enables the system to pass through BBB by receptor

mediated transcytosis (RMT). Lactoferrin (Lf) is a glycoprotein belonging to transferrin family

which is actively transported through BBB by its receptors. It has been demonstrated that Lf brain

uptake is greater than transferrin and OX-26 (an anti-transferrin receptor antibody)8; Therefore

Lf may be considered as a potential carrier for drug delivery in neurodegenerative disorders9. In

addition, an upregulation in Lf receptors which has been found in AD patients neurons and

capillaries, inspires the utilization of this carrier for brain drug delivery in AD8. Macromolecules

including Lf may further accumulate in the inflamed tissues due to enhanced permeation and

retention (EPR) effect10. This is highly important regarding the neuro-inflammatory nature of

neurodegenerative disorders and the existence of inflammation especially in vulnerable brain

areas of AD patients11. In addition, further benefits including a better water solubility and an

improved pharmacokinetics are achieved by drug conjugation to protein carriers12, 13.

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Deferasirox is a bis-hydroxyl triazole tridentate iron chelator with a high affinity and specificity

towards iron and a satisfactory safety profile. Deferasirox is clinically used to lower iron burden

and prevent iron overload implications in patients receiving blood transfusion therapies but is not

efficient in reducing brain iron burden14. The objective of the present study was to develop and

characterize novel Lf conjugates with deferasirox as a chelating agent. Lf conjugates were further

investigated for their neuroprotective potential and the molecular mechanisms behind it in PC12

neuronal cell culture model. For in vivo studies, the conjugates were administered

intraperitoneally to an AD rat model in order to examine their transport through BBB and their

protective effects on Aβ induced memory and learning deficits.

2. Experimental

2.1. Materials

Deferasirox was kindly donated by Osvah pharmaceutical company (Iran). 1-(3-

dimethylaminopropyl)ethyl carbodiimide (EDC), N-hydroxy-3-sulfo-succinimde (SNHS), Lf from

bovine milk, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), nerve growth

factor (NGF), monodansylcadaverine (MDC) and fluorescein Isothiocyanate (FITC) were

purchased from Sigma Aldrich (St. Louis, MO, USA).

DMEM/F12 with glutamax, horse serum, fetal bovine serum, trypsin, hoechst 33342 and acridine

orange (AO) were obtained from Life technologies (Grand Island, NY, USA). Antibodies directed

against caspase-3, Bax, Bcl-2, Atg7, Atg12, LC3B, β-actin and secondary antibody were obtained

from Cell Signaling Technology (Beverly, MA, USA). PARP was purchased from Santa Cruz

Biotechnology, Inc. (Santa Cruz, CA, USA) and Aβ (1-42) was obtained from GenScript (Piscataway,

NJ, USA). All other reagents and solvents, unless otherwise stated, were purchased from Merck

(Darmstadt, Germany).

2.2. Deferasirox activation and conjugation to Lf

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Deferasirox (4- [3,5-bis (2-hydroxyphenyl)-1,2,4-triazol-1-yl] benzoic acid) (6.72 mg, 18 µmol),

was dissolved in 1mL dimethylsulfoxide (DMSO) and the mixture was added to 1 mL of a 70:30

(v:v) solution of DMSO:dimethylformamide containing 36 µmol (6.9 mg) of EDC and 36 µmol (7.82

mg) of SNHS. The mixture stirred in room temperature for 5 hours and the resulted activated

deferasirox was used for Lf derivatization. In a general procedure, Lf (50 µM) was dissolved in a

potassium phosphate buffer (0.1 M plus 50 mM NaCl, pH= 7.3) and was added drop-wise to a

suitable molar excess of activated deferasirox between 10 to 20 times. The reaction mixture was

constantly stirred overnight in room temperature and was subjected to centrifugation (5000 rpm/

15 minutes). The supernatant was then separated, concentrated and purified by Amicon® ultra-

15 centrifugal filter devices (Millipore, MA, USA) with a nominal molecular weight cutoff of 30

kDa. The conjugates retained on the membrane were extensively dialyzed with a cutoff of 12 kDa.

The resulting conjugates were kept in 2-8°C and for long-term storage were lyophilized and

refrigerated.

For cellular uptake studies, 1 mg/ml FITC solution in DMSO was freshly prepared before labeling

reaction and was added in a slow manner to 2 mg/ml Lf conjugates solution in 0.1 M sodium

bicarbonate buffer (pH=9). The reaction mixture was incubated for 8 hours at 2-8 °C and was

purified by Amicon® ultra-15 centrifugal filter device and extensive dialysis to remove any

unbounded FITC. The molar ratio of FITC to protein was calculated by measuring the UV

absorption of labeled conjugates at 280 nm and 495 nm wave lengths. All procedures were

conducted in light protected conditions.

2.3. Determination of conjugation ratio

Deferasirox concentration was determined by UV spectrophotometry. Briefly, 1 mL of FeSO4

solution (3 mM), 1 mL deionized water and 200 µL HCl solution (0.1 M) were added to 1 mL of 10

to 100 µg/mL deferasirox solutions in DMSO. The mixtures were kept in room temperature for 24

hours and their UV absorbances were measured in 515 nm wavelength with a Scinco S 3100 UV

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spectrophotometer (Seoul, South Korea). The method was validated and its precision and

accuracy were evaluated. Free Lf did not show any interference in this wavelength.

The protein concentration was determined by a modified Bradford method in which UV

absorbance was measured in 450 nm and 595 nm wavelengths with bovine serum albumin

serving as standard. Consequently, conjugation ratio was determined as deferasirox number of

moles attached to 1 mole of Lf.

2.4. Characterization of conjugates

2.4.1. Gel permeation chromatography and gel electrophoresis

For gel permeation chromatography (GPC), a Knauer HPLC system (Berlin, Germany) consisting of

a Wellchrome K1001 pump, a Rheodyne injector equipped with a 20 µL sample loop, a K2600 UV

detector adjusted to 280 nm wavelength and a Chromgate chromatography manager were used. A

TSK G2000SW column (7.5 mm ID, 600 mm L, particle size 10 µm, pore size 125 Å) and a 0.2 M

potassium phosphate buffer were employed as stationary and mobile phases. The pH of mobile

phase was adjusted to 6.9 prior to use and was delivered at a flow rate of 0.8 mL/min.

Free and conjugated Lf solutions were prepared in mobile phase with a concentration of 2 mg/mL

and filtered with 0.22 µm filters before injection.

Furthermore, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was

performed in non-reducing condition with a 10% polyacrylamide gel and a standard ladder from

14400 to 97000 Da and the molecular weight of conjugates was estimated accordingly.

2.4.2. Size and Size Distribution

Particle size and size distribution of Lf conjugates were determined by photon correlation

spectroscopy (Zetasizer Nano ZS, Malvern, UK). The samples were prepared by suspending the

lyophilized conjugates in deionized water with an appropriate concentration and were examined

for their mean diameter, poly dispersity index (PDI) and zeta potential.

2.5. In vitro cell culture studies in PC12 cell line

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2.5.1. PC12 differentiation and cell culture

Rat pheochromocytoma cells (PC12) were obtained from Pasteur Institute of Iran (Tehran, Iran).

PC12 cell line was cultivated in Dulbecco’s modified Eagle’s medium (DMEM)/F12 (1/1) with L-

glutamine, containing 10% horse serum, 5% fetal bovine serum and 1% antibiotic mixture

consisting of penicillin and streptomycin, in a 5% CO2 humidified atmosphere at 37°C. Growth

medium was replaced three times per week. The cells were differentiated into neuronal

phenotype by an every other day treatment with NGF (50 ng/mL).

2.5.2. Determination of cell viability and morphological analysis

MTT reduction assay was employed for cell viability determination. Cells were treated for three

hours with free deferasirox, free Lf and different concentrations of Lf conjugates (3, 5 and 10

µg/mL according to their deferasirox content) followed by addition of H2O2 (150 µM) as stress

inducing agent. The formed purple formazan crystals in intact cells were dissolved in DMSO and

the related optical densities were measured at 550 nm wavelength. The absorbance of control

cells was assumed to be 100% and the results were expressed as the percentages of reduced MTT.

For morphological analysis, PC12 cells were seeded in 6 well flasks and were treated with free Lf,

free deferasirox and different concentrations of Lf conjugates. After 3 hours, 150 µM H2O2 was

added to generate oxidative stress induced cell damage. After 12 hours incubation, random images

were acquired by a focal contrast microscope (Olympus, Tokyo, Japan).

2.5.3. Cellular uptake studies

To investigate the cellular uptake, PC12 cells were seeded in 96 well plates intermittently where

each well was surrounded by free wells to avoid any interactions between the fluorescence

emitted from adjacent wells. Cells were incubated with FITC labeled conjugated Lf with a final

protein concentration of 10 µM. After 3 hours incubation at 37°C each well was washed three

times with phosphate buffered saline (PBS) and received 100 µl fresh medium in addition to 50 µl

Triton (0.5% in 0.2 N NaOH). The fluorescence intensity of each well was measured by a

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microplate reader with an excitation wavelength of 492 nm and an emission wavelength of 515

nm (Synergy 4, Biotek, VT, USA). Cellular uptake efficiency was defined as the percentage of FITC

concentration in each well to FITC concentration in initially used nanostructures.

In order to visualize the cellular uptake, PC12 cells were cultivated in 6 well plates and were

incubated for three hours with fluorescence labeled Lf conjugates. Each well was subsequently

washed with PBS (×3) and the cells were evaluated with a fluorescence microscope (Olympus,

Tokyo, Japan)

2.5.4. Hoechst staining

Hoechst 33342 was used to morphologically evaluate apoptosis. For this purpose, differentiated

PC12 cells were seeded in 6 well plates and were treated with various Lf conjugates (10 µM) for 3

hours followed by addition of H2O2 (150 µM) for 12 hours. The cells were then thoroughly washed

with PBS and fresh media was introduced in each well. Hoechst solution (1 µg/mL) was finally

introduced into the wells and the nuclear morphology was inspected with fluorescence

microscope.

2.5.5. Acridine orange and monodansylcadaverine staining

AO and MDC staining was used to evaluate the autophagy process by detecting autophagic

vesicles. Briefly, differentiated PC12 cells were seeded in 6 well plates and were treated with 10

µM concentration of various Lf conjugates for 3 hours followed by a 12 hours exposure to H2O2

(150 µM). The cells were then washed with PBS (×3) and fresh media was introduced in each well.

AO (1 µg/mL) or MDC (0.05 µM) solutions were added to wells and the cellular morphology was

inspected by fluorescence microscopy.

2.5.6. Western blot analysis

For western blot analysis, differentiated PC12 cells were pretreated by various Lf conjugates for

three hours followed by H2O2 (150 µM) exposure for an additional 12 hours. Cells were then lysed

in a lysis buffer consisting of a complete protease inhibitors mixture. Protein concentrations were

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determined by Bradford method where bovine serum albumin was used as reference standard for

achieving the calibration curve.

Total proteins were subjected to electrophoresis in a 12% SDS–PAGE gel. After separation on

polyacrylamide gel, proteins were transferred to polyvinylidenefluoride (PVDF) membranes (GE

Healthcare, UK) by western blotting and were probed with specific antibodies. Immunoreactive

polypeptides were detected using enhanced electrochemiluminescence (ECL) reagents

(Amersham Bioscience, USA) and were consequently analyzed by autoradiography.

The density of each band was measured by densitometric scan of films with ImageJ software.

2.6. In vivo animal studies

2.6.1. Animals

Adult male albino Wistar rats weighing 200 to 220 g were purchased from Pasteur Institute of

Iran (Tehran, Iran) and were randomly assigned into four experimental groups. The animals were

kept in 12 hours light and dark cycles with free access to normal rat chow and drinking water.

Room temperature was adjusted to 25±2°C. All experiments were conducted in accordance to

“guide for the care and use of laboratory animals”15 and were approved by ethical committee for

the care and use of laboratory animals of Tehran University of Medical Sciences.

2.6.2. Beta amyloid (1-42) preparation and fiber formation

Aβ was dissolved in PBS with a concentration of 200 ng/µL and was aliquoted and stored in -20°C.

Aβ solution was incubated for five days in 37°C and was diluted to a final concentration of 100

ng/µL on the test day.

2.6.3. Surgery

Rats were anaesthetized by intraperitoneal (i.p.) injection of xylazine (20 mg/kg) and ketamine

(100 mg/kg) and underwent surgery in stereotaxic apparatus (Stoelting, Wood Dale, IL, USA).

Stereotaxic coordinates for dorsal hippocampus were chosen according to the atlas of Paxinus and

Watson (anterior-posterior, 3.8 mm from the bregma; lateral, ±2.2mm from the central line and

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ventral, 2.7 mm from the surface)16. Aβ was injected by a Hamilton syringe in each side of dorsal

hippocampus and the volume of injection was 1 µL/side injected over at least 1 minute.

2.6.4. In vivo drug treatment

Animals were randomly assigned into four groups. The first group served as sham-control group

which underwent stereotaxic surgery but instead of Aβ, water for injection was administered

intrahippocampally. The second group (Aβ-control group), received i.p. normal saline injections

for 7 days followed by stereotaxic surgery on the eight day in which the animals were treated by

Aβ solution in their dorsal hippocampus. The third and fourth groups received i.p. Lf conjugates

solution with 20 times molar excess of deferasirox (DL20: 1 mg/kg and 5 mg/kg respectively) for

7 days followed by stereotaxic surgery on the eight day for Aβ injection.

2.6.5. Behavioral training and testing

Rats were trained in Morris water maze (MWM) apparatus consisting of a black circular pool with

a diameter of 136 cm filled with water (depth 35 cm) and the temperature was adjusted to

25±2°C. Appropriate visual cues with different shapes were attached on the walls and the pool

was virtually divided into four quadrants with four different starting points (north, south, east and

west). A black hidden platform made of Plexiglas with a diameter of 10 cm was submersed 1 cm

under the water surface in the north-west quadrant (target quadrant) of the pool.

Nineteen days after surgery, the behavioral test was initiated by a training session consisting of

eight trials17. In each trial, rats were randomly placed in one of the starting points. Swimming

pathway was recorded by a video camera installed above the pool, connected to a computer

equipped with EthoVision software (Noldus Information Technology, Wageningen, Netherlands).

During each trial the rat had 60 seconds to find the hidden platform. The animals were then

allowed to remain on the platform for 20 seconds. If the animal could not find the platform after

60 seconds, it was physically directed toward it. Spatial acquisition was evaluated by measuring

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escape latency (the required time to find the platform), traveled distance (the path length traveled

to reach the platform) and swimming speed.

Rats were kept in their cages after the training session completion for 24 hours until they were

tested for probe trial. In probe trial, the platform was removed and rats were allowed to freely

swim for 60 seconds and the time which each rat spent in the target quadrant was measured.

For assessing the visual ability of rats, their movement toward a visible platform was assessed. For

this purpose, the aluminum foil covered platform was placed 1 cm above the water surface in the

opposite position quadrant of the previously invisible platform.

It should be mentioned that all trials were performed at about the same time in the morning.

2.7. Data analysis

Comparing groups was made by ANOVA (one way analysis of variance) followed by Tukey’s post

hoc. In animal testing, one way ANOVA in addition to Newman-Kuels multiple comparisons post

hoc was used. A two way ANOVA followed by Bonferroni post hoc was employed for analyzing the

results from the invisible platform test over training trials. For comparing two groups, t-test was

applied. Statistical significance was achieved when P value was lower than 0.05.

3. Results

3.1. Lf-deferasirox conjugates characterization and quantification

In order to synthesize Lf conjugates, deferasirox carboxylic group was activated by SNHS and EDC

as a carbodiimide reagent and a highly active SNHS ester of deferasirox was produced. This ester

further reacts with nucleophilic lysine amines on Lf molecules resulting in Lf conjugation with

deferasirox molecules. Conjugation ratio was determined using a validated UV spectrophotometric

method in which deferasirox was exposed to Fe2+ in an acidic medium and the resulting colorful

chelated compounds were utilized for its quantification. The regression equation was Y= [2.18×10-

3±3.72×10-5]X+[4.75×10-2±2.88×10-3] where Y is the absorbance of chelated deferasirox in 515 nm

wavelength and X is deferasirox concentration. The intra-day and inter-day accuracy and

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precision were assessed accordingly (Table 1). Protein concentration was determined by a

modified Bradford method considering the fact that deferasirox does not show any significant UV

absorbance above 290 nm wavelength. For assessing the effect of deferasirox excess amount on

the conjugation ratio, three different conjugated populations were synthesized: DL10, DL15 and

DL20 prepared with 10, 15 and 20 times molar excess of deferasirox respectively. The degree of

derivatization was found to be to some extent proportional to the amount of excess used where it

changed between 4.285 ± 0.565 for DL10 to 6.544±0.602 for DL20.

The molecular weight of the conjugates was evaluated by non-reducing SDS-PAGE and GPC. SDS-

PAGE results showed that the molecular weight of Lf conjugates was approximately the same as

free Lf (Fig. 1A). The same results were observed in GPC although with increasing the molar ratio

of deferasirox to Lf to 60 times, a portion of conjugates appeared as aggregates with a higher

molecular weight (Retention time: 12.2 minutes versus 15.9 minutes) (Fig. 1B).

Lf conjugates were presented as nanostructures with a mean diameter of 100-500 nm. The size

and poly dispersity index (PDI) of nanostructure were significantly reduced when more excess

amount of activated deferasirox was used (P < 0.05) and the conjugate’s size reached to

137.0±33.65 nm for DL20 where the highest excess amount was used. Furthermore more excess

amount resulted in a more negative zeta potential (P < 0.05) (Fig. 2).

3.2. In vitro effects of Lf conjugates in PC12 cell line

3.2.1. Evaluation of neuroprotective effects of Lf conjugates on PC12 cell viability against H2O2

induced cell death

MTT reduction assay was used to evaluate the neuroprotective effects of Lf conjugates. According

to Fig. 3A, MTT assay results showed a significant protection in PC12 cells when the cells were

pretreated with Lf conjugates (P<0.05). The protection took place in a dose dependent manner

and the best protection was achieved with DL20 where cell viability reached to 89.4% when used

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with a 10 µM concentration. No cytotoxic effects were observed with free or conjugated Lf in PC12

cells (P > 0.05) (Fig. 3A).

The neuroprotective effect of Lf conjugates was further assessed by morphological evaluation (Fig.

3B). After 6 days incubation with NGF, PC12 cells displayed a neuronal phenotype which was

similar to that of the sympathetic neurons where the cells no more divide and extended neuritic

development is observed. Exposure to oxidative stress results in shape distortion and

heterogeneity and cellular separation from the well plate. As shown in Fig. 3B, pretreatment with

Lf conjugates has successfully prevented these oxidative damages.

3.2.2. Cellular uptake in PC12 cells

FITC/protein molar ratio was calculated in labeled conjugates by UV spectrophotometry and was

found to be approximately 1:1 for various Lf conjugates. Cellular uptake of fluorescence labeled Lf

conjugates with various sizes was quantitatively assessed in 96 well plates. As shown in Fig. 4A,

DL20 showed a significantly higher cellular uptake compared to DL10 and DL15 (P<0.05) where

its cellular uptake was 1.93 and 1.54 folds higher than DL10 and DL15 respectively. Fig. 4B shows

the microscopic image acquired after three hours incubation of PC12 cells with DL20 which

supports the previous quantitative results.

3.2.3. Morphological evaluation of apoptosis

Blue fluorescent Hoechst staining was used for morphological evaluation of apoptosis in PC12 cell

line. Hoechst 33342 preferentially binds to DNA adenine and thymine base pairs and was used

here to visualize the nuclei of PC12 cells where a more bright fluorescence due to nuclear

condensation and non-uniformity and DNA fragmentation differentiates dead cells from survived

ones18. The pictures obtained from Hoechst staining are shown in Fig. 5 which show a decline in

apoptotic cell death in stressed cells when receiving Lf conjugates pretreatment compared to

those which have solely received H2O2.

3.2.4. Effect of Lf conjugates on Bax/Bcl-2 ratio in H2O2 exposed PC12 cells

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The neuroprotective effect of Lf conjugates against apoptotic cell death was investigated at

molecular level by determining Bax/Bcl-2 ratio. Bax and Bcl-2 are two proteins which are involved

in caspase dependent apoptotic cascade, where Bax acts as a pro-apoptotic protein and Bcl-2 has

an anti-apoptotic role19. The results suggest that an increase in Bax/Bcl-2 ratio occurs in the

presence of H2O2 but the ratio was significantly decreased when DL15 and DL20 were used

(P<0.05) (Fig. 6A, 6B).

3.2.5. Effect of Lf conjugates on caspase-3 and PARP cleavage in H2O2 exposed PC12 cells

To further confirm protective effects of Lf conjugates against apoptosis, the level of caspase-3

activation and PARP cleavage were determined. Caspase-3 activation occurs through caspase

cleavage and results in a series of events called caspase cascade which leads to apoptotic cell

death19. It can be seen in Fig. 6C that in the presence of H2O2, the expression level of cleaved

caspase is increased. On the other hand, a decrease in cleaved caspase expression level is observed

in the presence of various Lf conjugates as demonstrated by its weaker bands (P< 0.05).

Nuclear enzyme poly (ADP-ribose) polymerase (PARP) is a DNA protective protein which is

cleaved into 89 and 24 kDa fragments in the presence of activated caspase-3 and directs cells

toward apoptosis20. As it can be seen in Fig. 6D, a higher expression level is observed for 89 and 24

kDa fragments in the presence of H2O2 while Lf conjugates pretreatment resulted in fragments

weaker bands and their lower expression (P< 0.05).

3.2.6. Morphological evaluation of autophagy

MDC and AO were used as autofluorescent acidotropic stains for labeling lysosomes in PC12 cells.

In both cases the increase in lysosomal staining intensity which is related to the extent of lysosme

acidity was used to predict autophagy level21. Pictures obtained from MDC staining are shown in

Fig. 7A which show an increase in autophagy process in Lf conjugates pretreated cells. In these

cells a more intensive fluorescence was observed and the number of stained lysosomes was higher

than both control and stressed cells. The same results were observed in case of AO staining (Fig.

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7B) which suggests an enhancement in autophagy process in Lf conjugates receiving cells in

presence of H2O2.

3.2.7. Effect of Lf conjugates on autophagy factors in H2O2 exposed PC12 cells

LC3-II to LC3-I ratio in addition to Atg7 and Atg12-Atg5 conjugate levels were assessed to evaluate

the neuroprotective effect of Lf conjugates in the molecular level. During autophagy, LC3-I is

cleaved to LC3-II and the LC3-II/LC3-I ratio is increased21. According to Fig. 8A and B, LC3-II/LC3-

I ratio is increased in H2O2 receiving cells when compared to control (P<0.05). When cells were

pretreated with DL20, the mentioned ratio was further increased in stressed cells (P<0.05). The

same results were observed for the other two autophagy molecular markers, Atg7 (Fig. 8A and C)

and Atg12-Atg5 (Fig. 8A and D), where both were increased in DL20 pretreated cells (P<0.05).

3.3. In vivo animal tests results

To evaluate the in vivo neuroprotective effects of Lf conjugates, i.p. administration of Lf conjugates

followed by behavioral testing of learning and memory was used. As shown in Fig. 9, data acquired

in training session showed a significant difference between the first and second four trials in both

escape latency and traveled distance in sham-control and DL20 (5 mg/kg) groups but Aβ-control

group did not show any significant differences (P>0.05).

As shown in Fig. 10A, hippocampus Aβ injection significantly increased the escape latency time in

comparison to sham-control group while 7 days i.p. pretreatment with Lf conjugates significantly

reduced this time in a dose dependent manner (P<0.05). Traveled distance showed a similar trend

where a significant increase was observed in Aβ-control group in comparison to sham-control

animals. Lf conjugates pretreatment was able to decrease this factor in a significant manner when

compared to Aβ-control group (P<0.05) (Fig. 10B).

To further evaluate the spatial memory of animals, a probe test was accomplished in which the

platform was removed and the time each rat spent in the target quadrant was measured. As

shown in Fig. 10C, Aβ receiving rats spent a significantly less time in target quadrant where

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pretreatment with Lf conjugates significantly increased this time (P < 0.05). As shown in Fig. 10D

the swimming speed was not significantly different between four groups (P>0.05) indicating that

no motor disturbances has occurred in animals.

Evaluation of motivation towards a visible platform showed no significant difference in escape

latency and traveled distance in finding the visible platform which confirms the visual ability of

animals in following the cues (Data not shown).

4. Discussion

Deferasirox, a practically water insoluble iron chelator was conjugated to Lf in order to provide

water soluble nanostructures with a better brain permeation to target metal active centers

involved in neurodegeneration development. Deferasirox was conjugated to Lf in the presence of

SNHS to produce an active SNHS ester of deferasirox through its carboxylic acid functional group.

The sulfo moiety on SNHS resulted in more hydrophilicity and a better derivatization took place

on Lf where N-hydroxysuccinimide produced an insoluble intermediate which reduced the

coupling degree drastically. The activated carboxylic moieties were then utilized for amide bond

formation with primary amino groups on lysine amino acids of Lf.

In order to evaluate the effect of excess amount of deferasirox to Lf, 10 to 20 times of molar excess

was used and a molar conjugation ratio of 4.3 to 6.5 was achieved respectively which shows that

the conjugation ratio is somewhat affected by an increase in the used molar excess amount. SDS-

PAGE and GPC revealed that no significant change in molecular weight is detected when

deferasirox is covalently conjugated to Lf. This is in favor of that covalent conjugation with 10 to

20 times excess has not affected appropriate physical and chemical properties of Lf as the protein

vector12. An attempt for increasing the conjugation ratio by using higher excess amounts of

deferasirox to Lf failed due to aggregation of Lf molecules which is manifested as an increased

molecular weight in GPC chromatograms.

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Size plays an important role in determining the cellular uptake of nanostructures and is

considered to be one of the major key factors in designing a drug delivery system22. Although

deferasirox is practically water insoluble, the small size of nanostructures contributes in its water

solubility after conjugation reaction. Size, PDI and zeta potential of nanostructures were found to

be related to the amount of deferasirox molar excess used. This means that when higher amount

of excess was used, the size was reduced from 460 nm for DL10 to 137 nm for DL20. The same

trend was observed for PDI where it reduced from 0.46 in DL10 to 0.31 in DL20. This may be the

result of the higher amount of carbodiimide reagent which other than enhancing the conjugation

ratio can promote the cross linking reaction intra-molecularly while diluted Lf solution was used

to reduce intermolecular cross linking reaction23. Furthermore, a more negative zeta potential was

obtained by an enhancement in deferasirox excess amount (-8.3 in DL20 versus 1.45 in DL10). The

higher excess amount results in a higher conjugation ratio and involves the positively charged

amino groups of lysine amino acids. As a result, the contribution of negatively charged carboxylic

groups is enhanced and a more negative zeta potential is observed24.

Conjugated nanostructures effect on neurodegeneration, was evaluated in H2O2 induced oxidative

stress in PC12 cell line which is among widely used in vitro models of cell death mechanism25.

Oxidative stress is considered to be a major key factor in neurodegeneration pathogenesis and

neuronal apoptosis. Results from morphological assays and cell viability tests confirmed a

neuroprotective effect for Lf conjugated deferasirox against H2O2 induced cell death and apoptosis

in PC12 cell line when used as a three hours pretreatment. Deferasirox covalently attached to Lf

molecules involves iron active centers and prevents ROS formation following H2O2 exposure and

oxidative induced injuries. The greatest neuroprotection was observed with 10 µM concentration

of DL20 where cell viability reached to 89.4% which is probably the result of the smaller size of

these conjugated nanostructures and their better cellular penetration.

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FITC was used as a fluorescence labeling marker to evaluate the relative cellular uptake of various

conjugated species. FITC labeling was achieved by a reaction between isothiocyanate group on

FITC molecule and intact amino groups on Lf structure 26. The results showed an elevated cellular

uptake when the size was decreased. Particle size and surface charge are two major factors which

may have effects on cellular uptake efficiency in targeted drug delivery. Size elevation results in a

much stronger driving force requirement where nano structures with sizes larger than 150 nm are

strongly excluded from cellular internalization. On the other hand positively charged

nanoparticles show a stronger affinity towards the cell membrane and a higher cellular uptake is

achieved. Although DL20 nanostructures have a more pronounced negative zeta potential which

may have an unfavorable impact on cellular absorption of nanostructures, it seems that their

smaller size prevails this negative impact and results in a better cellular viability with the same

deferasirox concentration.

To further elucidate the molecular mechanisms behind the observed neuroprotective effect,

several molecular markers of apoptosis were evaluated. The present study revealed an increase in

Bax/Bcl-2 ratio in H2O2 receiving cells which induces mitochondrial outer membrane

permeabilization and results in more apoptotic related events. Bcl2 (B cell lymphoma-2) family of

proteins plays a key role in mitochondrial (intrinsic) and endoplasmic reticulum mediated

pathways. Bcl2 family is comprised of anti-apoptotic and pro-apoptotic proteins. In contrast to

anti-apoptotic proteins including Bcl-2 which protect the integrity of mitochondria outer

membrane, the pro-apoptotic proteins such as Bax (Bcl2 associated X protein) induce

mitochondrial outer membrane permeabilization and apoptotic cell death. In the lack of pro-

survival inhibition on pro-apoptotic proteins, cellular damage and a loss in mitochondrial

functioning occur. Therefore Bax/Bcl-2 ratio is a critical factor in the regulation of apoptosis

level27. Pretreatment with Lf conjugates resulted in a decrease in Bax/Bcl-2 ratio which confirms a

protective role for Lf conjugates against apoptotic cell death.

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Caspases are another major group of apoptosis factors which drive cells toward apoptosis through

a chain of events called caspase cascade. Caspase-3 is one of the most significant members of

caspase family which is taken responsible for a number of proteolytic cleavages and apoptotic

cellular death19. The results showed an increase in cleaved caspase-3 in H2O2 exposed cells but the

cleavage level was significantly reduced by Lf conjugates pretreatment which suggests Lf

conjugates capability in apoptosis inhibition.

PARP, a nuclear enzyme which protects DNA and facilitates DNA repair when confronting

damages is cleaved by caspase-3 into 89 and 24 kDa fragments during apoptosis 20 and was

assessed here to confirm the observed results for cleaved caspase-3. The results showed an

increase in cleavage level of this caspase-3 downstream protein in stressed cells. The cleavage

level was reduced when cells were pretreated by various Lf conjugates which is in accordance

with the results obtained for caspase-3.

Autophagy is another major cellular mechanism which has been associated with oxidative stress.

Although autophagy was assumed as a cell death mechanism, the notion about it, has evolved

drastically and a pro-survival role has been pertained to this cellular machinery28. Autophagy is a

catabolic process involved in degradation and turnover of macromolecules and organelles in

which intracellular components are delivered to lysosomes to be degraded2. Autophagy is a

homeostatic related action by degrading various protein aggregates (e.g. fibrillar Aβ and

intracellular tangles) which are common pathological features of neurodegenerative disorders. In

fact, autophagy deficiency is implicated in AD pathogenesis and it has been confirmed that an

elevated autophagy level will result in a delayed neurodegeneration progression29. In early stages

of oxidative stress exposure and in mild oxidation conditions the lysosomes play a protective role

by removing damaged components via autophagy pathway. Autophagy decreases with human

fibroblast cell aging making cells more vulnerable to oxidative damages30. Here in, MDC and AO

staining were used to evaluate the autophagy process in PC12 cells receiving Lf conjugates. These

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two auto fluorescent acidotropic dyes pass through the lysosomal membrane in their neutral form

but are protonated and trapped inside the acidic lysosomes21. The pictures acquired by

fluorescence microscope showed a mild increase in autophagosomes after 12 hours exposure to

H2O2 which suggests an autophagy elevated level after 12 hours exposure to oxidative stress.

During autophagy, LC3 is converted from its soluble form (LC3-I) to lipidated form (LC3-II) and

LC3-II/LC3-I ratio is increased21. In addition, Atg12, a 21 kDa protein, is covalently linked to Atg5

(34 kDa) and produces a 70 kDa protein. This covalent linking is triggered under the stimulation

of Atg7 as the activating enzyme21. All of the above autophagy markers showed a mild increase

when cells were exposed to H2O2.

There are some controversies on autophagy induction following the administration of iron

chelating agents. It has been reported that cytosolic autophagy induction occurs due to iron

starvation following the administration of lipophilic and hydrophilic chelating agents in Hela

cells31. In another study, autophagy inducing ability was reported for deferoxamine, a chelating

agent derived from Streptomycespilosus, but more hydrophilic chelating agents including

deferriprone and deferasirox did not induce autophagy in fibroblast and epithelial like cells32.

Herein, Lf conjugated deferasirox pretreatment elevated autophagy process in H2O2 receiving cells

as indicated by a more intense fluorescence in MDC and AO stained wells. Furthermore, autophagy

inducing effect by Lf conjugates was assessed in the molecular level where LC3-II/LC3-I ratio, Atg7

and Atg12-Atg5 levels were enhanced in Lf conjugates pretreated cells. This suggests an

autophagy enhancing role for Lf conjugates which may act as a protective mechanism against

oxidative induced cell damage.

To elucidate the conjugated nanostructures potential in attenuating memory deficits, an in vivo

model of neurodegeneration was used. Neurotoxic Aβ fragments injection in hippocampus or

cerebral ventricles of rats is among widely used in vivo models of neurodegeneration25. Aβ is one

of the main components of senile plaques in AD patients’ brain. Metal ions have been implicated in

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Aβ aggregation where elevated levels of transition metal ions including iron were found in Aβ

deposits33. Intrahippocampal infusion of Aβ results in memory and learning deficits and the

related behavioral alterations mostly occurs 19 days after injection17. Lf conjugates successfully

improved spatial memory and learning in MWM when administered intraperitoneally and were

able to attenuate Aβ induced learning and memory deficits by significantly decreasing escape

latency and traveled distance in comparison with Aβ-control group. A comparison between the

first four trials with the second four trials confirmed that sham-control and DL20 (5 mg/kg)

groups were well trained where the escape latency and traveled distance were significantly

different between the first and second four trials. This suggests that DL20 was able to prevent the

destructive effects of Aβ on learning capability in rats. To evaluate any motor dysfunctions which

may interfere with memory effects observed, swimming speed was checked and the results

indicated that swimming speed is not affected when compared to sham-control group confirming

a lack of motor dysfunction. Furthermore, the results of visibility test confirmed that no visual

disturbance has occurred in animals. The results suggest that Lf conjugates have been able to

assert their neuroprotective effects via metal chelation strategy when administered

intraperitoneally.

5. Conclusions

Lf conjugated nanostructures of deferasirox with a brain targeting potential through receptor

mediated transcytosis were synthesized, purified and characterized. Cell culture studies indicated

a significant neuroprotective effect where Lf conjugates were involved in inhibiting apoptosis cell

death while enhancing the autophagy machinery. Lf conjugates successfully attenuated Aβ

memory and learning destructive effects in AD rat models when administered intraperitoneally.

The present study provides evidence for neuroprotective effect of Lf conjugates in vivo and in vitro

and states that Lf conjugates may present a valuable neuroprotective novel brain delivery system

which targets neurodegeneration via metal chelation therapy.

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Acknowledgement

This work was financially supported by a grant from Tehran University of Medical Sciences

(TUMS).

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ferritin autophagy. Free Radic. Biol. Med. 2011, 50, (11), 1647-1658.

32. De Domenico, I.; Ward, D. M. V.; Kaplan, J. Specific iron chelators determine the route of

ferritin degradation. Blood 2009, 114, (20), 4546-4551.

33. Jhoo, J. H.; Kim, H.-C.; Nabeshima, T.; Yamada, K.; Shin, E.-J.; Jhoo, W.-K.; Kim, W.; Kang,

K.-S.; Jo, S. A.; Woo, J. I. Beta-amyloid (1-42)-induced learning and memory deficits in mice:

involvement of oxidative burdens in the hippocampus and cerebral cortex. Behav. Brain Res. 2004, 155,

(2), 185.

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Table 1: Accuracy and precision data for UV spectrophotometric method of deferasirox assay

Known concentration (µg/mL)

10 20 30 50 80 100

Intra-day

Observed average conc. (n=5) 8.92 22.34 32.94 51.72 82.90 97.04

SD 0.39 0.96 1.01 1.80 1.26 1.07

RSD% 4.35 4.29 3.08 3.48 1.52 1.11

Accuracy 89.17 111.71 109.79 103.44 103.63 97.04

Inter-day

Observed average conc. (n=5) 8.59 22.37 33.43 54.06 82.07 95.22

SD 0.89 1.33 0.82 1.33 1.19 0.86

RSD% 10.41 5.93 2.45 2.46 1.44 0.91

Accuracy 85.85 111.83 111.43 108.12 102.59 95.22

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Figure legends:

Fig. 1: A) SDS-PAGE of conjugated lactoferrin prepared with 20 times molar excess of deferasirox

(DL20), free lactoferrin (Lf) and a mixture of free and conjugated lactoferrin; B) Gel permeation

chromatography of free and conjugated Lf prepared with 60 times molar excess of deferasirox.

When the molar ratio of deferasirox to Lf is increased, a small portion of aggregated form with a

higher molecular weight appears.

Fig. 2: Effect of deferasirox excess amount on size, poly dispersity index (PDI) and zeta potential of

Lf conjugated nanostructures prepared with different amounts of molar excess of deferasirox (10,

15 and 20 times molar excess of deferasirox (DL10, DL15 and DL20)). Each value is presented as

the mean ± SD (n = 3).

Fig. 3: A) Effect of various Lf conjugates on cell viability; A) Cell viability determined by MTT assay

in differentiated PC12 cells pretreated with different concentrations of Lf conjugates (3, 5 and 10

µM) in the presence or absence of H2O2 (150 µM) as stress inducing agent.

Viability was determined as the percentage of living cells in treated cultures to control. Each value

is presented as the mean ± SEM (n = 3). *significantly different from control cells. #significantly

different from H2O2 treated cells & significantly different from the adjacent group; B)

Morphological evaluation of differentiated PC12 cells pretreated with a concentration of 10 µM of

various Lf conjugates in the presence or absence of H2O2 (150 µM) as stress inducing agent,

acquired by focal contrast light microscopy.

DL10: Lf conjugates prepared with 10 times molar excess of deferasirox; DL15: Lf conjugates

prepared with 15 times molar excess of deferasirox; DL20: Lf conjugates prepared with 20 times

molar excess of deferasirox; Def: deferasirox; Lf: lactoferrin

Fig. 4: A) Cellular uptake of FITC labeled Lf conjugates (n=3); B) Fluorescence microscopy of PC12

cells after three hours incubation with FITC labeled DL20.

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31



molar excess of deferasirox

Fig. 5: Morphological evaluation of apoptosis in PC12 cells by Hoechst staining in presence or

absence of 150 µM H2O2 with a three hours pretreatment of various Lf conjugates (10 µM)

acquired by fluorescence microscopy. Morphological pattern of cells under apoptosis is described

in the manuscript. All experiments were repeated three times.



molar excess of deferasirox.

Fig. 6: Western blot analysis to evaluate the effect of various Lf conjugates on Bax/Bcl-2 ratio in

PC12 cells. A) Bax, Bcl-2, procaspase-3, caspase-3, full length PARP and its cleavage products

responses to various Lf conjugates. PC12 cells received Lf conjugates as a pretreatment and after 3

hours were exposed to H2O2 (150 µM) for 12 hours. Twenty µg proteins were separated on 12%

SDS-PAGE and were subjected to western blotting. The proteins were further probed with related

antibodies. (One representative western blot is shown; n = 3).

B) Bax/Bcl-2 density ratio C) Procaspase-3 and caspase-3 density ratios D) Full length PARP (116

kDa), its C-terminal cleavage product (89 kDa) and N-terminal cleavage product (24 kDa) density

ratios (Mean±SEM of three independent experiments is shown.). *significantly different from

control cells. # significantly different from H2O2-treated cells




Fig. 7: Morphological evaluation of autophagy in PC12 cells by A) monodansylcadaverine staining

and B) acridine orange staining in presence or absence of 150 µM H2O2 with a 3 hours

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32

pretreatment of various Lf conjugates (10 µM) acquired by fluorescence microscopy.

Morphological pattern of cells under autophagy is described in the manuscript. All experiments

were repeated three times.




Fig. 8: Western blot analysis for evaluating the effect of different Lf conjugates on autophagy

factors including LC3B-II/LC3B-I ratio, Atg7 and Atg12-Atg5 in PC12 cells. A) Antibody responses

to various Lf conjugates in PC12 cells pretreated with conjugates for three hours and exposed to

H2O2 (150 µM) for 12 hours. Twenty µg proteins were separated on 12% SDS-PAGE and were

subjected to western blotting. The proteins were further probed with related antibodies and anti-

β-actin antibodies. (One representative western blot is shown; n = 3).

B) LC3-II/LC3-I density ratio, C) Atg7 band density and D) Atg12-Atg5 conjugate band density

were measured. The mean of three independent experiments is shown. *significantly different

from control cells. # significantly different from H2O2-treated cells.




Fig. 9: Effect of Lf conjugates pretreatment with 20 times molar excess of deferasirox (DL20) on A)

escape latency to platform zone and B) traveled distance in MWM between the first and second

four trials in training session. Each point shows mean±SEM for 5 to 8 rats. *significantly different

from Aβ group. # significantly different from adjacent group.

Fig. 10: Effect of Lf conjugates pretreatment with 20 times molar excess of deferasirox (DL20) on

A) escape latency to platform zone B) traveled distance C) time spent in target quadrant and D)

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33

swimming speed in MWM. Each point shows mean±SEM for 5 to 8 rats. *significantly different

from sham-control group. # significantly different from Aβ-control group.

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34

Fig. 1:

A

B

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35

Fig. 2: Size (nm)

DL1

0

DL1

5

DL2

0

0

200

400

600

***

**

*

zeta potential (m

v)

DL1

0

DL1

5

DL2

0

-15

-10

-5

0

5

***

*

*

zeta potential (mv) PDI size (nm) Conjugation ratio

1.477±0.092 0.459±0.034 459.7±31.50 4.285 ± 0.565 DL10

-3.603±0.341 0.341±0.043 256.7±51.94 5.145±0.501 DL15

-8.830±2.753 0.310±0.051 137.0±33.65 6.544±0.602 DL20

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36

Fig. 3:

A

cell viability (% of control)

Con

trol

(150

µM)

2O2H

DL2

0 (3

µM

)

DL2

0 (5

µM

)

DL2

0 (1

0 µM

)

(150

µM)

2O2

DL1

0 (3

µM

)+ H

(150

µM)

2O2

DL1

0 (5

µM

)+ H

(150

µM)

2 O2

DL1

0 (1

0 µM

)+ H

(150

µM)

2O2

DL1

5 (3

µM

)+ H

(150

µM)

2O2

DL1

5 (5

µM

)+ H

(150

µM)

2O2

DL1

5 (1

0 µM

)+ H

(150

µM)

2O2

DL2

0 (3

µM

)+ H

(150

µM)

2O2

DL2

0 (5

µM

)+ H

(150

µM)

2O2

DL2

0 (1

0 µM

)+ H

free

Lf (1

0 µM

)

(150

µM)

2O2

free

Lf (1

0 µM

)+H

Def

(10

µM)

(150

µM)

2O2

Def

(10

µM)+

H

0

50

100

***

######

###

###

### ###

###

###

######

&&&

&&

&&

&&

&&

&&

&

&&

&&

&

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37

B

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38

Fig. 4:

A

cellular uptake efficiency (%)

DL1

0

DL1

5

DL2

0

0

5

10

15

20

25

**

B

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39

Fig. 5:

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40

Fig. 6:

A

B

Bax/ Bcl-2 ratio

(arbitrary unit)

Con

trol 2O

2HM

)µ

DL2

0 (1

02O

2

M) +

H

µ

DL1

0 (1

0

2O2

M) +

H

µ

DL1

5 (1

0

2O2

M) +

H

µ

DL2

0 (1

0

0

1

2

3

4

***

#####

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41

C Caspase-3:ββ ββ-actin ratio

(arbitrary unit)

Con

trol 2O

2HM

)µ

DL2

0 (1

0 2O

2

M) +

H

µ

DL1

0 (1

0

2O2

M) +

H

µ

DL1

5 (1

0

2O2

M) +

H

µ

DL2

0 (1

0

0

1

2

3 Procaspase-3Caspase-3

## ##

###

##

###

###***

***

D

PARP:ββ ββ-actin ratio

(arbitrary unit)

Con

trol 2O

2HM

)µ

DL2

0 (1

0 2 O

2

M) +

H

µ

DL1

0 (1

0

2O2

M) +

H

µ

DL1

5 (1

0

2O2

M) +

H

µ

DL2

0 (1

0

0.0

0.2

0.4

0.6

119 kDa89 kDa

***

24 kDa

***

##

###

###

###

#

###

###

***

#

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42

Fig. 7:

A

B

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43

Fig. 8:

A

B

Lc3-II: LC3-I ratio

(arbitrary unit)

Con

trol 2O

2HM

)µ

DL2

0 (1

02O

2

M) +

H

µ

DL1

0 (1

0

2O2

M) +

H

µ

DL1

5 (1

0

2O2

M) +

H

µ

DL2

0 (1

0

0

1

2

3

4

**

#

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44

C Atg 7:ββ ββ-actin ratio

(arbitrary unit)

Con

trol 2O

2HM

)µ

DL2

0 (1

02O

2

M) +

H

µ

DL1

0 (1

0

2O2

M) +

H

µ

DL1

5 (1

0

2O2

M) +

H

µ

DL2

0 (1

0

0.0

0.5

1.0

1.5

2.0

**

#

D

Atg 12-Atg 5:ββ ββ-actin ratio

(arbitrary unit)

Con

trol 2O

2HM

)µ

DL2

0 (1

02O

2

M) +

H

µ

DL1

0 (1

0

2O2

M) +

H

µ

DL1

5 (1

0

2O2

M) +

H

µ

DL2

0 (1

0

0.0

0.5

1.0

1.5

*

##

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45

Fig. 9:

A

Escape latency (sec)

sham

-con

trol

-con

trol

βA

β

DL2

0 (1

mg/

kg)+

A β

DL2

0 (5

mg/

kg)+

A

0

20

40

60

** **

First four trialsSecond four trials

**

### ###

##

B

Traveled distance (cm)

sham

-con

trol

-con

trol

βA

β

DL2

0 (1

mg/

kg)+

A β

DL2

0 (5

mg/

kg)+

A

0

500

1000

1500

* *

### ##

First four trialsSecond four trials

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46

Fig. 10:

A

Escape latency (sec)

sham

-con

trol

-con

trol

βA

β

DL2

0 (1

mg/

kg)+

A β

DL2

0 (5

mg/

kg)+

A

0

10

20

30

40

50*

###

B

Traveled distance (cm)

sham

-con

trol

-con

trol

βA

β

DL2

0 (1

mg/

kg)+

A β

DL2

0 (5

mg/

kg)+

A

0

500

1000

1500

*# #

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47

C Tim

e spent in

target quadrant (sec)

sham

-con

trol

-con

trol

βA

β

DL2

0 (1

mg/

kg)+

A β

DL2

0 (5

mg/

kg)+

A

0

5

10

15

20

25

**

# #

D

Swim

ming speed (cm/sec)

sham

-con

trol

-con

trol

βA

β

DL2

0 (1

mg/

kg)+

A β

DL2

0 (5

mg/

kg)+

A

0

10

20

30

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enhanced brain delivery of deferasirox–lactoferrin conjugates for iron chelation therapy in...

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