DESIGN OF NANOPARTICLES

FOR BRAIN TARGETING

DISSDipartimento di Scienze della Salute

Francesca Re

Nanomedicine Seminar - Synthesis of nano-biomaterials, modelling, and applications

DRUG DELIVERY and DRUG TARGETING

common issues in the treatment/diagnosis of different diseases

worse for the treatment of diseases affecting the central nervous system (neurodegeneration and cerebral tumors)

There are increasingly high expectations for the delivery of

drugs to the brain using NANOPARTICLES

BLOOD-BRAIN BARRIER

DRUG DELIVERY BY NANOPARTICLES

current challenge:

Considerable efforts have been made to enhance the delivery of therapeutic molecules to the CNS

BUTafter two decades of research, nanotechnology approaches

to brain drug delivery remain yet underdeveloped

state of the art:

to develop drug delivery strategies that will allow the passage of drug molecules from the blood to the brain

in a safe and effective manner

The REASONS for low brain drugs delivery of

targeted nanoparticles:

Biological hurdles Modifications of the NP’s surface that occurs after

administration in biological environment Physical hurdles

SMART DESIGN OF NANOPARTICLES

Biological hurdles: the problem

BLOOD-BRAIN BARRIER

Highly selective barrier

Lack of specific/exclusive molecules on the BBB

Presence of transport mechanisms on the BBB

X2-3 nm

MECHANISMS OF TRANSPORT ACROSS THE BBB Y +

Functionalized nanoparticles

BRAIN

BLOOD

Biological hurdles: potential solutions

[Fernandes C. Pharm Res. 2010]

Lipoproteins

Transwell system for BBB model in vitro

CELLULAR UPTAKE

MONOLAYER PERMEABILITY (cm/min)

Brain capillary endothelial cells

IN VITRO MODELS OF BBB

CHARACTERIZATION OF BBB MODEL

10 11 12 13 14 15 16 17 180

20

40

60

80

100

120

140

Days after seeding (day)

TE

ER

(O

hm

s x

cm2)

TEER = 114.3Ωxcm2

TRANS-ENDOTHELIAL ELECTRICAL RESISTANCE

FUNCTIONAL PROPERTIESBIOELECTRICAL PROPERTIES

SUCROSE PROPRANOLOL

FUNCTIONAL PROPERTIES

RATIO PROPR/SUCR = 1,3

TJ: CLAUDIN AJ: CADERIN

[Re F.; Andreozzi P]

Adsorptive pathways: Cationic proteins: cationic albumin Cell-penetrating peptides: modified TAT-1 from HIV

POTENTIAL LIGANDS FOR THEBBB TARGETING

Receptor-mediated pathways:

A modified receptor-binding domain peptide of ApoE (CWLRKLRKRLLR or its tandem dimer) for LDLR

Anti-TfR antibodies (OX-26, RI-7217)

[Liu X. Biomaterials. 2013]

NP-Cationic albumin

NP-TAT-1 peptide

[Gregori M. J Nanomed Nanotech. 2013]

ADSORPTIVE TRANSCYTOSIS

IN VIVO IN VITRO

NP + modified peptide of the receptor-binding domain of ApoE

IN VITRO

RECEPTOR-MEDIATED TRANSCYTOSIS

[Re F. Nanomedicine. 2011][Bana L. Nanomedicine 2013, submitted]

[Balducci C. PNAS 2013, submitted]

IN VIVO

NP NP + anti-TfR antibody

[Salvati E. Int J Nanomed. 2013][Markoutsa E. Eur J Pharm Biopharm. 2011]

IN VITRO

RECEPTOR-MEDIATED TRANSCYTOSIS

THE NP CHEMICAL DESIGN AFFECTS THE BBB CROSSING:ligand density on the NP surface

LIGAND DENSITY IN THE NP SURFACE

[Re F. J Biotechnol. 2010]

NP-b/s-anti-TfR antibody NP-cov-anti-TfR antibody

THE NP CHEMICAL DESIGN AFFECTS THE BBB CROSSING:method of ligand conjugation on the NP surface

[Salvati E. Int J Nanomed. 2013]

NANOPARTICLES DRUG

NP-MEDIATED DRUG TRANSPORTACROSS THE BBB

[Re F. Nanomedicine. 2011]

The REASONS for low brain delivery of targeted

(drugs) nanoparticles:

Biological hurdles Modifications of the NP’s surface that occurs after

administration in biological environment Physical hurdles

SMART DESIGN OF NANOPARTICLES

The formation of protein corona depend of NP:

SIZE

SURFACE CURVATURE

SURFACE CHEMISTRY

NP

Y Y

YY

Targeting moieties

Protein corona

Y

Y

adsorption of biomolecules to the NP surface

NP with new biological identity

NP-cell membranes interaction

NP cellular uptake and trafficking Biodistribution in vivo

Adsorption of plasma proteins to the NP surface

Modifications of the NP’s surface administration: the problem

[Krol S. J Control Rel. 2012]

SMART SURFACE ENGINEERED APPROACHES

TO AVOID PROTEIN CORONADesign a NP surface that exhibits minimal interaction with biological environment

TO EXPLOIT PROTEIN CORONADesign a NP surface that exhibits a specific interaction with biological environment

NP

Apolipoproteins (ApoE)

Tween 80

Human serum albumin

Modifications of the NP’s surface administration: potential solutions

[Mahon E. J Control Rel. 2012]

Exploiting the protein corona to cross the BBBStriped gold NP

[Verma A. Nat Mater. 2008]

[Verma A. Nat Mater. 2008]

0,0E+00

2,0E-05

4,0E-05

6,0E-05

8,0E-05

1,0E-04

1,2E-04

ST1 ST2 MUS1 MUS2 all-MUS FITC-dex(40 kDa)

sucrose(342 Da)

propranolol(259 Da)

BODIPY

Perm

eabi

lity (

cm/s

ec)

PBS

MEDIUM

CONTROL MOLECULESAu NANOPARTICLES(new)

???(era tutto aggregato)

???(peggio ancora

in medium)

#

#

# **

Ratio prop:sucr~ 1.7

IN VITRO

[unpublished data]

0,0E+00

5,0E-05

1,0E-04

1,5E-04

2,0E-04

2,5E-04

3,0E-04

PBS 2 % FBS 10% FBS

Perm

eabi

lity (

cm/s

ec)

Au NANOPARTICLES(prime preparazioni di striped)

#

*

IN VITRO

[unpublished data]

[unpublished data]

The REASONS for low brain delivery of targeted

(drugs) nanoparticles:

Biological hurdles Modifications of the NP’s surface that occurs after

administration in biological environment Physical hurdles

SMART DESIGN OF NANOPARTICLES

nanoparticles

1° step: NP dilution into the blood

brain

2° step: NP dilution into CSF

An increased retention of the nanoparticles in the brain blood capillaries combined with an adsorption to the capillary walls. This could create a higher concentration gradient that would increase the transport across the endothelial cell layer and as a result enhance the delivery to the brain.

Physical hurdles: the problem

Physical hurdles: potential solutions

[Krol S. J Control Rel. 2012]

[Kreuter J. Adv Drug Del Rev. 2013]

Drugs bound to NP for brain delivery

The development of delivery system to transport drugs into the

brain in a safe and effective manner and in a non-homeopathic

doses are still under exploration

TREATED WITH PBS TREATED WITH LIP

AD MICE MODEL TREATED WITH AMYLOSOMES(functionalized with mApoE as BBB ligand)

Immunohistoch. Cortex + Hippocampus (Ab 6E10)

*

-40%

[Balducci C. PNAS 2013, submitted]

The BBB represents the main mechanism of defense of the CNS

The risk-benefit balance due to NP accumulation in the CNS should be carefully evaluated

NANO-NEUROTOXICITY

Some NP (e.g. gold, TiO2 and silica NP) are able to reach the brain even in the absence of any specific functionalization [Sousa F, 2010 Nanoscale; Wu J, 2011 ACS Nano]