Magnetic nanoparticles Applications in gene delivery and gene therapy

Artificial Cells, Nanomedicine, and Biotechnology
An International Journal
ISSN: 2169-1401 (Print) 2169-141X (Online) Journal homepage: www.tandfonline.com/journals/ianb20
Magnetic nanoparticles: Applications in gene
delivery and gene therapy
Sima Majidi, Fatemeh Zeinali Sehrig, Mohammad Samiei, Morteza Milani,
Elham Abbasi, Kianoosh Dadashzadeh & Abolfazl Akbarzadeh
To cite this article: Sima Majidi, Fatemeh Zeinali Sehrig, Mohammad Samiei, Morteza
Milani, Elham Abbasi, Kianoosh Dadashzadeh & Abolfazl Akbarzadeh (2016) Magnetic
nanoparticles: Applications in gene delivery and gene therapy, Artificial Cells, Nanomedicine,
and Biotechnology, 44:4, 1186-1193, DOI: 10.3109/21691401.2015.1014093
To link to this article: https://doi.org/10.3109/21691401.2015.1014093
Published online: 02 Mar 2015.
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Copyright © 2015 Informa Healthcare USA, Inc.
ISSN: 2169-1401 print / 2169-141X online
DOI: 10.3109/21691401.2015.1014093
Magnetic nanoparticles: Applications in gene delivery and gene therapy
Sima Majidi2,3, Fatemeh Zeinali Sehrig2,3, Mohammad Samiei2,5, Morteza Milani1,2, Elham Abbasi1,2,
Kianoosh Dadashzadeh4 & Abolfazl Akbarzadeh1,2
1Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran, 2Department of Medical Nanotechnology,
Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran, 3Higher Academic Education Institute
of Rabe Rashid, Tabriz, Iran, 4Department of Laboratory Sciences, Marand Branch, Islamic Azad University, Marand, Iran,
5Department of Endodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran
Introduction
Nanotechnology denes the formation and application
of materials, devices, and systems through the control of
nanometer-sized materials, and their application in physics,
chemistry, biology, engineering, applied science and other
activities. In particular, rigorous eorts are in progress to
develop nanomaterials for medical use as means that can be
targeted to specic cells, tissues, and organs (Chouly et al.
1996, Schlorf et al. 2010, Kami et al. 2011).
Many dierent types of nanoparticles, magnetic nanopar-
ticles (MNPs) being just a class among them, present excit-
ing opportunities for technologies at the interfaces between
biology, physics, and chemistry. A number of MNPs have
already been used in clinical practice as contrast-enhancing
agents for magnetic resonance imaging (MRI) (Prijic and
Sersa 2011). Furthermore, several methods have been used
to create these complexes, comprising hydrophobic inter-
actions (Namiki et al. 2009) and electrostatic interactions
(Zheng et al. 2009, Li et al. 2012).
e base of this therapeutic technique is to introduce a
gene encoding a practical protein, altering the expression
of an endogenous gene or possessing the capacity to cure
or prevent the development of a disease (Rapti et al. 2011,
Correspondence: Abolfazl Akbarzadeh, Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. Tel/Fax:  984133355789. E-mail:
[email protected]
(Received 17 January 2015; revised 27 January 2015; accepted 28 January 2015)
Abstract
Gene therapy is dened as the direct transfer of genetic material
to tissues or cells for the treatment of inherited disorders and
acquired diseases. For gene delivery, magnetic nanoparticles
(MNPs) are typically combined with a delivery platform to
encapsulate the gene, and promote cell uptake. Delivery
technologies that have been used with MNPs contain polymeric,
viral, as well as non-viral platforms. In this review, we focus on
targeted gene delivery using MNPs.
Keywords: cell uptake, gene therapy, magnetic nanoparticles,
non-viral platforms
Pouton and Seymour 2001, Robbins and Ghivizzani 1998,
Dizaj et al. 2014).
e procedure, based on the association of MNPs with
gene vectors, is called magnetofection, which is used in order
to enhance gene transfer in the presence of a magnetic eld.
It was developed by Christian Plank and coworkers for gene
transfer in cell cultures and in vivo, using MNP-naked DNA
complexes or MNP-viral vector complexes (Scherer et al.
2002). In this situation, the approach of magnetofection in
cells was assumed to be simple: the MNP-DNA complex is
added to a culture of adherent cells. e magnetic complexes
are attracted to the bottom by a magnet, placed close below the
bottom of the ask or plate, where they come in close contact
with the cells and are physically internalized, without any par-
ticular inuence of the magnetic force on the endocytic uptake
mechanism (Figure 1) (Huth et al. 2004, Schwerdt et al. 2012).
In vivo, magnetic elds focused over the target site have
the potential to not only increase transfection but also target
the therapeutic gene to a specic organ or location within
the body (Figure 2). Commonly, particles carrying the thera-
peutic gene are injected intravenously, and high-gradient
external magnets are used to capture the particles as they
ow through the bloodstream. Once captured by the eld,
the particles are detained at the target, where they are taken
up by the tissue (Dobson 2006).
e delivery carriers are required to be small enough to
be internalized into the cells and enter the nucleus, crossing
through the cytoplasm and escaping the endosome/lyso-
some process following endocytosis (Figure 3). e use of
nanoparticles in gene delivery can benet both the targeted
and maintained gene delivery by protecting the gene against
nuclease degradation and improving its stability (Dizaj
et al. 2014, Dobson 2006, Zhou et al. 2011, Sinha et al. 2006,
Morachis et al. 2012).
Genetic medicine can prospectively benet many diseases
ranging from cancer (Rapti et al. 2011, Pouton and Seymour
2001) to hemophilia (Robbins and Ghivizzani 1998). is
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Artificial Cells, Nanomedicine, and Biotechnology 2016; 44: 1186–1193
1186

therapy is not only used in genetic decits, but also in other
complicated illnesses, such as autoimmunity (rheumatoid
arthritis), viral infection (human immunodeciency virus),
artery disease, diabetes, and coronary diseases (Hendriks
et al. 2004). With the development of this method, gene ther-
apy will become an eective therapeutic technique for neu-
rodegenerative conditions, AIDS, asthma, and the myriad of
other genetic and developed diseases that aect humanity
(Pouton and Seymour 2001, Dizaj et al. 2014). A key hurdle to
its clinical application is the deciency of safe and operative
delivery systems (Park et al. 2006, omas et al. 2003). ere
are many barriers to gene delivery, comprising intracellular
barriers such as intracellular uptake, DNA release, nuclear
uptake, and endosomal escape, and extracellular barriers
such as targeting to specic tissues and/or cells of interest,
avoidance of particle clearance mechanisms, and protection
of DNA from degradation (Putnam 2006, Pack et al. 2005,
Harris et al. 2010).
In this study, we focus on targeted gene delivery via MNPs
(called as magnetofection) and the application of these parti-
cles as therapeutic agents for some diseases. Moreover, gene
delivery to cells and organs has been investigated (Fekri Aval
et al. 2014, Zohre et al. 2014, Valizadeh et al. 2014, Mellatyar
et al. 2014, Dadashzadeh et al. 2014, Rahimzadeh et al. 2014,
Ebrahimi et al. 2014, Badrzadeh et al. 2014).
Non-viral and viral vectors
In gene delivery, it is fairly common to follow biomimetic
methods. Biological systems contain modied viruses and
Figure 2. Schematic representation (side view section) of magnetic
nanoparticle-based gene targeting in vivo. Dashed gray rings indicate
the lines of magnetic flux due to the ex vivo permanent disk magnet.
F mag is the magnetic force vector exerted on the particles as they flow
through the bloodstream (Dobson 2006).
Figure 1. Diagrammatic representation of the magnetofection principle
in cells. MNPs are complexed to RAds and the complex is attracted to
cells by a magnetic eld. (Kindly provided by OZ Biosciences, Marseille,
France, www.ozbiosciences.com) (Schwerdt et al. 2012).
Figure 3. Internalization of non-viral vectors into cell and passage to nucleus through the cytoplasm, following endocytosis (Dizaj et al. 2014).
LABB_A_1014093.indd 2 9/16/2015 11:22:18 AM
Applications of magnetic nanoparticles in gene delivery and gene therapy 1187

non-pathogenic bacteria. In the investigations of mag-
netic carriers for gene therapy, a viral vector which carries
the therapeutic gene is coated onto the magnetic carrier’s
surface. By holding the carrier at the target location using
external magnetic elds, the virus is kept in contact with the
tissue for a longer period of time, increasing the efciency
of gene transfection and expression (Mah et al. 2000, Mah
et al. 2002). New magnetic carriers are being developed
specially for these applications (Hughes et al. 2001), and
this is an area which shows great promise (Pankhurst et al.
2003). Viral vectors are more eective than non-viral vec-
tors for DNA delivery, but may display a signicant threat
to patients, although non-viral carriers are inherently safer
than viral carriers (Higashi et al. 2009, Kostarelos and Miller
2005, Mastrobattista et al. 2006). In contrast to the viral gene
delivery structures, the non-viral carriers are expected to be
less immunogenic, with simple preparation and a possible
adaptable surface modication (Philippi et al. 2010).
e non-viral vectors are usually made of lipids or poly-
mers with or without using other inorganic substances,
where they can also be prepared from a lipid-polymer or
lipid-polymer-inorganic hybrid (Lu 2009). Naked DNA, gen-
erally in plasmid form, is the most basic form of non-viral
transfer of a gene into a target cell (Conwell and Huang 2005,
Niidome and Huang 2002, Bigger et al. 2001, Mayrhofer et al.
2009). Non-viral delivery vectors can be classied as organic
systems such as lipid complexes and conjugated polymers,
and inorganic systems such as MNPs and gold nanoparticles
(Lee et al. 2013).
In considering the viral gene delivery vector, with its safety
concerns regarding the risk of extreme immune response
(adenovirus) and supplement mutagenesis, the usage of non-
viral vectors can overcome the safety problems mentioned
(Bharali et al. 2005). Owing to the low transferring eciency
of a naked plasmid, several chemical (liposomes) and
physical (electroporation) approaches have been exploited,
to increase their transferring eciency (Dizaj et al. 2014,
Deelman and Sharma 2009).
Targeted gene delivery in vivo
Gene delivery methods eciently present a gene of interest
in order to express its encoded protein in an appropriate host
or host cell (Kami et al. 2011). In the case of magnetofection,
the gene is attached directly to the carrier. ese carriers
commonly consist of a magnetic iron-oxide either dispersed
within a polymer matrix – such as silica, polyvinyl alcohol
(PVA), or dextran – or encapsulated within a polymer or
metallic shell (Dobson 2006, Harris et al. 2003, Neuberger
et al. 2005).
To obtain a large-sized nucleic acid molecule, the cyto-
plasm, or even the nucleus, an appropriate carrier system,
such as virosomes, cationic liposomes, and nanoparticles,
are required to deliver genes to cells, which improve cell
internalization and protect the DNA molecule from nuclease
enzymatic degradation. To achieve a suitable carrier struc-
ture, nanoparticles can be considered as good candidates for
therapeutic applications because of several reasons, as follows
(Akbarzadeh et al. 2012b): ey exist in the same size range
as proteins (Wu et al. 2008), they have large surface areas and
ability to attach to a large number of surface functional groups
(Indira and Lakshmi 2010), and they have controllable absorp-
tion and release properties, as also surface characteristics and
particle size (Dizaj et al. 2014, Nitta and Numata 2013).
Inorganic nanoparticles, polymer-based nanoparticles,
lipid-based nanoparticles and hybrid nanoparticles are four
major groups exploited in gene delivery. MNPs are inorganic
nanoparticles which are normally utilized as gene delivery
carriers. e previous study reports have demonstrated that
they are not subject to microbial attack and show also good
storage stability (Dizaj et al. 2014, Jin et al. 2014).
Magnetism-based targeted delivery was rst dened in
1978 (Widder et al. 1978). However, techniques similar to
those used for drug delivery have important potential to be
used for gene therapy. For these applications, the approach
must be adapted to account for the size and charge of nucleic
acids (Li et al. 2012).
Currently, there are three primary gene delivery meth-
ods that use viral vectors, nucleic acid electroporation, and
nucleic acid transfection. ese systems vary in eciency
(Table I). It has been demonstrated that gene delivery by
viral vectors can be highly eective, but may supplement
viral vector nucleic acid sequences into the host genome,
potentially causing undesirable eects, such as unsuitable
expression of deleterious genes (Kami et al. 2011).
e use of MNPs to increase the eectiveness of the cell-
fusion vector hemagglutinating virus Japan envelope (HVJ-E)
was represented by Morishita and others. ey found that by
associating protamine sulfate (PS)-coated MNPs to HVJ-E,
transfection was improved in vitro in BHK21 cells, even with
a reduction in the amount of HVJ-E and no proof of toxicity
(Dobson 2006, Morishita et al. 2005). However, in order for
MNPs to act as ecient carriers for DNA or pharmaceutical
drugs, the external surface of the particles must rst be mod-
ied to allow attachment of the target molecules. Molecules
can be attached to the surface of the particles in some ways,
such as employing cleavable linkers or utilizing electrostatic
interactions between the particle surface and the therapeu-
tic agent (McBain et al. 2008).
MNPs can be coated with compounds such as natural
polymers (proteins and carbohydrates) (Akbarzadeh et al.
2012c, Valizadeh et al. 2012, Akbarzadeh et al. 2013, Akbarza-
deh et al. 2012a, Akbarzadeh et al. 2012d, Akbarzadeh et al.
2012e), synthetic organic polymers (polyethylene glycol, PVA,
poly-L-lactic acid) (Akbarzadeh et al. 2013, Mollazade et al.
2013, Nejati-Koshki et al. 2013, Rezaei-Sadabady et al. 2013),
silica (Fallahzadeh et al. 2010), and gold (Kami et al. 2011,
Ebrahimnezhad et al. 2013, Pourhassan-Moghaddam et al.
2013). In the case of in vitro magnetofection, the particles are
generally coated with polyethylenimine (PEI), which attaches
Table I. Gene delivery systems (Kami et al. 2011).
Expression
type
Eciency
(%)
Cell
Viability (%) Safety
Virus *Stable, or
Transient
80–90% 80–90% Low
Electroporation Transient 50–70% 40–50% High
TF reagent ** Transient 20–30% 80–90% High
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S. Majidi et al.
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Today, research has made progress in nding a way to use
MNPs which are ultra-small and biocompatible, to improve
the overall uptake of genetically engineered cells like mono-
cytes or macrophages by tumors, following their systemic
administration (Davaran et al. 2014). Muthana and cowork-
ers suggested that this new magnetic targeting method
could be used to target ‘therapeutically armed’ monocytes
or other forms of cellular gene delivery vehicles to tumors,
and thus overcome the diculty of poor targeting in current
cell-based gene therapy protocols (Figure 5) (Davaran et al.
2014).
As early as 1960, Freeman (Kouhi et al. 2014) proposed
that such MNPs could be transported through the vascular
system and concentrated in a special part of the body using
DNA to the particle’s surface via charge interactions (Dobson
2006). In the rst study to show targeted delivery of DNA using
MNPs, Cathryn Mah, Barry Byrne, and coworkers coated the
adeno-associated virus (AAV) encoding Green Fluorescent
Protein (GFP) to the surface of MNPs using a cleavable hepa-
rin sulfate linker (Mah et al. 2000, McBain et al. 2008).
Although the use of target-specic linkers undoubtedly
supplies an elegant approach to the attachment of target
molecules, it is not always possible. An optional approach for
binding DNA to the surface of particles is to employ the elec-
trostatic interactions between the negatively charged phos-
phate backbone of DNA and the positively charged molecules
connected to the particle surface. A current choice for this
approach is the cationic polymer PEI (Ahmadi et al. 2014).
It is now understood that particle DNA complexes normally
enter the cell by endocytosis through clathrin-dependent
pits (Davaran et al. 2013), it is possible that this property of
PEI may remain favorable for PEI-coated particles (McBain
et al. 2008).
Another innovative and interesting approach to nanopar-
ticle-mediated gene delivery is the use of nanotubes, which
has been reported by (Ghasemali et al. 2013). is approach
is based upon using nickel-embedded carbon nanotubes
covered in DNA. When the nanotubes are hosted to cells
in the presence of a specially oriented magnetic eld, the
nanotubes align with the magnetic ux lines as they are
pulled towards the cells. is allows the nanotubes to spear
the cells, pass through the membrane, and deliver the target
DNA, and this technique has been successfully used to trans-
fect a number of various cell types, while maintaining a high
rate of cell viability after transduction (McBain et al. 2008).
Gene delivery using MNPs and magnetic force
MNPs are already in use by some researchers to enhance
transfection eciencies of cultured cells. erefore, MNP-
nucleic acid complexes are added to cell culture media
and then onto the cell surface by applying a magnetic force
(Figure 4) (McBain et al. 2008).
Figure 5. Schematic representation of the possible role of MNPs in enhancing monocyte-based gene delivery to tumors. MNP-loaded monocytes
injected into the bloodstream of the patient circulate and are then drawn out of the blood vessels in the tumor under the influence of a local
magnetic eld (Davaran et al. 2014).
Figure 4. MNP gene delivery system (Magnetofection). Plasmids are
bound to MNPs, which are then moved from the media to the cell
surface by applying a magnetic force (Sadat et al. 2014).
LABB_A_1014093.indd 4 9/16/2015 11:22:19 AM
Applications of magnetic nanoparticles in gene delivery and gene therapy 1189