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Drug Discovery Today � Volume 19, Number 6 � June 2014 REVIEWS

Electrospinning for regenerativemedicine: a review of the main topics

Daikelly I. Braghirolli1,2,4, Daniela Steffens1,2,4 and Patricia Pranke1,2,3

1Hematology and Stem Cell Laboratory, Faculty of Pharmacy, Federal University of Rio Grande do Sul, Porto Alegre 90610-000, Brazil2 Post Graduate Program in Physiology, Federal University of Rio Grande do Sul, Porto Alegre 90010-170, Brazil3 Stem Cell Research Institute, Porto Alegre 90020-010, Brazil

Electrospun fibers are promising tissue engineering scaffolds that offer the cells an environment that

mimics the native extracellular matrix. Fibers with different characteristics can be produced by the

electrospinning technique according to the needs of the tissue to be repaired. In this review, the process

of electrospinning was examined, providing a description of the common techniques used for the

physicochemical and biological characterization of electrospun fibers. The review also discusses the

potential applications of electrospun scaffolds for tissue engineering, based on scientific literature.

IntroductionFailure of organ and/or tissue function as a result of injury, disease or

aging has a high impact on quality of life and also incurs a large

social and economic cost. Current treatments vary with the organ

affected, but all of them have their limitations [1]. Frequently, organ

transplantation is the indicated therapy for these clinical cases;

however, there are several disadvantages in using autologous or

allogenic grafts, including shortage of appropriate donor organs,

risk of disease transmission and immune rejection [2]. Tissue engi-

neering (TE) is an exciting area that involves engineering and

biological knowledge to create or restore tissue and organs. It utilizes

three basic tools: cells, biomaterials and biomolecules. Electrospin-

ning (ES) is a simple and versatile technique that produces scaffolds

formed by nano- and micro-fibers, which offer a favorable micro-

environment for cellular development by mimicking the native

extracellular matrix [3]. The aim of this review paper is to describe

the production of electrospun scaffolds and examine the most

commonly used techniques for their physicochemical and biologi-

cal characterizations. It also discusses the main biomedical applica-

tions of electrospun fibers and the cell sources used in TE.

The electrospinning processFrom the techniques used to construct biomaterials to be culti-

vated with cells, ES is the most widely studied and it has also

Corresponding author: Pranke, P. ([email protected])4 These authors contributed equally to this paper.

1359-6446/06/$ - see front matter � 2014 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.drudis.

been demonstrated as giving the most promising results in

terms of TE applications. The first recorded citation detailing

the application of high electrical potentials to generate aerosols

from drops of fluids was in 1745; but not until 1929 was the

application of an electrical field to produce artificial silk

described. Until the 1990s, there was no commercial interest

in this technique, although advances and patents in the field

were achieved [4]. A search in February 2014 for the keyword

‘electrospinning’ in PubMed showed an increased interest for

this technique after 2000.

The electrospinning process works by the electrostatic principle.

As can be seen in Fig. 1, the machine is basically composed of a

syringe with a nozzle, a counter electrode (normally a metal plate),

a source of electrical field and a pump. The solution to be electro-

spun is applied to the system via the nozzle of the syringe and is

pulsed by the pump. It is then subjected to a difference in an

electrical voltage present between the nozzle and the counter

electrode. This electrical voltage generated by the source causes

a cone-shaped deformation of the drop of polymer solution. The

solvent in the solution evaporates on its way to the counter

electrode and, at the end of the process, solid continuous filaments

are yielded [5]. It is important to note that the gravitational forces

do not interfere in the process because the acceleration of the fiber

formation is up to 600 m/s2, which is close to two orders of

magnitude greater than the acceleration of gravitational forces.

Because of this, it is possible to form fibers from top-down, bottom-

up or other types of arrangements [6].

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REVIEWS Drug Discovery Today � Volume 19, Number 6 � June 2014

Polymersolution

Appliedvoltage

Counter electrodeDrug Discovery Today

FIGURE 1

Example of an electrospinning machine.

(a)

(b)

(c)

Drug Discovery Today

FIGURE 2

Morphology of the fibers. (a) Random fibers. (b) Fibers with beads. (c)Aligned fibers.Photographs courtesy of the Stem Cell Laboratory archives, Federal

University of Rio Grande do Sul.Review

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Although it appears at first to be an easy method, the process

depends on a multitude of molecular, processing and technical

parameters [4]. This includes: (i) environmental parameters, such

as solution temperature, humidity and air velocity in the ES

chamber; (ii) solution properties, such as elasticity, viscosity,

conductivity and surface tension; and (iii) governing variables,

such as distance between the tip and counter electrode, electrical

potential, flow rate, molecular weight of the selected polymers,

geometry of the collector, among others [6,7]. The environmental

parameters and the nozzle distance from the counter electrode are

crucial for the morphology and structure of the fibers, achieving

wet or dry fibers with or without beads. The solution properties

have an influence on the capacity of the spinneret. Low concen-

tration solution forms droplets owing to the influence of surface

tension, whereas higher concentration prohibits fiber formation as

a result of higher viscosity. In general, it is observed that fibers

become more uniform with increased polymer concentration in

the solution. At lower concentrations, increasingly thinner fibers

are formed with the presence of beads. Fiber diameter and the pore

diameter increase with an increase in the polymer concentration

and the polymer flow rate. An increase in applied voltage causes a

change in the shape of the jet initiating point and consequently in

the structure and morphology of the fibers. The geometry of the

collector will influence the arrangement of the fibers [8–10].

Through optimization of the cited parameters, fibers can be

obtained randomly or in an ordered way: larger, thinner and with

or without beads (Fig. 2a–c). The choice by determined parameters

is made, based on the polymer solution and the applicability of the

formed fibers.

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The important advantages of the ES technique include the

production of fibers a few nanometers to micrometers in diameter,

high porosity and large surface areas, which can mimic the extra-

cellular matrix structure in terms of the chemistry and dimensions

[11]. The ease of functionalization for various purposes, superior

mechanical properties and relative simplicity and ease of control

over the key process parameters have also made this method

attractive [10,12]. However, the parameters must be strictly set

to fabricate large and complex 3D structures to allow the cells to fill

the structure in a 3D manner. There is also the possibility of


Drug Discovery Today

FIGURE 3

Mesenchymal stem cells (MSCs) seeded onto scaffolds through the

combination of the electrospray and electrospinning methods after one day

of culture. The multicolored dots are the cells stained with hematoxylin–eosinwithin the scaffolds, constructed by the combination of the methods cited

above.

Photograph courtesy of the Stem Cell Laboratory archives, Federal University

of Rio Grande do Sul.


making some modifications of the traditional ES technique. The

most recent modifications are presented below.

The core–shell structures are obtained through co-electrospin-

ning. Using this compound spinneret method, two components

can be fed through different coaxial capillary channels and are

integrated into a core–shell-structured composite fiber [13]. Coax-

ial ES is applied to obtain polymer core–shell fibers, hollow poly-

mer core–shell fibers, hollow fibers containing polymer and/or

ceramics and for the immobilization of functional objects or

molecules. This methodology is very useful for drug and/or protein

delivery, for the encapsulation of cells, bacteria, viruses, growth

factors and others [11,14].

Another modification is electrospray, which is frequently used

in association with ES. During this technique an aerosol is gener-

ated between two charged electrodes. The needle holding the flow

of media is raised to different electrical potentials in relation to a

collector, which promotes the charged media, stimulating the

needle to accelerate toward the electrode and resulting in the

formation of a spray [15]. Then, when associated with ES it is

possible to obtain 3D structures with the cells occupying the whole

environment, because the scaffold is fabricated (Fig. 3) in a dif-

ferent way to traditional ES – where the cells are seeded on top of

the scaffolds and take days or weeks to fill all the structure. It is also

possible to spray some molecules of interest for different kinds of

applications.

Finally, the material choice depends on the application of the

scaffold. For TE purposes, biodegradable and biocompatible poly-

mers are preferably used. The choice is based on the properties of

the tissue to be regenerated, as well as its time of regeneration. The

mostly synthetic materials used in TE are polyesters [6,16], such as

poly(lactide) (PLA), poly(glycolyde) (PGA) and poly(caprolactone)

(PCL). Sometimes, it is beneficial to obtain a material that has

properties of two or more polymers. In these cases, co-polymers or

blends of polymers are selected for electrospinning [17]. The

natural materials, such as proteins or polysaccharides, are of

interest for use in regenerative medicine because the material

becomes more recognizable for the cells. Cellulose [18], collagen

[19], natural silk [20], fibrinogen [21], chitin, chitosan [22], hya-

luronic acid [23] and even DNA [24] have already been electro-

spun. These natural materials can be electrospun solely or as a

blend with synthetic materials. It is also important to bear in mind

that this technology is not only applicable to the medical field but

in several other areas as well, such as catalysis, filtration, the textile

industry, agriculture and electronic and optical devices, among

others [4,12,25,26].

Functionalization of electrospun scaffoldsThe fibers constructed by ES have attracted substantial attention

over recent years for TE application, owing to their capability of

closely mimicking the structure of the native environment of the

cells. Perhaps this apparent advantage is that the polymers that are

commonly used to construct the scaffolds do not possess any

specific groups that interact with the cells. Therefore, the incor-

poration of biomolecules into electrospun fibers could lead to a

biofunctional scaffold, which would determine the efficiency of

these fibers for regenerating biological functional tissues [10].

Because of this important perspective, scientists around the world

have been studying biomolecules to be incorporated, as well as

ways of improving the efficiency of the incorporation of these

agents.

One of the first steps to functionalize a biomaterial is to improve

the hydrophilicity. Most of the treatments used to reach this goal

(plasma, UV, g-radiation, high temperature, acid or basic solu-

tions) can destroy the structure of the fibers. This is more worrying

if biodegradable polymers are being used. Thus, these treatments

must be optimized to maintain the 3D structure. There are differ-

ent ways of functionalizing the surface of the fibers. The attaching

and adsorption of the bioactive agents to electrospun fibers cova-

lently is a frequently used option [11].

In a study performed by Ye and colleagues [27], vascular

endothelial growth factor (VEGF)-coated scaffolds were developed

through the functionalization of PCL–heparin solution to be used

as vascular substitutes. Heparin was mixed with PCL in a solution

that resulted in the formation of nonwoven tubular scaffolds via

ES. It was observed that these scaffolds had a low water contact

angle and plasma protein adsorption was significantly suppressed

when compared with PCL scaffolds. It clearly showed that PCL–

heparin conjugate has good blood compatibility, reducing the

inflammation and thrombus risk in vivo. Also, because of the

negatively charged surface of the PCL–heparin conjugate, the

scaffold has a much higher affinity for adsorption of VEGF, which

is positively charged. These scaffolds also showed better cell com-

patibility with good results for cell viability and morphology.

These results were confirmed by the in vivo studies performed in

the femoral artery of dogs.

Ji-Eun Kim and colleagues [28] developed a poly(lactide-co-

caprolactone) (PLCL) nanofiber with a fibronectin peptide called

FN10, which contains the RGD sequence of the central cell-bind-

ing domain. To bind FN10, they formed covalent linkages through

carboxylation in an alkaline solution and cross-linking with a

carbodiimide agent. They found that the cell spreading area was

approximately two to three times higher on the FN10-coupled

nanofiber than on the control nanofiber. Also, the cells on

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FN10-coupled PLCL nanofibers exhibit a much higher viability at

2, 3 and 6 hours, showing significant difference in comparison

with the PLCL nanofiber. The coupling process used in this study

can be easily applied to different proteins or peptides, as well as

polymers.

Boccafoschi and colleagues [29] performed a study in which

poly-L-lactide (PLLA) scaffolds were coated and grafted with pep-

tides and proteins in several different groups. Although these

experiments compared the response of cells to some proteins

and peptides, they did not show clearly any comparison among

the proteins and peptides. They also did not use different incor-

poration methods for proteins and peptides (proteins for adsorp-

tion and peptides for adherence).

In the literature there is no consensus regarding the best method

for functionalizing the surface of biomaterials, neither for the use

of proteins or peptides. Some advantages that the authors cited in

using peptides are their independence from conformation, ease of

manipulation and favorable cost:benefit ratio while maintaining

key biological functionality. However, this field is not yet well

elucidated in the literature and more research about this theme

must be performed. The incorporation of the biomolecules could

be made either by mixing or encapsulation, as will be discussed in

the next section.

Drug and protein deliveryThe simplest method for the incorporation of molecules in scaf-

folds is to embed them in a solution containing a given drug.

Bolgen and colleagues [30] embedded PCL scaffolds in an anti-

biotic solution to be used as membranes for prevention of abdom-

inal adhesion in rats. The drug release was measured every 3 hours

to obtain the in vitro release kinetics. About 80% of the drug was

released in 3 hours and this was almost completed in 18 hours.

This behavior was expected, owing to the type of incorporation

that the researchers used because only the molecules are adsorbed

onto the structure and are easily released.

ES emulsion has been used as a method for preparing fibrous

materials and scaffolds for several therapeutic agents, among them

the growth factors. This arrangement protects the growth factors

from possible enzymatic degradation and it also prevents toxic

effects resulting from bolus release. Factors, such as type and

concentration of the surfactant, mechanical agitation and bioac-

tive molecule, affect the ES emulsion and some research about this

topic can be found in the literature [31,32].

Natural products are also used for drug and protein delivery. In a

recent study, Brahatheeswaran and colleagues [33] used zein pro-

tein to form fibers for the delivery of curcumin, which was only

mixed with the ES solution. Curcumin is a fluorescent molecule

with various therapeutic properties, such as anti-inflammatory,

antibacterial, antitumor, hepatoprotection, as well as early-epithe-

lialization, improved neovascularization and migratory activity of

various cells into the wound bed, among others. The evaluations

showed a burst release of the drug in the first hours, followed by a

slight delivery. The experiment with cells also showed good cyto-

compatibility, which was attributed to the drug release from the

fibers.

Chen and colleagues [34] investigated the sandwich structure,

which consists of poly(lactide-co-glycolide) (PLGA)–collagen on

the surface layers and PLGA-vancomycin-gentamicin-lidocaine in


the core, as in antibiotic-loaded wound dressings. The results

showed that the membranes released high, sustainable concentra-

tions of vancomycin and gentamicin for four and three weeks,

respectively, in vitro (well above the minimum inhibition concen-

tration) and lidocaine for two weeks. It is also important to observe

that the consequence of the drugs released in the cell proliferation

cycle was negligible.

As is explicit above, the release profile is dependent on how the

bioactive agent is dispersed in the biomaterial. When the bioagents

are only dissolved and dispersed in the polymer solution or in an

emulsion before ES, there is always a high probability of a great

quantity of them remaining on the surface of the fibers, leading to a

burst release in the initial periods [14,31,35]. An alternative method

to encapsulate drugs, proteins, growth factors, genes, among others,

inside polymeric nanofibers is by coaxial electrospinning [10]. In

this way, there is controlled release of the core of the core–shell

structure, normally through aqueous pores or by the degradation of

the polymer that is in the shell. This technique has the advantage of

providing temporal protection of the biomolecules in the core and

preventing their action until shell degradation starts.

Weijie Xu and colleagues [36] developed a study with the aim of

producing a delivery system based on electrospun fibrous PLGA

scaffolds combined with different concentrations of Pluronic1 F-

127 (PF127) to provide controllable delivery of multiple proteins

for target locations in a controlled manner. They hypothesized

that the hydrophilicity of protein carrier materials can actively

influence the release kinetics of proteins from the scaffolds. In this

way, PF127, which is an amphiphilic triblock copolymer, provides

hydrophilicity for the polymeric scaffolds. For proteins they used

bovine serum albumin (BSA) and myoglobin. The results indicate

that the hydrophilicity of the scaffolds accelerates the protein

release from the scaffolds by diffusion. They also demonstrated

that, by combining polymers with different hydrophilicities, it is

possible to obtain different release curves of the proteins. It is

important to emphasize that in this study they used co-electro-

spinning, which resulted in high encapsulation efficiency and

controlled release.

Huiyong Zhu and colleagues [37] used co-electrospinning to

form core–shell fibers with recombinant human bone morphoge-

netic protein 2 (rhBMP-2). Among several in vitro tests, they

showed that after the release of rhBMP-2 in PBS and culture

medium it was still active. These results were also confirmed by

the in vivo tests, because rhBMP-2 was released in the critical defect

created on the calvarium of rabbits and this contributed enor-

mously to a higher mineralization when compared with the con-

trol group (only lesion) and with the group where the animals only

received the scaffolds without the protein.

Angiogenesis is among the most challenging and important

issues in TE. In an attempt to mimic the body’s chemotaxis

microenvironment, Guo and colleagues [38] created a scaffold

by the combination of co-electrospinning, electrospraying and

ES. The fabrication process simultaneously involves ES PCL fibers,

encapsulating basic fibroblast growth factor (bFGF) into PLGA

microspheres by co-electrospinning, and electrospraying these

microspheres into the PCL fibers. Among several types of scaffolds

that were fabricated, they created scaffolds with bFGF gradients to

mimic the chemotaxis process during the formation of native

blood vessels. In vitro and in vivo studies demonstrated that the



bFGF gradients were able to attract cell migration into the scaffolds

more effectively than scaffolds without the gradient. In vivo tests

have also shown that, after subcutaneous implantation, a high

density of mature blood vessels [stained with CD31+ and a-

smooth muscle actin (SMA)+] was formed in the scaffolds loaded

with bFGF gradient in greater density than the control and the

non-gradient scaffolds. These studies and many others demon-

strate that biologically active agents can be released over a pro-

longed period from the core of coaxial electrospun membranes

with in vivo and in vitro activities.

Analysis of the scaffold properties: physicochemicaland biological characterizationThe success of a 3D biomaterial depends on many parameters,

which range from nano to macro scale. The degradability,

mechanical properties and quality of the porosity of these scaffolds

are key parameters to be analyzed before choosing the material to

be used. Moreover, surface properties, such as topography, surface

energy, residual solvents and wettability, should be determined to

correlate them to the biological response of the constructs. A key

feature for the successful application of biomaterials in TE is that

they need to promote cell adhesion. In this way, accommodation

and cell behavior are strongly affected by the structure of the

biomaterials [39].

The roughness directly influences adhesion, proliferation and

cell viability [40], whereas the contact angle with water reflects the

hydrophilicity of the matrix and, consequently, cell–matrix inter-

action [41]. To date, there is still no profile available for interpret-

ing the results, owing to the effect of the roughness of the

biomaterial applicable to all cell types and biomaterials, so it is

not possible to determine which is the best value for this property

[40]. For the contact angle with water, several studies have shown

that the more hydrophilic characteristics result in greater adhesion

and proliferation [42–44]. The measurement of the roughness can

be made by atomic force microscopy and the water contact angle

can be made with a goniometer [40,45].

Mechanical analyses are important to evaluate the strain defor-

mation to which the matrix can be subjected in order to guarantee

that disruption of the structure does not occur, which is vital for

the cells and for tissue regeneration [46,47]. It is measured through

the application of tensile tests [48,49]. This mechanical property is

closely related to the porosity, pore size, fiber diameter and thick-

ness of the scaffold [50]. The porosity and pore size are efficiently

evaluated by mercury porosimetry and gravimetric analysis [51–

53]. The scaffold thickness is measured with a caliper rule [54]. The

porosity, pore size and pore interconnectivity are important con-

siderations for promoting tissue growth, vascularization and the

delivery of nutrients through the newly formed tissue; it also has

an influence on cell differentiation [55,56]. Pore size, pore inter-

connectivity and fiber diameter are generally measured in photo-

graphs from scanning electron microscopy [45,53]. Another

important fact is that the minimum pore size required is decided

by the diameter of the cells, and therefore varies from one cell type

to another. Inappropriate pore size could lead to no infiltration of

the cells, which results in a 1D or 2D structure [11].

Degradation is closely related to the stability of the biomaterial

in vivo and an adequate time of degradation is extremely important

for proper tissue regeneration [56]. The degradability of the

polymer can be evaluated after different periods of incubation

in PBS at 378C in a gel permeation chromatograph or by the

measurement of the weight loss [45,57]. Ideally, the rate of degra-

dation of the biomaterial can be equal to the rate of tissue regen-

eration. In this way, the biomaterial acts as a support for the

development of the tissue, without at the same time acting as a

barrier to regeneration. In general, the degradation of biodegrad-

able polymers depends on several factors, which include its crystal-

linity, molecular weight, dimensions, composition and the pH of

the surrounding medium [56]. Because the use of organic solvents

is currently applied in the fabrication of tissue engineering scaf-

folds, which are mostly toxic to cells, the measurement of the

residual solvent is required for the verification of the complete

absence of solvent in the fabricated matrix [45]. This evaluation is

commonly performed by thermogravimetric analysis (TGA) [45].

The functionalization of the biomaterials with proteins or

growth factors must be evaluated for their presence and bioavail-

ability. Their presence in most cases is verified by fluorescence

[28,58], high-resolution X-ray photoelectron spectra [59], ELISA

[38,60], among others. The mostly common quantitation methods

used are colorimetry [28] and fluorescence [59]. The effect of these

biomolecules is accessed by the behavior of the cells on the

functionalized scaffolds [28,59–61].

The main goal of TE is to develop a biomaterial that can be used

to regenerate tissue in vivo. However, in vitro models are the first

approach used to understand the cell–substrate interaction and

biocompatibility of the materials. Because of this, cell cultures are

ideal systems for the analysis of a specific cell type under certain

conditions, therefore avoiding the complexity of the several vari-

ables involved in in vivo studies [10]. The following assays are

commonly used to evaluate cell interaction with the biomaterial:

(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide

(MTT), lactate dehydrogenase (LDH), cell counting kit 8 (WST-

8), y[3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-

2-(4-sulfophenyl)-2H-tetrazolium (MTS), scanning electron micro-

scopy and confocal microscopy [22,27,34,45,62,63]. More-specific

analyses are performed according to the aim of each study

[18,33,64–66].

Cell sources used in tissue engineeringAs mentioned above, TE utilizes three basic tools: cells, biomater-

ials and growth factors. The cells have a crucial function in this

system: they synthesize an adequate extracellular matrix provid-

ing the in vitro organization and development of the new tissue

[67]. The choice of cell type is very important and has a great

influence on the success of TE. Different cell sources can be used

for association with the biomaterials, according to the tissue that is

to be repaired [68–71]. Stem cells represent an important factor for

regenerative medicine, owing to their properties of self renewal

and their capacity of differentiation into different cell types.

Because of this, they have been extensively associated with scaf-

folds.

Mesenchymal stem cells (MSCs) are multipotent adult stem cells

that exhibit a great plasticity and can give rise to mesenchymal

and non-mesenchymal tissue [72,73]. Additionally, MSCs exhibit

intrinsic secretory activity because they can synthesize and secrete

large amounts of bioactive factors with immunoregulatory effects.

The cytokines and/or growth factors secreted by MSCs show



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trophic effects, contributing to scarring and apoptosis inhibition,

angiogenesis stimulation and mitosis of tissue-intrinsic stem or

progenitor cell stimulation. These effects contribute to the estab-

lishment of a regenerative microenvironment at the tissue injury

or damage sites [74]. Consequently, the combined use of MSCs and

scaffolds is a promising tool that can be used for the repair and

regeneration of many types of tissue.

The efficacy of electrospinning depends on the interaction

between the cells and the scaffolds surface. The fiber diameter, pore

size and roughness are some parameters that can be modulated

during the production of the scaffold and that affect its nano- or

micro-topography. This property directly affects cell behavior

including proliferation, vitality, adhesion and spreading onto the

surface of the scaffold [75]. It has been observed that each type of cell

shows a distinct response to different electrospun fibers. In their

work, Whited and Rylander showed that endothelial cells exhibited

a greater spreading morphology on 100–300 nm fibers than on

1200 nm fibers; yet, on the nanofibers the cells were able to form

a confluent endothelium [76]. When the fibroblast was cultivated

onto the nano- and micro-fibers and the efficiency of the cultivation

was compared within these different fiber sizes, it was observed that

the fiber diameter has a great effect on the behavior of these cells.

Nanofibers favored a higher initial proliferation of fibroblasts; how-

ever, after two weeks of cultivation, a higher proliferation was

observed on the microfiber scaffolds and actin stress fibers, and

focal adhesion complexes were more easily observed on them [77].

Electrospun fibers of various polymers with different diameters and/

or morphologies have already been tested as substrates for the

cultivation of MSCs. These scaffolds exhibit considerable biocom-

patibility with the MSCs, favoring their adhesion and growth in in

vitro cultivations [45,78,79]. Furthermore, recent studies have

reported the general flexibility of fiber scaffolds for supporting

MSC differentiation. MSCs have been successfully differentiated

onto various electrospun scaffolds and into different cellular

lineages, including endothelial, hepatic, osteogenic and cardiomyo-

genic [80–83].

Electrospinning for tissue engineering applicationsVascular bioengineeringCardiovascular diseases are major causes of death worldwide [84,85].

The autologous bypass vascular grafts are primarily used in clinical

settings; however, some disadvantages have been shown, such as

thrombosis, limited availability and the need for a second surgical

procedure [84,86]. An alternative to autologous bypass is artificial

grafts, such as polytetrafluoroethylene (PTFE) and Dacron1; how-

ever, their performance is not satisfactory when applied to small

diameter vessels (<5 mm) [87]. Electrospun tubular scaffolds have

been studied for use as vascular substitutes. It has been shown that

these scaffolds can guide the contact and adhesion of the host cells,

increase the biological response and promote vessel regeneration

[88]. PCL is one the most commonly used polymers for constructing

vascular scaffolds, mainly because of its good mechanical integrity.

Currently, different studies have developed vascular scaffolds using

PCL combined with hydrophilic molecules, such as heparin. The

presence of heparin can suppress the adsorption of proteins on the

biomaterial surface, preventing coagulation and subsequent failure

of the vascular grafts. Ye and colleagues evaluated the in vitro

anticoagulant activity of PCL–heparin conjugate by activated


partial thromboplastin time (APTT) assay. The conjugate showed

excellent anticoagulation properties when compared with PCL

control (PCL–heparin >300 s, PCL 51.8 � 0.7 s) [89]. Polyurethane

[90], sulfated silk fibroin [91], poly(trimethylene carbonate-co-L-

lactide) [92], albumin [93] and blends of PCL–collagen [94,95] are

other materials that have also been studied to produce scaffolds for

use as vascular grafts. In their work, Wang and colleagues showed

that heparin-bonded poly(L-lactide-co-e-caprolactone) [P(LLA-CL)]

electrospun scaffolds seeded with autologous endothelial cells are

great candidates for vascular grafts for small-diameter vessels. The

scaffolds exhibited mechanical properties similar to natural canine

femoral arteries and had a biocompatible surface that favored the

adhesion and growth of endothelial cells [96]. Scaffolds functiona-

lized with angiogenic factors, such as VEGF and FGF2, have also

been studied to produce vascular scaffolds. The use of these growth

factors can help the formation and organization of blood vessels

[84,89,97].

Cartilage bioengineeringCartilaginous tissue has a limited capacity for spontaneous repair

potential because of its avascular nature, insufficient number of

chondrocytes and low mitotic activity [98,99]. Consequently,

tissue engineering offers a promising alternative for the restoration

of damaged cartilage. A limited number of works have focused on

the use of scaffolds produced by electrospinning for restoration of

damaged cartilage; however, despite the limited amount of

research, important results have been found. Shafiee and collea-

gues showed that poly(vinyl alcohol)–PCL (PVA–PCL) scaffolds

can support the in vitro chondrogenic MSC differentiation and

improve healing of cartilage defects. The use of PVA–PCL scaffolds

seeded with MSCs favored the production of hyaline-like cartilage

for creating full-thickness knee cartilage defects in rabbits [71].

Articular cartilage has a complex structure, exhibiting anisotropic

mechanical properties as a result of the different specific cell and

extracellular matrix organization or orientation of each zone that

forms the hyaline cartilage. To mimic the protein orientation and

zonal tensile properties of articular cartilage, McCullen and col-

leagues created trilaminar electrospun scaffolds by varying fiber

size and orientation. The trilaminar scaffolds were able to mimic

collagen fibril arrangement and zonal mechanical properties of the

native cartilage and also supported in vitro cartilage formation,

favoring chondrocyte proliferation and glycosaminoglycan pro-

duction [100]. The menisci are crescent-shaped fibro-cartilaginous

tissues that transmit and distribute loads between the femur and

tibia and are essential for the performance of the knee joint.

Unfortunately, meniscal injuries are common and the currently

available treatments have disadvantages, for example they can

often lead to cartilage degeneration, increase of pain and loss of

function [101,102]. In their work, Fisher and colleagues produced

organized nanofiber scaffolds that could mimic the macroscopic

and microscopic architecture of the knee meniscus. The developed

scaffolds exhibited spatial variation of fiber orientation on a

macroscopic scale and aligned fiber orientation on a microscopic

scale, showing similar organization to the native meniscus [103].

Bone bioengineeringThe use of engineering scaffolds is a potential strategy to facilitate

the repair of damaged bone tissue caused by trauma or genetic



diseases [104]. A large amount of bone tissue engineering work has

used the electrospinning technique to produce the scaffolds.

Electrospun scaffolds for bone bioengineering have been gener-

ated from a large variety of natural and synthetic polymers, such as

chitosan, collagen, alginate, PCL, PGA, PLA and PLGA. Frequently,

different polymers are also mixed for electrospinning to produce

blended nanofibers. Currently, research has focused on the devel-

opment of electrospun scaffolds functionalized with osteogenic

factors and/or nanostructured materials that are favorable for bone

repair because they enhance the biomaterial structure, mechanical

characteristics and cellular osteogenic differentiation on their

surface. Hydroxyapatite (HA) is a phosphate-based ceramic that

has a chemical structure similar to minerals present in native bone

and is extensively employed to create composite scaffolds by

increasing their mechanical and osteoconductive properties

[105,106]. In addition, HA can enhance surface topographical

characteristics of scaffolds, promoting greater adhesion and

growth of cells [107–109]. Furthermore, it was reported that elec-

trospun scaffolds containing HA can induce osteogenic differen-

tiation of MSCs without the addition of other osteogenic factors,

and can increase alkaline phosphatase activity and osteocalcin

expression [110]. Bone repair can also be enhanced by providing

growth factors in the defect tissue. Nie and colleagues combined

bone morphogenetic protein 2 (BMP-2) and HA to develop elec-

trospun scaffolds from homogeneous emulsion. The scaffolds

showed a sustained delivery of BMP-2, according to the HA con-

centration used, and were good substrates for MSC development

[111]. Yan Su and colleagues produced BMP-2- and dexametha-

sone-loaded scaffolds through coaxial electrospinning. When

MSCs were seeded onto the developed scaffolds an increase in

ALP activity, mineralization and osteoblast marker expression was

observed, illustrating the potential application of coaxial electro-

spun nanofibers for bone repair [112]. Although extensive research

is being carried out involving electrospinning to produce scaffolds

for bone regeneration, few studies so far have used electrospun

scaffolds with cells in animal models with bone injury. Park and

colleagues found important results when they applied electrospun

PLGA scaffolds seeded with adipose-derived stromal cells (ASCs)

onto rat tibial defect models. Before implantation, the ASCs were

differentiated in vitro into osteoblast-like cells onto the PLGA

scaffolds. The differentiated ASCs on the PLGA scaffold were able

to induce osteogenesis in the absence of stimulation when

implanted in a surgical defect, accelerating the repair of tibial

defects. In addition, the PLGA–ASC increased angiogenesis

throughout the connective tissue on the defect site [113].

Peripheral nerve bioengineeringPeripheral nerve injuries can result from physical trauma, cuts or

acute nerve compression and can interfere with brain and muscle

communication, affecting the capacity of movement of deter-

mined muscles or normal sensations [114]. The use of biodegrad-

able scaffolds can help in the restoration of the damaged nerves by

connecting the cut ends and supporting the growth of neural cells

[115]. Various studies have obtained good results when unidirec-

tional aligned electrospun fibers were used for neural regeneration.

The orientation of the fibers can direct the outgrowth of neurons,

providing guidance cues for the regeneration of axons and enhan-

cing Schwann cell extension [116–118]. Xie and colleagues

demonstrated the topographic influence of electrospun scaffolds

on embryonic stem cell differentiation. Aligned nanofibers could

guide the neurite outgrowth and extension better than random

nanofibers [119]. Recently, several studies have shown that the

association of different cues (topographic, biochemical, electrical)

could provide a more effective method for promoting nerve

regeneration and functional recovery. In an earlier report, Xie

and colleagues demonstrated that the combination of electrical

stimulation and aligned electrospun nanofibers can increase the

neurite extension from the dorsal root ganglion in vitro [120]. The

association of topographic and biochemical cues by encapsulating

neural growth factors into the fibers is another strategy that can

promote greater functional recovery of the peripheral nerves [121–

123]. In their study, Wang and colleagues compared aligned PLGA

nanofibers with aligned PLGA nanofibers containing nerve growth

factor (NGF) in their core for the regeneration of rat sciatic nerve

defect. The study demonstrated that the combined effect of phy-

sical guidance cues and biomolecular signals provided by the NGF–

PLGA scaffolds improve the peripheral nerve regeneration. The

aligned NGF–PLGA nanofiber group showed significantly higher

amplitude of compound muscle action potential amplitude

(CMAP) and recovery of the gastrocnemius muscle than the

aligned PLGA nanofibers. Moreover, more nerve fibers with greater

maturity were regenerated in the PLGA–NGF group [123].

Spinal cord bioengineeringTraumatic spinal cord injury results in permanent neurological

and functional deficits as a result of the degeneration of tissue by

cellular necrosis, inflammation and glial reaction. These patholo-

gical changes are involved in the formation of an inhibitory

microenvironment that restricts the limited spontaneous regen-

eration of damaged neurons and axons [124]. The consequences of

damage to the spinal cord are devastating and, unfortunately,

effective methods of treatment are lacking. The use of scaffolds

has been studied as an alternative for reconstructing spinal cord

tissue owing to their capacity for providing guidance for the

regeneration of axons and prevention of the infiltration of scar

tissue and cyst formation [125]. Recently, Zamani and colleagues

showed that PLGA nanofiber scaffolds could support the axonal

regeneration of injured spinal cord. In their study, the implant of

electrospun scaffolds in a transected spinal cord rat model pro-

duced better locomotor and sensory scores than the control group

(animals that did not receive the scaffold) [126]. In an earlier

report, Andrychowski and colleagues demonstrated that electro-

spun scaffolds could reduce scar formation and epidural fibrosis on

injured spinal cord. This initial study suggested that this bioma-

terial could be considered for application in postsurgical spinal

cord cicatrisation prevention [127]. Despite the positive results,

only limited studies have been conducted using electrospun scaf-

folds in spinal cord tissue engineering, therefore extensive

research still needs to be carried out in this area.

Skin regenerationDifferent types of biomaterials have been used to produce electro-

spun scaffolds for the treatment of cutaneous defect and burn

wound care. The materials used for skin regeneration should be

stable until the natural extracellular matrix and the new tissue is

re-established. It should also protect wounds from infections and



Review

s�P

OSTSCREEN

fluid loss [128]. Successful regeneration of skin using biomaterials

depends crucially on the presence of self-renewing keratinocytes

for re-epitheliazation and a functional dermal scaffold with ade-

quate cellular and acellular components, which can minimize

scarring and favor vascularization on the site. Electrospun scaf-

folds can support the adhesion and spread of fibroblasts and

keratinocytes and are also capable of supporting the MSC growth

and differentiation into cells of epidermal lineage [42,129,130].

Electrospun fibers can also be associated with angiogenic and/or

vasculogenic factors, epidermal factors and molecules with anti-

inflammatory and antimicrobial properties to favor and enhance

skin regeneration [45,131–134]. Steffens and colleagues associated

the microalga Spirulina with P(DL)LA to produce electrospun

scaffolds for use in dermal damage models because of its anti-

inflammatory and antioxidant properties. The nanofiber scaffolds

were good substrates for adhesion and proliferation of MSCs and

had appropriate physicochemical properties for use as dermal

substitutes [45]. Spadaccio and colleagues functionalized PLA

fibrous scaffolds with granulocyte colony-stimulating factor (G-

CSF), a growth factor that plays an important part in wound

healing homeostasis by improving granulation and ulcer healing.

When fibroblasts and keratinocytes were seeded onto the G-CSF–

PLA scaffolds, an arrangement in a cutaneous tissue-like structure

was observed. The scaffolds favored the organization of an epi-

dermal-like layer, formed by a variety of cell phenotypes, usually

encountered in native mature skin tissue [135].

Advances in the use of electrospun scaffoldsAs has been shown in this review, electrospun scaffolds represent

an important tool for the regeneration of different types of tissue.

With positive results in in vitro assays and in animal models, some

clinical trials with scaffolds using the electrospinning technique

are being conducted with caution. Despite the fact that these

scaffolds have been successfully applied in animal models of

different categories of tissue injury, their application in humans

has been restricted in skin damage.

Topic nanofiber nitric oxide (NO)-releasing patch, made by

electrospinning, was evaluated for the treatment of patients with

cutaneous leishmaniasis. The topical application of NO-releasing

patch was compared with the intramuscular administration of

meglumine antimoniate (MA) in a controlled, randomized-

blinded clinical trial. The scaffold NO-releasing patch exhibited

a lower efficacy of treatment in comparison with MA; however, the

system caused a significantly lower frequency of nonserious

adverse events and a reduced variation in serum markers in

comparison with the MA administration. These results associated

with the facility of topical use of the scaffold justify the


development of new generations of scaffold systems for the treat-

ment of cutaneous leishmaniasis [136]. In another study, nanofi-

bers containing tetraphenylporphyrin (TPP) photosensitizer were

used as a light-activated antimicrobial covering in patients with

leg ulcers. Their application supported the decrease of wound size

and related pain [137]. Another focus for the study of electrospun

scaffolds is their use in decontamination of the skin surface from

hazardous substances in the case of chemical accidents and ter-

rorist attacks. Lademann and colleagues showed that polyur-

ethane nanofibers containing super-absorbing particles can be

good candidates for decontamination of the skin surface. These

scaffolds were effective in the removal of a model substance from

the skin without washing or massage, preventing its penetration

into the hair follicles [138]. These results show that more studies

involving the use of electrospun scaffolds in tissue engineering

should be realized. They encourage the application of fibers in

other types of tissue damage.

Concluding remarksElectrospinning is a versatile technique that enables the produc-

tion of fiber scaffolds with different characteristics for various

biomedical applications. As has been shown in this paper, electro-

spun scaffolds offer a suitable structure for growth and develop-

ment of different types of cells. Several studies have shown the

successful use of electrospun fibers for repair of different tissue,

including skin, bone, cartilage, blood vessels and nervous tissue.

Despite positive results, there is only a limited amount of work

reported that uses electrospun scaffolds associated with cells in in

vivo models of tissue damage. Extensive work still needs to be

realized in this area.

Although electrospinning was described many years ago,

attention to this technique has dramatically increased within

the past 15 years, mainly owing to the rising interest in nanos-

cale properties and materials; however, this technology is still at

the laboratory level and it is of extreme importance that it is

scaled-up to industry level, with a view to future commercial

and clinical application in tissue engineering. In the present

study it has been possible to see some of the current applications

of this technique for a quick and informative understanding of

the state-of-art in tissue engineering. It is hoped that this can

help researchers planning future studies, because electrospun

fiber scaffolds show great promise and potential for application

in regeneration of many types of tissue using regenerative

medicine principles.

Conflicts of interestThe authors declare that there are no conflicts of interest.

References

1 Zhang, N. and Kohn, D.H. (2012) Using polymeric materials to control stem cell

behavior for tissue regeneration. Birth Defects Res. C Embryo Today 96, 63–81

2 Naderi, H. et al. (2011) Review paper: critical issues in tissue engineering:

biomaterials, cell sources, angiogenesis, and drug delivery systems. J. Biomater.

Appl. 26, 383–417

3 Boudriot, U. et al. (2006) Electrospinning approaches toward scaffold engineering

– a brief overview. Artif. Organs 30, 785–792

4 Greiner, A. and Wendorff, J.H. (2007) Electrospinning: a fascinating method for

the preparation of ultrathin fibers. Angew. Chem. Int. Ed. Engl. 46, 5670–5703

5 Sahoo, S.K. et al. (2007) The present and future of nanotechnology in human

health care. Nanomedicine 3, 20–31

6 Wendorff, J. et al. eds (2012) Electrospinning – Materials, Processing, and Applications,

Wiley-VCH

7 Doshi, J. and Reneker, D. (1995) Electrospinning process and applications of

electrospun fibers. J. Electrostat. 35, 151–160

8 Pham, Q.P. et al. (2006) Electrospinning of polymeric nanofibers for tissue

engineering applications: a review. Tissue Eng. 12, 1197–1211

http://refhub.elsevier.com/S1359-6446(14)00118-4/sbref0005




















9 Subbiah, T. et al. (2005) Electrospinning of nanofibers. J. Appl. Polym. Sci. 96, 557–

569

10 Agarwal, S. et al. (2008) Use of electrospinning technique for biomedical

applications. Polymer 49, 5603–5621

11 Agarwal, S. et al. (2009) Progress in the field of electrospinning for tissue

engineering applications. Adv. Mater. 21, 3343–3351

12 Tamayol, A. et al. (2013) Fiber-based tissue engineering: progress, challenges, and

opportunities. Biotechnol. Adv. 31, 669–687

13 Chakraborty, S. et al. (2009) Electrohydrodynamics: a facile technique to fabricate

drug delivery systems. Adv. Drug Deliv. Rev. 61, 1043–1054

14 Sahoo, S. et al. (2010) Growth factor delivery through electrospun nanofibers in

scaffolds for tissue engineering applications. J. Biomed. Mater. Res. A 93, 1539–1550

15 Kempski, H. et al. (2008) Pilot study to investigate the possibility of cytogenetic

and physiological changes in bio-electrosprayed human lymphocyte cells. Regen.

Med. 3, 343–349

16 Ramakrishna, S. et al. eds (2005) An Introduction to Electrospinning and Nanofibers,

World Scientific

17 Dong, Y. et al. (2010) Distinctive degradation behaviors of electrospun

polyglycolide, poly(DL-lactide-co-glycolide), and poly(L-lactide-co-epsilon-

caprolactone) nanofibers cultured with/without porcine smooth muscle cells.

Tissue Eng. Part A 16, 283–298

18 Chen, X. et al. (2013) Regulation of the osteogenesis of pre-osteoblasts by spatial

arrangement of electrospun nanofibers in two- and three-dimensional

environments. Nanomedicine 9, 1283–1292

19 Shields, K.J. et al. (2004) Mechanical properties and cellular proliferation of

electrospun collagen type II. Tissue Eng. 10, 1510–1517

20 Meinel, A.J. et al. (2012) Electrospun matrices for localized drug delivery: current

technologies and selected biomedical applications. Eur. J. Pharm. Biopharm. 81, 1–13

21 Ravichandran, R. et al. (2012) Expression of cardiac proteins in neonatal

cardiomyocytes on PGS/fibrinogen core/shell substrate for cardiac tissue

engineering. Int. J. Cardiol. 167, 1461–1468

22 Hu, W.W. and Yu, H.N. (2013) Coelectrospinning of chitosan/alginate fibers by

dual-jet system for modulating material surfaces. Carbohydr. Polym. 95, 716–727

23 Kim, T.G. et al. (2008) Macroporous and nanofibrous hyaluronic acid/collagen

hybrid scaffold fabricated by concurrent electrospinning and deposition/leaching

of salt particles. Acta Biomater. 4, 1611–1619

24 Fang, X. and Reneker, D.H. (1997) DNA fibers by electrospinning. J. Macromol. Sci.

Part B: Phys. 36, 169–173

25 Li, D. and Xia, Y. (2004) Electrospinning of nanofibers: reinventing the wheel?

Adv. Mater. 16, 1151–1170

26 Huang, Z.M. et al. (2003) A review on polymer nanofibers by electrospinning and

their applications in nanocomposites. Compos. Sci. Technol. 63, 2223–2253

27 Ye, L. et al. (2012) The in vitro and in vivo biocompatibility evaluation of heparin-

poly(epsilon-caprolactone) conjugate for vascular tissue engineering scaffolds. J.

Biomed. Mater. Res. A 100, 3251–3258

28 Kim, J-E. et al. (2010) A fibronectin peptide-coupled biopolymer nanofibrous

matrix to speed up initial cellular events. Adv. Biomater. 12, 94–100

29 Boccafoschi, F. et al. (2012) The biological response of poly(L-lactide) films

modified by different biomolecules: role of the coating strategy. J. Biomed. Mater.

Res. A 100, 2373–2381

30 Bolgen, N. et al. (2007) In vivo performance of antibiotic embedded electrospun

PCL membranes for prevention of abdominal adhesions. J. Biomed. Mater. Res. B:

Appl. Biomater. 81, 530–543

31 Briggs, T. and Arinzeh, T.L. (2013) Examining the formulation of emulsion

electrospinning for improving the release of bioactive proteins from electrospun

fibers. J. Biomed. Mater. Res. A 102, 674–684

32 Wei, K. et al. (2011) Emulsion electrospinning of a collagen-like protein/PLGA

fibrous scaffold: empirical modeling and preliminary release assessment of

encapsulated protein. Macromol. Biosci. 11, 1526–1536

33 Brahatheeswaran, D. et al. (2012) Hybrid fluorescent curcumin loaded zein

electrospun nanofibrous scaffold for biomedical applications. Biomed. Mater. 7,

045001

34 Chen, D.W. et al. (2012) Sustainable release of vancomycin, gentamicin and

lidocaine from novel electrospun sandwich-structured PLGA/collagen

nanofibrous membranes. Int. J. Pharm. 430, 335–341

35 Ji, W. et al. (2013) Incorporation of stromal cell-derived factor-1alpha in PCL/

gelatin electrospun membranes for guided bone regeneration. Biomaterials 34,

735–745

36 Xu, W. et al. (2013) Controllable dual protein delivery through electrospun fibrous

scaffolds with different hydrophilicities. Biomed. Mater. 8, 1–8

37 Zhu, H. et al. (2013) Biological activity of a nanofibrous barrier membrane

containing bone morphogenetic protein formed by core–shell electrospinning as a

sustained delivery vehicle. J. Biomed. Mater. Res. B: Appl. Biomater. 101, 541–552

38 Guo, X. et al. (2012) Creating 3D angiogenic growth factor gradients in fibrous

constructs to guide fast angiogenesis. Biomacromolecules 13, 3262–3271

39 Andrews, K.D. et al. (2007) Effects of sterilisation method on surface topography

and in-vitro cell behaviour of electrostatically spun scaffolds. Biomaterials 28, 1014–

1026

40 Gentile, F. et al. (2010) Cells preferentially grow on rough substrates. Biomaterials

31, 7205–7212

41 Sahoo, S. et al. (2006) Characterization of a novel polymeric scaffold for potential

application in tendon/ligament tissue engineering. Tissue Eng. 12, 91–99

42 Jin, G. et al. (2011) Stem cell differentiation to epidermal lineages on electrospun

nanofibrous substrates for skin tissue engineering. Acta Biomater. 7, 3113–3122

43 Wei, J.D. et al. (2012) Characterizations of chondrocyte attachment and

proliferation on electrospun biodegradable scaffolds of PLLA and PBSA for use in

cartilage tissue engineering. J. Biomater. Appl. 26, 963–985

44 Ku, S.H. and Park, C.B. (2010) Human endothelial cell growth on mussel-inspired

nanofiber scaffold for vascular tissue engineering. Biomaterials 31, 9431–9437

45 Steffens, D. et al. (2013) A new biomaterial of nanofibers with the microalga

Spirulina as scaffolds to cultivate with stem cells for use in tissue engineering. J.

Biomed. Nanotechnol. 9, 710–718

46 Kuppan, P. et al. (2011) Development of poly(3-hydroxybutyrate-co-3-

hydroxyvalerate) fibers for skin tissue engineering: effects of topography,

mechanical, and chemical stimuli. Biomacromolecules 12, 3156–3165

47 Bao, C. et al. (2011) Effects of electrospun submicron fibers in calcium phosphate

cement scaffold on mechanical properties and osteogenic differentiation of

umbilical cord stem cells. Acta Biomater. 7, 4037–4044

48 Ji, Y. et al. (2014) Electrospinning and characterization of chitin nanofibril/

polycaprolactone nanocomposite fiber mats. Carbohydr. Polym. 101, 68–74

49 Kwon, I. et al. (2005) Electrospun nano- to microfiber fabrics made of

biodegradable copolyesters: structural characteristics, mechanical properties and

cell adhesion potential. Biomaterials 26, 3929–3939

50 Kim, G. et al. (2008) Hybrid process for fabricating 3D hierarchical scaffolds

combining rapid prototyping and electrospinning. Macromol. J. 29,

1577–1581

51 Sirc, J. et al. (2012) Controlled gentamicin release from multi-layered electrospun

nanofibrous structures of various thicknesses. Int. J. Nanomed. 7, 5315–5325

52 Pham, Q.P. et al. (2006) Electrospun poly(epsilon-caprolactone) microfiber and

multilayer nanofiber/microfiber scaffolds: characterization of scaffolds and

measurement of cellular infiltration. Biomacromolecules 7, 2796–2805

53 Lowery, J.L. et al. (2010) Effect of fiber diameter, pore size and seeding method on

growth of human dermal fibroblasts in electrospun poly(epsilon-caprolactone)

fibrous mats. Biomaterials 31, 491–504

54 Braghirolli, D.I. et al. (2013) The effect of sterilization methods on electrospun

poly(lactide-co-glycolide) and subsequent adhesion efficiency of mesenchymal

stem cells. J. Biomed. Mater. Res. B: Appl. Biomater. http://dx.doi.org/10.1002/

jbm.b.33049

55 Mittal, A. et al. (2010) Integration of porosity and bio-functionalization to

form a 3D scaffold: cell culture studies and in vitro degradation. Biomed. Mater. 5,

045001

56 Navarro, M. et al. (2006) Development of a biodegradable composite scaffold for

bone tissue engineering: physicochemical, topographical, mechanical,

degradation, and biological properties. Adv. Polym. Sci. 200, 209–231

57 Yu, Q. et al. (2013) Structure–property relationship of regenerated spider silk

protein nano/microfibrous scaffold fabricated by electrospinning. J. Biomed. Mater.

Res. A http://dx.doi.org/10.1002/jbm.a.35051

58 Li, X. et al. (2010) Encapsulation of proteins in poly(L-lactide-co-caprolactone)

fibers by emulsion electrospinning. Colloids Surf. B: Biointerfaces 75, 418–424

59 Zander, N.E. et al. (2012) Quantification of protein incorporated into electrospun

polycaprolactone tissue engineering scaffolds. ACS Appl. Mater. Interfaces 4, 2074–

2081

60 Tsai, W.B. et al. (2011) Poly(dopamine) coating of scaffolds for articular cartilage

tissue engineering. Acta Biomater. 7, 4187–4194

61 Rainer, A. et al. (2010) A biomimetic three-layered compartmented scaffold for

vascular tissue engineering. Conf. Proc. IEEE Eng. Med. Biol. Soc. 2010, 839–842

62 Cheng, L.C. et al. (2013) Nano-bio effects: interaction of nanomaterials with cells.

Nanoscale 5, 3547–3569

63 Masaeli, E. et al. (2012) Does the tissue engineering architecture of poly(3-

hydroxybutyrate) scaffold affects cell-material interactions? J. Biomed. Mater. Res. A

100, 1907–1918

64 Chandrasekaran, A.R. et al. (2011) Fabrication of a nanofibrous scaffold with

improved bioactivity for culture of human dermal fibroblasts for skin

regeneration. Biomed. Mater. 6, 015001

65 Wittmer, C.R. et al. (2011) Multifunctionalized electrospun silk fibers promote

axon regeneration in central nervous system. Adv. Funct. Mater. 21, 4232–4242



























































































































http://dx.doi.org/10.1002/jbm.b.33049

http://dx.doi.org/10.1002/jbm.b.33049







http://dx.doi.org/10.1002/jbm.a.35051























Review

s�P

OSTSCREEN

66 Kai, D. et al. (2012) Mechanical properties and in vitro behavior of nanofiber-

hydrogel composites for tissue engineering applications. Nanotechnology 23,

095705

67 Stock, U.A. and Vacanti, J.P. (2001) Tissue engineering: current state and

prospects. Annu. Rev. Med. 52, 443–451

68 Wang, H.B. et al. (2010) Varying the diameter of aligned electrospun fibers alters

neurite outgrowth and Schwann cell migration. Acta Biomater. 6, 2970–2978

69 Kempf, M. et al. (2011) A denatured collagen microfiber scaffold seeded with

human fibroblasts and keratinocytes for skin grafting. Biomaterials 32, 4782–4792

70 Thorvaldsson, A. et al. (2008) Electrospinning of highly porous scaffolds for

cartilage regeneration. Biomacromolecules 9, 1044–1049

71 Shafiee, A. et al. (2011) Electrospun nanofiber-based regeneration of cartilage

enhanced by mesenchymal stem cells. J. Biomed. Mater. Res. A 99, 467–478

72 da Silva Meirelles, L. et al. (2006) Mesenchymal stem cells reside in virtually all

post-natal organs and tissues. J. Cell Sci. 119, 2204–2213

73 Zheng, Y.H. et al. (2013) Multilineage differentiation of human bone marrow

mesenchymal stem cells and. Exp. Ther. Med. 5, 1576–1580

74 Caplan, A.I. (2007) Adult mesenchymal stem cells for tissue engineering versus

regenerative medicine. J. Cell. Physiol. 213, 341–347

75 Soliman, S. et al. (2011) Controlling the porosity of fibrous scaffolds by modulating

the fiber diameter and packing density. J. Biomed. Mater. Res. A 96, 566–574

76 Whited, B.M. and Rylander, M.N. (2014) The influence of electrospun scaffold

topography on endothelial cell morphology, alignment, and adhesion in response

to fluid flow. Biotechnol. Bioeng. 111, 184–195

77 Hsia, H.C. et al. (2011) The fiber diameter of synthetic bioresorbable extracellular

matrix influences human fibroblast morphology and fibronectin matrix assembly.

Plast. Reconstr. Surg. 127, 2312–2320

78 Li, W.J. et al. (2006) Fabrication and characterization of six electrospun poly(alpha-

hydroxy ester)-based fibrous scaffolds for tissue engineering applications. Acta

Biomater. 2, 377–385

79 Zanatta, G. et al. (2012) Mesenchymal stem cell adherence on poly(D,L-lactide-co-

glycolide) nanofibers scaffold is integrin-beta 1 receptor dependent. J. Biomed.

Nanotechnol. 8, 211–218

80 Zonari, A. et al. (2012) Endothelial differentiation of human stem cells seeded onto

electrospun polyhydroxybutyrate/polyhydroxybutyrate-co-hydroxyvalerate fiber

mesh. PLoS ONE 7, e35422

81 Ghaedi, M. et al. (2012) Hepatic differentiation from human mesenchymal stem

cells on a novel nanofiber scaffold. Cell. Mol. Biol. Lett. 17, 89–106

82 Ravichandran, R. et al. (2013) Cardiogenic differentiation of mesenchymal stem

cells on elastomeric poly (glycerol sebacate)/collagen core/shell fibers. World J.

Cardiol. 5, 28–41

83 Peng, H. et al. (2012) Electrospun biomimetic scaffold of hydroxyapatite/chitosan

supports enhanced osteogenic differentiation of mMSCs. Nanotechnology 23,

485102

84 Du, F. et al. (2012) Gradient nanofibrous chitosan/poly varepsilon-caprolactone

scaffolds as extracellular microenvironments for vascular tissue engineering.

Biomaterials 33, 762–770

85 Laurenti, R. et al. (2000) Ischemic heart disease, hospitalization, length of stay and

expenses in Brazil from 1993 to 1997. Arq. Bras. Cardiol. 74, 488–492

86 He, W. et al. (2013) The preparation and performance of a new polyurethane

vascular prosthesis. Cell. Biochem. Biophys. 66, 855–866

87 Kannan, R.Y. et al. (2005) Current status of prosthetic bypass grafts: a review. J.

Biomed. Mater. Res. B: Appl. Biomater. 74, 570–581

88 Mrowczynski, W. et al. (2013) Porcine carotid artery replacement with

biodegradable electrospun poly-e-caprolactone vascular prosthesis. J. Vasc. Surg.

59, 210–219

89 Ye, L. et al. (2010) Heparin-conjugated PCL scaffolds fabricated by electrospinning

and loaded with fibroblast growth factor 2. J. Biomater. Sci. Polym. Ed. (Epub ahead

of print)

90 Bergmeister, H. et al. (2012) Electrospun small-diameter polyurethane vascular

grafts: ingrowth and differentiation of vascular-specific host cells. Artif. Organs 36,

54–61

91 Liu, H. et al. (2011) Electrospun sulfated silk fibroin nanofibrous scaffolds for

vascular tissue engineering. Biomaterials 32, 3784–3793

92 Dargaville, B.L. et al. (2013) Electrospinning and crosslinking of low-molecular-

weight poly(trimethylene carbonate-co-(L)-lactide) as an elastomeric scaffold for

vascular engineering. Acta Biomater. 9, 6885–6897

93 Nseir, N. et al. (2013) Biodegradable scaffold fabricated of electrospun albumin

fibers: mechanical and biological characterization. Tissue Eng. Part C: Methods 19,

257–264

94 Tillman, B.W. et al. (2009) The in vivo stability of electrospun polycaprolactone-

collagen scaffolds in vascular reconstruction. Biomaterials 30, 583–588


95 Ju, Y.M. et al. (2010) Bilayered scaffold for engineering cellularized blood vessels.


96 Wang, S. et al. (2013) Fabrication of small-diameter vascular scaffolds by heparin-

bonded P(LLA-CL) composite nanofibers to improve graft patency. Int. J. Nanomed.

8, 2131–2139

97 Singh, S. et al. (2011) The enhancement of VEGF-mediated angiogenesis by

polycaprolactone scaffolds with surface cross-linked heparin. Biomaterials 32,

2059–2069

98 Kim, M. et al. (2012) Composite system of PLCL scaffold and heparin-based

hydrogel for regeneration of partial-thickness cartilage defects. Biomacromolecules

13, 2287–2298

99 Toyokawa, N. et al. (2010) Electrospun synthetic polymer scaffold for cartilage

repair without cultured cells in an animal model. Arthroscopy 26, 375–383

100 McCullen, S.D. et al. (2012) Anisotropic fibrous scaffolds for articular cartilage

regeneration. Tissue Eng. Part A 18, 2073–2083

101 Esposito, A.R. et al. (2013) PLDLA/PCL-T scaffold for meniscus tissue engineering.

Bioresour. Open Access 2, 138–147

102 Gu, Y. et al. (2012) Repair of meniscal defect using an induced myoblast-loaded

polyglycolic acid mesh in a canine model. Exp. Ther. Med. 3, 293–298

103 Fisher, M.B. et al. (2013) Organized nanofibrous scaffolds that mimic the

macroscopic and microscopic architecture of the knee meniscus. Acta Biomater. 9,

4496–4504

104 Ko, E.K. et al. (2008) In vitro osteogenic differentiation of human mesenchymal

stem cells and in vivo bone formation in composite nanofiber meshes. Tissue Eng.

Part A 14, 2105–2119

105 Lee, J.H. et al. (2010) Control of osteogenic differentiation and mineralization of

human mesenchymal stem cells on composite nanofibers containing poly[lactic-

co-(glycolic acid)] and hydroxyapatite. Macromol. Biosci. 10, 173–182

106 Jose, M.V. et al. (2010) Aligned bioactive multi-component nanofibrous

nanocomposite scaffolds for bone tissue engineering. Macromol. Biosci. 10, 433–

444

107 Chae, T. et al. (2013) Novel biomimetic hydroxyapatite/alginate nanocomposite

fibrous scaffolds for bone tissue regeneration. J. Mater. Sci. Mater. Med. 24, 1885–

1894

108 Liu, H. et al. (2013) The promotion of bone regeneration by nanofibrous

hydroxyapatite/chitosan scaffolds by effects on integrin-BMP/Smad signaling

pathway in BMSCs. Biomaterials 34, 4404–4417

109 Fang, R. et al. (2010) Electrospun PCL/PLA/HA based nanofibers as scaffold for

osteoblast-like cells. J. Nanosci. Nanotechnol. 10, 7747–7751

110 Lu, L.X. et al. (2013) Effects of hydroxyapatite-containing composite nanofibers on

osteogenesis of mesenchymal stem cells in vitro and bone regeneration in vivo. ACS

Appl. Mater. Interfaces 5, 319–330

111 Nie, H. et al. (2008) Three-dimensional fibrous PLGA/HAp composite scaffold for

BMP-2 delivery. Biotechnol. Bioeng. 99, 223–234

112 Su, Y. et al. (2012) Controlled release of bone morphogenetic protein 2 and

dexamethasone loaded in core–shell PLLACL-collagen fibers for use in bone tissue

engineering. Acta Biomater. 8, 763–771

113 Park, B.H. et al. (2012) Enhancement of tibial regeneration in a rat model by

adipose-derived stromal cells in a PLGA scaffold. Bone 51, 313–323

114 Biazar, E. et al. (2010) Types of neural guides and using nanotechnology for

peripheral nerve reconstruction. Int. J. Nanomed. 5, 839–852

115 Prabhakaran, M.P. et al. (2009) Mesenchymal stem cell differentiation to neuronal

cells on electrospun nanofibrous substrates for nerve tissue engineering.


116 Gupta, D. et al. (2009) Aligned and random nanofibrous substrate for the in vitro

culture of Schwann cells for neural tissue engineering. Acta Biomater. 5, 2560–2569

117 Leach, M.K. et al. (2011) The culture of primary motor and sensory neurons in

defined media on electrospun poly-L-lactide nanofiber scaffolds. J. Vis. Exp. http://

dx.doi.org/10.3791/2389

118 Masaeli, E. et al. (2013) Fabrication, characterization and cellular compatibility of

poly(hydroxy alkanoate) composite nanofibrous scaffolds for nerve tissue

engineering. PLoS ONE 8, e57157

119 Xie, J. et al. (2009) The differentiation of embryonic stem cells seeded on

electrospun nanofibers into neural lineages. Biomaterials 30, 354–362

120 Xie, J. et al. (2009) Conductive core-sheath nanofibers and their potential

application in neural tissue engineering. Adv. Funct. Mater. 19, 2312–2318

121 Chew, S.Y. et al. (2007) Aligned protein-polymer composite fibers enhance nerve

regeneration: a potential tissue-engineering platform. Adv. Funct. Mater. 17, 1288–

1296

122 Liu, J-J. et al. (2010) Peripheral nerve regeneration using composite poly(lactic

acid-caprolactone)/nerve growth factor conduits prepared by coaxial

electrospinning. J. Biomed. Mater. Res. A 96, 13–20







































































































































http://dx.doi.org/10.3791/2389

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123 Wang, C.Y. et al. (2012) The effect of aligned core–shell nanofibres delivering NGF

on the promotion of sciatic nerve regeneration. J. Biomater. Sci. Polym. Ed. 23,

167–184

124 Liu, J. et al. (2013) Fibrin scaffolds containing ectomesenchymal stem cells

enhance behavioral and histological improvement in a rat model of spinal cord

injury. Cells Tissues Organs 198, 35–46

125 Du, B.L. et al. (2013) A comparative study of gelatin sponge scaffolds and PLGA

scaffolds transplanted to completely transected spinal cord of rat. J. Biomed. Mater.

Res. A http://dx.doi.org/10.1002/jbm.a.34835

126 Zamani, F. et al. (2014) Promotion of spinal cord axon regeneration by 3D

nanofibrous core-sheath scaffolds. J. Biomed. Mater. Res. A 102, 506–513

127 Andrychowski, J. et al. (2013) Nanofiber nets in prevention of cicatrisation in

spinal procedures. Experimental study. Folia Neuropathol. 51, 147–157

128 van der Veen, V.C. et al. (2011) New dermal substitutes. Wound Repair Regen. 19

(Suppl 1), 59–65

129 Min, B.M. et al. (2004) Electrospinning of silk fibroin nanofibers and its effect on

the adhesion and spreading of normal human keratinocytes and fibroblasts in vitro.


130 Vatankhah, E. et al. (2013) Development of nanofibrous cellulose acetate/gelatin

skin substitutes for variety wound treatment applications. J. Biomater. Appl. 28,

909–921

131 Jin, G. et al. (2013) Controlled release of multiple epidermal induction factors

through core–shell nanofibers for skin regeneration. Eur. J. Pharm. Biopharm. 85,

689–698

132 Guthrie, K.M. et al. (2012) Antibacterial efficacy of silver-impregnated

polyelectrolyte multilayers immobilized on a biological dressing in a murine

wound infection model. Ann. Surg. 256, 371–377

133 Yari, A. et al. (2012) Synthesis and evaluation of novel absorptive and antibacterial

polyurethane membranes as wound dressing. J. Mater. Sci. Mater. Med. 23, 2187–2202

134 Losi, P. et al. (2013) Fibrin-based scaffold incorporating VEGF- and bFGF-loaded

nanoparticles stimulates wound healing in diabetic mice. Acta Biomater. 9, 7814–

7821

135 Spadaccio, C. et al. (2010) A G-CSF functionalized PLLA scaffold for wound repair:

an in vitro preliminary study. Conf. Proc. IEEE Eng. Med. Biol. Soc. 2010, 843–846

136 Lopez-Jaramillo, P. et al. (2010) A controlled, randomized-blinded clinical trial to

assess the efficacy of a nitric oxide releasing patch in the treatment of cutaneous

leishmaniasis by Leishmania (V.) panamensis. Am. J. Trop. Med. Hyg. 83, 97–101

137 Arenbergerova, M. et al. (2012) Light-activated nanofibre textiles exert

antibacterial effects in the setting of chronic wound healing. Exp. Dermatol. 21,

619–624

138 Lademann, J. et al. (2011) Decontamination of the skin with absorbing materials.

Skin Pharmacol. Physiol. 24, 87–92








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