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Electrospun 3D multi-scale fibrous scaffold for enhanced human dermal fibroblasts infiltration

[7]
for skin tissue regeneration and wound healing . Sca- µm below scaffold surface using rat insulinoma cell
ffold fabrication techniques, e.g., electrospinning, self- line INS-1. This research demonstrated the feasibility
assembling peptides and phase separation, have been to produce porous nanofibrous 3D scaffold using elec-
outlined as the three promising methods to create trospinning with customized collector. Even though
scaffold of fiber sizes close to the ECM fibrils in na- the response of human cells was not investigated in
[8]
noscale . Among them, electrospinning offers supe- the FLUF mesh, this study has proven the concept of
rior versatility capable of fabricating nanofibrous changing collection method in a way of changing the
scaffold of high porosity at controllable structure, low electrical field to collect electrospinning fibers in 3D.
cost, and high repeatability from a wide range of po- However, such a collector must be tailor-made to in-
lymers. Furthermore, the use of electrospinning allows dividual electrospinning setup due to the difference in
tailoring of scaffold’s properties according to targeted the dimension and environment which may interfere
tissue. The large surface to volume ratio of the nano- with the electrical field. Practically this system is dif-
fiber scaffold also promotes cell adhesion and cell ficult to be implemented to different kinds of conven-
migration. tional setup as there are too many parameters which
Conventional electrospinning collects nanofibers on may affect the fiber formation. These parameters in-
a plate collector where nanofibers are formed and col- clude the diameter, thickness and material of the
lected as a 2D mat. This results in densely packed na- spherical dish, position, number, length and diameter
nofibers with reduced pore size and porosity and it is of the needles.
challenging to build a scaffold with thickness beyond In this work, we aim to fabricate 3D poly-ε-cap-
[9]
100 µm using this conventional method . The limited rolactone (PCL) scaffold with multi-scale fibers via an
cell infiltration due to the densely packed structure improved electrospinning process based on the con-
and small pore size has restricted the application of ventional setup. The method is easy to set up and
electrospun scaffold [10] . Numerous approaches have be- can be adapted by any conventional electrospinning
en reported to increase the pore size of the traditional setup. The scaffold fabricated was then surface mod-
electrospun scaffold [11,12] , including mechanical ex- ified to improve the hyrophilicity of the PCL material
pansion [13] , inclusion of porogen [14] , increment of the for better cell adhesion and penetration. Human der-
fiber diameter [15] , incorporation of sacrificial fibers [16,17] , mal fibroblasts (HDFs) were used to check the effec-
cryogenic electropinning [18] , and addition of microscale tiveness of the 3D multi-scale scaffold for cell infiltra-
(3~10 µm) [19,20] or macroscale (~300 µm) [21,22] fibers tion and ECM protein deposition. This strategy pro-
into the nanoscale fiber (~600 nm) scaffold. However, vides a cost-effective and feasible solution for over-
the fabricated scaffold’s thickness is still limited and coming the current challenges based on conventional
cellular infiltration was either not studied or limited to electrospinning to produce 3D instead of 2D scaffold
the surface of the scaffold. and has great potential across a wide range of tissue
A thicker scaffold, with versatility to be optimized engineering applications [26] .
to the dimension of wound size, may be helpful for
treatment of deep skin injury where greater structural 2. Materials and Methods
support is required to enhance wound healing. To 2.1 Materials
overcome this inherent limitation associated with tra-
ditional electrospinning technique, several variants of Poly (ε-caprolactone) (PCL) (Mn 80,000) granules, Type
electrospinning have been devised [23,24] . In recent stu- A gelatin derived from porcine skin, 25% glutaralde-
dies, collector design has been changed from tradi- hyde, and ethylenediamine (Fluka) were purchased
tional flat surface to protruded shape to increase pore from Sigma Aldrich. Organic solvent dichloromethane
size in electrospun scaffold [23,25] . For example, fabri- (DCM) was purchased from TEDIA, USA. N,N-Di-
cation of cotton ball-like 3D scaffold called FLUF methylformamide (DMF) was purchased from Merck,
(Focused, Low density, and Uncompressed nanoFibr- USA. HDFs were purchased from Life Technologies,
ous) mesh used an array of point collectors embedded USA. Phosphate buffer saline (PBS), low glucose
in a spherical dish [23] . The pore size of the FLUF mesh Dulbecco’s Modified Eagle Medium (DMEM), high
was increased from typical <1 µm to between 2 µm to glucose DMEM, gold fetal bovine serum (FBS),
5 µm as viewed under scanning electron microscopy L-glutamine and 1% penicillin-streptomycin were
(SEM). The cell infiltration was demonstrated at ~300 purchased from PAA Laboratories, Pasching, Austria.

82 International Journal of Bioprinting (2016)–Volume 2, Issue 1