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Electrospun Fibrous Scaffolds for Tissue Engineering: Viewpoints on Architecture and Fabrication
Jun, Indong,Han, Hyung-Seop,Edwards, James R.,Jeon, Hojeong MDPI 2018 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.19 No.3
<P>Electrospinning has been used for the fabrication of extracellular matrix (ECM)-mimicking fibrous scaffolds for several decades. Electrospun fibrous scaffolds provide nanoscale/microscale fibrous structures with interconnecting pores, resembling natural ECM in tissues, and showing a high potential to facilitate the formation of artificial functional tissues. In this review, we summarize the fundamental principles of electrospinning processes for generating complex fibrous scaffold geometries that are similar in structural complexity to the ECM of living tissues. Moreover, several approaches for the formation of three-dimensional fibrous scaffolds arranged in hierarchical structures for tissue engineering are also presented.</P>
Jun, Indong,Chung, Yong-Woo,Heo, Yun-Hoe,Han, Hyung-Seop,Park, Jimin,Jeong, Hongsoo,Lee, Hyunjung,Lee, Yu Bin,Kim, Yu-Chan,Seok, Hyun-Kwang,Shin, Heungsoo,Jeon, Hojeong American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.5
<P>Developing an artificial extracellular matrix that closely mimics the native tissue microenvironment is important for use as both a cell culture platform for controlling cell fate and an in vitro model system for investigating the role of the cellular microenvironment. Electrospinning, one of the methods for fabricating structures that mimic the native ECM, is a promising technique for creating fibrous platforms. It is well-known that align or randomly distributed electrospun fibers provide cellular contact guidance in a single pattern. However, native tissues have hierarchical structures, i.e., topographies on the micro- and nanoscales, rather than a single structure. Thus, we fabricated randomly distributed nanofibrous (720 +/- 80 nm in diameter) platforms via a conventional electrospinning process, and then we generated microscale grooves using a femtosecond laser ablation process to develop engineered fibrous platforms with patterned hierarchical topographies. The engineered fibrous platforms can regulate cellular adhesive morphology, proliferation, and distinct distribution of focal adhesion proteins. Furthermore, confluent myoblasts cultured on the engineered fibrous platforms revealed that the direction of myotube assembly can be controlled. These results indicate that our engineered fibrous platforms may be useful tools in investigating the roles of nano- and microscale topographies in the communication between cells and ECM.</P>
Jun, Indong,Kim, Seok Joo,Lee, Ji‐,Hye,Lee, Young Jun,Shin, Young Min,Choi, Eunpyo,Park, Kyung Min,Park, Jungyul,Park, Ki Dong,Shin, Heungsoo WILEY‐VCH Verlag 2012 Advanced functional materials Vol.22 No.19
<P><B>Abstract</B></P><P>The structure of tissue plays a critical role in its function and therefore a great deal of attention has been focused on engineering native tissue‐like constructs for tissue engineering applications. Transfer printing of cell layers is a new technology that allows controlled transfer of cell layers cultured on smart substrates with defined shape and size onto tissue‐specific defect sites. Here, the temperature‐responsive swelling‐deswelling of the hydrogels with groove patterns and their versatile and simple use as a template to harvest cell layers with anisotropic extracellular matrix assembly is reported. The hydrogels with a cell‐interactive peptide and anisotropic groove patterns are obtained via enzymatic polymerization. The results show that the cell layer with patterns can be easily transferred to new substrates by lowering the temperature. In addition, multiple cell layers are stacked on the new substrate in a hierarchical manner and the cell layer is easily transplanted onto a subcutaneous region. These results indicate that the evaluated hydrogel can be used as a novel substrate for transfer printing of artificial tissue constructs with controlled structural integrity, which may hold potential to engineer tissue that can closely mimic native tissue architecture.</P>
Femtosecond Laser Ablation of Polymer Thin Films for Nanometer Precision Surface Patterning
Indong Jun,Jee-Wook Lee,Myoung-Ryul Ok,Yu-Chan Kim,Hojeong Jeon 한국표면공학회 2016 한국표면공학회지 Vol.49 No.1
Femtosecond laser ablation of ultrathin polymer films on quartz glass using laser pulses of 100 fs and centered at λ=400 nm wavelength has been investigated for nanometer precision thin film patterning. Singleshot ablation craters on films of various thicknesses have been examined by atomic force microscopy, and beam spot diameters and ablation threshold fluences have been determined by square diameter-regression technique. The ablation thresholds of polymer film are about 1.5 times smaller than that of quartz substrate, which results in patterning crater arrays without damaging the substrate. In particular, at a 1/e<SUP>2</SUP> laser spot diameter of 0.86 μm, the smallest craters of 150-nm diameter are fabricated on 15-nm thick film. The ablation thresholds are not influenced by the film thickness, but diameters of the ablated crater are bigger on thicker films than on thinner films. The ablation efficiency is also influenced by the laser beam spot size, following a w0q<SUP>-0.45</SUP> dependence.
Genetically Engineered Myoblast Sheet for Therapeutic Angiogenesis
Lee, Joan,Jun, Indong,Park, Hyun-Ji,Kang, Taek Jin,Shin, Heungsoo,Cho, Seung-Woo American Chemical Society 2014 Biomacromolecules Vol.15 No.1
<P>Peripheral arterial disease is a common manifestation of systemic atherosclerosis, which results in more serious consequences of ischemic events in peripheral tissues such as the lower extremities. Cell therapy has been tested as a treatment for peripheral ischemia that functions by inducing angiogenesis in the ischemic region. However, the poor survival and engraftment of transplanted cells limit the efficacy of cell therapy. In order to overcome such challenges, we applied genetically engineered cell sheets using a cell-interactive and thermosensitive hydrogel and nonviral polymer nanoparticles. C2C12 myoblast sheets were formed on Tetronic-tyramine (Tet-TA)-RGD hydrogel prepared through a highly efficient and noncytotoxic enzymatic reaction. The myoblast sheets were then transfected with vascular endothelial growth factor (VEGF) plasmids using poly(β-amino ester) nanoparticles to increase the angiogenic potential of the sheets. The transfection increased the VEGF expression and secretion from the C2C12 sheets. The enhanced angiogenic effect of the VEGF-transfected C2C12 sheets was confirmed using an in vitro capillary formation assay. More importantly, the transplantation of the VEGF-transfected C2C12 sheets promoted the formation of capillaries and arterioles in ischemic muscles, attenuated the muscle necrosis and fibrosis progressed by ischemia, and eventually prevented ischemic limb loss. In conclusion, the combination of cell sheet engineering and genetic modification can provide more effective treatment for therapeutic angiogenesis.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/bomaf6/2014/bomaf6.2014.15.issue-1/bm401605f/production/images/medium/bm-2013-01605f_0010.gif'></P>
Kim, Min Sup,Jun, Indong,Shin, Young Min,Jang, Wonhee,Kim, Sun I.,Shin, Heungsoo WILEY-VCH Verlag 2010 Macromolecular bioscience Vol.10 No.1
<P>Composite nanofibers of poly(caprolactone) (PCL) and gelatin crosslinked with genipin are prepared. The contact angles and mechanical properties of crosslinked PCL-gelatin nanofibers decrease as the gelatin content increases. The proliferation of myoblasts is higher in the crosslinked PCL-gelatin nanofibers than in the PCL nanofibers, and the formation of myotubes is only observed on the crosslinked PCL-gelatin nanofibers. The expression level of myogenin, myosin heavy chain, and troponin T genes is increased as the gelatin content is increased. The results suggest that PCL-gelatin nanofibers crosslinked with genipin can be used as a substrate to modulate proliferation and differentiation of myoblasts, presenting potential applications in muscle tissue engineering.</P><P> <img src='wiley_img/16165187-2010-10-1-MABI200900168-gra001.gif' alt='wiley_img/16165187-2010-10-1-MABI200900168-gra001'> </P> <B>Graphic Abstract</B> <P>Poly(caprolactone) (PCL)-gelatin nanofibers crosslinked with genipin are developed, and their morphological and physical properties are investigated. The effect of gelatin on the cultured myoblasts are also investigated. The proliferation and differentiation of myoblasts are controlled by the increase in the gelatin content, suggesting that the nanofibers can be used as a substrate for engineering muscle tissue. <img src='wiley_img/16165187-2010-10-1-MABI200900168-content.gif' alt='wiley_img/16165187-2010-10-1-MABI200900168-content'> </P>