Browsing by Author "Lee, Chen-Ju"

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Elongation of Axon Extension for Human iPSC-Derived Retinal Ganglion Cells by a Nano-Imprinted Scaffold
(2017-09-01)
Yang, Tien-Chun
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Chuang, Jen-Hua
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Buddhakosai, Waradee
;
Wu, Wen-Ju
;
Lee, Chen-Ju
Optic neuropathies, such as glaucoma and Leber's hereditary optic neuropathy (LHON) lead to retinal ganglion cell (RGC) loss and therefore motivate the application of transplantation technique into disease therapy. However, it is a challenge to direct the transplanted optic nerve axons to the correct location of the retina. The use of appropriate scaffold can promote the proper axon growth. Recently, biocompatible materials have been integrated into the medical field, such as tissue engineering and reconstruction of damaged tissues or organs. We, herein, utilized nano-imprinting to create a scaffold mimicking the in vitro tissue microarchitecture, and guiding the axonal growth and orientation of the RGCs. We observed that the robust, long, and organized axons of human induced pluripotent stem cell (iPSC)-derived RGCs projected axially along the scaffold grooves. The RGCs grown on the scaffold expressed the specific neuronal biomarkers indicating their proper functionality. Thus, based on our in vitro culture system, this device can be useful for the neurophysiological analysis and transplantation for ophthalmic neuropathy treatment.
Nanoimprinted Anisotropic Topography Preferentially Guides Axons and Enhances Nerve Regeneration
(2018-12-01)
Huang, Yun-An
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Ho, Chris T.
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Lin, Yu-Hsuan
;
Lee, Chen-Ju
;
Ho, Szu-Mo
Surface topography has a profound effect on the development of the nervous system, such as neuronal differentiation and morphogenesis. While the interaction of neurons and the surface topography of their local environment is well characterized, the neuron-topography interaction during the regeneration process remains largely unknown. To address this question, an anisotropic surface topography resembling linear grooves made from poly(ethylene-vinyl acetate) (EVA), a soft and biocompatible polymer, using nanoimprinting, is established. It is found that neurons from both the central and peripheral nervous system can survive and grow on this grooved surface. Additionally, it is observed that axons but not dendrites specifically align with these grooves. Furthermore, it is demonstrated that neurons on the grooved surface are capable of regeneration after an on-site injury. More importantly, these injured neurons have an accelerated and enhanced regeneration. Together, the data demonstrate that this anisotropic topography guides axon growth and improves axon regeneration. This opens up the possibility to study the effect of surface topography on regenerating axons and has the potential to be developed into a medical device for treating peripheral nerve injuries.
Polymer-dispersed liquid crystal nanocomposites comprising montmorillonite clay modified by conducting pentamerous oligoaniline
(2012)
Tsai, Tsung-Yen
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Lee, Chun-Yi
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Lee, Chen-Ju
;
Lin, Mu-Yin
;
Lee, Wei
Pentamerous oligoaniline (POA) was protonated with sulfuric acid to form emeraldine salts (ES) and then intercalated in montmorillonite (MMT) CL120 to develop a functional conductive organo-layered material. The characteristics of the modified clay CL120/ES-POA were analyzed by wide-angle X-ray diffraction (WAXD) to find the d-spacing of the MMT layer distance, and by Fourier transform infrared (FTIR) spectroscopy for the oligoaniline functional group in CL120/ES-POA, and high-resolution thermogravimetric analysis (TGA) to determine the theoretical intercalation capacity of the modifying agent in the clay. We successfully intercalated the ES-POA into the MMT by ionic exchange reaction. Polymer-dispersed liquid crystal (PDLC) composites were prepared from the modified clay of 1 wt% loaded in the mixtures of 49 wt% photosensitive monomer and 50 wt% nematic liquid crystal (NLC), in a specific case, so as to generate novel functional nanocomposites. The hybridization of CL120/ES-POA clearly improved the electro-optical properties of the PDLCs. In this work, doping CL120/ES-POA at 1 wt% beneficially lowered the driving voltage by almost 70%, increased the transmission contrast ratio by five times and reduced the response time from 4.6 to 0.7 ms at 25 V-rms at the expense of the viewing-angle properties.
The Anastomotic Angle of Hemodialysis Arteriovenous Fistula Is Associated With Flow Disturbance at the Venous Stenosis Location on Angiography
(2020-07-23)
Yang, Chih-Yu
;
Li, Ming-Chia
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Lan, Chien-Wen
;
Lee, Wang-Jiun
;
Lee, Chen-Ju
The juxta-anastomotic stenosis of an arteriovenous fistula (AVF) is a significant clinical problem in hemodialysis patients with no effective treatment. Previous studies of AV anastomotic angles on hemodynamics and vascular wall injury were based on computational fluid dynamics (CFD) simulations using standardized AVF geometry, not the real-world patient images. The present study is the first CFD study to use angiographic images with patient-specific outcome information, i.e., the exact location of the AVF stenotic lesion. We conducted the CFD analysis utilizing patient-specific AVF geometric models to investigate hemodynamic parameters at different locations of an AVF, and the association between hemodynamic parameters and the anastomotic angle, particularly at the stenotic location. We analyzed 27 patients who used radio-cephalic AVF for hemodialysis and received an angiographic examination for juxta-anastomotic stenosis. The three-dimensional geometrical model of each patient's AVF was built using the angiographic images, in which the shape and the anastomotic angle of the AVF were depicted. CFD simulations of AVF hemodynamics were conducted to obtain blood flow parameters at different locations of an AVF. We found that at the location of the stenotic lesion, the AV angle was significantly correlated with access flow disturbance (r= 0.739;p< 0.001) and flow velocity (r= 0.563;p= 0.002). Furthermore, the receiver operating characteristic (ROC) curve analysis revealed that the AV angle determines the lesion's flow disturbance with a high area under the curve value of 0.878. The ROC analysis also identified a cut-off value of the AV angle as 46.5 degrees, above or below which the access flow disturbance was significantly different. By applying CFD analysis to real-world patient images, the present study provides evidence that an anastomotic angle wider than 46.5 degrees might lead to disturbed flow generation, demonstrating a reference angle to adopt during the anastomosis surgery.