In the case of tracheal rupture or stenosis, most effective way is to insert a commercially available metal stent. However, the implantation often causes a fever or a pain on the contact surface between trachea and the stent. And also the metal stent should be removed after a certain time implantation. Thus, we developed a functional tracheal drug eluting stent consisting of indomethacin, a nonsteroidal anti-inflammatory drug (NSAID), loaded nanofibers on a bare metal stent. To control the drug release kinetics and enhancement of mucosal regeneration, gelatin and PLCL were coated layer by layer on a metal stent by an electrospinning method. Indomethacin was loaded in the gelatin layer by soaking and drying method (0.1, 0.5, and 1 wt% in ethanol for 10 min). The morphology of functional drug eluting tracheal stent was characterized by scanning electron microscope (SEM). And mechanical properties of the constructs such as air leak pressure, ultimate tensile stress, and modulus were calculated and evaluated. Drug release was performed by a high performance liquid chromatography (HPLC). Stably coated gelatin and poly(L-lactide- co-epsilon-caprolactone) (PLCL) nanofibers were observed by SEM. Bi-layered nanofibers-coated stent showed enough mechanical properties as a tracheal stent, which confirmed by a custom-designed air leak mechanical test. For indomethacin loading on a stent, stent was immersed in a series of drug solutions (different concentrations) for 10 min. At the result of HPLC, total amounts of indomethacin on a stent were approximately 77, 323, and 670 ug/stent, respectively. Time dependent drug release kinetics of the tracheal stent showed a sustained release profile regardless of indomethacin content. Thus, functionally designed nanofiber coated tracheal stent with anti-inflammatory drug may be useful for tracheal regeneration.
Recently, neural prosthetic electrodes covered with polyimide (PI) have been developed for chronic recording and stimulation of nervous system function. However, when these devices are implanted onto the nerve trunk, nerves might be damaged by the presence of the electrode due to the mechanical mismatch between the stiff probe and the soft biological tissue. Consequently, newly formed tissue layer may isolate the electrode from neural tissue, resulting in poor signal detection. In this study, we found a method to solve this problem. As the method, we designed and prepared poly(ethylene glycol) (PEG)-grafted PI film to function cell fouling resistance. The PEG-grafted PI film was characterized by X-ray photoelectron spectroscopy (XPS) and static water contact angle measurements. Protein adsorption experiment was carried out to evaluate protein fouling resistance because protein adsorption is closely related to cell adhesion. In vitro cell behavior on PEG-grafted PI film was evaluated by confocal laser scanning microscopy (CLSM) and CCK assays. The results showed that PEG-grafted PI film has characteristics of protein and cell fouling resistances as compared to bare and hydrolyzed PI films under in vitro. We suggested that PEG-grafted PI film can be useful for a neural implantable electrode.
Electrospun Nanofiber sheets have been shown to mimic the structure of extracellular matrix (ECM). Although these nanofibers have shown great potential for use as tissue engineering scaffolds, it is difficult for the electrospun nanofiber based sheets to be shaped into the desired three-dimensional structure. In this study, poly(L-lactic acid) (PLLA), a biodegradable and biocompatible polyester, was electrospun to produce nanofibers that were treated with an amino group containing base in order to fabricate polymeric nanocylinders. The aspect ratio of the PLLA nanocylinders was tunable by varying the aminolysis time and density of the amino group containing base. The effects of changes in nanofibrous morphology of the PLLA nanocylinders/macro-porous gelatin scaffolds on cell adhesion and proliferation were evaluated. The results revealed different cell morphology, adhesion, and proliferation in the nanocylinders composite gelatin scaffold versus gelatin scaffold alone. Confocal laser scanning microscopy observation showed more spreading and a more flattened cell morphology after NIH3T3 cells were cultured on PLLA nanocylinders/gelatin scaffolds for 10 hours and 4 days. These results indicate that the gelatin/PLLA nanocylinder composite is a promising way to fabricate 3D nanofibrous scaffolds that accelerates cell adhesion and proliferation for tissue engineering.
In this study, we developed poly(ε-caprolactone) (PCL) 3D scaffolds using a solid free form fabrication (SFF) technique. β-cyclodextrin (βCD) was grafted to hydroxyapatite (HAp) and this βCD grafted HAp was coated onto the PCL scaffold surface, followed by drug loading through an inclusion complex interaction between the βCD and adamantane (AD) or between βCD and simvastatin (SIM). The scaffold structure was characterized by scanning electron microscopy (SEM). The release profile of simvastatin in the β-CD grafted HAp was also evaluated. Osteogenic differentiation of adipose-derived stromal cells (ADSCs) was examined using an alkaline phosphatase activity (ALP) assay. The results suggest that drug loaded PCL-HAp 3-D scaffolds enhances osteogenic differentiation of ADSCs.
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