Ju Yeon Jeong

Three-dimensional electrospun silk-fibroin nanofiber for skin tissue engineering.

Tissue-engineered skin substitutes may offer an effective therapeutic option for the treatment of patients with skin damages. In this study, a novel three-dimensional (3D) scaffold composed of electrospun silk fibroin (SF) nanofiber was fabricated using electrospinning with the addition of NaCl crystals. It has well known that the electrospun SF nanofibers were excellent scaffold for tissue. However, it is generally difficult for cells to infiltrate the electrospun silk fibroin due to its small pore size. To resolve this problem, we dropped the NaCl crystals above the rotating collector, which become incorporated into the nanofibers. Three methods (freeze-drying, salt-leaching, and electrospinning with NaCl) for fabrication of SF scaffolds were compared to the difference of their characteristics using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), mechanical strength, porosity, swelling abilities, and cell proliferation. Additionally, using air-liquid culture system, keratinocytes were co-cultured with fibroblasts in each type of SF scaffolds to construct an artificial bilayer skin in vitro. In our experimental results, histologic findings in only electrospun SF scaffolds showed more proliferation of fibroblasts in deep layer and more differentiation of keratinocytes in superficial layer. The present study suggests that 3D electrospun SF scaffolds might be a suitable for skin tissue engineering.

Fabrication of 3D porous SF/β‐TCP hybrid scaffolds for bone tissue reconstruction

Bio-ceramic is a biomaterial actively studied in the field of bone tissue engineering. But, only certain ceramic materials can resolve the corrosion problem and possess the biological affinity of conventional metal biomaterials. Therefore, the recent development of composites of hybrid composites and polymers has been widely studied. In this study, we aimed to select the best scaffold of silk fibroin and β-TCP hybrid for bone tissue engineering. We fabricated three groups of scaffold such as SF (silk fibroin scaffold), GS (silk fibroin/small granule size of β-TCP scaffold) and GM (silk fibroin/medium granule size of β-TCP scaffold), and we compared the characteristics of each group. During characterization of the scaffold, we used scanning electron microscopy (SEM) and a Fourier transform infrared spectroscopy (FTIR) for structural analysis. We compared the physiological properties of the scaffold regarding the swelling ratio, water uptake and porosity. To evaluate the mechanical properties, we examined the compressive strength of the scaffold. During in vitro testing, we evaluated cell attachment and cell proliferation (CCK-8). Finally, we confirmed in vivo new bone regeneration from the implanted scaffolds using histological staining and micro-CT. From these evaluations, the fabricated scaffold demonstrated high porosity with good inter-pore connectivity, showed good biocompatibility and high compressive strength and modulus. In particular, the present study indicates that the GM scaffold using β-TCP accelerates new bone regeneration of implanted scaffolds. Accordingly, our scaffold is expected to act a useful application in the field of bone tissue engineering.

Novel fabrication method of the peritoneal dialysis filter using silk fibroin with urease fixation system

During the last decade, there has been a great advance in the kidney dialysis system by wearable artificial kidney (WAK) system for end-stage renal disease patients. Uremic solute removal and water regeneration system are the most prerequisite for WAK to work properly. In this study, we designed a filtering membrane system by using immobilized urease silk fibroin filter and evaluated its comparative effectiveness with a PVDF filtering system in peritoneal dialysate regeneration system by urea removal efficacy. We evaluated this membranes characteristic and performances by conducting SEM-EDX analyze, water-binding abilities and porosity test, removal abilities of urea, cytotoxicity assay and enzyme activity assay. Under the condition for optimization of urease, the percentage removal of urea was about 40% and 60% in 50 mg/dL urea solution by urease immobilized PVDF and silk fibroin scaffolds, respectively. The batch experimental result showed that immobilized filter removed more than 50% of urea in 50 mg/dL urea solution. In addition silk fibroin with urease filter removed 90 percent of urea in the peritoneal dialysate after 24 h filtration. We suggest that silk fibroin with urease fixation filter can be used more effectively for peritoneal dialysate regeneration system, which have hydrophilic property and prolonged enzyme activity.

A prospective cohort study of the silk fibroin patch in chronic tympanic membrane perforation

Silk fibroin patching has been used to repair acute tympanic membrane perforations. Here, we describe the advantages and outcomes of this technique for chronic tympanic membrane perforations.

Fabrication and characterization of the porous duck’s feet collagen sponge for wound healing applications

Abstract There are several artificial dermis commonly use to cover the wound and promote healing. The major goal of wound management is fast and scarless healing. However, there is no ideal skin substitute, that is effective to accelerate wound healing without scar formation. Artificial dermis substitute also has some drawbacks, such as high cost, insufficient available period and donor pathogen infection. To overcome these problems, we developed duck’s feet collagen (DFC) sponge as artificial dermal substitutes for the treatment of full-thickness skin defects. We measured these DFC sponge’s comparative characteristics and performances with an artificial dermis Colladerm by carried out SEM-EDX analyze, water-binding abilities and porosity test. Biocompatibility test was also performed using CCK-8 cytotoxicity assay. We also evaluated its wound healing effects for a full-thickness skin wound and compared with Colladerm in a rat model. Histological studies were carried via hematoxylin and eosin and Masson’s Trichrome staining. Although the wound healing effect of the DFC sponge was almost similar to that of Colladerm, the DFC sponge did not induce scar formation and wound contracture like Colladerm. We suggest that DFC sponge can be used as an ideal dermal substitute to the treatment of full-thickness skin wound.

Application of a Collagen Patch Derived from Duck Feet in Acute Tympanic Membrane Perforation

We investigated the utility of the duck-feet collagen extraction patching procedure in the traumatic tympanic membrane (TM) perforation via a comparison with spontaneous healing or paper patch. Fifty-six ears of adult male Sprague-Dawley rats, each weighing in the range of 250 to 300 g, were used for the animal studies. Sixteen rats had one-side ear in the control group and the opposite-side ear in the treated groups. The remaining twelve rats had a one-side ear with the duck-feet collagen patch and the opposite-side ear with a paper patch. The proliferating cell nuclear antigen (PCNA) expression cells were calculated among the 200 basal cells, and the expression percentage was identified as the labeling index. The healing of the perforation in the duck-feet collagen patch group was confirmed to be more rapid compared to the healing of the other groups. PCNA staining was observed in the migrating portion of PCNA enhanced cell to collagen scaffold in Post operative day (POD) 7 of collagen patch group. Thus, the adhesive effect of the duck-feet collagen patch to perforated margin was better than that of the paper patch. After completing the healing process, the collagen patch shrank and detached from the tympanic membrane (POD 14). In this study, we confirmed that the use of a duck-feet collagen patch had the advantage of early healing, inducing natural TM contour, and disappearing ability after the patch effect is complete.

New fabrication method of silk fibroin plate and screw based on a centrifugal casting technique

Recently, a newer generation of absorbable biomaterials has been developed from silk. Silk is approved by the US Food and Drug Administration, has robust mechanical features, and is biocompatible. Moreover, it offers the ability to be functionalized with bioactive compounds, making it ideal for use in new medical devices. Thus, many researchers have considered that absorbable devices made from silk may be able to overcome current limitations and could be used to meet a broader range of fixation needs. Here, we describe a novel method for the fabrication of silk fibroin (SF)–based bioabsorbable fixation systems using a centrifugal casting technique and incorporating a 3D printer. This approach allows us to create the desired geometric design for the fixation system easily. Moreover, our products demonstrated smoother surface profiles and more homogenous and dense cross‐sectional architectures. Furthermore, our plates exhibited very similar mechanical properties compared with commercially used one, and our screws showed more than 70% of their initial mass after 7 weeks on the enzymatic degradation test. On in vivo analysis, we found that our devices were well‐maintained in the location of initial fixation, and new bone formation was also observed around this. By these results, we suggest that the SF‐based plate/screw prepared by our novel method might be used for the internal fixation of fracture sites.

Novel transparent collagen film patch derived from duck’s feet for tympanic membrane perforation

Abstract To increase healing rate of tympanic membrane (TM) perforations, patching procedure has been commonly conducted. Biocompatible, biodegradable patching materials which is not limited across cultures is needed. The authors evaluated the effectiveness of novel transparent duck’s feet collagen film (DCF) patch in acute traumatic TM perforation. This procedure was compared with spontaneous healing and paper patching. Cell proliferation features were observed in paper and DCF patches. Forty-eight TMs of 24 rats were used for animal experiment, perforations were made on each TMs, and divided into three groups according to treatment modality. Sixteen were spontaneously healed, 16 were paper patched and 16 were DCF patched. The gross and histological healing results were analyzed. Both paper and DCF patch showed no cytotoxicity, but cell proliferations were more active in DCF than paper in early stage. In animal study, the healing of TM perforations were completed within 14 days in all three groups, but found to be faster in DCF patch group than paper patch or spontaneous healing group. The DCF patches were transparent and size of DCF patches were gradually decreased, so there were no need to remove the DCF patches to check the wound status or after the completion of healing. According to this result, authors concluded that DCF patch is transparent, biocompatible and biodegradable material, and can induce fast healing in acute traumatic TM perforations.