• KSBB Journal
• /
• v.19 no.3
• /
• pp.210-214
• /
• 2004

Whole liver transplantation, the currently available treatment of end-stage liver disease, has limitations including serious donor shortage, fatal surgical complications, risk of allograft rejection, and the requirement of life-long immunosuppression. In this study, we investigated the possibility of reconstructing liver tissues in vivo by implanting fetal hepatocytes on polymer scaffolds as a potential method to replace the current treatments. Fetal hepatocytes were freshly isolated from mice and seeded onto porous mesh scaffolds fabricated from polyglycolic acid, a biodegradable synthetic polymer. The seeded scaffolds were implanted into peritoneal cavity of athymic mice for one week. As a control, fetal hepatocytes were implanted without scaffold. One week after transplantation, liver-like tissues formed. Histological and immunohistochemical analyses indicated that the hepatocyles and liver tissue structures (bile ducts) were present in the newly formed tissues. In the control group, no transplanted hepatocytes were observed. Theses preliminary results suggest that liver tissues may be regeneration by transplanting fetal hepatocytes on polymer scaffolds.

• Polymer(Korea)
• /
• v.36 no.5
• /
• pp.651-655
• /
• 2012

Considerable effort has been directed toward the use of silk fibroin as a biotechnological material in biomedical applications on account of its excellent biodegradability, biocompatibility, and unique mechanical properties. For use in tissue engineering, it is very important to design and control the pore architecture of polymeric scaffolds, which provide the vital framework for seeded cells to organize into functioning tissue. In the present study, a silk fibroin scaffold with controlled interconnectivity and pore size was prepared using an electrospinning method with poly(ethylene oxide).

• Archives of Plastic Surgery
• /
• v.34 no.4
• /
• pp.413-419
• /
• 2007

Purpose: In this study, porous type I collagen scaffolds were cross-linked using dehydrothermal(DHT) treatment and/or 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide(EDC), in the presence and absence of chondroitin-6-sulfate(CS) and cultured autologous chondrocytes(Chondro) for cartilage regeneration. Methods: Cartilage defects were created in the proximal part of the ear of New Zealand rabbits. Four prepared types of scaffolds(n=4) were inserted. The groups included Chondro-Collagen-DHT(Group 1), Chondro- Collagen-DHT-EDC(Group 2), Chondro-CS-Collagen- DHT(Group 3), and Chondro-CS-Collagen-DHT-EDC (Group 4). Histomorphometric analysis and cartilage-specific gene expression of the reconstructed tissues were evaluated 4, 8, and 12 weeks after implantation. Results: EDC cross-linked groups 2 and 4 regenerated more cartilage than other groups. However, calcification was observed in the 4th week after implantation. CS did not increase chondrogenesis in all groups. Cartilage-specific type II collagen mRNA expression increased in the course of time in all groups.Conclusion: EDC cross-linking methods maintain the scaffold and promote extracellular matrix production of chondrocytes.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.17 no.1
• /
• pp.108-115
• /
• 2018

In bone tissue engineering, polycaprolactone (PCL) is one of the most widely used biomaterials to manufacture scaffolds as a synthetic polymer with biodegradability and biocompatibility. The polymer deposition system (PDS) with four axis heads, which can dispense bio-polymers, has been used in scaffold fabrication for tissue engineering applications. A dual-head deposition technology of PDS is an effective technique to fabricate 3D scaffolds. The electrospinning technology has been widely used to fabricate porous and highly interconnected polymer fibers. Thus, PDS can fabricate nanofiber-combined hybrid scaffolds using fused deposition modeling (FDM) and electrospinning methods. This study aims to fabricate nanofiber-combined scaffolds with uniform nanofibers using PDS. The PCL nanofibers were fabricated and evaluated according to the fabrication process parameters. PCL nanofibers were successfully fabricated when the applied voltage, tip-to-collector distance, flow rate, and solution concentration were 5 kV, 1 cm, 0.1 ml/h, and 8 wt%, respectively. The cell proliferation was evaluated according to the electrospinning time. Scanning electron microscopy was used to acquire images of the cross-sectioned hybrid scaffolds. The cell proliferation test of the PCL and nanofiber-combined hybrid scaffolds was performed using a CCK-8 assay according to the electrospinning time. The result of in-vitro cell proliferation using osteosarcoma MG-63 cells shows that the hybrid scaffold has good potential for bone regeneration.

• Macromolecular Research
• /
• v.11 no.5
• /
• pp.368-374
• /
• 2003

Porous scaffolds composed of gelatin and polysaccharides such as hyaluronic acid and $\beta$-glucan were prepared by using the freeze-drying method after cross-linking with l-ethyl-(3-3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). The scaffold had an inter-connected pore structure with the sufficient pore size for use as a support for the growth of fibroblasts. Results for the contact angle and cell attachment confirmed that high gelatin content in a mixture was suitable for cellular attachment and distribution in two- or three-dimensional fibroblast cultures. However, the addition of polysaccharides aroused the synergistic effects of morphologic and mechanical property of gelatin-based scaffolds. To prepare the artificial dermis for the wound dressing to mimic the normal human dermal skin, fibroblasts were isolated from a child's foreskin, and cultured in gelatin-based scaffolds. An in vivo study showed that the artificial dermis containing the fibroblasts enhanced the wound healing rate and re-epithelialization of a full-thickness skin defect rather than the acellular scaffold after one week.

• Polymer(Korea)
• /
• v.29 no.3
• /
• pp.282-287
• /
• 2005

A novel ice particle leaching method for fabrication of porous and biodegradable PLGA scaffold has been proposed for the application to tissue engineering. After uniform mixing of poly(L-lactide-co-glycolide) (PLGA) and bovine serum albumin-fluorescein isothiocyanate (FITC-BSA), the FITC-BSA loaded scaffold was fabricated by adding various ratio of ice particle. The release profiles of FITC-BSA were examined using pH 7.4 PBS for 28 days at $37^{circ}$. The release amount was determined by fluorescence intensity by using the fluorescence spectrophotometer and the morphological change of the scaffolds was observed by scanning electron microscope. The release initial burst of BSA containing scaffolds was lower than that of simple dipping scaffolds resulting in constant release aspect. Although the BSA concentration increased. the initial burst was not increased. As a result of this study, it can be suggested that ice particle leaching method for the tissue engineered scaffold miff be very useful and it is possible to impregnate with water soluble factors like cytokine. We suggest that ice particle leaching method may be useful to tissue engineered organ regeneration.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2009.11a
• /
• pp.12.1-12.1
• /
• 2009

Nano-hydroxyapatite (N-HAp)has shown the pivotal role in producing bone-regenerative materials since it has similarity to natural bone minerals in terms of size, morphology, and the composition. Currently, the combination of biopolymers and N-HAp is recognizedas an attractive approach in generating hybrid scaffolds for bone tissueengineering. Surface engineering is an important issue since it determines whether cells can effectively adhere and proliferate on porous scaffolds. We aim to develop a synthetic approach to porous 3D scaffolds by immobilizing N-HAp on pore surfaces. The discrete nano-level anchoring of N-HAp on the scaffold pore surface is achieved using surface-repellent stable colloidal N-HAp with surface phosphate functionality. This rational surface engineering enables surface-anchored N-HAp to express its overall intrinsic bioactivity,since N-HAp is not phase-mixed with the polymers. The porous polymer scaffolds with surface-immobilized N-HAp provide more favorable environments thanconventional bulk phase-mixed polymer/N-HAp scaffolds in terms of cellular interaction and growth. In vitro biological evaluation using alkalinephosphatase activity assay supports that immobilized N-HAp on pore surfaces of polymer scaffolds contributed to the more enhanced in vitro osteogenicpotential. Besides, the scaffolds with surface-exposed N-HAp provide favorable environments for enhanced in vivo bone tissue growth, estimated by characteristic biomarkers of bone formation such as collagen. The results suggest that newly developed hybrid scaffolds with surface-immobilized N-HApmay serve as a useful 3D substrate with pore surfaces featuring excellent bonetissue-regenerative properties. Acknowledgement. This research was supported by a grant (code #: 2009K000430) from 'Center for Nanostructured Materials Technology' under '21st Century Frontier R&D Programs' of the Ministry of Education, Science and Technology, Korea.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.2
• /
• pp.79-86
• /
• 2022

Numerous fabrication techniques have been used to mimic cylindrical natural tissues, such as blood vessels, tendons, ligaments, and skeletal muscles. However, most processes have limitations in achieving the biomimetic properties of multilayered and porous architectures. In this study, to embrace both features, a novel self-assembly method was proposed using electrospun microfibrous sheets. A bilayer microfibrous structure, comprising two sheets with different internal stresses, was fabricated by electrospinning a polycaprolactone (PCL) sheet on a uniaxially stretched thermoplastic polyurethane (TPU) sheet. Then, by removing the stretching tension, the sheet was rolled into a hollow cylindrical structure with a specific internal diameter. The internal diameter could be quantitatively controlled by adjusting the thickness of the PCL sheet against that of the TPU sheet. Through this self-assembly method, biomimetic cylindrical structures with multilayer and porous features can be manufactured in a stable and controllable manner. Therefore, the resulting structures may be applied to various tissue engineering scaffolds, especially vascular and connective tissues.

• Polymer(Korea)
• /
• v.37 no.6
• /
• pp.669-676
• /
• 2013

Demineralized bone particle (DBP) is a biomaterial used widely in the field of tissue engineering. In this study, in order to study the effect of DBP/poly(lactic-co-glycolic acid) (PLGA) scaffold on disc regeneration in vivo environment, we prepared the porous DBP/PLGA hybrid scaffold. Disc defect was induced by removing the nucleus pulposus tissue after incision the annulus fibrosus tissue in half and scaffolds were transplanted. After 1, 2 and 3 months later, the extracted discs were confirmed by collagen synthesis and glycosaminoglycan (sGAG). We conducted histology (H&E, Safranin-O, Alcian blue, Type I Collagen, Type II Collagen). From the results, it was confirmed that collagen and sGAG content were high in DBP/PLGA scaffold, and the regeneration of intervertebral disc was possible.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.38
• /
• pp.2.1-2.9
• /
• 2016

Background: We reviewed the biological and mechanical properties of porous hydroxyapatite (HA) compared to other synthetic materials. Computer-aided design/computer-aided manufacturing (CAD/CAM) was also evaluated to estimate its efficacy with clinical and radiological assessments. Method: A systematic search of the electronic literature database of the National Library of Medicine (PubMed-MEDLINE) was performed for articles published in English between January 1985 and September 2013. The inclusion criteria were (1) histological evaluation of the biocompatibility and osteoconductivity of porous HA in vivo and in vitro, (2) evaluation of the mechanical properties of HA in relation to its porosity, (3) comparison of the biological and mechanical properties between several biomaterials, and (4) clinical and radiological evaluation of the precision of CAD/CAM techniques. Results: HA had excellent osteoconductivity and biocompatibility in vitro and in vivo compared to other biomaterials. HA grafts are suitable for milling and finishing, depending on the design. In computed tomography, porous HA is a more resorbable and more osteoconductive material than dense HA; however, its strength decreases exponentially with an increase in porosity. Conclusions: Mechanical tests showed that HA scaffolds with pore diameters ranging from 400 to $1200{\mu}m$ had compressive moduli and strength within the range of the human craniofacial trabecular bone. In conclusion, using CAD/CAM techniques for preparing HA scaffolds may increase graft stability and reduce surgical operating time.