• Journal of Biomedical Engineering Research
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• v.36 no.6
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• pp.251-263
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• 2015

Scaffolds play a crucial role in the tissue engineering. Biodegradable polymers with great processing flexibility and biocompatability are predominant scaffolding materials. New developments in biodegradable polymers and their nanocomposites for the tissue engineering are discussed. Recent development in the scaffold designs that mimic nano and micro features of the extracellular matrix (ECM) of bones, cartilages, and vascular vessels are presented as well.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.3-23
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• 2017

The achievement of tissue engineering can be highly depending on the capability to generate complicated, cell seeded three dimensional (3D) micro/nano-structures. So, various fabrication techniques that can be used to precisely design the architecture and topography of scaffolding materials will signify a key aspect of multi-functional tissue engineering. Previous methods for obtaining scaffolds based on top-down are often not satisfactory to produce complex micro/nano-structures due to the lack of control on scaffold architecture, porosity, and cellular interactions. However, a bioprinting method can be used to design sophisticated 3D tissue scaffolds that can be engineered to mimic the tissue architecture using computer aided approach. Also, in recent, the method has been modified and optimized to fabricate scaffolds using various natural biopolymers (collagen, alginate, and chitosan etc.). Variation of the topological structure and polymer concentration allowed tailoring the physical and biological properties of the scaffolds. In this presentation, the 3D bioprinting supplemented with a newly designed plasma treatment for attaining highly bioactive and functional scaffolds for tissue engineering applications will be introduced. Moreover, various in vivo and in vitro results will show that the fabricated scaffolds can carry out their structural and biological functionality.

• Journal of Periodontal and Implant Science
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• v.52 no.3
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• pp.242-257
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• 2022

Purpose: This study investigated periodontal ligament (PDL) restoration in osseointegrated implants using stem cells. Methods: Commercial pure titanium and zirconium oxide (zirconia) were coated with beta-tricalcium phosphate (β-TCP) using a long-pulse Nd:YAG laser (1,064 nm). Isolated bone marrow mesenchymal cells (BMMSCs) from rabbit tibia and femur, isolated PDL stem cells (PDLSCs) from the lower right incisor, and co-cultured BMMSCs and PDLSCs were tested for periostin markers using an immunofluorescent assay. Implants with 3D-engineered tissue were implanted into the lower right central incisors after extraction from rabbits. Forty implants (Ti or zirconia) were subdivided according to the duration of implantation (healing period: 45 or 90 days). Each subgroup (20 implants) was subdivided into 4 groups (without cells, PDLSC sheets, BMMSC sheets, and co-culture cell sheets). All groups underwent histological testing involving haematoxylin and eosin staining and immunohistochemistry, stereoscopic analysis to measure the PDL width, and field emission scanning electron microscopy (FESEM). The natural lower central incisors were used as controls. Results: The BMMSCs co-cultured with PDLSCs generated a well-formed PDL tissue that exhibited positive periostin expression. Histological analysis showed that the implantation of coated (Ti and zirconia) dental implants without a cell sheet resulted in a well-osseointegrated implant at both healing intervals, which was confirmed with FESEM analysis and negative periostin expression. The mesenchymal tissue structured from PDLSCs only or co-cultured (BMMSCs and PDLSCs) could form a natural periodontal tissue with no significant difference between Ti and zirconia implants, consequently forming a biohybrid dental implant. Green fluorescence for periostin was clearly detected around the biohybrid implants after 45 and 90 days. FESEM showed the invasion of PDL-like fibres perpendicular to the cementum of the bio-hybrid implants. Conclusions: β-TCP-coated (Ti and zirconia) implants generated periodontal tissue and formed biohybrid implants when mesenchymal-tissue-layered cell sheets were isolated from PDLSCs alone or co-cultured BMMSCs and PDLSCs.

• Journal of the Optical Society of Korea
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• v.19 no.2
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• pp.175-181
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• 2015

Optical coherence tomography (OCT) is a noninvasive technique for microscopic investigation of tissue. We thought that the OCT method could be a potential tool for monitoring the healing process of a tendon. In this study we used two rat models, denervated and non-denervated groups, to observe a variety of healing phases of Achilles tendon (AT) injury. We made samples of AT injury lesions, to take OCT images and to make histopathological samples of serial sectional tissue. In an OCT image the denervated rat showed no specific finding, but the non-denervated rat showed a large defect lesion that was scaffolding tissue. OCT findings combined with pathologic findings showed advantages in visualization of tendon microstructure over other imaging modalities such as MRI and US, and OCT is beneficial to making a treatment plan, especially the timing and intensity of rehabilitation. Therefore a multimodal platform using OCT for evaluation of tendon injury may be potentially useful for many applications.

• Polymer(Korea)
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• v.32 no.6
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• pp.516-522
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• 2008

Biodegradable polymers have been used extensively as scaffolding materials to regenerate new tissues and the ingrowth of tissue have been reported to be dependent directly of the porosity, pore diameter, pore shape, and porous structure of the scaffold. In this study, porous poly (L-lactide-co-glycolide) (PLGA) scaffolds with five different pore sizes were fabricated to investigate the effect of pore sizes for AF tissue regeneration. Cellular viability and proliferation were assayed by MTT test. Hydroxyproline/DNA content of AF cells on each scaffold was measured. sGAG analyses were performed at each time point of 2 and 6 weeks. Scaffold seeded AF cells were implanted into the back of athymic nude mouse to observe the difference of formation of disc-like tissue depending on pore size in vivo. We confirmed that scaffold with $180{\sim}250{\mu}m$ pores displayed high cell viability in vitro and produced higher ECM than scaffold with other pore sizes in vivo.

• Archives of Plastic Surgery
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• v.33 no.1
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• pp.21-30
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• 2006

Alginate, a polymer of guluronic and mannuronic acid, is used as a scaffolding material in biomedical applications. The research was to produce highly-purified alginate from seaweeds and to evaluate the efficacy of alginate as dermal substrate. Our alginate purification method showed a production rate as high as 25%. The purified alginate contained little polyphenol contents and endotoxin, proteins. For study of wound healing, full thickness skin defects were made on the dorsal area of the animal models. And then alginate, fibroblast-growth-factor mixed alginate, alginate-collagen complex, vaseline gauze as control were applied on the wound, respectively, and were evaluated grossly and histopathologically. For biocompatibility test, alginate and alginate-collagen complex discs were implanted on the back of Sprague-Dawly rats. Four weeks after implantation, the animals were examined immunologically against alginate and collagen. Alginate and FGF-mixed alginate, alginate-collagen complex group showed statistically higher percentage of wound contraction and wound healing than control group(p<0.05). Alginate-collagen complex group and FGF-mixed alginate group showed statistically higher percentage of wound healing than alginate group. The experiment of biocompatibility and immunologic reaction against impanted alginate or collagen needs more investigation. Highly-purified alginate from seaweeds by our purification method, showed the effect of wound healing, and addition of FGF or collagen increases the alginate's wound healing effect. It shows the possibility of alginate as a dermal substrate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.8
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• pp.875-880
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• 2014

Recently, three-dimensional scaffolds and nanofibers are being developed for bone tissue regeneration. In this study, we fabricated a hybrid scaffold using a nano-micro precision deposition system. The fabrication process involved the application of the solid freeform fabrication (SFF) technology and electrospinning. The hybrid scaffolds were combined using micro scaffolds and nanofibers. The nanofibers were deposited on each layer of the micro scaffolding using the electrospinning process. The micro scaffolds were fabricated using the SFF technology at a temperature of $100^{\circ}C$, pressure of 650 kPa, and scan velocity of 250 mm/s. Nanofiber fabrication was conducted by means of electrospinning using the flow rate, solution concentration, distance from the tip to the collector (TCD), and voltage. The nanofibers were fabricated using a flow rate of 0.1 ml/min, voltage of 5 kV, TCD of 1 mm, and 10 wt% of solution concentration. MG-63 cells were seeded into the hybrid scaffold for the purpose of its evaluation.

• Journal of Animal Science and Technology
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• v.63 no.4
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• pp.693-724
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• 2021

The in-vitro meat is a novel concept in food biotechnology comprising field of tissue engineering and cellular agriculture. It involves production of edible biomass by in-vitro culture of stem cells harvested from the muscle of live animals by self-organizing or scaffolding methodology. It is considered as efficient, environmental friendly, better ensuring public safety and nutritional security, as well as ethical way of producing meat. Source of stem cells, media ingredients, supply of large size bioreactors, skilled manpower, sanitary requirements, production of products with similar sensory and textural attributes as of conventional meat, consumer acceptance, and proper set up of regulatory framework are challenges faced in commercialization and consumer acceptance of in-vitro meat. To realize any perceivable change in various socio-economic and environmental spheres, the technology should be commercialized and should be cost-effective as conventional meat and widely accepted among consumers. The new challenges of increasing demand of meat with the increasing population could be fulfill by the establishment of in-vitro meat production at large scale and its popularization. The adoption of in-vitro meat production at an industrial scale will lead to self-sufficiency in the developed world.

• Clinical and Experimental Reproductive Medicine
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• v.49 no.4
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• pp.259-269
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• 2022

Objective: Animal-free scaffolds have emerged as a potential foundation for consistent, chemically defined, and low-cost materials. Because of its good potential for high biocompatibility with reproductive tissues and well-characterized scaffold design, we investigated whether polyglycolic acid (PGA) could be used as an animal-free scaffold instead of natural fibrin-agarose, which has been used successfully for three-dimensional human endometrial cell culture. Methods: Isolated primary endometrial cells was cultured on fibrin-agarose and PGA polymers and evaluated various design parameters, such as scaffold porosity and mean fiber diameter. Cytotoxicity, scanning electron microscopy (SEM), and immunostaining experiments were conducted to examine cell activity on fabricated scaffolds. Results: The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay and SEM results showed that endometrial cells grew and proliferated on both scaffolds. Immunostaining showed cytokeratin and vimentin expression in seeded cells after 7 days of culture. On both scaffolds, an epithelial arrangement of cultured cells was found on the top layer and stromal arrangement matrix on the bottom layer of the scaffolds. Therefore, fibrin-agarose and PGA scaffolds successfully mimicked the human endometrium in a way suitable for in vitro analysis. Conclusion: Both fibrin-agarose and PGA scaffolds could be used to simulate endometrial structures. However, because of environmental and ethical concerns and the low cost of synthetic polymers, we recommend using PGA as a synthetic polymer for scaffolding in research instead of natural biomaterials.

• Textile Coloration and Finishing
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• v.30 no.2
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• pp.117-129
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• 2018

Cellulose has been widely applied into various medical fields including scaffolding, tissue engineering and tissue formation. In this study, we manufactured cellulose medical fiber from Styela clava tunics(SCT-CS) and analyzed the tensile strength, elongation at break, fluid uptake and surface morphology. And then, the biocompatibility and toxicity of SCT-CS were measured in Sprague-Dawley(SD) rats after the implantation for 30, 60 and 90 days. The level of tensile strength and fluid uptake were lower in SCT-CS than chromic catgut(CCG), while elongation at break level were maintained the higher in SCT-CS. Also, the roughness with pronounced surface patterns as a result of in vivo degradation was significantly greater in CCG than this of SCT-CS although these levels gradually appeared with time in both groups. After implantation for 90 days, SCT-CS and CCG was successfully implanted around muscle of thigh without any significant immune response. Furthermore, no significant alterations were measured in serum parameters and the specific pathological features induced by most toxic compounds for liver and kidney toxicity. Therefore, these results suggest that SCT-CS showing good biocompatibility and non-toxicity can be successfully prepared from cellulose powder of SCT as well as has the potential for use as a powerful biomaterial for medical sutures.