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의학/생물학 관련 연구에서 기계공학의 역할에 대한 고찰
신정욱(Jung-Woog Shin),김동화(Dong Hwa Kim),허수진(Su-Jin Heo) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Considering that human body is continuously experiencing mechanical stimuli due to daily activities, the micro-physical environments of cells/tissues should be considered for the successful outcomes in tissue engineering and/or related researches. Obviously, there are many factors involved in cell-based researches. In this presentation, the current trends and some of outcomes ar introduced. Through this studies, the roles of mechanical engineering in relation to medical/biological researches are to be emphasized.
이현옥,이성재,신정욱,Lee, Hyun-Ok,Lee, Sung-Jae,Shin, Jung-Woog 대한물리치료학회 2001 대한물리치료학회지 Vol.13 No.1
Aging has been recognized as the primary cause of disc degeneration. A biomechanical characteristics of disc degeneration has been demonstrated that intradiscal pressure is reduced. With the increasing population of elderly people, disc degeneration and associated problems of nerve entrapment are becoming more prevalent. Presently, research on reduced intradiscal pressure associated with degeneration is insufficient. In this study. we used the Finite Element Method (FEM) of computerized simulations to investigate the effects of variation in intradiscal pressure on mechanical behaviours of L4-5 intervertebral disc degeneration. Degeneration was classified using four grades based on initial intradiscal pressure; Normal (135 kPa), mild(107 kPa), moderate (47 kPa) and severe (15 kPa). The predicted results f3r bending loads were as follows; 1 . Range of motion increased progressively with severity of degeneration with flexion and lateral bending moments, but decreased with extension moments. 2. Discal bulging of posterolateral aspect was larger in lateral bending and extension moment. But bulging was increased with severity of degeneration in lateral bending and torsion(same side).3. The rate of increasing intradiscal pressure was decreased in all bending motions with severity of degeneration. In conclusion, lateral bending and extension moment yield greatest bulging in severe degeneration. In torsion, although bending load produces disc bulging, disc bulging was associated more strongly with severity of degeneration than increasing torsional moments. Clinical Implications: Discal bulging may produce nerve root impingement and irritation. The effect of loading and posture on the varying degrees of disc degeneration has important implications especially in the elderly. In the presence of disc degeneration, avoidance of end range postures, especially extension and lateral bending may help reduce discal bulging and in turn, nerve entrapment.
물리적 인장 자극에 의한 줄기세포의 분화에 동반되는 미토콘드리아의 특성 변화에 관한 고찰
신지원 ( Ji Won Shin ),김혜림 ( Hye Lim Kim ),강윤경 ( Yun Gyeong Kang ),박소희 ( So Hee Park ),김영미 ( Young Mi Kim ),신정욱 ( Jung Woog Shin ) 한국조직공학과 재생의학회 2015 조직공학과 재생의학 Vol.12 No.1s
Recent studies have confirmed that the direction of stem cell differentiation can be modulated by physical stimuli even without biochemical growth factors. This implies stem cells attribute their differentiation to mechanical signaling directly or indirectly. However, the role or changes in mitochondria, one of the major energy sources in a cell, during differentiation have not been investigated. This study applied mechanical stretching of two different magnitudes (3% and 10%) to human mesenchymal stem cells without any relevant growth factors. We confirmed differentiation of stem cells into two different directions: osteogenic- and smooth muscle-like cells. Along with these results we found the expression of NOX4 was increased with stretching magnitude. As the expression of NOX4 is closely related to mitochondrial biogenesis and morphology various markers were also investigated. The expressions of the markers in relation to biogenesis (PGC-1alpha, TFA) and fusion (MFN1, MFN2, OPA1) were increased with stretching magnitude. However, the expression of Drp1 was observable with stretching of 3%. This study showed that the magnitude of physical stimulation affects the expression of NOX4, which has been known to be closely related to the biogenesis and morphological changes of mitochondria and stem cell differentiation. Therefore, further study of NOX4 due to physical stimulation for the control of stem cell differentiation accompanied by mitochondria functions is worth to be performed.
기계적 자극이 다층 구조의 나노파이버 지지체의 평활근 세포에 미치는 영향
신지원,김동화,허수진,김수향,김영직,신정욱,Shin, Ji-Won,Kim, Dong-Hwa,Heo, Su-Jin,Kim, Su-Hyang,Kim, Young-Jick,Shin, Jung-Woog 대한의용생체공학회 2008 의공학회지 Vol.29 No.1
The object of this study is to investigate the effects of intermittent cyclic stretching on the smooth muscle cells (SMCs) seeded onto aligned multi-layered fibrous scaffold. To make multi-layered fibrous scaffold, polyurethane (PU) and poly(ethylene oxide) (PEO) were electrospun alternatively, then were immersed into distilled water to extract PEO. Various types of scaffolds were fabricated depending on fiber directions, i.e., aligned or randomly oriented. The direction of stretching was either parallel or vertical to the fiber direction for the aligned scaffolds. The stretching was also applied to the randomly aligned scaffolds. The duration of stretching was 2 min with 15 min resting period. During the stretching, the maximum and minimum strain was adjusted to be 10 and 7%, respectively with the frequency of 1 Hz. The bioactivities of cells on the scaffolds were assessed by quantifying DNA, collagen, and glycosaminoglycan (GAG) levels. And the cell morphology was observed by staining F-actin. SMCs under parallel stretching to the fiber direction responded more positively than those in other conditions. From the results, we could explain the morphological effect of a substrate on cellular activities. In addition the synergistic effects of substrate and mechanical stimuli effects were confirmed.
혼합배지와 지지체 특성에 의한 줄기세포 분화제어: 골연골 조직을 중심으로
한정윤 ( Jeong Yoon Han ),신지원 ( Ji Won Shin ),박소희 ( So Hee Park ),김동화 ( Dong Hwa Kim ),김수향 ( Su Hyang Kim ),강윤경 ( Yun Gyeong Kang ),신정욱 ( Jung Woog Shin ) 한국조직공학과 재생의학회 2011 조직공학과 재생의학 Vol.8 No.2s
This article investigated the potential of substrate characteristics for the control of differentiation of stem cells. For this, two distinctive materials, alginate and HA (hydroxiapatite) contained PCL, were selected. Utilizing rapid prototype (RP) technique we fabricated each type of scaffold. Mesenchymal stem cells (MSCs) derived from New Zealand White rabbits were suspended into alginate solution and the solution was plotted utilizing RP technique. The cocktail media which contain chondrogenic and osteogenic growth factors were used. The basal media were also used for comparison. During 14 days of experiments the samples were harvested four times. The results showed that MSCs tended to be differentiated into osteo- and chondrocyte-like cells when they were on PCL and in alginate scaffold, respectively even both of the two types of scaffolds were in basal media. These findings were more observable when the cocktail media were used. From this research we can stipulate that the characteristics of substrate materials should be considered along with biochemical reagents in the control of differentiation of stem cells. It is also recommended that the biomechanical factors, such as mechanical stimuli, should be considered in view of bio-mimetic environments.
공배양 및 물리적 환경하에서의 중간엽 줄기세포의 혈관 관련 세포로의 분화 경향
박소희 ( So Hee Park ),신지원 ( Ji Won Shin ),김수향 ( Su Hyang Kim ),강윤경 ( Yun Gyeong Kang ),전강진 ( Kang Jin Jeon ),김선연 ( Seon Yeon Kim ),현진숙 ( Jin Sook Hyun ),신정욱 ( Jung Woog Shin ) 한국조직공학·재생의학회 2013 조직공학과 재생의학 Vol.10 No.1s
How to control the differentiation of mesenchymal stem cells (MSCs) into vascular lineage cells have still left much unclear even with numerous studies. Most in vitro studies on the differentiation of stem cells have utilized biochemical reagents. However, recent studies show the potentials of physical and co-culturing environments in control of differentiation. Therefore, we first factored out the in vivo conditions into biochemical reagents, co-culture, and physical stimulation. Then combinational effects of those factors on the differentiation of MSCs into vascular lineage cells were studied. For this EGM (R) -2, co-culture, and shear stress were adopted to meet biochemical, neighboring cells, and physical condition, respectively. A total 4 experimental groups were set depending on co-culture and shear stress. Cell density was 1×104cells/cm2 at all group. For the co-cultures, MSCs were mixed with human umbilical vein endothelial cells (HUVECs) in the ratio of 1:2. The 12 dyne/cm2 of shear stress was engaged: 4 hr/ day for 2 days followed by 48 hr after seeding. For the analyses, the immunofluorescent staining and PCR was performed to evaluate the differentiation of MSCs into vascular lineage cells. The co-culture group without shear stress showed the ECs-related markers even on the first day of the culture. And this was more observable on day 4. However, differentiation of MSCs into smooth muscle cells was found dominant when shear stress was engaged even MSCs were cultured with HUVECs and EGM (R) -2. From this study we confirmed that physical stimulation (12 dyne/ cm2 in our study) plays an important role in controlling differentiation of MSCs into vascular lineage cell types when MSCs were co-cultured with ECs.
Polyurethane과 Poly(Ethylene Oxide)를 이용한 hybrid 나노섬유 지지체의 제작
신지원,신호준,허수진,김지희,황영미,김동화,신정욱,Shin, Ji-Won,Shin, Ho-Jun,Heo, Su-Jin,Kim, Ji-Hee,Hwang, Young-Mi,Kim, Dong-Hwa,Shin, Jung-Woog 대한의용생체공학회 2006 의공학회지 Vol.27 No.5
The object of this study is to investigate the potential of dual-electrospun polymer based structure for vascular tissue engineering, especially for the medium or small sue blood vessels. Polyurethane(PU), which is known to be biocompatible in this area, was electrospun with poly(ethylene oxide) (PEO). Concentration of PU was fixed at 20wt%, while that of PEO was set from 15 to 35wt%. Morphological features were observed by SEM image and measurement of porosity and cellular responses were tested before and after extracting PEO from the hybrid scaffolds by immersing the scaffolds into distilled water. The diameter of PEO fibers were ranged from 200nm to 500nm. The lower concentration of PEO tended to show beads. The porosity of the scaffolds after extracting PEO was highly increased with higher concentration of PEO as expected. Also, higher proliferation rate of smooth muscle cells was observed at higher concentration of PEO than at the lower concentration and without PEO. As conclusions, this dual electrospinning technique combined with PU and PEO is expected to overcome the current barrier of cell penetration by providing more space for cells to proliferation.
기계적 자극이 3차원 공배양을 통한 중간엽 줄기세포의 chondrogenesis에 미치는 영향
김동화 ( Dong Hwa Kim ),허수진 ( Su Jin Heo ),신지원 ( Ji Won Shin ),박소희 ( So Hee Park ),신정욱 ( Jung Woog Shin ) 한국조직공학·재생의학회 2009 조직공학과 재생의학 Vol.6 No.4
The goal of this study is to investigate the effects of mechanical stimulation on chondrogenesis of mesenchymal stem cells(MSCs) via 3D co-culturing system. The chondrocytes and MSCs were isolated and cultured from New Zealand White male rabbits. Cells were maintained in chondrogenic differentiation media containing 10 ng/mL TGF-β1. MSCs and chondrocytes were suspended in different alginate beads respectively. Those two types of beads were separated by a track-etched membrane of 3 ?m pore. The intermittent hydrostatic pressure(2 min pressurizing/15 min resting, 0.2 MPa) was applied for 3 days, starting on the third day after seeding and ending on the sixth day for 4 hrs/day. Proliferation and production of glycosaminoglycan(GAG) were evaluated along with immunocytochemistry observations. The rate of MSC proliferation tended to decrease during the culture period, while that of chondrocytes increased regardless of mechanical stimulation. However, on 7 day the mechanical stimulation affected proliferation of chondrocytes. The differentiation of MSCs and chondrocytes were affected by the mechanical stimulation on 14 day. When amount of GAG in each group was normalized by its DNA quantity to investigate differentiation activity of each cell, the efficacy of mechanical stimulation was observed after 7 day in MSCs. These results suggested that during co-culture with stimulation some secretion from chondrocytes, which are fully developed, tended to suppress the proliferation of MSCs while tended to promote differentiation of MSCs. In addition, the efficacy of mechanical stimulation was confirmed through this study.
Hydroxyapatite/poly ε-caprolactone 다공성 지지체의 제조 및 평가
현용택 ( Yong Taek Hyun ),김승언 ( Seung Eon Kim ),허수진 ( Su Jin Heo ),신정욱 ( Jung Woog Shin ),이향미 ( Hyang Mi Lee ),윤석영 ( Seog Young Yoon ) 대한금속재료학회 ( 구 대한금속학회 ) 2006 대한금속·재료학회지 Vol.44 No.6
Porous and bioactive composite scaffolds were successfully fabricated by salt leaching method using poly ε-caprolactone (PCL) and hydroxyapatite (HA). The scaffolds have interconnected pore structure with pore size ranging from 200 to 230 ㎛. The pore size of pure PCL scaffolds and PCL/HA scaffolds was similar to that of the salt particles (200-300 ㎛). However, the porosity and the pore size of the PCL/HA composite scaffolds slightly decreased as the HA concentration increased. In addition, the pore walls became thick and the small pores decreased, and consequently the interconnectivity of the pores decreased. The cell viability and response of the scaffolds were assessed by MTT assay. The biological assessment results showed that HA content did not affect initial cell attachment in both scaffolds with and without HA. The osteoblasts proliferated in both types of the scaffolds, but the cell number was higher in the PCL/HA composite scaffolds. It was clearly demonstrated that the incorporation of hydroxyapatite enhances bone cell proliferation rather than initial cell attachment in PCL/HA composite scaffolds. Combining HA and biodegradable polymer could be applicable to bone scaffolding materials.