Biomedical subjects

Seung-Woo Cho

Publications and source records attributed to Seung-Woo Cho.

16 recordsLinked to original sources

PubMed2006

Enhancement of adipose tissue formation by implantation of adipogenic-differentiated preadipocytes.

Engineered adipose tissue could be used for the reconstruction or augmentation of soft tissues lost due to mastectomy or lumpectomy in plastic and reconstructive surgery. Preadipocytes are a feasible cell source for adipose tissue regeneration. However, the enhancement of the in vivo adipogenic conversion of preadipocytes remains a major task. In vitro, the adipogenic differentiation of preadipocytes prior to implantation might enhance the adipose tissue regeneration. In the present study, we investigated whether implantation of adipogenic-differentiated preadipocytes enhances the adipose tissue formation compared with implantation of undifferentiated preadipocytes. We also investigated whether basic fibroblast growth factor (bFGF) further enhances the adipose tissue formation mediated by the implantation of adipogenic-differentiated preadipocytes. A fibrin matrix containing human preadipocytes cultured in adipogenic differentiation-inducing conditions with (group 1) or without (group 2) bFGF was injected into the subcutaneous spaces of athymic mice. Fibrin matrices containing undifferentiated human preadipocytes with (group 3) or without (group 4) bFGF were also implanted. Six weeks after implantation, the implanted cells formed new tissues in all groups. Importantly, the implantation of adipogenic-differentiated preadipocytes resulted in more extensive adipogenesis than the implantation of undifferentiated preadipocytes, as evaluated by adipose tissue area and human adipocyte-specific gene expression in the newly formed tissues. In addition, bFGF enhanced neovascularization in the newly formed tissues and further enhanced the adipogenesis mediated by the adipogenic-differentiated preadipocytes. The present study demonstrates that the implantation of adipogenic-differentiated preadipocytes enhances adipose tissue regeneration, as compared with the implantation of undifferentiated preadipocytes, and that cell transplantation-mediated adipogenesis can be further enhanced by the delivery of bFGF.

Adipocytes↗

PubMed2006

Angiogenesis facilitated by autologous whole bone marrow stem cell transplantation for Buerger's disease.

We hypothesized that angiogenesis can be triggered by autologous whole bone marrow stem cell transplantation. Twenty-seven patients (34 lower limbs) with Buerger's disease, who were not candidates for surgical revascularization or radiologic intervention, were enrolled in this study. Six sites of the tibia bone were fenestrated using a 2.5-mm-diameter screw under fluoroscopic guidance. Clinical status and outcome were determined using the "Recommended Standards for Reports." To mobilize endothelial progenitor cells (EPCs) from bone marrow, recombinant human granulocyte colony-stimulating factor (r-HuG-CSF) was injected subcutaneously as a dose of 75 microg, preoperatively. During the follow-up period (19.1 +/- 3.5 months), one limb showed a markedly improved outcome (+3), and 26 limbs showed a moderately improved outcome (+2). Thirteen limbs among 17 limbs with nonhealing ulcers healed. Postoperative angiograms were obtained for 22 limbs. Two limbs showed marked (+3), five limbs moderate (+2), and nine limbs slight (+1) collateral development. However, six limbs showed no collateral development (0). Peripheral blood and bone marrow samples were analyzed for CD34 and CD133 molecules to enumerate potential EPCs, and EPC numbers were found to be increased in peripheral blood and in bone marrow after r-HuG-CSF injection. In conclusion, the transplantation of autologous whole BMCs by fenestration of the tibia bone represents a simple, safe, and effective means of inducing therapeutic angiogenesis in patients with Buerger's disease.

Adult↗

PubMed2006

Enhancement of in vivo endothelialization of tissue-engineered vascular grafts by granulocyte colony-stimulating factor.

Successful reconstruction of large-diameter blood vessel in humans has been demonstrated using the tissue engineering technique, but improvement in patency of small-diameter bioartificial vascular graft remains a great challenge. This study reports that granulocyte colony-stimulating factor (G-CSF) can enhance in vivo endothelialization of tissue-engineered vascular grafts, which could be used to improve patency of small-diameter vascular graft. Vascular grafts were tissue engineered with decellularized canine abdominal aortas and canine autologous bone marrow-derived cells. Prior to cell seeding onto decellularized graft matrices, bone marrow-derived cells were induced to differentiate into endothelial cells and smooth muscle cells. The cell-seeded vascular grafts were implanted into the abdominal aortas of bone marrow donor dogs. Before and after graft implantation, G-CSF was administered subcutaneously to the dogs (n = 3). The grafts implanted into the dogs not receiving G-CSF were used as controls (n = 3). Eight weeks after implantation, grafts in both groups showed regeneration of vascular tissues including endothelium and smooth muscle. Importantly, endothelium formation was more extensive in the G-CSF-treated grafts than in the control grafts, as assessed with reverse transcription polymerase chain reaction, western blot, and immunohistochemistry. In addition, intimal hyperplasia was significantly reduced in the G-CSF-treated grafts compared to the control grafts. This study suggests that G-CSF administration could be applied to improve patency of small-diameter tissue-engineered vascular grafts.

Animals↗

PubMed2006

A method for the effective formation of hepatocyte spheroids using a biodegradable polymer nanosphere.

Cultures of hepatocytes in spheroid form are known to maintain higher cell viability and exhibit better hepatocyte functions than those in monolayer cultures. In this study, a method for the formation of hepatocyte spheroids was developed using biodegradable polymer nanospheres. The addition of poly(lactic-co-glycolic acid) nanospheres to hepatocyte cultures in spinner flasks increased the efficiency of hepatocyte spheroid formation (the number of cells in spheroids divided by the total cell number) as compared with hepatocyte cultures without nanospheres (control). The viability and mitochondrial activity of the hepatocyte spheroids in the nanosphere-added cultures were significantly higher than those in the control. In addition, the mRNA expression levels of albumin and phenylalanine hydroxylase, both of which are hepatocyte-specific proteins, were significantly higher in the nanosphere-added cultures than in the control. This new culture method improves upon the conventional method of forming hepatocyte spheroids in terms of spheroid formation efficiency, cell viability, and hepatocyte function.

Absorbable Implants↗

PubMed2006

Enhancement of the osteogenic efficacy of osteoblast transplantation by the sustained delivery of basic fibroblast growth factor.

Previously, the sustained delivery of basic fibroblast growth factor (bFGF) has been demonstrated to promote bone regeneration in bone defects that had not been treated with osteogenic cell transplantation. In this study, we tested the hypothesis that the sustained delivery of bFGF could enhance osteoblast transplantation-mediated ectopic bone formation. Rat osteoblasts and bFGF were mixed with an injectable fibrin matrix and subcutaneously transplanted to rats (cell + bFGF group). The fibrin matrix played roles in both the cell transplantation matrix and the bFGF sustained delivery matrix. The transplantation of osteoblasts suspended in a fibrin matrix without bFGF served as a control. Twelve weeks after transplantation, histological analyses of retrieved transplants showed that new bone formation was more abundant and mature in the cell + bFGF group than in the control group. The bone formation area and the calcium content in the cell + bFGF group were two- and nine-fold higher, respectively, than those in the control group. Enhanced bone formation by the sustained delivery of bFGF may be attributed to the enhanced osteogenic gene expression of the transplanted cells and neovascularization of the transplants, as both mRNA expression of various osteogenic markers and arteriole density in the cell + bFGF group were significantly higher than those in the control group. This study demonstrates that the sustained delivery of bFGF can potentiate ectopic bone regeneration by osteoblast transplantation. This combination therapy may have effective implications for bone regeneration in large bone defects in which extensive osteogenic cell migration and angiogenesis are required.

Animals↗

PubMed2006

Preliminary experience with tissue engineering of a venous vascular patch by using bone marrow-derived cells and a hybrid biodegradable polymer scaffold.

OBJECTIVE: Currently available synthetic polymer vascular patches used in cardiovascular surgery have shown serious shortcomings, including thrombosis, calcification, infection, and lack of growth potential. These problems may be avoided by vascular patches tissue-engineered with autologous stem cells and biodegradable polymeric materials. The objective of this study was to develop a tissue-engineered vascular patch by using autologous bone marrow-derived cells (BMCs) and a hybrid biodegradable polymer scaffold. METHODS: Hybrid biodegradable polymer scaffolds were fabricated from poly(lactide-co-epsilon-caprolactone) (PLCL) copolymer reinforced with poly(glycolic acid) (PGA) fibers. Canine bone marrow mononuclear cells were induced in vitro to differentiate into vascular smooth muscle cells and endothelial cells. Tissue-engineered vascular patches (15 mm wide x 30 mm long) were fabricated by seeding vascular cells onto PGA/PLCL scaffolds and implanted into the inferior vena cava of bone marrow donor dogs. RESULTS: Compared with PLCL scaffolds, PGA/PLCL scaffolds exhibited tensile mechanical properties more similar to those of dog inferior vena cava. Eight weeks after implantation of vascular patches tissue-engineered with BMCs and PGA/PLCL scaffolds, the vascular patches remained patent with no sign of thrombosis, stenosis, or dilatation. Histological, immunohistochemical, and scanning electron microscopic analyses of the retrieved vascular patches revealed regeneration of endothelium and smooth muscle, as well as the presence of collagen. Calcium deposition on tissue-engineered vascular patches was not significantly different from that on native blood vessels. Immunofluorescent double staining confirmed that implanted BMCs survived after implantation and contributed to regeneration of endothelium and vascular smooth muscle in the implanted vascular patches. CONCLUSIONS: This study demonstrates that vascular patches can be tissue-engineered with autologous BMCs and hybrid biodegradable polymer scaffolds.

Absorbable Implants↗

PubMed2006

Enhancement of angiogenic efficacy of human cord blood cell transplantation.

We tested the hypotheses that angiogenic efficacy of cord blood mononuclear cell (CBMNC) transplantation would be enhanced by using matrix and that combined therapy of CBMNC transplantation using matrix and sustained delivery of basic fibroblast growth factor (bFGF) would be synergistic in angiogenesis induction in ischemic limbs. One day after surgical induction of hindlimb ischemia, C57BL/6J mice were randomized to receive either medium injection, CBMNC transplantation using medium, CBMNC transplantation using fibrin matrix, sustained delivery of bFGF, or a combination of sustained delivery of bFGF and CBMNC transplantation using fibrin matrix. Four weeks after treatment, the angiogenic efficacy of the treatments was evaluated by immunohistochemical examinations and microvessel density determination in the ischemic sites. Transplanted CBMNCs survived, proliferated, and participated in capillary formation in ischemic limbs. CBMNC transplantation using fibrin matrix significantly increased the densities of capillaries and arterioles compared with CBMNC transplantation using medium. Importantly, combined therapy of sustained delivery of bFGF and CBMNC transplantation using fibrin matrix further increased the densities of capillaries and arterioles compared with either therapy alone. The angiogenic efficacy of angiogenic cell transplantation is enhanced by cell transplantation using matrix. Combined therapy of sustained release of angiogenic protein and angiogenic cell transplantation synergistically enhances angiogenesis in ischemic limbs compared to each therapy separately.

Animals↗

PubMed2006

Tissue engineering of heart valves in vivo using bone marrow-derived cells.

In this study, we tissue-engineered heart valves in vivo using autologous bone marrow-derived cells (BMCs). Canine BMCs were differentiated into endothelial cell (EC)-like cells and myofibroblast (MF)-like cells. Decellularized porcine pulmonary valves were seeded with BMCs and implanted to abdominal aorta and pulmonary valve of bone marrow donor dogs. Histological examination of the explants identified the regeneration of valvular structures expressing CD31 and smooth muscle alpha-actin, indicating the presence of EC-like and MF-like cells in the grafts at 3 and 1 week, respectively, after implantation. Fluorescent microscopic examinations identified the presence of fluorescently labeled cells in the explants, indicating that the implanted BMCs survived and participated in the heart valve reconstitution. This study reports, for the first time, on tissue engineering of heart valve in vivo using BMCs.

Animals↗

PubMed2005

Granulocyte colony-stimulating factor treatment enhances the efficacy of cellular cardiomyoplasty with transplantation of embryonic stem cell-derived cardiomyocytes in infarcted myocardium.

We tested the hypothesis that granulocyte colony-stimulating factor (G-CSF) administration would enhance the efficacy of cellular cardiomyoplasty with embryonic stem (ES) cell-derived cardiomyocytes in infarcted myocardium. Three weeks after myocardial infarction by cryoinjury, Sprague-Dawley rats were randomized to receive either an injection of medium, ES cell-derived cardiomyocyte transplantation, G-CSF administration, or a combination of G-CSF administration and ES cell-derived cardiomyocyte transplantation. Eight weeks after treatment, the cardiac tissue formation, neovascularization, and apoptotic activity in the infarct regions were evaluated by histology and immunohistochemistry. The left ventricular (LV) dimensions and function of the treated heart were evaluated by echocardiography. Transplanted ES cell-derived cardiomyocytes survived and participated in the myocardial regeneration in the infarcted heart. A combination of G-CSF treatment and ES cell-derived cardiomyocyte transplantation significantly promoted angiogenesis and reduced the infarct area and cell apoptosis in the infarcted myocardium compared with ES cell-derived cardiomyocyte transplantation alone. The combination therapy also attenuated LV dilation, as compared with ES cell-derived cardiomyocyte transplantation alone. G-CSF treatment can enhance the efficacy of cellular cardiomyoplasty by ES cell-derived cardiomyocyte transplantation to treat myocardial infarction.

Animals↗

PubMed2005

Implantation of bone marrow mononuclear cells using injectable fibrin matrix enhances neovascularization in infarcted myocardium.

Neovascularization may improve cardiac function and prevent further scar tissue formation in infarcted myocardium. A number of studies have demonstrated that bone marrow-derived cells have the potential to induce neovascularization in ischemic tissues. In this study, we hypothesized that implantation of bone marrow mononuclear cells (BMMNCs) using injectable fibrin matrix further enhances neovascularization in infarcted myocardium compared to BMMNC implantation without matrix. To test this hypothesis, infarction was induced in rat myocardium by cryoinjury. Three weeks later, rat BMMNCs were mixed with fibrin matrix and injected into the infarcted myocardium. Injection of either BMMNCs or medium alone into infarcted myocardium served as controls. Eight weeks after the treatments, histological analyses indicated that implantation of BMMNCs using fibrin matrix resulted in more extensive tissue regeneration in the infarcted myocardium compared to BMMNC implantation without matrix. Examination with fluorescence microscopy revealed that cells labeled with a fluorescent dye prior to implantation survived in the infarcted myocardium at 8 weeks of implantation. Importantly, implantation of BMMNCs using fibrin matrix resulted in much more extensive neovascularization in infarcted myocardium than BMMNC implantation without matrix. The microvessel density in infarcted myocardium was significantly higher (p < 0.05) when BMMNCs were implanted using fibrin matrix (350 +/- 22 microvessels/mm2) compared to BMMNC implantation without matrix (262 +/- 13 microvessels/mm2) and medium injection (76 +/- 9 microvessels/mm2). In addition, average internal diameter of microvessels was significantly larger (p < 0.05) in BMMNC implantation with fibrin matrix group (14.6 +/- 1.2 microm) than BMMNC implantation without matrix group (10.2 +/- 0.7 microm) and medium injection group (7.3 +/- 0.5 microm). These results suggest that fibrin matrix could serve as a cell implantation matrix that enhances neovascularization efficacy for myocardial infarction treatment.

Animals↗

PubMed2005

Mechano-active tissue engineering of vascular smooth muscle using pulsatile perfusion bioreactors and elastic PLCL scaffolds.

Blood vessels are subjected in vivo to mechanical forces in a form of radial distention, encompassing cyclic mechanical strain due to the pulsatile nature of blood flow. Vascular smooth muscle (VSM) tissues engineered in vitro with a conventional tissue engineering technique may not be functional, because vascular smooth muscle cells (VSMCs) cultured in vitro typically revert from a contractile phenotype to a synthetic phenotype. In this study, we hypothesized that pulsatile strain and shear stress stimulate VSM tissue development and induce VSMCs to retain the differentiated phenotype in VSM engineering in vitro. To test the hypothesis, rabbit aortic smooth muscle cells (SMCs) were seeded onto rubber-like elastic, three-dimensional PLCL [poly(lactide-co-caprolactone), 50:50] scaffolds and subjected to pulsatile strain and shear stress by culturing them in pulsatile perfusion bioreactors for up to 8 weeks. As control experiments, VSMCs were cultured on PLCL scaffolds statically. The pulsatile strain and shear stress enhanced the VSMCs proliferation and collagen production. In addition, a significant cell alignment in a direction radial to the distending direction was observed in VSM tissues exposed to radial distention, which is similar to that of native VSM tissues in vivo, whereas VSMs in VSM tissues engineered in the static condition randomly aligned. Importantly, the expression of SM alpha-actin, a differentiated phenotype of SMCs, was upregulated by 2.5-fold in VSM tissues engineered under the mechano-active condition, compared to VSM tissues engineered in the static condition. This study demonstrates that tissue engineering of VSM tissues in vitro by using pulsatile perfusion bioreactors and elastic PLCL scaffolds leads to the enhancement of tissue development and the retention of differentiated cell phenotype.

Animals↗

PubMed2005

Vascular patches tissue-engineered with autologous bone marrow-derived cells and decellularized tissue matrices.

Synthetic polymer vascular patches used in cardiovascular surgery have shortcomings such as thrombosis, intimal hyperplasia, calcification, infection, and no growth potential. Tissue-engineered vascular patches using autologous vascular cells may solve these problems. In this study, we developed a tissue-engineered vascular patch using autologous bone marrow-derived cells (BMCs) and decellularized tissue matrices. Vascular smooth muscle cells and endothelial cells were differentiated from bone marrow mononuclear cells in vitro. Tissue-engineered vascular patches were fabricated by seeding these cells onto decellularized canine inferior vena cava matrices and implanted into the inferior vena cava of dogs. Three weeks after implantation, the tissue-engineered vascular patches were patent with no sign of thrombus formation. Histological, immunohistochemical, and electron microscopic analyses of the vascular patches retrieved 3 weeks after implantation revealed regeneration of endothelium and smooth muscle and the presence of collagen and elastin. BMCs labeled with a fluorescent dye prior to implantation were detected in the retrieved vascular patches, indicating that the BMCs survived after implantation and contributed to the vascular tissue regeneration. This study demonstrates that vascular patches can be tissue-engineered with autologous BMCs and decellularized tissue matrices.

Animals↗

PubMed2005

Engineering of volume-stable adipose tissues.

Autologous adipose tissues have been clinically used for augmentation of soft tissues lost due to mastectomy or lumpectomy in plastic and reconstructive surgery. However, this therapy has problems of absorption and subsequent volume loss of the implanted adipose tissues. In this study, volume-stable adipose tissues were engineered in vivo using mechanical support structures fabricated from biodegradable synthetic polymers. Dome-shaped mechanical support structures were fabricated by reinforcing poly(glycolic acid) fiber-based matrices with poly(L-lactic acid). The support structures were placed into subcutaneous pockets of athymic mice, and human preadipocytes suspended in fibrin matrix were injected into the space under the support structures (group I). Injection of either fibrin matrix without preadipocytes under the support structures (group II) or fibrin matrix containing preadipocytes into subcutaneous spaces with no support structures (group III) served as controls. Six weeks after implantation, the original implant volume was maintained approximately in groups I and II, whereas, group III showed significant implant shrinkage. The compressive modulus of the mechanical support structures did not change significantly over 6-week incubation in phosphate-buffered saline at 37 degrees C. Histological analyses of the implants showed regeneration of adipose tissues in group I. In contrast, groups II and III did not show extensive adipose tissue formation. This study demonstrates that volume-stable adipose tissues can be engineered in vivo using mechanical support structures. This technique offers the potential for augmentation of adipose tissues with volume conservation.

Adipocytes↗

PubMed2005

Small-diameter blood vessels engineered with bone marrow-derived cells.

OBJECTIVE: The objective of this study is to investigate if bone marrow-derived cells (BMCs) regenerate vascular tissues and improve patency in tissue-engineered small-diameter (internal diameter = 3 mm) vascular grafts. SUMMARY BACKGROUND DATA: BMCs have demonstrated the ability to differentiate into endothelial-like cells and vascular smooth muscle-like cells and may offer an alternative cell source for vascular tissue engineering. Thus, we tissue-engineered small-diameter vascular grafts with BMCs and decellularized arteries. METHODS: Canine BMCs were differentiated in vitro into smooth muscle alpha-actin/smooth muscle myosin heavy-chain-positive cells and von Willebrand factor/CD31-positive cells and seeded onto decellularized canine carotid arteries (internal diameter = 3 mm). The seeded grafts were implanted in cell donor dogs. The vascular-tissue regeneration and graft patency were investigated with immunohistochemistry and angiography, respectively. RESULTS: The vascular grafts seeded with BMCs remained patent for up to 8 weeks in the canine carotid artery interposition model, whereas nonseeded grafts occluded within 2 weeks. Within 8 weeks after implantation, the vascular grafts showed regeneration of the 3 elements of artery (endothelium, media, and adventitia). BMCs labeled with a fluorescent dye prior to implantation were detected in the retrieved vascular grafts, indicating that the BMCs participated in the vascular tissue regeneration. CONCLUSIONS: Here we show that BMCs have the potential to regenerate vascular tissues and improve patency in tissue-engineered small-diameter vascular grafts. This is the first report of a small-diameter neovessel engineered with BMCs as a cell source.

Animals↗

PubMed2004

HEK 293 cell suspension culture using fibronectin-adsorbed polymer nanospheres in serum-free medium.

Previously, we reported on suspension culture of anchorage-dependent animal cells using plain polymer nanospheres in serum-containing medium. For commercial cell culture, it is more advantageous to use serum-free medium than serum-containing medium. To culture anchorage-dependent animal cells using polymer nanospheres in serum-free medium, the nanospheres need to be coated with cell adhesion proteins. In this study, we utilized fibronectin-adsorbed polymer nanospheres for suspension culture of anchorage-dependent animal cells in serum-free medium. Fibronectin was adsorbed onto poly(lactic-co-glycolic acid) nanospheres (433 nm in average diameter) by immersing the nanospheres in fetal bovine serum. The nanospheres were used to culture human embryonic kidney (HEK) 293 cells in serum-free medium in stirred suspension bioreactors. Nanospheres attached between HEK 293 cells and promoted cell aggregate formation compared with culture without nanospheres. Most cells in the aggregates were viable over a 10-day culture period. Importantly, the use of poly(lactic-co-glycolic acid) nanospheres promoted the cell growth significantly, compared with culture without nanospheres (3.8- vs 1.8-fold growth). The nanosphere culture method developed in this study removes the time-consuming and costly process of adaptation of anchorage-dependent animal cells to suspension culture in serum-free medium. This culture method may be useful for the large-scale suspension culture of various types of anchorage-dependent animal cells in serum-free medium.

Animals↗

PubMed2004

Smooth muscle-like tissues engineered with bone marrow stromal cells.

Bone marrow-derived cells have demonstrated the ability to differentiate into multiple mesenchymal cell lineages. Here we tested whether smooth muscle (SM)-like tissues can be created in vivo with bone marrow stromal cells (BMSCs). Cultured canine BMSCs, which expressed SM cell-specific markers including SM alpha-actin and SM myosin heavy chain, were seeded on three-dimensional, biodegradable polymer scaffolds and implanted into peritoneal cavity of athymic mice. The cell-scaffold constructs retrieved 4 weeks after implantation formed three-dimensional tissues. Immunohistochemical analyses showed that the tissue reconstructs expressed SM alpha-actin and SM myosin heavy chain. Masson's trichrome staining showed the presence of significant amounts of collagen in the tissue reconstructs. Cells labeled with a fluorescent tracer prior to implantation were still present in the tissue reconstructs 4 weeks after implantation. Non-seeded scaffolds (control groups) retrieved 4 weeks after implantation did not exhibit extensive tissue formation. This study demonstrates the potential of BMSCs as an alternative cell source for tissue engineering of SM.

Absorbable Implants↗