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Michael Garwood - One of the best experts on this subject based on the ideXlab platform.
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noninvasive assessment of tissue Engineered Graft viability by oxygen 17 magnetic resonance spectroscopy
Biotechnology and Bioengineering, 2017Co-Authors: Samuel A Einstein, Bradley P Weegman, Jennifer P Kitzmann, Klearchos K Papas, Michael GarwoodAbstract:Transplantation of macroencapsulated tissue-Engineered Grafts (TEGs) is being investigated as a treatment for type 1 diabetes, but there is a critical need to measure TEG viability both in vitro and in vivo. Oxygen deficiency is the most critical issue preventing widespread implementation of TEG transplantation and delivery of supplemental oxygen (DSO) has been shown to enhance TEG survival and function in vivo. In this study, we demonstrate the first use of oxygen-17 magnetic resonance spectroscopy (17O-MRS) to measure the oxygen consumption rate (OCR) of TEGs and show that in addition to providing therapeutic benefits to TEGs, DSO with 17O2 can also enable measurements of TEG viability. Macroencapsulated TEGs containing βTC3 murine insulinoma cells were prepared with three fractional viabilities and provided with 17O2. Cellular metabolism of 17O2 into nascent mitochondrial water (H217O) was monitored by 17O-MRS and, from the measured data, OCR was calculated. For comparison, OCR was simultaneously measured on a separate, but equivalent sample of cells with a well-established stirred microchamber technique. OCR measured by 17O-MRS agreed well with measurements made in the stirred microchamber device. These studies confirm that 17O-MRS can quantify TEG viability noninvasively. This article is protected by copyright. All rights reserved
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development and validation of noninvasive magnetic resonance relaxometry for the in vivo assessment of tissue Engineered Graft oxygenation
Tissue Engineering Part C-methods, 2016Co-Authors: Samuel A Einstein, Bradley P Weegman, Klearchos K Papas, Meri T Firpo, Michael GarwoodAbstract:Techniques to monitor the oxygen partial pressure (pO2) within implanted tissue-Engineered Grafts (TEGs) are critically necessary for TEG development, but current methods are invasive and inaccurate. In this study, we developed an accurate and noninvasive technique to monitor TEG pO2 utilizing proton (1H) or fluorine (19F) magnetic resonance spectroscopy (MRS) relaxometry. The value of the spin-lattice relaxation rate constant (R1) of some biocompatible compounds is sensitive to dissolved oxygen (and temperature), while insensitive to other external factors. Through this physical mechanism, MRS can measure the pO2 of implanted TEGs. We evaluated six potential MRS pO2 probes and measured their oxygen and temperature sensitivities and their intrinsic R1 values at 16.4 T. Acellular TEGs were constructed by emulsifying porcine plasma with perfluoro-15-crown-5-ether, injecting the emulsion into a macroencapsulation device, and cross-linking the plasma with a thrombin solution. A multiparametric calibration equation containing R1, pO2, and temperature was empirically generated from MRS data and validated with fiber optic (FO) probes in vitro. TEGs were then implanted in a dorsal subcutaneous pocket in a murine model and evaluated with MRS up to 29 days postimplantation. R1 measurements from the TEGs were converted to pO2 values using the established calibration equation and these in vivo pO2 measurements were simultaneously validated with FO probes. Additionally, MRS was used to detect increased pO2 within implanted TEGs that received supplemental oxygen delivery. Finally, based on a comparison of our MRS data with previously reported data, ultra-high-field (16.4 T) is shown to have an advantage for measuring hypoxia with 19F MRS. Results from this study show MRS relaxometry to be a precise, accurate, and noninvasive technique to monitor TEG pO2 in vitro and in vivo.
Cato T Laurencin - One of the best experts on this subject based on the ideXlab platform.
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tissue engineering of the anterior cruciate ligament using a braid twist scaffold design
Journal of Biomechanics, 2007Co-Authors: Joseph W Freeman, Mia D Woods, Cato T LaurencinAbstract:The anterior cruciate ligament (ACL) is the most commonly injured intra-articular ligament of the knee. The insufficient vascularization of this tissue prevents it from healing completely after extreme tearing or rupture, creating a need for ACL Grafts for reconstruction. The limitations of existing Grafts have motivated the investigation of tissue-Engineered ACL Grafts. A successful tissue-Engineered Graft must possess mechanical properties similar to the ACL; to date no commercially available synthetic Graft has achieved this. To accomplish this goal we have combined the techniques of polymer fiber braiding and twisting to design a novel poly L-lactic acid (PLLA) braid-twist scaffold for ACL tissue engineering. The scaffold is designed to accurately mimic the biomechanical profile and mechanical properties of the ACL. In this study, braid-twist scaffolds were constructed and compared to braided scaffolds and twisted fiber scaffolds. The addition of fiber twisting to the braided scaffold resulted in a significant increase in the ultimate tensile strength, an increase in ultimate strain, and an increase in the length of the toe region in these constructs over scaffolds that were braided. Based on the findings of this study, the braid-twist scaffold studied was found to be a promising construct for tissue engineering of the ACL.
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three dimensional bioactive biodegradable polymer bioactive glass composite scaffolds with improved mechanical properties support collagen synthesis and mineralization of human osteoblast like cells in vitro
Journal of Biomedical Materials Research Part A, 2003Co-Authors: Helen H Lu, Saadiq F Elamin, Kimberli D Scott, Cato T LaurencinAbstract:In the past decade, tissue engineering-based bone Grafting has emerged as a viable alternative to biological and synthetic Grafts. The biomaterial component is a critical determinant of the ultimate success of the tissue-Engineered Graft. Because no single existing material possesses all the necessary properties required in an ideal bone Graft, our approach has been to develop a three dimensional (3-D), porous composite of polylactide-co-glycolide (PLAGA) and 45S5 bioactive glass (BG) that is biodegradable, bioactive, and suitable as a scaffold for bone tissue engineering (PLAGA-BG composite). The objectives of this study were to examine the mechanical properties of a PLAGA-BG matrix, to evaluate the response of human osteoblast-like cells to the PLAGA-BG composite, and to evaluate the ability of the composite to form a surface calcium phosphate layer in vitro. Structural and mechanical properties of PLAGA-BG were measured, and the formation of a surface calcium phosphate layer was evaluated by surface analysis methods. The growth and differentiation of human osteoblast-like cells on PLAGA-BG were also examined. A hypothesis was that the combination of PLAGA with BG would result in a biocompatible and bioactive composite, capable of supporting osteoblast adhesion, growth and differentiation, with mechanical properties superior to PLAGA alone. The addition of bioactive glass granules to the PLAGA matrix resulted in a structure with higher compressive modulus than PLAGA alone. Moreover, the PLAGA-BA composite was found to be a bioactive material, as it formed surface calcium phosphate deposits in a simulated body fluid (SBF), and in the presence of cells and serum proteins. The composite supported osteoblast-like morphology, stained positively for alkaline phosphatase, and supported higher levels of Type I collagen synthesis than tissue culture polystyrene controls. We have successfully developed a degradable, porous, polymer bioactive glass composite possessing improved mechanical properties and osteointegrative potential compared to degradable polymers of poly(lactic acid-glycolic acid) alone. Future work will focus on the optimization of the composite scaffold for bone tissue-engineering applications and the evaluation of the 3-D composite in an in vivo model.
Hiromi Kurosawa - One of the best experts on this subject based on the ideXlab platform.
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midterm clinical result of tissue Engineered vascular autoGrafts seeded with autologous bone marrow cells
The Journal of Thoracic and Cardiovascular Surgery, 2005Co-Authors: Toshiharu Shinoka, Takeshi Konuma, Masayoshi Nagatsu, Narutoshi Hibino, Goki Matsumura, Yuji Naito, Manabu Watanabe, Takahiko Sakamoto, Hiromi KurosawaAbstract:Objective Prosthetic and bioprosthetic materials currently in use lack growth potential and therefore must be repeatedly replaced in pediatric patients as they grow. Tissue engineering is a new discipline that offers the potential for creating replacement structures from autologous cells and biodegradable polymer scaffolds. In May 2000, we initiated clinical application of tissue-Engineered vascular Grafts seeded with cultured cells. However, cell culturing is time-consuming, and xenoserum must be used. To overcome these disadvantages, we began to use bone marrow cells, readily available on the day of surgery, as a cell source. The aim of the study was to assess the safety and feasibility of this technique for creating vascular tissue under low-pressure systems such as pulmonary artery or venous pressure. Methods Since September 2001, tissue-Engineered Grafts seeded with autologous bone marrow cells have been implanted in 42 patients. The patients or their parents were fully informed and had given consent to the procedure. A 5-mL/kg specimen of bone marrow was aspirated with the patient under general anesthesia before the skin incision. The polymer tube serving as a scaffold for the cells was composed of a copolymer of l-lactide and ϵ-caprolactone (50:50). This copolymer is degraded by hydrolysis. The matrix is more than 80% porous, and the diameter of each pore is 20 to 100 μm. Polyglycolic acid woven fabric with a thickness of 0.5 mm was used for reinforcement. Twenty-three tissue-Engineered conduits (Grafts for extracardiac total cavopulmonary connection) and 19 tissue-Engineered patches were used for the repair of congenital heart defects. The patients' ages ranged from 1 to 24 years (median 5.5 years). All patients underwent a catheterization study, computed tomographic scan, or both, for evaluation after the operation. The patients received anticoagulation therapy for 3 to 6 months after surgery. Results Mean follow-up after surgery was 490 ± 276 days (1.3–31.6 months, median 16.7 months). There were no complications such as thrombosis, stenosis, or obstruction of the tissue-Engineered autoGrafts. One late death at 3 months after total cavopulmonary connection was noted in patient with hypoplastic left heart syndrome; this was unrelated to the tissue-Engineered Graft function. There was no evidence of aneurysm formation or calcification on cineangiography or computed tomography. All tube Grafts were patent, and the diameter of the tube Graft increased with time (110% ± 7 % of the implanted size). Conclusion Biodegradable conduits or patches seeded with autologous bone marrow cells showed normal function (good patency to a maximum follow-up of 32 months). As living tissues, these vascular structures may have the potential for growth, repair, and remodeling. The tissue-engineering approach may provide an important alternative to the use of prosthetic materials in the field of pediatric cardiovascular surgery. Longer follow-up is necessary to confirm the durability of this approach.
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extracardiac total cavopulmonary connection using a tissue Engineered Graft
The Journal of Thoracic and Cardiovascular Surgery, 2003Co-Authors: Yukihisa Isomatsu, Takeshi Konuma, Masayoshi Nagatsu, Narutoshi Hibino, Goki Matsumura, Toshiharu Shinoka, Hiromi KurosawaAbstract:Abstract Objective Extracardiac and lateral tunnel total cavopulmonary connection are currently 2 major options for patients with a single ventricle physiology. However, each procedure has some disadvantages over the other. We developed a new technique of extracardiac total cavopulmonary connection using a tissue-Engineered Graft to overcome some of the disadvantages previously associated with both the extracardiac and lateral tunnel procedures. Methods Between February 2001 and October 2002, 8 patients underwent an extracardiac total cavopulmonary connection using a tissue-Engineered Graft in our institution. Collected bone marrow cells (1 × 10 8 mononucleocytes) from a patient (∼1-4 mL/kg body weight) were seeded onto a biodegradable scaffold composed of polycaprolactone-polylactic acid copolymer reinforced with woven polylactic acid. After a 2- to 4-hour cultivation, the seeded scaffold was implanted as an extracardiac conduit during the total cavopulmonary connection operation. Results There were no hospital or late deaths. At a mean follow-up of 13.4 months (range 4-25 months), all patients are alive and asymptomatic with no need for repeat surgery. A postoperative catheter examination or computed tomography showed all tissue-Engineered Grafts to be patent and revealed no stenosis, obstruction, or aneurysmal change in the 8 patients. Conclusion We believe that extracardiac total cavopulmonary connection using a tissue-Engineered Graft has the potential to overcome some of the disadvantages previously associated with extracardiac or lateral tunnel total cavopulmonary connection. However, an extended follow-up period is required to clarify the long-term clinical outcome for the tissue-Engineered Graft.
Toshiharu Shinoka - One of the best experts on this subject based on the ideXlab platform.
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midterm clinical result of tissue Engineered vascular autoGrafts seeded with autologous bone marrow cells
The Journal of Thoracic and Cardiovascular Surgery, 2005Co-Authors: Toshiharu Shinoka, Takeshi Konuma, Masayoshi Nagatsu, Narutoshi Hibino, Goki Matsumura, Yuji Naito, Manabu Watanabe, Takahiko Sakamoto, Hiromi KurosawaAbstract:Objective Prosthetic and bioprosthetic materials currently in use lack growth potential and therefore must be repeatedly replaced in pediatric patients as they grow. Tissue engineering is a new discipline that offers the potential for creating replacement structures from autologous cells and biodegradable polymer scaffolds. In May 2000, we initiated clinical application of tissue-Engineered vascular Grafts seeded with cultured cells. However, cell culturing is time-consuming, and xenoserum must be used. To overcome these disadvantages, we began to use bone marrow cells, readily available on the day of surgery, as a cell source. The aim of the study was to assess the safety and feasibility of this technique for creating vascular tissue under low-pressure systems such as pulmonary artery or venous pressure. Methods Since September 2001, tissue-Engineered Grafts seeded with autologous bone marrow cells have been implanted in 42 patients. The patients or their parents were fully informed and had given consent to the procedure. A 5-mL/kg specimen of bone marrow was aspirated with the patient under general anesthesia before the skin incision. The polymer tube serving as a scaffold for the cells was composed of a copolymer of l-lactide and ϵ-caprolactone (50:50). This copolymer is degraded by hydrolysis. The matrix is more than 80% porous, and the diameter of each pore is 20 to 100 μm. Polyglycolic acid woven fabric with a thickness of 0.5 mm was used for reinforcement. Twenty-three tissue-Engineered conduits (Grafts for extracardiac total cavopulmonary connection) and 19 tissue-Engineered patches were used for the repair of congenital heart defects. The patients' ages ranged from 1 to 24 years (median 5.5 years). All patients underwent a catheterization study, computed tomographic scan, or both, for evaluation after the operation. The patients received anticoagulation therapy for 3 to 6 months after surgery. Results Mean follow-up after surgery was 490 ± 276 days (1.3–31.6 months, median 16.7 months). There were no complications such as thrombosis, stenosis, or obstruction of the tissue-Engineered autoGrafts. One late death at 3 months after total cavopulmonary connection was noted in patient with hypoplastic left heart syndrome; this was unrelated to the tissue-Engineered Graft function. There was no evidence of aneurysm formation or calcification on cineangiography or computed tomography. All tube Grafts were patent, and the diameter of the tube Graft increased with time (110% ± 7 % of the implanted size). Conclusion Biodegradable conduits or patches seeded with autologous bone marrow cells showed normal function (good patency to a maximum follow-up of 32 months). As living tissues, these vascular structures may have the potential for growth, repair, and remodeling. The tissue-engineering approach may provide an important alternative to the use of prosthetic materials in the field of pediatric cardiovascular surgery. Longer follow-up is necessary to confirm the durability of this approach.
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extracardiac total cavopulmonary connection using a tissue Engineered Graft
The Journal of Thoracic and Cardiovascular Surgery, 2003Co-Authors: Yukihisa Isomatsu, Takeshi Konuma, Masayoshi Nagatsu, Narutoshi Hibino, Goki Matsumura, Toshiharu Shinoka, Hiromi KurosawaAbstract:Abstract Objective Extracardiac and lateral tunnel total cavopulmonary connection are currently 2 major options for patients with a single ventricle physiology. However, each procedure has some disadvantages over the other. We developed a new technique of extracardiac total cavopulmonary connection using a tissue-Engineered Graft to overcome some of the disadvantages previously associated with both the extracardiac and lateral tunnel procedures. Methods Between February 2001 and October 2002, 8 patients underwent an extracardiac total cavopulmonary connection using a tissue-Engineered Graft in our institution. Collected bone marrow cells (1 × 10 8 mononucleocytes) from a patient (∼1-4 mL/kg body weight) were seeded onto a biodegradable scaffold composed of polycaprolactone-polylactic acid copolymer reinforced with woven polylactic acid. After a 2- to 4-hour cultivation, the seeded scaffold was implanted as an extracardiac conduit during the total cavopulmonary connection operation. Results There were no hospital or late deaths. At a mean follow-up of 13.4 months (range 4-25 months), all patients are alive and asymptomatic with no need for repeat surgery. A postoperative catheter examination or computed tomography showed all tissue-Engineered Grafts to be patent and revealed no stenosis, obstruction, or aneurysmal change in the 8 patients. Conclusion We believe that extracardiac total cavopulmonary connection using a tissue-Engineered Graft has the potential to overcome some of the disadvantages previously associated with extracardiac or lateral tunnel total cavopulmonary connection. However, an extended follow-up period is required to clarify the long-term clinical outcome for the tissue-Engineered Graft.
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creation of viable pulmonary artery autoGrafts through tissue engineering
The Journal of Thoracic and Cardiovascular Surgery, 1998Co-Authors: Toshiharu Shinoka, Dominique Shumtim, Peter X, Ronn E Tanel, Noritaka Isogai, Robert Langer, Joseph P Vacanti, John E MayerAbstract:Abstract Background: "Repair" of many congenital cardiac defects requires the use of conduits to establish right ventricle to pulmonary artery continuity. At present, available homoGrafts or prosthetic conduits lack growth potential and can become obstructed by tissue ingrowth or calcification leading to the need for multiple conduit replacements. Tissue engineering is an approach by which cells are grown in vitro onto biodegradable polymers to construct "tissues" for implantation. A tissue engineering approach has recently been used to construct living cardiac valve leaflets from autologous cells in our laboratory. This study assesses the feasibility of a tissue engineering approach to constructing tissue-Engineered "living" pulmonary artery conduits. Materials and methods: Ovine artery (group A, n = 4) or vein (group V, n = 3) segments were harvested, separated into individual cells, expanded in tissue culture, and seeded onto synthetic biodegradable (polyglactin/polyglycolic acid) tubular scaffolds (20 mm long × 15 mm diameter). After 7 days of in vitro culture, the autologous cell/polymer vascular constructs were used to replace a 2 cm segment of pulmonary artery in lambs (age 68.4 ± 15.5 days, weight 18.7 ± 2.0 kg). One other control animal received an acellular polymer tube sealed with fibrin glue without autologous cells. Animals were sacrificed at intervals of 11 to 24 weeks (mean follow-up 130.3 ± 30.8 days, mean weight 38.9 ± 13.0 kg) after echocardiographic and angiographic studies. Explanted tissue-Engineered conduits were assayed for collagen (4-hydroxyproline) and calcium content, and a tissue deoxyribonucleic acid assay ( bis- benzimide dye) was used to estimate number of cell nuclei as an index of tissue maturity. Results: The acellular control Graft developed progressive obstruction and thrombosis. All seven tissue-Engineered Grafts were patent and demonstrated a nonaneurysmal increase in diameter (group A = 18.3 ± 1.3 mm = 95.3% of native pulmonary artery; group V = 17.1 ± 1.2 mm = 86.8% of native pulmonary artery). Histologically, none of the biodegradable polymer scaffold remained in any tissue-Engineered Graft by 11 weeks. Collagen content in tissue-Engineered Grafts was 73.9% ± 8.0% of adjacent native pulmonary artery. Histologically, elastic fibers were present in the media layer of tissue-Engineered vessel wall and endothelial specific factor VIII was identified on the luminal surface. Deoxyribonucleic acid assay showed a progressive decrease in numbers of cell nuclei over 11 and 24 weeks, suggesting an ongoing tissue remodeling. Calcium content of tissue-Engineered Grafts was elevated (group A = 7.95 ± 5.09; group V = 13.2 ± 5.48; native pulmonary artery = 1.2 ± 0.8 mg/gm dry weight), but no macroscopic calcification was found. Conclusions: Living vascular Grafts Engineered from autologous cells and biodegradable polymers functioned well in the pulmonary circulation as a pulmonary artery replacement. They demonstrated an increase in diameter suggesting growth and development of endothelial lining and extracellular matrix, including collagen and elastic fibers. This tissue-engineering approach may ultimately allow the development of viable autologous vascular Grafts for clinical use.(J Thorac Cardiovasc Surg 1998;115:536-46)
Dongwoo Cho - One of the best experts on this subject based on the ideXlab platform.
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development of a 3d cell printed structure as an alternative to autologs cartilage for auricular reconstruction
Journal of Biomedical Materials Research Part B, 2017Co-Authors: Ju Young Park, Jinhyung Shim, Yeongjin Choi, Jeong Hun Park, Dongwoo ChoAbstract:Surgical technique using autologs cartilage is considered as the best treatment for cartilage tissue reconstruction, although the burdens of donor site morbidity and surgical complications still remain. The purpose of this study is to apply three-dimensional (3D) cell printing to fabricate a tissue-Engineered Graft, and evaluate its effects on cartilage reconstruction. A multihead tissue/organ building system is used to print cell-printed scaffold (CPS), then assessed the effect of the CPS on cartilage regeneration in a rabbit ear. The cell viability and functionality of chondrocytes were significantly higher in CPS than in cell-seeded scaffold (CSS) and cell-seeded hybrid scaffold (CSHS) in vitro. CPS was then implanted into a rabbit ear that had an 8 mm-diameter cartilage defect; at 3 months after implantation the CPS had fostered complete cartilage regeneration whereas CSS and autologs cartilage (AC) fostered only incomplete healing. This result demonstrates that cell printing technology can provide an appropriate environment in which encapsulated chondrocytes can survive and differentiate into cartilage tissue in vivo. Moreover, the effects of CPS on cartilage regeneration were even better than those of AC. Therefore, we confirmed the feasibility of CPS as an alternative to AC for auricular reconstruction. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1016-1028, 2017.