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At least 973 records · Page 54Linked to original sources
PubMed1999

[A study on guided tissue regeneration and tissue engineering-transplantation of collagen membrane seeded with cultured hyaline chondrocytes].

OBJECTIVE: Lack of transplant material is a main problem in the repair and reconstruction of tissue or organ defects. To seek the succedaneum of transplants, we studied and used tissue-engineered growth hyaline cartilage. METHODS: The articular hyaline cartilage obtained from newborn calf within 6 hours of sacrifice was enzymatically dissolved. The chondrocytes were then seeded onto the medical collagen membrane of guided tissue regeneration in a 24 well plate in RPMI1640 medium. One week later, the chondrocyte medical collagen membrane of guided tissue regeneration complex was implanted subcutaneously into the back of nude mice. Eight weeks after implantation, the animals were sacrificed. RESULTS: The present study seems to demonstrate that the cartilage-like tissue was strong enough to be transferred after being implanted for 8 weeks. The cartilage-like tissue was proved to be tissue-engineered hyaline cartilage by HE stain. The chondrocytes could secrete chondroitin sulfate as proved by Lev-Spicer stain. CONCLUSION: Tissue engineering technique was used to make tissue-engineered cartilage in vitro. It will provide a new transplant material for the repair of tissue or organ defects.

Animals↗
PubMed2002

Germline engineering: the moral challenges.

Not only is the use of germline genetic engineering likely in the long run to be inevitable, there are also no convincing secular moral grounds to forbid this technology in principle. Instead, the general secular moral constraints on the use of germline genetic engineering are either procedural or without predetermined content. Nor can one develop a coherent distinction between eliminating disease and enhancing human abilities. At best, in secular morality one can establish the principle to proceed with care, though the invocation of the precautionary principle argues as much in favor of the development of germline genetic engineering as against its use. Because germline genetic engineering, by eliminating certain genetic defects, offers the prospect of decreasing human suffering and decreasing the use of prenatal diagnosis and abortion, there is an obligation, all else being equal, to change the human genome. In a post-modern world, humans face the challenge of directing their own evolution, although they share no common understanding of human destiny and purpose. Such understandings, though available within religious contexts, are not available to secular bioethics.

Bioethics↗
PubMed1999

[The experimental study on optimal cell density and formation time of tissue engineered autologous cartilage].

OBJECTIVE: This paper aims to investigate the suitable cell density and the best formation time of tissue engineered autologous cartilage and to provide theoretical basis and parameters for clinical application. METHODS: The chondrocytes isolated from mini swines' ears were mixed with injectable biocompatible matrix (Pluronic), and the density of cell suspensions were 10, 20, 30, 40, 50, 60, 70 x 10(4)/ml. The chondrocyte-polymer constructs were subcutaneously injected into the abdomen of autologous swine. The specimens were observed grossly and histologically after 6 weeks, and investigated the suitable cell density. Then the chondrocyte-polymer constructs with suitable cell density were transplanted into the abdomen of autologous swine and evaluated grossly and histologically in 1, 3, 6, 9, 15 weeks after transplantation to investigate the best formation time of tissue engineered cartilage. RESULTS: The experiments demonstrated that the tissue engineered autologous cartilage was similar to the natural cartilage on animals with normal immune system in histological characteristics. The optimal chondrocyte density is 50 x 10(6)/ml, and the proper harvest time is the sixth week. CONCLUSION: With tissue engineering skills, we have identified the optimal chondrocyte density and the proper harvest time.

Animals↗
PubMed2002

Growth factors in cartilage tissue engineering.

Tissue engineering of cartilage consists of two steps. Firstly, the cells from a small biopsy of patient's own tissue have to be multiplied. During this multiplication process they lose their cartilage phenotype. In the second step, these cells have to be stimulated to re-express their cartilage phenotype and produce cartilage matrix. Growth factors can be used to improve cell multiplication, redifferentiation and production of matrix. The choice of growth factors should be made for each phase of the tissue engineering process separately, taking into account cell phenotype and the presence of extracellular matrix. This paper demonstrates some examples of the use of growth factors to increase the amount, the quality and the assembly of the matrix components produced for cartilage tissue engineering. In addition it shows that the "culture history" (e.g., addition of growth factors during cell multiplication or preculture period in a 3-dimensional environment) of the cells influences the effect of growth factor addition. The data demonstrate the potency as well as the limitations of the use of growth factors in cartilage tissue engineering.

Animals↗
PubMed2002

Bioreactor studies of native and tissue engineered cartilage.

Functional tissue engineering of cartilage involves the use of bioreactors designed to provide a controlled in vitro environment that embodies some of the biochemical and physical signals known to regulate chondrogenesis. Hydrodynamic conditions can affect in vitro tissue formation in at least two ways: by direct effects of hydrodynamic forces on cell morphology and function, and by indirect flow-induced changes in mass transfer of nutrients and metabolites. In the present work, we discuss the effects of three different in vitro environments: static flasks (tissues fixed in place, static medium), mixed flasks (tissues fixed in place, unidirectional turbulent flow) and rotating bioreactors (tissues dynamically suspended in laminar flow) on engineered cartilage constructs and native cartilage explants. As compared to static and mixed flasks, dynamic laminar flow in rotating bioreactors resulted in the most rapid tissue growth and the highest final fractions of glycosaminoglycans and total collagen in both tissues. Mechanical properties (equilibrium modulus, dynamic stiffness, hydraulic permeability) of engineered constructs and explanted cartilage correlated with the wet weight fractions of glycosaminoglycans and collagen. Current research needs in the area of cartilage tissue engineering include the utilization of additional physiologically relevant regulatory signals, and the development of predictive mathematical models that enable optimization of the conditions and duration of tissue culture.

Animals↗
PubMed2002

[Comparative study on graft of autogeneic iliac bone and tissue engineered bone].

OBJECTIVE: To compare the clinical results of repairing bone defect of limbs with tissue engineering technique and with autogeneic iliac bone graft. METHODS: From July 1999 to September 2001, 52 cases of bone fracture were randomly divided into two groups (group A and B). Open reduction and internal fixation were performed in all cases as routine operation technique. Autogeneic iliac bone was implanted in group A, while tissue engineered bone was implanted in group B. Routine postoperative treatment in orthopedic surgery was taken. The operation time, bleeding volume, wound healing and drainage volume were compared. The bone union was observed by the X-ray 1, 2, 3, and 5 months after operation. RESULTS: The sex, age and disease type had no obvious difference between groups A and B. all the wounds healed with first intention. The swelling degree of wound and drainage volume had no obvious difference. The operation time in group A was longer than that in group B (25 minutes on average) and bleeding volume in group A was larger than that in group B (150 ml on average). Bone union completed within 3 to 7 months in both groups. But there were 2 cases of delayed union in group A and 1 case in group B. CONCLUSION: Repair of bone defect with tissue engineered bone has as good clinical results as that with autogeneic iliac bone graft. In aspect of operation time and bleeding volume, tissue engineered bone graft is superior to autogeneic iliac bone.

Adolescent↗
PubMed2000

[Huge thoracic wall defect repaired by tissue engineered bone transplantation].

OBJECTIVE: A rare huge desmoplastic fibroma on thoracic wall in 1 female case of 25 years old was resected, and the accompanying huge thoracic wall defect, ribs and soft tissues were repaired by tissue engineered bone and pedicled flap. The paper aims to explore the clinical results of early stage after operation. METHODS: Autogeneic bone marrow stromal cells (MSC) were obtained from bone marrow puncture of iliac bone and isolated and cultured according to the Houghton's methods, MSC were directively induced and differentiated to osteoblasts. Allogeneic ribs were made to the bio-derived bone scaffold materials after treatment of decell, deantigen, decalcification and dry freezing. 5 x 10(6)/ml MSC were cocultured with the bio-derived bone for 6 days in vitro. After intact resection of tumor, the diaphragm flap was applied to repair pleural cavity, the three defect ribs were repaired by tissue engineered bone and the soft tissue defect was repaired by transfer of pedicled ipsilateral abdominal flaps. RESULTS: The patient recovered well with first intention. Followed up for 3 months, tissue engineered ribs were matured in vitro and the heart and pulmonary functions were improved markedly. CONCLUSION: The tissue engineered bone constructed by autogeneic MSC is advantageous in individual treatment.

Adult↗
PubMed2002

[Theories and methodologies of engineering designs on sustainable agricultural land consolidation project--a case study of Xuemeiyang land consolidation project in Changtai County, Fujian Province].

The concept and characteristics of engineering designs on sustainable agricultural land consolidation project were discussed in this paper. Principles, basic methods and procedures of engineering designs on agricultural land consolidation project were put forward, which were successfully adopted for designing agricultural land consolidation in Xuemeiyang region of Changtai County, including diversity designs of sustainable land use, engineering designs of soil improvement, roads, ditches, and drains for protecting existent animal environments, and design of ecological shelter-forests in farmland. Moreover, from sustainable economic, ecological and social points, the results of these engineering designs were evaluated based on fouteen important indexes. After carrying out these engineeringdesigns, the eco-environments and agricultural production conditions were significantly improved, and the farm income was increased in planned regions.

Agriculture↗
PubMed2002

[Bio-derived bone transplantation with tissue engineering technique: preliminary clinical trial].

OBJECTIVE: To sum up the clinical results of bio-derived bone transplantation in orthopedics with tissue engineering technique. METHODS: From January 2000 to May 2002, 52 cases with various types of bone defect were treated with tissue engineered bone, which was constructed in vitro by allogeneous osteoblasts from periosteum (1 x 10(6)/ml) with bio-derived bone scaffold following 3 to 7 days co-culture. Among them, there were 7 cases of bone cyst, 22 cases of non-union or malunion of old fracture, 15 cases of fresh comminuted fracture of bone defect, 4 cases of spinal fracture and posterior route spinal fusion, 3 cases of bone implant of alveolar bone, 1 case of fusion of tarsotarsal joint. The total weight of tissue engineered bone was 349 g in all the cases, averaged 6.7 g in each case. RESULTS: All the cases were followed up after operation, averaged in 18.5 months. The wound in all the case healed by first intention, but 1 case with second intention. Bone union was completed within 3 to 4.5 months in 50 cases, but 2 cases of delayed union. Six cases were performed analysis of CD3, CD4, CD8, ICAM-1 and VCAM-1 before and after operation, and no obvious abnormities were observed. CONCLUSION: Bio-derived tissue engineered bone has good osteogenesis. No obvious rejection and other complications are observed in the clinical application.

Bone Substitutes↗
PubMed2002

[Advances in research and development of tissue engineering].

OBJECTIVE: From the point of view of material science, the methods of tissue repair and defect reconstruct were discussed, including mesenchymal stem cells (MSCs), growth factors, gene therapy and tissue engineered tissue. METHODS: The advances in tissue engineering technologies were introduced based on the recent literature. RESULTS: Tissue engineering should solve the design and preparation of molecular scaffold, tissue vascularization and dynamic culture of cell on the scaffolds in vitro. CONCLUSION: Biomaterials play an important role in the tissue engineering. They can be used as the matrices of MSCs, the delivery carrier of growth factor, the culture scaffold of cell in bioreactors and delivery carrier of gene encoding growth factors.

Biocompatible Materials↗
PubMed2003

Witnessing a revolution in voice research: genomics, tissue engineering, biochips and what's next!

Due to advances in genomics and tissue engineering, new tools and methods are available for use in voice research. Microarray analysis, a method for examining the expression levels of thousand of genes within 24-48 hours, is a very powerful research tool and has greatly hastened the development of biochips for medical application. The use of microarray analysis in voice research will be discussed and the feasibility of a biochip for voice is presented. Gene expression profiles, a fundamental part of biochip development, are now commonly performed in some voice laboratories. Tissue engineering initiatives have led to the ability to grow and work with laryngeal fibroblasts, Because of the extreme conditions (intense vibration, exposure to inhalants, etc.) that vocal fold fibroblasts tolerate, engineering living lamina propria of vocal folds is complex and challenging. Research efforts to explore these conditions in-vitro and their effect on fibroblast growth is detailed. In summary, applying tools from genomic and tissue engineering fields to vocal science is fruitful and holds great clinical promise.

Down-Regulation↗
PubMed2003

[The experimental study of tissue engineered autologous cartilage using chitosan-gelatin complex scaffolds].

OBJECTIVE: To investigate whether man-made porous chitosan-gelatin complex scaffold was a appropriate scaffold for tissue engineering cartilage. METHODS: Chondrocytes isolated from Changfeng crossbred swines' auricular cartilage were seeded onto chitosan- gelatin scaffolds to be cultured in a three dimensional environment. The chondrocyte- polymer constructs were implanted into the subcutaneous tissue of the swines' abdomenal wall. Specimens were harvested and analyzed by gross observation, histology, type II collagen immunohistochemistry and biochemistry after 10 and 16 weeks in vivo respectively. RESULTS: H.E staining showed cartilage was formed, and chondrocytes were enclosed in lacuna with histological characteristics similar to natural cartilage. Some clusters of neocartilage surrounded by fibrous tissues were observed. Elastic fibres were observed in the mesenchyma of cartilage 16 weeks after by Vehoeff's staining. Immunohistochemical staining of the neocartilage with anti- type II collagen showed the presence of type II collagen in the ECM of tissue engineered cartilage. The proteoglycans content in tissue engineered cartilage was close to that of natural swine's auricular cartilage. CONCLUSION: The experiments demonstrated that using chitosan-gelatin complex scaffold we can generate autologous cartilage on animals with normal immune system. Porous chitosan- gelatin complex scaffolds may be a suitable scaffolds for tissue engineered cartilage.

Animals↗
PubMed2003

[Experimental study of tissue engineered blood vessel with vascular endothelial cell and vascular smooth muscle cell].

OBJECTIVE: To investigate the feasibility to seed vascular endothelial cell(VEC) and vascular smooth muscle cell (VSMC) into tissue engineered blood vessel scaffold material. METHODS: 1. A blood vessel scaffold with a combined polymer was designed, which mainly is composed of rabbit VSMC and collagen with reinforcement by a non-spinning fabric mesh made of polyglycolic acid (PGA). 2. VEC were isolated from rabbit thoracic aorta by enzyme digestion methods and subcultured and purified. Then the cells were seeded into scaffold material. The morphological characteristics of tissue engineered blood vessel was analyzed by scanning electron microscopy. RESULTS: VEC could adhere well to the inner surface of the tissue engineered tubular scaffold material with a tenacity and elasticity. VSMC could sustain bioactivity of cell. CONCLUSION: Non-spinning PGA porous biodegradable materials coated with collagen is benefit for cells to adhere and grow. It will lay a foundation of a laminated structure of tissue engineered blood vessel.

Animals↗
PubMed1992

Biomedical engineering. A means to add new dimension to medicine and research.

Biomedical engineering is an evolving science that seeks to insert technically oriented and trained personnel to assist medical professionals in solving technological problems in the pursuit of innovations in the delivery of health care. Consequently, engineering solutions are brought to bear on problems that previously were outside the training of physicians and beyond the understanding or appreciation of the conventionally educated electrical or mechanical engineers. This physician/scientist/engineer team has a capability to extend medicine and research far beyond the capability of a single entity operating alone. How biomedical engineering has added a new dimension to medical science at the Kennedy Space Center is described.

Adaptation, Physiological↗
PubMed2003

[Maxillary growth following tissue engineered oral mucosal implantation on mucoperiosteal denudated palate process in young rat].

OBJECTIVE: To observe the effectiveness of prevention and cure for maxillary growth deformity following tissue engineered oral mucosa implantation on mucoperiosteal denuded palate process in young rat. METHODS: Hard palate mucoperiosteum of a SD baby rat were excised and oral keratinocytes were isolated and cultured. Tissue engineered oral mucosa was fabricated with the cultured oral keratinocytes and the membrane made of sodium alginate (SA). 80 female three-week-old SD rats were used as subjects in this study. The animals were divided randomly into a normal control group and 3 experimental groups, each group included 20 rats. Normal control group (NG) were not operated. Hard palate mucoperiosteum on left side in all experimental groups were excised, exposed bone were not treated in denuded group (DG), but repaired with membrane in material group (MG) and repaired with the tissue engineered oral mucosa in mucosal group (MUG). All the animals were sacrificed at 9th week postoperatively (12 weeks old), and the clean widths of right and left hard palatal were measured under a dissection microscope. The difference between palatal widths of two sides and the asymmetry ratio between the different groups were compared and analyzed. RESULTS: No significant difference in asymmetry was discovered between the DG and the MG, but the asymmetry in MUG was less than DG or MG. CONCLUSION: Tissue engineered oral mucosal implantation in palatoplasty is an effective method in preventing and curing secondary maxilla deformity by repairing denuded bone wound.

Animals↗
PubMed2003

[Repair of upper tibial epiphyseal defect with engineered epiphyseal cartilage in rabbits].

OBJECTIVE: To observe the effect of engineered epiphyseal cartilage regenerated in vitro with 3-D scaffold by chondrocytes from epiphyseal plate in repairing the tibial epiphyseal defect, and to explore the methods to promote the confluence between engineered cartilage and epiphyseal plate. METHODS: Chondrocytes were isolated enzymatically from the epiphyseal plates of immature rabbits, and then planted into the tissue culture flasks and cultivated. The first passage chondrocytes were collected and mixed fully with the self-made liquid biological gel at approximately 2.5 x 10(7) cells/ml to form cell-gel fluid. The cell-gel fluid was dropped into the porous calcium polyphosphate fiber/poly-L-lactic acid(CPPf/PLLA)scaffold, and a cell-gel-scaffold complex formed after being solidified. The defect models of 40% upper tibial epiphyseal plate were made in 72 immature rabbits; they were divided into 4 groups: group A(the cell-gel-scaffold complex was transplanted into the defect and the gap filled with chondrocyte-gel fluid), group B (with noncell CPPf/PLLA scaffold), group C(with fat) and group D(with nothing). The changes of roentgenograph, gross and histology were investigated after 2, 4, 6, 8, 12 and 16 weeks of operation. RESULTS: In group A, the typical histological structure of epiphyseal plate derived from the engineered cartilage with a fine integration between host and donor tissues after 2 weeks. The repaired epiphyseal plate had normal histological structure without deformation of tibia after 4 weeks. The early histological change of epiphyseal closure appeared in the repaired area with varus and shortening deformation of the tibia after 8 weeks. The epiphyseal plate was closed in the repaired area with more evident deformation of tibia; the growth function of repaired epiphyseal plate was 43.6% of the normal one. In groups B, C and D, deformation of tibia occurred after 2 weeks; the defect area of epiphyseal plate was completely closed after 4 weeks. The deformation was very severe without growth of the injured epiphyseal plate after 16 weeks, and no significant difference was observed between the three groups. CONCLUSION: Engineered epiphyseal cartilage can repair the epiphyseal defect in the histological structure with partial recovery of the epiphyseal growth capability. Injecting the suspension of fluid chondrocyte-gel into the defects induces a fine integration of host and donor tissues.

Animals↗
PubMed2003

[The study of hBMP-4 gene modified tissue-engineered bone].

OBJECTIVE: Bone marrow stromal cells (bMSCs) of rabbits transferred with mammalian hBMP-4 expression plasmid were used to construct tissue-engineered bone. Gene therapy combined with tissue-engineering technique was explored to further improve osteogenesis. METHODS: pEGFP-hBMP-4 plasmid was constructed by subcloning technique. bMSCs were then transferred with either pEGFP-hBMP-4, pEGFP plasmid by lipofectamine or left uninfected in vitro. The cells from the 3 groups were combined with natural non-organic bone (NNB) to construct tissue-engineered bones, which were subcutaneously implanted into nude mice (6 implants per group) for 4 weeks. Specimens were evaluated through histological and computerized new bone formation analysis. RESULTS: pEGFP-hBMP-4 plasmid was successfully constructed. bMSCs could attach and proliferate on the surface on NNB. In vivo experiment showed that new bone formation in pEGFP-hBMP-4 group was higher than those of the control groups. CONCLUSIONS: Tissue-engineered bone using hBMP-4 gene modified bMSCs might be an ideal alternative for the repair of bone.

Animals↗
PubMed2003

[Mesenchymal stem cells for tissue engineering of bone and cartilage].

The adult bone marrow contains mesenchymal stem cells. These cells show the capacity to undergo an extensive replication in vitro. In addition, mesenchymal stem cells have the potential to develop either in vitro or in vivo into mesenchymal tissues like bone and cartilage, which suggests these cells being an attractive source for tissue engineering approaches. Tissue engineering allows to isolate patient's own cells from tissue biopsies, to expand them, to combine them with carrier materials and growth factors, and to retransplant the constructs into the patient. Due to the prerequisite for tissue engineering to ensure a sufficient number of tissue-specific cells, much attention has been drawn to multipotential progenitor cells such as mesenchymal stem cells. In this article, important aspects of tissue engineering of bone and cartilage will be reviewed with emphasis on mesenchymal stem cells.

Bone Regeneration↗