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At least 991 records · Page 55Linked to original sources
PubMed2004

[Study status of collagen-based biomaterials in drug release and tissue engineering].

OBJECTIVE: To introduce the development of the collagen materials in drug release and tissue engineering. METHODS: Literature review and complex analysis were adopted. RESULTS: In recent years, some good progress has been made in the studies of collagen, and study on collagen-based materials has become an investigative hotspot especially in tissue engineering. Some new collagen-based drug delivery and engineered materials have come into clinically-demonstrated moment, which will promote their clinical applications in tissue repairs. CONCLUSION: Collagen has been considered a good potential material in drug release, especially in the tissue-engineering field. To give collagen new characters we should pay more attention to grafting with different function branches through chemistry technique in the future work, except moderate cross-linking treatment or commingling with other nature or synthesized macromolecules.

Biocompatible Materials↗
PubMed2004

[A study on the effects of cells and scaffolds tissue engineering on the periodontal regeneration].

OBJECTIVE: To observe the effects of cells and scaffolds tissue engineering on the periodontal regeneration, and to evaluate the feasibility of nano-Hap-collagen (nHAC) as the scaffold material for periodontal tissue engineering. METHODS: Dog autogenous periodontal ligament cells (PDLCs) cultured in vitro were collected and seeded on the three-dimensional framework of nHAC. The cell growth in the scaffolds was observed by scanning electron microscope. And then the PDLCs-nHAC composites were transplanted into man-made periodontal defects, and the groups filled with nothing or filled only with nHAC were the controls. The dogs were sacrificed after 8 weeks and the periodontal regeneration was observed histologically. RESULTS: Scanning electron microscope showed the porous structure of nHAC and the eugonic growth of cells in the nHAC scaffolds. The histological observation showed that the PDLCs-nHAC groups exhibited more new bone, new periodontal ligament and new cementum occupying the majority of the defects than the control groups, and the epitheliums were not observed. CONCLUSIONS: Periodontal regeneration could be enhanced by the cells and scaffolds tissue engineering, and the PDLCs and nHAC could be used as the seed cell and the scaffold material for periodontal tissue engineering.

Animals↗
PubMed2004

[Research advance of corneal tissue engineering].

OBJECTIVE: To review research progress of corneal tissue engineering. METHODS: The recent articles on corneal tissue engineering focus on source and selection of corneal cells, the effects of growth factors on culture of corneal cells in vitro. The preparation and selection of three-dimensional biomaterial scaffolds and their strong and weak points were discussed. RESULTS: The corneal tissue engineering cells come from normal human corneal cells. The embryo corneal cell was excellent. Several kinds of growth factors play important roles in culture, growth and proliferation of corneal cell, and incorporated into matrix. Growth factors including basic fibroblast growth factor, keratinocyte growth factor, transforming growth factor beta 1 and epidermal growth factor was favor to corneal cell. Collagen, chitosan and glycosaninoglycans were chosen as biomaterial scaffolds. CONCLUSION: Human tissue engineering cornea can be reconstructed and transplanted. It has good tissue compatibility and can be used as human corneal equivalents.

Biocompatible Materials↗
PubMed2004

[Subcloning of human neurotrophin-3 gene and construction of its genetically engineered cell model].

OBJECTIVE: To subclone human neurotrophin-3 gene (NT3) and transfer this gene into human bone marrow mesenchymal stem cells (BM-MSCs) to construct genetically engineered cells that produce NT3 in vitro. METHODS: Human BM-MSCs were cultured in low-glucose DMEM supplemented with 10% fetal bovine serum and 10 ng/ml epidermal growth factor. Flow cytometry (FCM) was used to examine the phenotypes of the cells. The eukaryotic expression vector pcDNA3.1(+)/NT3 was constructed and transferred into human BM-MSCs in vitro via liposomes. The genetically engineered BM-MSCs were selected several times with G418 and the clones were obtained and then amplified, followed by extraction of the RNA for detection of NT3 gene expression by reverse transcriptional (RT) PCR. The biological activity of the genetically engineered cells was examined by the collecting the supernatant of the culture medium for incubation of guinea pig cochlea hair cells. RESULTS: The cultured cells expressed CD13, CD29 and CD59, but no7 CD11, CD14, CD31, CD34, CD45, CD80, CD86, CD117 or HLA-DR. The BM-MSCs genetically modified with pcDNA3.1(+)/NT3 not only expressed and produced NT3, but also promoted the survival of the guinea pig cochlea hair cells in vitro. CONCLUSION: It is possible to construct the genetically engineered BM-MSCs that excrete NT3 in vitro.

Animals↗
PubMed2004

Functional tissue engineering of chondral and osteochondral constructs.

Due to the prevalence of osteoarthritis (OA) and damage to articular cartilage, coupled with the poor intrinsic healing capacity of this avascular connective tissue, there is a great demand for an articular cartilage substitute. As the bearing material of diarthrodial joints, articular cartilage has remarkable functional properties that have been difficult to reproduce in tissue-engineered constructs. We have previously demonstrated that by using a functional tissue engineering approach that incorporates mechanical loading into the long-term culture environment, one can enhance the development of mechanical properties in chondrocyte-seeded agarose constructs. As these gel constructs begin to achieve material properties similar to that of the native tissue, however, new challenges arise, including integration of the construct with the underlying native bone. To address this issue, we have developed a technique for producing gel constructs integrated into an underlying bony substrate. These osteochondral constructs develop cartilage-like extracellular matrix and material properties over time in free swelling culture. In this study, as a preliminary to loading such osteochondral constructs, finite element modeling (FEM) was used to predict the spatial and temporal stress, strain, and fluid flow fields within constructs subjected to dynamic deformational loading. The results of these models suggest that while chondral ("gel alone") constructs see a largely homogenous field of mechanical signals, osteochondral ("gel bone") constructs see a largely inhomogeneous distribution of mechanical signals. Such inhomogeneity in the mechanical environment may aid in the development of inhomogeneity in the engineered osteochondral constructs. Together with experimental observations, we anticipate that such modeling efforts will provide direction for our efforts aimed at the optimization of applied physical forces for the functional tissue engineering of an osteochondral articular cartilage substitute.

Biocompatible Materials↗
PubMed2004

[Histologic pattern and mechanical properties of tissue-engineered tendon implants for tendon defects].

This is a study on the histologic pattern and mechanical properties of tissue-engineered tendon implanted for treatment of tendon defects. Tendons were resected from Roman chickens. Tendon cells were isolated from the tendons and cultured in vitro. The 2nd-4th passages of tendon cells were seeded on the degradable polyglycolic acid mesh to form cell-scaffold composites, which were further cultured for 7-10 days to construct tissue-engineered tendons. The tendon defects, 0.5 cm-0.8 cm in length, were made in the second digit flexor tendon bilaterally in 20 Roman chickens and then bridged with the constructed tissue-engineered tendons. At 2 weeks, 4 weeks, 6 weeks, and 8 weeks post-operation, the samples of regenerated tendons were collected for gross examination, histologic staining and biomechanical test. After implantation of the tissue-engineered tendons, the wounds healed well. The gross appearance, the cells and collagen fibers arrangement of the regenerated tendons were similar to those of natural tendons, but there were relatively not many closely packed collagen fiber bundles organized in parallel with the tendons ("remodel"), so the maximum tensile force increased slowly and its value was 15.40+/-10.63 N at 8 weeks after surgery, reaching only 23% of that of natural tendon. The maximum strain was 22.49%+/-10.21% at 8 weeks, being 10% higher than that of natural tendons. Polyglycolic acid scaffolds are degraded in vivo so rapidly that the regenerated tendons lose the normal biomechanical stimulus and then are unable to be remodeled. As a result, the mechanical strength of regenerated tendons is much lower than that of natural tendons. These results suggest that the normal biomechanical stimulus may be an important factor for the regenerated tendons to remodel.

Animals↗
PubMed2004

[The research progress of zebrafish gene engineering].

The research progress of zebrafish gene engineering is reviewed, in including the recent explosion status of transgenic zebrafish lines, transgeneic zebrafish in targeted screens, the development of transgenic technology in zebrafish as well as the current hotspots and future perspective of zebrafish gene engineering. By now the zebrafish gene engineering, nuclear transplantation and chromosome set manipulation technologies have been established in China. With firm foundation of zebrafish cytogenetics and embryology, we will obtain gene engineering zebrafish with gene targeting integration and promote the advancement and development of biotechnology in applied research field in near future.

Animals↗
PubMed2004

[The application and advancement of rapid prototyping technology in bone tissue engineering].

In bone tissue engineering, a highly porous artificial extracellular matrix or scaffold is essential to the attachment, proliferation and differentiation of bone cells (osteoblast, osteoclast and osteocytes) and the formation of bone tissue. However, conventional scaffold materials for bone tissue engineering proved less valuable for actual applications because they lack mechanical strength, interconnected channel network, and controllable porosity or channel size. Therefore,to explore the ideal scaffold materials is one of the popular studies on current bone tissue engineering. In this paper, we review, the application and advancement of a newly-developed technology generally known as rapid prototyping (RP) techniques in bone tissue engineering.

Bone Substitutes↗
PubMed2005

[Research progress in genetic engineering of plant secondary metabolism].

Secondary metabolism plays an important role in plant life as well as the interaction between plants and environmental factors. Many secondary metabolites derived from plants have been used for the production of medicines, dyes, insecticides, food flavors, fragrances and so on. With increasingly comprehensive understanding of the plant metabolic networks, great progress has been made in the genetic improvement of plant secondary metabolic pathways through gene engineering. Strategies for the genetic engineering of plant secondary metabolism include: (1) enabling the host plant to accumulate a novel desirable compound by transformation of single/multiple enzyme gene (s) or a whole metabolic pathway; (2) decreasing target gene expression or inhibiting competitive metabolic pathway to achieve metabolic flux towards higher production of particular molecules through antisense RNA and RNA interference technologies; (3) effectively manipulating the transcription factors responsible for the metabolic regulation at multiple steps in a given pathway so as to have a great synthesis of the target bio-chemicals. Basing on author's research work on flavonoid synthesis mechanism in soybean seed and its gene engineering, recent progress in the engineering of plant secondary metabolism involved in the synthesis of anthocyanins, flavonoids, alkaloids, terpenoids, benzoic acid derivatives etc are reviewed.

Gene Expression Regulation, Plant↗
PubMed2005

Mesenchymal stem cells in musculoskeletal tissue engineering: a review of recent advances in National University of Singapore.

A key factor in the tissue engineering approach to tissue repair and regeneration is the use of appropriate cells. Mesenchymal stem cells (MSCs) are derived from bone marrow stroma or connective tissues and they have the potential to differentiate into various mesenchymal cell lines in vitro and in vivo. These cells hold great promise for musculoskeletal tissue engineering. This review is based mainly on the work which has been done in the National University of Singapore on the use of MSCs for engineering cartilage, growth plate, bone and tendon/ligament as well as the clinical trail of autologous chondrocyte implantation. It can help to shape future research on musculoskeletal tissue engineering.

Animals↗
PubMed2005

[Experimental study on biomechanics characteristics of combined collagen tissue engineering tendon].

OBJECTIVE: To investigate the influence of collagen on the biomechanics strength of tissue engineering tendon. METHODS: All of 75 nude mice were made the defect models of achilles tendons, and were divided into 5 groups randomly. Five different materials including human hair, carbon fibre (CF), polyglycolic acid (PGA), human hair and PGA, and CF and PGA with exogenous collagen were co-cultured with exogenous tendon cells to construct the tissue engineering tendons. These tendons were implanted to repair defect of achilles tendons of right hind limb in nude mice as experimental groups, while the materials without collagen were implanted to repair the contralateral achilles tendons as control groups. In the 2nd, 4th, 6th, 8th and 12th weeks after implantation, the biomechanical characteristics of the tissue engineering tendon was measured, meanwhile, the changes of the biomechanics strength were observed and compared. RESULTS: From the 2nd week to the 4th week after implantation, the experimental groups were stronger than the control groups in biomechanics, there was statistically significant difference (P < 0.05). From the 6th to 12th weeks, there was no statistically significant difference between the experiment and control groups (P > 0.05). Positive correlation existed between time and intensity, there was statistically significant difference (P < 0.05). The strength of materials was good in human hair, followed by CF, and PGA was poor. CONCLUSION: Exogenous collagen can enhance the mechanics strength of tissue engineering tendon, and is of a certain effect on affected limb

Animals↗
PubMedDate not supplied

Clinical engineering in Romania. The coming of age.

Biomedical engineering (BME) includes clinical engineering and bioengineering. Bioengineering is academically oriented towards theory and research in biology using the methods of exact sciences such as maths and physics, while clinical engineering (CE) has a rather practical orientation focusing on the general management of clinic/hospital equipment and providing aid to the medical staff in the use of advanced technologies for diagnosis and therapy purposes. The Romanian physiological community has been closely involved in the growth of BME that has now come of age in this country. Radu Vrâncianu's great intuition in opening the door to this science and its practical application in an institution created by Daniel Danielopolu definitely represented a good chance for Romanian public health. Recently, both clinical engineering and medical bioengineering have been introduced into the Romanian Classification of Occupations.

Biomedical Engineering↗
PubMed2005

[The application of basic fibroblast growth factor in tendon tissue engineering].

OBJECTIVE: To review the recent researches of basic fibroblast growth factor (bFGF) in tendon tissue engineering. METHODS: Recent original related literature was extensively reviewed and analyzed. RESULTS: bFGF played an important role in establishing standard tendon tissue engineering cell lines, inducing the compound and analysis of extracellular matrix, enhancing interactions between cells and extracellular matrix and accelerating tissue engineering materials' neovascularization. CONCLUSION: The progresses in increasing endogenetic bFGF expression, controlling the release of exogenous bFGF and improving the bio-utilization of bFGF has laid foundation for wider use of bFGF in tendon tissue engineering.

Animals↗
PubMed2006

[Relief effect of beta-galactosidase genetically engineered lactococcus lactis on the cell toxicity caused by lactose].

OBJECTIVE: To assess the relief effect of beta-galactosidase genetically engineered Lactococcus lactis on the cell toxicity caused by lactose in vitro. METHODS: An in vitro toxic Caco-2 cell model caused by lactose was established to evaluate the relief effect of beta-galactosidase genetically engineered Lactococcus lactis. Cell morphological parameters and proliferation activity parameter were used. RESULTS: The in vitro toxic Caco-2 cell model caused by lactose was successfully established; the genetically engineered Lactococcus lactis constructed in the authors' laboratory could enable the Caco-2 cell to have normal appearance with the presence of lactose and could improve the proliferation activity with the presence of high concentration of lactose (P < 0.01). CONCLUSION: The beta-galactosidase genetically engineered Lactococcus lactis has significant relief effect on the cell toxicity caused by lactose in vitro, which lays a foundation for food-grade alternation of this bacterium.

Caco-2 Cells↗
PubMed2006

Introducing the concept of the 3Rs into tissue engineering research.

Tissue engineering, defined as using a combination of cultured cells and biodegradable scaffolds to repair tissue damaged by injury or disease, represents a booming sector of biomedical research. Animal experimentation is routinely performed prior to clinical trials. The presented study tries to translate the aspect of the 3Rs to tissue engineering research: Cell culture protocols were adapted to antibiotic free and serum free conditions. Biomaterials (Bio-Gide and a collagen sponge prototype) were pre-tested using the HET-CAM assay. CAM-testing suggested a protocol change for application of the Bio-Gide scaffold and demonstrated unsuitable material properties of the collagen sponge. Application of 3R compliant protocols for tissue engineering research led to increased cell proliferation, higher synthesis of extracellular matrix molecules, reduced dedifferentiation and more information about the biomaterials at an early experimental stage. Tissue engineering research can therefore profit from the increased efforts to validate in vitro alternatives and supplements to animal testing.

Animal Testing Alternatives↗
PubMed2006

[Growth of compound layer tissue engineered oral mucosa and its clinical application in hetero-transplantation].

OBJECTIVE: To investigate the growth of the tissue engineered mucosa after its hetero-transplantation. METHODS: The epithelial cells and fibroblasts were isolated from a postoperative tissue of the 3-month patient with labial cleft. The epithelial cells and fibroblasts were separately seeded on the polylactic/glycolic acid copolymer membrane, and then they were exposed to the air-liquid interface. Seven volunteer patients, whose traumatic beds were repaired with the tissue engineered oral mucosa. The biopsy tissue from one of the seven patients was observed under light microscope 18 and 30 days after transplantation, respectively. RESULTS: The tissue engineered oral mucosa having 5-6 layers anti-cytokeratin staining positively cells in the epithelial layer and 3-7 layers anti-Cytokeratin staining negatively cells in the subepithelial layer grew well after the hetero-transplantation. No difference could be found between the transplanting and normal areas. At 18 days, the epithelial layer and lamina propria grew well and the fibroblasts were found; at 30 days, collagen was obviously observed. The structures in both the transplanting and the normal areas were similar. CONCLUSION: The tissue engineered oral mucosa can grow well after the hetero-transplantation.

Adolescent↗
PubMed2006

[Advance in urethral reconstruction with tissue engineering techniques].

OBJECTIVE: To sum up the research advances in urethra reconstruction with tissue engineering techniques. METHODS: The recent original articles about urethra reconstruction with engineering techniques were extensively reviewed. RESULTS: At present, human urothelium and smooth muscle cells have been successfully harvested, cultivated, and expanded in vitro in sufficient quantities for reconstruction. Tissue engineering for urethral reconstruction includes matrices alone, the body's natural ability which induces new tissue growth, or the use of matrices with cells. CONCLUSION: The tissue engineering materials for urethral reconstruction has been used successfully to repair defect of hypospadias and urethral strictures. The reconstruction of complex urethral defects need to be improved and developed.

Biocompatible Materials↗
PubMed2006

The use of moral dilemmas for teaching agricultural engineers.

Agricultural engineers' jobs are especially related to sustainability and earth life issues. They usually work with plants or animals, and the aim of their work is often linked to producing food to allow people to improve their quality of life. Taking into account this dual function, the moral requirements of their day-to-day professional practice are arguably greater than those of other professions. Agricultural engineers can develop their ability to live up to this professional responsibility by receiving ethical training during their university studies, not only by taking courses specifically devoted to ethics, but also by having to deal with moral questions that are integrated into their technical courses through a program of Ethics Across the Curriculum (EAC). The authors feel that a suitable pedagogical technique for achieving this goal is the use of moral dilemmas, following Kohlberg's theory of levels of morality (1981), with the final objective of attaining a post-conventional level. This paper examines the possibilities and limitations of using moral dilemmas as a pedagogical technique for training agricultural engineers. The cases, discussions, and evaluation used in the Agricultural Engineering Department of the Technical University of Valencia (Spain) are also presented.

Agriculture↗