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At least 829 records · Page 46Linked to original sources
PubMed2005

[Study of antithrombotic function of endothelium in vascular tissue engineering].

OBJECTIVE: To investigate the current situation and developing trend of antithrombotic function study of endothelium in vascular tissue engineering. METHODS: The effect of several elements on the antithrombotic ability of endothelium, including the source of endothelium, the characteristic of the matrix materials, the cell culture methods, and the endothelium's gene modification were analyzed. RESULTS: The normal antithrombotic function of tissue engineered vascular relied on the source of endothelium, gene modification of seeding cells, the cell culture methods in vitro, and the characteristic of the scaffolds. CONCLUSION: The establishment of an ideal antithrombotic functional tissue engineering vascular still requires further studies in various aspects including seeding cells, matrix materials, and cell culture methods. Gene modification of vascular endothelium, which improves the antithrombotic ability, deserves more attention.

Animals↗
PubMed2006

[Fast harvest of seed cells for composite tissue engineered skin at one time].

OBJECTIVE: To find a feasible method that can fast isolate seed cells, keratinocyte stem cell and fibroblasts, for composite tissue engineered skin. METHODS: The foreskin could be attained from posthectomy, the subcutaneous tissue was removed completely, and the full-thick skin was cut into pieces, 2 mm x 2 mm in size, then the pieces were submerged into a centrifuge tube containing collagenase I in a oscillator. After 3-hour digestion at 37 degrees C, the dermis was dissolved completely with all the fibroblasts in the digestion solution and the epidermis could be separated easily. With more than 10-minute digestion in trypsin at 37 degrees C, the epidermal cells could be harvested. Then flowcytometry and FITC-immunofluorescence for cytokeratin 19 of epidermal cells and FITC-immunofluorescence of vimentin of fibroblast were conducted to identify keratinocyte stem cells in the epidermal cells and fibroblasts in the digestion solution. Moreover, epidermal cells and fibroblasts were cultured in vitro for 7 days to investigate their biological behavior. RESULTS: Using collagenase I combined with trypsin, epidermal cells and fibroblasts could be isolated at one time within 3 hours. Up to 17% cells demonstrated cytokeratin 19 positive in the epidermal cells, with fibroblast vimentin positive. The amount of fibroblast could be enlarged to more than 100 times within 6 days, but the putative keratinocyte stem cells were difficult for subculture. CONCLUSION: Seed cells for composite tissue engineered skin could be harvested fast at one time, that made it possible to reconstruct composite tissue-engineered skin in vitro.

Adolescent↗
PubMed2005

Formation of in vivo tissue engineered human hyaline cartilage in the shape of a trachea with internal support.

OBJECTIVE: Treatment and management of congenital as well as post-traumatic trachea stenosis remains a challenge in pediatric surgery. The aim of this study was to reconstruct a trachea with human nasal septum chondrocytes by using the combination of biodegradable hydrogel and non-biodegradable high-density polyethylene (HDP) as the internal predetermined shape scaffold. METHODS: Human nasal septum cartilage was harvested as excessive tissue after elective septoplasty and digested in 0.6% collagenase II. Chondrocytes were cultured in an equal volume mix of Ham's F12 medium and Dulbecco's modified eagle medium added with 10% fetal bovine serum and basic fibroblast growth factor. After two passages, the cultured chondrocytes were trypsinized and mixed with biodegradable hydrogel Pluronic F127. The chondrocytes-hydrogel admixture was then painted over the HDP as the internal support in a predetermined trachea shape. The composite was then implanted subcutaneously in athymic mice. RESULTS: After 8 weeks of in vivo implantation, the tissue engineered trachea constructs were harvested. Macroscopic appearance of the tissue engineered trachea constructs demonstrated that the HDP were 80-90% covered with yellowish glistering cartilage like tissue without any sign of inflammation. The tissue engineered trachea cartilage consisted of evenly spaced lacunae embedded in basophilic matrix and stained red with Safranin-O staining denoting abundant proteoglycans production. Type II collagen gene which was expressed in native cartilage was highly expressed in this tissue engineered trachea cartilage. CONCLUSION: We have successfully reconstructed a trachea in vivo with human nasal septum chondrocytes using HDP as the internal support. This construct has the advantage of bio-inert and strength in which both are important properties in tracheal reconstruction.

Animals↗
PubMed1999

Successful anastomosis between tissue-engineered intestine and native small bowel.

BACKGROUND: Previous work from this laboratory has shown that isolated intestinal epithelial organoid units on porous biodegradable polymer scaffolds formed vascularized cysts lined by a neomucosa. The purpose of this study was to demonstrate anastomosis between tissue-engineered intestine and the native small bowel and to observe the effect of this anastomosis on cyst growth. METHODS: Intestinal epithelial organoid units from neonatal Lewis rats were seeded onto porous biodegradable polymer tubes made of polyglycolic acid, and they were implanted into the omentum of adult male Lewis rats. Three weeks after implantation, the unit-polymer constructs were anastomosed in a side-to-side fashion to the native jejunum in 20 rats (group 1). The other 18 rats were closed without anastomosis (group 2). All 38 tissue-engineered constructs were harvested 10 weeks after implantation. Four rats underwent upper gastrointestinal (GI) study before they were killed. RESULTS: The rats in group 1 increased their body weights equal to those in group 2, and there was no statistically significant difference between the two groups. Upper GI examinations revealed no evidence of either bowel stenosis or obstruction at the anastomotic site. Grossly, the patency of the anastomosis was 90% and the lumen of the cyst was visualized by the upper GI study. At the second operation, there was no significant difference in the size of the cysts in either group: however, at the time the rats were killed, the length of the cysts in group 1 was significantly longer than that in group 2 (P<0.05 using Mann-Whitney U test). Histological examination showed that cysts after anastomosis were lined by a neomucosa in continuity to native small bowel across the anastomotic site and also demonstrated crypt-villus structures. Morphometric study demonstrated that cysts in group 1 had significantly greater villus number, height, and surface length than did those in group 2. CONCLUSIONS: Anastomosis between tissue-engineered intestine and native small bowel resulted in no complications after the operation, kept a high patency rate, and maintained mucosal continuity between the tissue-engineered intestine and native small bowel. Furthermore, anastomosis had a positive effect on cyst size and development of the mucosa in the tissue-engineered intestine.

Anastomosis, Surgical↗
PubMed2003

[BMP-2 gene modified tissue-engineered bone repairing segmental tibial bone defects in goats].

OBJECTIVE: To evaluate the effectiveness of the tissue-engineered bone substitute loaded with adenovirus mediated human bone morphogenetic protein-2 gene (Adv-hBMP-2) transfected bone marrow derived mesenchymal stem cells (BMSC) in the repair of diaphyseal segmental bone defect of large animal. METHODS: The right tibial bone defects (2.6 cm) model of 26 goats were established and divided into 5 groups: I. Adv-hBMP-2 transfected BMSC/calcined bone (CB) group (n = 9); II. adenovirus-beta-galactosidase (Adv-betagal) gene transfected BMSC/CB group (n = 6); III. untransfected BMSC/CB group (n = 6); IV. single CB group (n = 3); VI. untreated group (n = 2). The above tissue-engineered bone substitutes were implanted in the bone defects respectively except group VI. Roentgenography, histomorphometrical analysis and biomechanical measurement were studied at various times. RESULTS: X-ray: at 4 - 8th weeks after implantation, more bony callus was found in the bone defects of group I. The complete healing rates of group I, II, III, IV, and V were 5/8, 1/5, 0/5, 0/2, 0/1 respectively at 26th week after implantation. Histomorphometrical analysis showed much more new bony callus including cortical bone formed in group I than those of other groups. The compression strength of the implanted bone substitute of group I is significantly higher than those of group II and III. CONCLUSION: The tissue-engineered bone substitute loaded with human BMP-2 gene transfected BMSC can repair diaphyseal segmental bone defect of large animal (goat).

Animals↗
PubMed2005

A three-dimensional nanofibrous scaffold for cartilage tissue engineering using human mesenchymal stem cells.

The utilization of adult stem cells in tissue engineering is a promising solution to the problem of tissue or organ shortage. Adult bone marrow derived mesenchymal stem cells (MSCs) are undifferentiated, multipotential cells which are capable of giving rise to chondrocytes when maintained in a three-dimensional culture and treated with members of the transforming growth factor-beta (TGF-beta) family of growth factors. In this study, we fabricated a nanofibrous scaffold (NFS) made of a synthetic biodegradable polymer, poly(-caprolactone) (PCL), and examined its ability to support in vitro chondrogenesis of MSCs. The electrospun PCL porous scaffold was constructed of uniform, randomly oriented nanofibers with a diameter of 700 nm, and structural integrity of this scaffold was maintained over a 21-day culture period. MSCs cultured in NFSs in the presence of TGF-beta1 differentiated to a chondrocytic phenotype, as evidenced by chondrocyte-specific gene expression and synthesis of cartilage-associated extracellular matrix (ECM) proteins. The level of chondrogenesis observed in MSCs seeded within NFSs was comparable to that observed for MSCs maintained as cell aggregates or pellets, a widely used culture protocol for studying chondrogenesis of MSCs in vitro. Due to the physical nature and improved mechanical properties of NFSs, particularly in comparison to cell pellets, the findings reported here suggest that the PCL NFS is a practical carrier for MSC transplantation, and represents a candidate scaffold for cell-based tissue engineering approaches to cartilage repair.

Aged↗
PubMed2006

Magnetic resonance microscopy for monitoring osteogenesis in tissue-engineered construct in vitro.

Magnetic resonance microscopy (MRM) is used to monitor osteogenesis in tissue-engineered constructs. Measurements of the developing tissue's MR relaxation times (T(1) and T(2)), apparent diffusion coefficient (ADC) and elastic shear modulus were conducted over a 4-week growth period using an 11.74 T Bruker spectrometer with an imaging probe adapted for MR elastography (MRE). Both the relaxation times and the ADC show a statistically significant decrease after only one week of tissue development while the tissue stiffness increases progressively during the first two weeks of in vitro growth. The measured MR parameters are correlated with histologically monitored osteogenic tissue development. This study shows that MRM can provide quantitative data with which to characterize the growth and development of tissue-engineered bone.

Alkaline Phosphatase↗
PubMed1998

Tissue engineering of heart valves--human endothelial cell seeding of detergent acellularized porcine valves.

OBJECTIVE: Tissue engineering of heart valves represents a new experimental concept to improve current modes of therapy in valvular heart disease. Drawbacks of glutaraldehyde fixed tissue valves or mechanical valves include the short durability or the need for life-long anticoagulation, respectively. Both have in common the inability to grow, which makes valvular heart disease especially problematic in children. The aim of this study was to develop a new methodology for a tissue engineered heart valve combining human cells and a xenogenic acellularized matrix. METHODS: Porcine aortic valves were acellularized by deterging cell extraction using Triton without tanning. Endothelial cells were isolated in parallel from human saphenous veins and expanded in vitro. Specimens of the surface of the acellular matrix were seeded with endothelial cells. Analysis of acellularity was performed by light microscopy and scanning electron microscopy. Cell viability following seeding was assayed by fluorescence staining of viable cells. RESULTS: The acellularization procedure resulted in an almost complete removal of the original cells while the 3D matrix was loosened at interfibrillar zones. However the 3D arrangement of the matrix fibers was grossly maintained. The porcine matrix could be seeded with in vitro expanded human endothelial cells and was maintained in culture for up to 3 days to document the formation of confluent cultures. CONCLUSIONS: Porcine aortic valves can be almost completely acellularized by a non-tanning detergent extraction procedure. The xenogenic matrix was reseeded with human endothelial cells. This approach may eventually lead to the engineering of tissue heart valves repopulated with the patients own autologous cells.

Animals↗
PubMedDate not supplied

Muscle tissue engineering for partial glossectomy defects.

BACKGROUND: Tongue reconstruction represents a difficult reconstructive problem, based on the tongue's complex multimodality function. Existing methods of tongue reconstruction often result in significant deficits in speech and deglutition. A functional neotongue requires adequate soft tissue bulk and restoration of coordinated muscle function. Tissue engineering, a scientific approach that allows introduction of isolated cell populations of interest within 3-dimensional polymer scaffolds to create new tissue, may allow the generation of more highly functional tissue in tongue reconstruction. OBJECTIVES: To apply muscle-tissue engineering techniques in the reconstruction of partial glossectomy defects in rats, and to compare the gross and histological nature of tissue found after reconstruction of the hemiglossectomy defect with acellular vs tissue-engineered composite material. MATERIALS AND METHODS: Thirty mature Lewis rats underwent a left-sided mucosa-sparing partial glossectomy. The defects were then filled with 1 of the following 3 substances: isotonic sodium chloride solution, a collagen-rich hydrogel, or hydrogel containing a suspension of neonatal myoblasts from syngeneic rats. The animals were killed after 6 weeks and the tongues were harvested. The control and operated-on tongue halves were evaluated for weight differences and histological features. RESULTS: The group receiving the hydrogel-myoblast composite injections demonstrated a statistically significant increase in tongue weight of the operated-on side compared with the control side. In contrast, the isotonic sodium chloride solution and hydrogel groups demonstrated loss of tongue weight. These findings correlated with the results of the histological evaluation. Hemitongues from the composite group demonstrated formation of new tissue with areas of musclelike tissue extending from islands of residual hydrogel, and we found evidence of neovascularization and possible neurotization. In contrast, the isotonic sodium chloride solution group exhibited dense fibrous scar with loss of muscle architecture and dramatic loss of tongue volume. The hydrogel group demonstrated preservation of tongue volume with persistent islands of gel, but no clear evidence of new tissue formation. CONCLUSIONS: The introduction of a hydrogel into the rat hemiglossectomy pocket appears to promote volume preservation and/or muscle regeneration. The addition of myoblasts suspended in collagen gel supports the development of new tissue that preserves weight and volume after hemiglossectomy and may possess muscle properties similar to the tissue desired. This tissue-engineering approach represents a promising new strategy in tongue reconstruction and merits further investigation into the possible functional advantages it offers compared with current techniques.

Animals↗
PubMedDate not supplied

Tissue engineering of ligaments: a comparison of bone marrow stromal cells, anterior cruciate ligament, and skin fibroblasts as cell source.

Anterior cruciate ligament (ACL) reconstruction surgery still has important problems to overcome, such as "donor site morbidity" and the limited choice of grafts in revision surgery. Tissue engineering of ligaments may provide a solution for these problems. Little is known about the optimal cell source for tissue engineering of ligaments. The aim of this study is to determine the optimal cell source for tissue engineering of the anterior cruciate ligament. Bone marrow stromal cells (BMSCs), ACL, and skin fibroblasts were seeded onto a resorbable suture material [poly(L-lactide/glycolide) multifilaments] at five different seeding densities, and cultured for up to 12 days. All cell types tested attached to the suture material, proliferated, and synthesized extracellular matrix rich in collagen type I. On day 12 the scaffolds seeded with BMSCs showed the highest DNA content (p < 0.01) and the highest collagen production (p < 0.05 for the two highest seeding densities). Scaffolds seeded with ACL fibroblasts showed the lowest DNA content and collagen production. Accordingly, BMSCs appear to be the most suitable cells for further study and development of tissue-engineered ligament.

Animals↗
PubMed2005

Poly(lactide-co-glycolide) microspheres as a moldable scaffold for cartilage tissue engineering.

This study demonstrates the use of biodegradable poly(lactide-co-glycolide) (PLG) microspheres as a moldable scaffold for cartilage tissue engineering. Chondrocytes were delivered to a cylindrical mold with or without PLG microspheres and cultured in vitro for up to 8 weeks. Cartilagenous tissue formed using chondrocytes and microspheres maintained thickness, shape, and chondrocyte collagen type II phenotype, as indicated by type II collagen staining. The presence of microspheres further enhanced total tissue mass and the amount of glycosaminoglycan that accumulated. Evaluation of microsphere composition demonstrated effects of polymer molecular weight, end group chemistry, and buffer inclusion on tissue-engineered cartilage growth. Higher molecular weight PLG resulted in a larger mass of cartilage-like tissue formed and a higher content of proteoglycans. Cartilage-like tissue formed using microspheres made from low molecular weight and free carboxylic acid end groups did not display increases in tissue mass, yet a modest increased proteoglycan accumulation was detected. Microspheres comprised of PLG with methyl ester end groups yielded a steady increase in tissue mass, with no real increase in matrix accumulation. The microencapsulation of Mg(OH)(2) had negative effects on tissue mass and matrix accumulation. The data herein reflect the potential utility of a moldable PLG-chondrocyte system for tissue-engineering applications.

Absorbable Implants↗
PubMed2004

Cartilage tissue engineering on the surface of a novel gelatin-calcium-phosphate biphasic scaffold in a double-chamber bioreactor.

Tissue engineering is a new approach to articular cartilage repair; however, the integration of the engineered cartilage into the host subchondral bone is a major problem in osteochondral injury. The aim of the present work, therefore, was to make a tissue-engineered osteochondral construct from a novel biphasic scaffold in a newly designed double-chamber bioreactor. This bioreactor was designed to coculture chondrocytes and osteoblasts simultaneously. The aim of this study was to prove that engineered cartilage could be formed with the use of this biphasic scaffold. The scaffold was constructed from gelatin and a calcium-phosphate block made from calcined bovine bone. The cartilage part of the scaffold had a uniform pore size of about 180 microm and approximate porosity of 75%, with the trabecular pattern preserved in the bony part of the scaffold. The biphasic scaffolds were seeded with porcine chondrocytes and cultured in a double-chamber bioreactor for 2 or 4 weeks. The chondrocytes were homogeneously distributed in the gelatin part of the scaffold, and secretion of the extracellular matrix was demonstrated histologically. The chondrocytes retained their phenotype after 4 weeks of culture, as proven immunohistochemically. After 4 weeks of culture, hyaline-like cartilage with lacuna formation could be clearly seen in the gelatin scaffold on the surface of the calcium phosphate. The results show that this biphasic scaffold can support cartilage formation on a calcium-phosphate surface in a double-chamber bioreactor, and it seems reasonable to suggest that there is potential for further application in osteochondral tissue engineering.

Animals↗
PubMed2002

Tissue engineering of bone.

Despite well-established bone-grafting techniques, large bone defects still represent a challenge for orthopaedic and reconstructive surgeons. Efforts have therefore been made to develop osteoconductive, osteoinductive and osteogenic bone-replacement systems. According to its original definition, tissue engineering is an 'interdisciplinary field that applies the principles of engineering and the life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function'. It is based on the understanding of tissue formation and regeneration, and aims to grow new functional tissues rather than to build new spare parts. This review focuses on the principles of tissue engineering applied to the creation of bioartificial bone tissue. Important aspects, such as osteogenic cells, matrix materials, inter- and intra-cellular communication, growth factors, gene therapy and current concepts of bone tissue engineering are reviewed. First clinical applications are discussed. An outlook provides insight into the possible future perspectives of bone tissue engineering.

Journal Article↗
PubMed2002

Tissue engineering of biological cardiovascular system surrogates.

Cardiovascular diseases are common in ageing communities globally. This fact is most striking in the industrialised world where the aged population makes up a large proportion of society. Elderly patients are frequently treated surgically with grafts to replace damaged tissues and vessels. The number of human-donated components is insufficient and synthetic surrogates are sought. These might be wholly mechanical, wholly biological, or tissue engineered complexes of cells and their products growing in a scaffold. At present, many such composites exist with potential for use as substitutes for specific blood vessels. The challenges of producing tissue engineered heart valves are now being widely explored. Neotissues must provide an effective, durable, non-thrombogenic and non-immunogenic substitute that will fulfil the purpose of the natural tissue. The aims and scope of this paper are to review current and novel concepts in the field of tissue engineering of biological cardiovascular system surrogates. Mechanical stresses and strains on cardiovascular cells in vitro have been recognised and can be measured by a culture force monitor. Physiological stresses can be generated by a tensioning culture force monitor and applied to engineered tissue, aligning the cells and mimicking arterial wall architecture. The hydrostatic forces a vessel experiences and mechanical parameters of blood vessels can be studied in the tubular culture system of a multi-cue bioreactor.

Journal Article↗
PubMed2002

Matrices for tissue-engineered skin.

Academic, clinical and industrial efforts are increasingly being directed toward the use of molecular- and cell-based therapies for diagnosis and treatment of a great number and broad variety of pathologies and injuries. Hence, tissue engineering is, next to genetic engineering, widely heralded as the healthcare technology heir of the revolutionary advances in life sciences. In a cost-controlled healthcare environment, only those technologies capable of providing a major enhancement to quality of life and a reduction in expenditure will be driven forward. Skin tissue engineering concepts based on the application of a scaffold/cell construct represent a treatment concept with the clear potential to meet this criterion. Several important issues concerning the research and product strategy (e.g., choice of matrix of natural or synthetic polymer origin and the use of autogenic versus allogenic cells) remain to be fully resolved. However, there is little doubt that wound regeneration via modern tissue engineering strategies will present significant therapeutic benefits when compared with existing treatments. This paper reviews the biography and future research directions of matrices used in skin tissue engineering.

Adipose Tissue↗
PubMedDate not supplied

Electrospun nanofiber fabrication as synthetic extracellular matrix and its potential for vascular tissue engineering.

Substantial effort is being invested by the bioengineering community to develop biodegradable polymer scaffolds suitable for tissue-engineering applications. An ideal scaffold should mimic the structural and purposeful profile of materials found in the natural extracellular matrix (ECM) architecture. To accomplish this goal, poly (L-lactide-co-epsilon-caprolactone) [P(LLA-CL)] (75:25) copolymer with a novel architecture produced by an electrospinning process has been developed for tissue-engineering applications. The diameter of this electrospun P(LLA-CL) fiber ranges from 400 to 800 nm, which mimicks the nanoscale dimension of native ECM. The mechanical properties of this structure are comparable to those of human coronary artery. To evaluate the feasibility of using this nanofibrous scaffold as a synthetic extracellular matrix for culturing human smooth muscle cells and endothelial cells, these two types of cells were seeded on the scaffold for 7 days. The data from scanning electron microscopy, immunohistochemical examination, laser scanning confocal microscopy, and a cell proliferation assay suggested that this electrospun nanofibrous scaffold is capable of supporting cell attachment and proliferation. Smooth muscle cells and endothelial cells seeded on this scaffold tend to maintain their phenotypic shape. They were also found to integrate with the nanofibers to form a three-dimensional cellular network. These results indicate a favorable interaction between this synthetic nanofibrous scaffold with the two types of cells and suggest its potential application in tissue engineering a blood vessel substitute.

Biocompatible Materials↗
PubMed2006

Fabrication and evaluation of porous 2,3-dialdehydecellulose membrane as a potential biodegradable tissue-engineering scaffold.

A simple, novel method to produce porous 2,3-dialdehydecellulose (DAC) membranes as a potential tissue-engineering scaffold has been developed from methylolcellulose by the simultaneous water-induced phase separation and sodium chloride salt leaching techniques, followed by oxidation with sodium periodate in water. Membrane pores increased in size with increasing weight or particle size of the sodium chloride salt. The porosity of the membrane was not affected by the salt particle size, but it increased with an increase in the salt weight to 60%. At higher salt weight percentages, no significant change in the membrane porosity was observed. The oxidation step had no effect on the membrane porosity or pore size. All membranes with a porosity value ranging between 87 and 93% showed interconnected porous structures. The use of these membranes as a potential tissue-engineering scaffold was evaluated with the use of human neonatal skin fibroblast cells. Confocal microscopy showed cell attachment and spreading on these membranes. Immunohistochemical tests revealed the presence of collagen type III and fibronectin, indicating that the cells were viable and formed the extracellular matrix. In conclusion, the DAC membrane supports cell adhesion and proliferation and hence shows potential to be used as a tissue-engineering scaffold.

Absorbable Implants↗