PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Tissue Engineering”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29Linked to original sources
PubMed2003

Differentiated chondrocytes for cartilage tissue engineering.

Trauma to the articular cartilage surface of the joint represents a challenging clinical problem due to the very limited ability of this tissue to self-repair. Moreover, repair techniques such as microfracture, which introduce cells into the joint, have unpredictable clinical outcomes as they produce a fibrocartilage tissue that degenerates with time. Alternative treatments include tissue reconstruction with autograft and allograft tissue. However, these procedures are restricted by the availability of suitable donor tissue. These limitations have been the driving force behind the emerging field of articular cartilage tissue engineering. This paper will highlight and contrast the key challenges associated with the tissue engineering of this neo-tissue using differentiated adult cells. The various components of the tissue engineering process will be described including the choice of donor cell/tissue type and the selection of scaffolds that guide the formation of tissue. The ability of the tissue engineered implants to stimulate the repair of defects in vivo will also be discussed. Tissue engineering approaches may, in the future, provide an ideal alternative to the current surgical treatments for cartilage repair.

Adult↗
PubMed2002

[Repair of tibial defect with tissue-engineered bone graft and radionuclide bone imaging in goats].

OBJECTIVE: To observe the effect of tissue-engineered bone grafts in repairing large tibial defect in goats, and assess the value of radionuclide bone imaging in monitoring the therapeutic effect of this approach. METHODS: Tibial defects measuring 2 cm was artificially made in the left tibia of 27 normal goats that were subsequently divided into 3 groups (9 each) to undergo treatment with tissue-engineered bone grafts, artificial bone grafts or without any grafts (as control group) respectively. The tissue-engineered bone grafts contained bone marrow stroma cells (BMSCs) of the goats and coral hydroxyapatite (CHAP), while the artificial bone grafts were from CHAP only. After the operations, radionuclide bone imaging was used to monitor the therapeutic effects at 2, 4 and 8 postoperative weeks. RESULTS: The 99mTc-MDP uptake of the region of interest (ROI) and the target to non-target ratios (T/NT) of the control group did not indicate any process of revascularization or bone regeneration. An increasing tendency of the revascularization and bone regeneration, in contrast, was observed in goats receiving the artificial bone grafts, a tendency that was far more obvious in the goats with tissue-engineered bone grafts. CONCLUSION: Tissue-engineered bone graft is eligible in repairing large defect in the caprine tibia, and radionuclide bone imaging may accurately monitor the revascularization and bone regeneration after the bone graft implantation.

Animals↗
PubMed2006

In vitro fabrication of a tissue engineered human cardiovascular patch for future use in cardiovascular surgery.

BACKGROUND: One approach to tissue engineering has been the development of in vitro conditions for the fabrication of functional cardiovascular structures intended for implantation. In this experiment, we developed a pulsatile flow system that provides biochemical and biomechanical signals in order to regulate autologous, human patch-tissue development in vitro. METHODS: We constructed a biodegradable patch scaffold from porous poly-4-hydroxy-butyrate (P4HB; pore size 80 to 150 microm). The scaffold was seeded with pediatric aortic cells. The cell-seeded patch constructs were placed in a self-developed bioreactor for 7 days to observe potential tissue formation under dynamic cell culture conditions. As a control, cell-seeded scaffolds were not conditioned in the bioreactor system. After maturation in vitro, the analysis of the tissue engineered constructs included biochemical, biomechanical, morphologic, and immunohistochemical examination. RESULTS: Macroscopically, all tissue engineered constructs were covered by cells. After conditioning in the bioreactor, the cells were mostly viable, had grown into the pores, and had formed tissue on the patch construct. Electron microscopy showed confluent smooth surfaces. Additionally, we demonstrated the capacity to generate collagen and elastin under in vitro pulsatile flow conditions in biochemical examination. Biomechanical testing showed mechanical properties of the tissue engineered human patch tissue without any statistical differences in strength or resistance to stretch between the static controls and the conditioned patches. Immunohistochemical examination stained positive for alpha smooth muscle actin, collagen type I, and fibronectin. There was minor tissue formation in the nonconditioned control samples. CONCLUSIONS: Porous P4HB may be used to fabricate a biodegradable patch scaffold. Human vascular cells attached themselves to the polymeric scaffold, and extracellular matrix formation was induced under controlled biomechanical and biodynamic stimuli in a self-developed pulsatile bioreactor system.

Absorbable Implants↗
PubMed2002

Synthesis and characterization of photocrosslinkable, degradable poly(vinyl alcohol)-based tissue engineering scaffolds.

Hydrogels have many advantages that make them prime candidates for tissue engineering applications: high water content, tissue-like elasticity, and relative biocompatibility. We aim to tissue engineer heart valves using a hydrogel scaffold based on poly(vinyl alcohol) (PVA), and the design parameters for a suitable tissue engineering scaffold are quite stringent. In this research, we develop degradable and photocrosslinkable poly(lactic acid)-g-PVA multifunctional macromers that can be reacted in solution to form degradable networks. The mass loss profiles and bulk properties of the resulting scaffolds are easily tailored by modifying the structure of the starting macromers. Specifically, altering the number of lactide repeat units per crosslinking side chain, percent substitution, molecular weight of PVA backbone, and macromer solution concentration, the rate of mass loss from these degradable networks is controlled. In addition, by increasing the network's hydrophobicity, valve interstitial cell adhesion is improved.

Animals↗
PubMed2001

Tissue engineering of the small intestine by acellular collagen sponge scaffold grafting.

Tissue engineering of the small intestine will prove a great benefit to patients suffering from short bowel disease. However cell seeding in tissue engineering, such as fetal cell use, is accompanied by problems of ethical issues, rejection, and short supply. To overcome these problems, we carried out an experimental study on tissue engineering of the small intestine by acellular collagen sponge scaffold grafting. We resected the 5 cm long jejunum from beagle dogs and reconstructed it by acellular collagen sponge grafting with a silicon tube stent. The graft was covered with the omentum. At 1 month after operation, the silicon stent was removed endoscopically. Animals were sacrificed 1 and 4 months after operation, and were examined microscopically. Neo-intestinal regeneration was observed and the intestinal mucosa covered the luminal side of the regenerated intestine across the anastomosis. Thus, the small intestine was regenerated by tissue engineering technology using an acellular collagen sponge scaffold.

Animals↗
PubMedDate not supplied

Evaluation of biodegradable, three-dimensional matrices for tissue engineering of heart valves.

A crucial factor in tissue engineering of heart valves is the type of scaffold material. In the following study, we tested three different biodegradable scaffold materials, polyglycolic acid (PGA), polyhydroxyalkanoate (PHA), and poly-4-hydroxybutyrate (P4HB), as scaffolds for tissue engineering of heart valves. We modified PHA and P4HB by a salt leaching technique to create a porous matrix. We constructed trileaflet heart valve scaffolds from each polymer and tested them in a pulsatile flow bioreactor. In addition, we evaluated the cell attachment to our polymers by creating four tubes of each material (length equals 4 cm; inner diameter, 0.5 cm), seeding each sample with 8,000,000 ovine vascular cells, and incubating the cell-polymer construct for 8 days (37 degrees C and 5% CO2). The seeded vascular constructs were exposed to continuous flow for 1 hour. Analysis of samples included DNA assay before and after flow exposure, 4-hydroxyproline assay, and environmental scanning electron microscopy (ESEM). We fabricated trileaflet heart valve scaffolds from porous PHA and porous P4HB, which opened and closed synchronously in a pulsatile bioreactor. It was not possible to create a functional trileaflet heart valve scaffold from PGA. After seeding and incubating the PGA-, PHA-, and P4HB-tubes, there were significantly (p < 0.001) more cells on PGA compared with PHA and P4HB. There were no significant differences among the materials after flow exposure, but there was a significantly higher collagen content (p < 0.017) on the PGA samples compared with P4HB and PHA. Cell attachment and collagen content was significantly higher on PGA samples compared with PHA and P4HB. However, PHA and P4HB also demonstrate a considerable amount of cell attachment and collagen development and share the major advantage that both materials are thermoplastic, making it possible to mold them into the shape of a functional scaffold for tissue engineering of heart valves.

Animals↗
PubMed2004

[Basic researches on cell adhesion and its application in tendon tissue engineering].

Cell adhesion is a basic and very important tissue in the field of tissue engineering. Fibronectin and integrins are the most important elements to cell adhesion. Some surface receptors of fibroblast can also conjugate with type I collagen in extracellular matrix (ECM) directly. Laminin receptors on the surface of fibroblast bound to laminin also play a role in cell adhesion. In this paper are reviewed a number of related articles. The structures and function of fibronectin and integrins are discussed in detail; the tendon cell's adhesion structures are also discussed. Yet, there was scarcely any paper on the effects which the preservation of tissue engineered products may have on cells' adhesion fo ECM. Therefore, researching on cell adhesion and finding a way of preservation that has no or very little adverse effect on cell adhesion is an important topic. Results from expected advanced researches on cell adhesion may probably find promising applications in the field of tissue engineering.

Cell Adhesion↗
PubMed2006

Adipose tissue engineering by human adipose-derived stromal cells.

Tissue engineering has emerged as a promising alternative approach to current clinical treatments for restoration of soft tissue defects. The purpose of this study was to investigate adipose tissue formation in vitro and in vivo by using human adipose-derived stromal cells (ADSCs) utilizing a gelatin sponge (Gelform) as a scaffold. Adipogenic potentials of human ADSCs were demonstrated by Oil-O-red staining and cellular morphology. After seeding human ADSCs in a density of 3 x 10(6) cells/ml on three-dimensional gelatin sponges, tissue-engineered constructs were exposed to adipogenic differentiation medium for in vitro studies and implanted in the backs of severe combined immunodeficient (SCID) mice for in vivo adipose regeneration. Adipogenesis of ADSC-seeded gelatin sponges was confirmed by Oil-O-red staining after 4 weeks of in vitro incubation. The optical density of the elution from Oil-O-red staining of adipogenic constructs is significantly higher than that of the control group (p < 0.05, n = 4). With short-term in vitro differentiation, adipogenic constructs turned into fat tissue 4 weeks after in vivo implantation, confirmed by biochemical and immunohistochemical examination. No adipogenic-morphological change or fat formation was observed in in vitro or in vivo studies when ADSCs were exposed to a control medium without adipogenic stimulation. These results indicate that engineered adipose tissue can be achieved using human ADSCs and biocompatible and degradable gelatin sponges.

Adipose Tissue↗
PubMed2002

Tissue engineering of a differentiated cardiac muscle construct.

Cardiac tissue engineering is an emerging field. The suitability of engineered heart tissue (EHT) for both in vitro and in vivo applications will depend on the degree of syncytoid tissue formation and cardiac myocyte differentiation in vitro, contractile function, and electrophysiological properties. Here, we demonstrate that cardiac myocytes from neonatal rats, when mixed with collagen I and matrix factors, cast in circular molds, and subjected to phasic mechanical stretch, reconstitute ring-shaped EHTs that display important hallmarks of differentiated myocardium. Comparative histological analysis of EHTs with native heart tissue from newborn, 6-day-old, and adult rats revealed that cardiac cells in EHTs reconstitute intensively interconnected, longitudinally oriented, cardiac muscle bundles with morphological features resembling adult rather than immature native tissue. Confocal and electron microscopy demonstrated characteristic features of native differentiated myocardium; some of these features are absent in myocytes from newborn rats: (1) highly organized sarcomeres in registry; (2) adherens junctions, gap junctions, and desmosomes; (3) a well-developed T-tubular system and dyad formation with the sarcoplasmic reticulum; and (4) a basement membrane surrounding cardiac myocytes. Accordingly, EHTs displayed contractile characteristics of native myocardium with a high ratio of twitch (0.4 to 0.8 mN) to resting tension (0.1 to 0.3 mN) and a strong beta-adrenergic inotropic response. Action potential recordings demonstrated stable resting membrane potentials of -66 to -78 mV, fast upstroke kinetics, and a prominent plateau phase. The data indicate that EHTs represent highly differentiated cardiac tissue constructs, making EHTs a promising material for in vitro studies of cardiac function and tissue replacement therapy.

Action Potentials↗
PubMed2001

Tissue engineering in urology.

Techniques that are aimed at regeneration of human tissues and organs (tissue engineering) have recently entered into clinical practice. Tissue engineering is currently among the fastest growing areas in medicine, and involves the application of the principles of biology and engineering to the development of functional substitutes for damaged tissues. One of the main limitations of reconstructive surgery in the genitourinary tract is the lack of autologous tissue. This could be changed by the ability to cultivate the patient's own tissues in vitro, or by stimulating the cells in vivo into regeneration of new tissues. The present review discusses how tissue engineering can be used to regenerate some of the tissues of the genitourinary tract. Even though these methods have only recently been introduced clinically into genitourinary medicine, numerous scientific studies have been reported that indicate that these techniques may be of great importance in the near future.

Artificial Organs↗
PubMed2004

Poly(N-isopropylacrylamide)-grafted gelatin as a thermoresponsive cell-adhesive, mold-releasable material for shape-engineered tissues.

Poly(N-isopropylacrylamide)-grafted gelatin (PNIPAM-gelatin) can be used as a thermoresponsive cell-adhesive matrix and mold-releasable material for shape-engineered tissues. An example of such a tissue with predetermined shape is realized by fabrication of a tubular endothelial cell construct. A solution containing a mixture of PNIPAM-gelatin and PNIPAM was coated on the luminal surface of a glass capillary tube. After air-drying, endothelial cells were seeded and cultured for four days at 37 degrees C. The infusion of the culture medium into the tube at 20 degrees C resulted in the spontaneous detachment and removal of a tubular vascular tissue composed of endothelial cells and supramolecularly organized extracellular matrices produced by endothelial cells on the basal side of the tissue. The potential use of a thermoresponsive cell-adhesive and mold-releasable material in complex-shaped tissue-engineered devices is discussed.

Acrylic Resins↗
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↗
PubMed2002

Novel bioresorbable and bioactive composites based on bioactive glass and polylactide foams for bone tissue engineering.

Bioresorbable and bioactive tissue engineering scaffolds based on bioactive glass (45S5 Bioglass(R)) particles and macroporous poly(DL-lactide) (PDLLA) foams were fabricated. A slurry dipping technique in conjunction with pretreatment in ethanol was used to achieve reproducible and well adhering bioactive glass coatings of uniform thickness on the internal and external surfaces of the foams. In vitro studies in simulated body fluid (SBF) demonstrated rapid hydroxyapatite (HA) formation on the surface of the composites, indicating their bioactivity. For comparison, composite foams containing Bioglass(R) particles as filler for the polymer matrix (in concentration of up to 40 wt %) were prepared by freeze-drying, enabling homogenous glass particle distribution in the polymer matrix. The formation of HA on the composite surfaces after immersion in phosphate buffer saline (PBS) was investigated to confirm the bioactivity of the composites. Human osteoblasts (HOBs) were seeded onto as-fabricated PDLLA foams and onto PDLLA foams coated with Bioglass(R) particles to determine early cell attachment and spreading. Cells were observed to attach and spread on all surfaces after the first 90 min in culture. The results of this study indicate that the fabricated composite materials have potential as scaffolds for guided bone regeneration.

Journal Article↗
PubMed2001

Development and characterization of tissue-engineered aortic valves.

Tissue-engineered aortic valves, known as recellularized heart valves, were developed by seeding human neonatal fibroblasts onto decellularized, porcine aortic valves. Recellularized heart valves were cultured up to 8 weeks in a novel bioreactor that imposed dynamic pulsatile fluid flow to expose the dermal fibroblasts to mechanical forces. Our data showed that, under static or dynamic flow conditions, dermal fibroblasts attached to and migrated into the decellularized, porcine valve scaffolding. The human cells remained viable as indicated by MTT viability staining. Gradual colonization of the decellularized porcine scaffolding by the human dermal fibroblasts was shown histologically by hematoxylin & eosin staining, immunocytochemically using a monoclonal antibody directed against prolyl-4-hydroxylase (an intracellular enzyme expressed by human fibroblasts synthesizing collagen), and quantitative digital image analyses. Thymidine and proline radiolabeled analog studies at 1, 2 and 4 weeks of individual leaflets cultured statically demonstrated that the human fibroblasts were mitotic and synthesized human extracellular matrix proteins, thereby supplementing the existing porcine matrix. The overall approach results in a heart valve populated with viable human cells. In the development of valves that perform in a similar manner as natural biological structures, this approach may present some unique benefits over current medical therapies.

Animals↗
PubMed2002

Use of tissue-engineered skin in the dermal atrophy patient with traumatic avulsion injuries.

Tissue-engineered skin has been approved by the Food and Drug Administration for use in certain chronic ulcers (venous stasis ulcers and diabetic foot ulcers). Its use has also been reported in acute (surgical) excisional wounds. The authors report the use of tissue-engineered skin in traumatic avulsion wounds in a series of 10 patients with dermal atrophy. All patients were older than 60 years of age and clinically had thin, atrophic skin. Most were older than 70 years of age and were steroid users. Tissue-engineered skin (Apligraf or Living Skin Equivalent; Organogenesis, Inc. [corrected], Canton, MA) was used for subacute and acute wound coverage. All wounds healed 100%. Average healing time overall was 9.2 weeks. No wound has recurred with an average follow-up of 14 months. There were no wound infections. The authors conclude that tissue-engineered skin provides a safe, efficacious, and convenient solution for acute avulsion wounds in the patient with age- and/or steroid-related dermal atrophy.

Aged↗
PubMed1996

Toward development of an implantable tissue engineered liver.

Hepatocyte transplantation on implantable devices is a tissue engineering approach to improve the treatment of liver disease and the efficacy of ex vivo gene therapy. Diverse physiological functions and high metabolic activity of the liver represent significant challenges to engineering implantable devices that provide long-term hepatic support. Liver tissue engineering research has explored alternatives to direct hepatocyte injection that include hepatocyte attachment to microcarriers, encapsulation and transplantation on biodegradable polymer scaffolds. Successful function of hepatocytes transplanted on implantable devices in animal models has been documented by production of albumin and other liver-specific markers, and clearance of bilirubin and urea metabolites. Strategies used to achieve these successes are reviewed, with particular emphasis on biodegradable polymer scaffolds, and two areas of investigation that may improve the function of implantable tissue engineered liver devices are highlighted.

Animals↗
PubMed2004

Bioreactor-based bone tissue engineering: the influence of dynamic flow on osteoblast phenotypic expression and matrix mineralization.

An important issue in tissue engineering concerns the possibility of limited tissue ingrowth in tissue-engineered constructs because of insufficient nutrient transport. We report a dynamic flow culture system using high-aspect-ratio vessel rotating bioreactors and 3D scaffolds for culturing rat calvarial osteoblast cells. 3D scaffolds were designed by mixing lighter-than-water (density, <1g/ml) and heavier-than-water (density, >1g/ml) microspheres of 85:15 poly(lactide-co-glycolide). We quantified the rate of 3D flow through the scaffolds by using a particle-tracking system, and the results suggest that motion trajectories and, therefore, the flow velocity around and through scaffolds in rotating bioreactors can be manipulated by varying the ratio of heavier-than-water to lighter-than-water microspheres. When rat primary calvarial cells were cultured on the scaffolds in bioreactors for 7 days, the 3D dynamic flow environment affected bone cell distribution and enhanced cell phenotypic expression and mineralized matrix synthesis within tissue-engineered constructs compared with static conditions. These studies provide a foundation for exploring the effects of dynamic flow on osteoblast function and provide important insight into the design and optimization of 3D scaffolds suitable in bioreactors for in vitro tissue engineering of bone.

Alkaline Phosphatase↗