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 469 records · Page 26Linked to original sources

PubMed2003

Tissue engineering: current state of clinical application.

Despite several, mostly isolated successes, few controlled, prospective trials have yet validated clinical tissue engineering applications. Although this may, at least in part, be explained by the very young age of this field, tissue engineering involves the need for an elaborate and expensive infrastructure, not to mention qualified personnel. This translates into an inherent difficulty in establishing multicenter trials. Moreover, companies mostly devoted to tissue engineering have yet to prove themselves economically viable. On the other hand, although very few engineered tissues have been approved by the US Food and Drug Administration (FDA), more than 70 companies have recently been developing new products. Many challenges are yet to be overcome before "off-the-shelf" tissues can be offered commercially. Nevertheless, given the scientific promise, potential social impact, and young age of the field, many believe that it should be only a matter of time until tissue engineering reaches the mainstream of surgical practice.

Humans↗

PubMed2004

[Tissue engineered cartilage for biological repair of cartilage defects].

Recent developments in tissue engineering techniques in cartilage repair were discussed. Recently, the novel two-step method, the alginate-recovered-chondrocyte method (ARC method), which does not require the aid of an exogenous synthetic matrix, was developed. The first step of this method consists of culturing phenotypically stable chondrocytes under conditions optimal for the formation of a proteoglycan-rich cell-associated matrix (CM) in alginate beads. Then, the cells with their CM are recovered from the alginate and allowed to rapidly integrate into a solid mass of tissue on a culture insert with a porous membrane. The use of a growth factor, recombinant human osteogenic protein-1 (OP-1) maximized the formation of tissue engineered cartilaginous tissue from adult human articular cartilage. Using the ARC method, the enhancement of matrix formation by OP-1 will produce a larger volume of tissue-engineered cartilage to cover large defects.

Activin Receptors, Type I↗

PubMed2006

Macroporous elastomeric scaffolds with extensive micropores for soft tissue engineering.

Macroporous scaffolds are of great value in tissue engineering. We have developed a method to fabricate macroporous scaffolds from a biocompatible and biodegradable elastomer, poly(glycerol sebacate) (PGS). This method is potentially very useful for soft tissue engineering. Our fabrication method produced macroporous scaffolds with extensive micropores. We fabricated flat scaffolds and tubular scaffolds of uniform thickness. This fabrication method demonstrated good control of variables such as pore size, porosity, and pore interconnectivity. Sodium chloride (salt) crystals, which served as solid porogens, were packed into a mold and fused in a humid chamber. PGS was cured while dispersed throughout the fused salt template. Dissolution of the salt and subsequent lyophilization produced elastomer sponges with approximately 90% porosity, interconnected macropores (75-150 microm), and extensive micropores (5-20 microm). The macropores were generated by the salt particles, while the micropores were likely generated by glycerol vapor formed during PGS curing. Such numerous micropores could facilitate cell-cell interactions and mass transport. Fibroblasts adhered to and proliferated well within the PGS scaffolds and formed three-dimensional tissue-engineered constructs within 8 days.

Animals↗

PubMedDate not supplied

Skeletal muscle tissue engineering.

The reconstruction of skeletal muscle tissue either lost by traumatic injury or tumor ablation or functional damage due to myopathies is hampered by the lack of availability of functional substitution of this native tissue. Until now, only few alternatives exist to provide functional restoration of damaged muscle tissues. Loss of muscle mass and their function can surgically managed in part using a variety of muscle transplantation or transposition techniques. These techniques represent a limited degree of success in attempts to restore the normal functioning, however they are not perfect solutions. A new alternative approach to addressing difficult tissue reconstruction is to engineer new tissues. Although those tissue engineering techniques attempting regeneration of human tissues and organs have recently entered into clinical practice, the engineering of skeletal muscle tissue ist still a scientific challenge. This article reviews some of the recent findings resulting from tissue engineering science related to the attempt of creation and regeneration of functional skeletal muscle tissue.

Animals↗

PubMed2006

Evaluation of the anterior cruciate ligament, medial collateral ligament, achilles tendon and patellar tendon as cell sources for tissue-engineered ligament.

This study investigated four different connective tissue cell types to determine which cell type should be the source for seeding a tissue-engineered anterior cruciate ligament (ACL) replacement. Cells derived from the ACL, medial collateral ligament (MCL), achilles tendon (AT), and patellar tendon (PT) of New Zealand White rabbits were isolated and cultured. Each cell type was cultured in vitro after seeding on three-dimensional (3-D) braided polymer scaffolds and on tissue culture polystyrene that served as a control. Samples were evaluated and compared for their morphology, proliferation, and gene expression of fibronectin, type I and type III collagen. Scanning electron microscopy (SEM) photomicrographs verified cell attachment of all four types of connective tissue fibroblasts to the scaffolds. Preliminary results comparing proliferation indicate that cells obtained from the PT and AT have the fastest proliferation. Whereas gene expression of the phenotypic markers measured using real-time reverse transcription polymerase chain reaction (RT-PCR) indicates ACL cells have the highest gene expression for the matrix markers. This leads to the question of which cell type should be the cell source for tissue-engineering of ligament, the highly proliferating cells or the differentiated matrix producing cells. This study would suggest that ACL differentiated matrix producing cells are the most suitable cells for further study and development of a tissue-engineered ligament.

Achilles Tendon↗

PubMed2006

Nondestructive evaluation of osteogenic differentiation in tissue-engineered constructs.

Conventional measurements of osteogenesis in tissue-engineered constructs are destructive to living cells and incapable to provide three-dimensional information. In the present study, noninvasive magnetic resonance (MR) microscopy was used to evaluate osteogenic differentiation in vitro in human mesenchymal stem cell-based tissue-engineered constructs. The constructs were prepared by seeding the cells (10(6)cells/ml) on 4 x 4 x 4 mm gelatin sponge cubes and subsequently exposing them to osteogenic differentiation or basic medium. During the 4-week experiment, alkaline phosphatase (ALP) activity and calcium content of differentiated constructs were significantly increased compared to the basic medium controls. The T1, T2, and apparent diffusion coefficient (ADC) of differentiated constructs were significantly lower than those of the control group at each time point (p < 0.05). The MR parameters of constructs were significantly correlated to their ALP activities (r to T1, T2, and ADC = -0.57, -0.78, and -0.81, respectively) and calcium content (r to T1, T2, and ADC = 0.48, 0.90, and 0.92, respectively) measured by biochemical techniques. MR microscopy can be a promising tool for noninvasive assessment of osteogenic differentiation and to provide three-dimensional information about tissue-engineered constructs.

Alkaline Phosphatase↗

PubMed2003

[Polymeric materials for tissue engineering].

As regeneration scaffolds or templates in tissue engineering, polymeric materials play key roles in inducing tissue regeneration, and mediating cell growth and differentiation, i.e. functioning as artificial extracellular matrix. The polymeric materials including biological derived biopolymers and synthetic polymers, which are usually employed in tissue engineering, are reviewed in this paper.

Biocompatible Materials↗

PubMed2005

Insulin-transferrin-selenium prevent human chondrocyte dedifferentiation and promote the formation of high quality tissue engineered human hyaline cartilage.

This study was to investigate the effects of insulin-transferrin-selenium (ITS) on the proliferation and quantitative gene expression of adult human nasal septum chondrocytes in monolayer culture expansion and the formation of tissue engineered hyaline cartilage. Effects of ITS on human nasal septum chondrocytes monolayer culture expansion and gene expression were evaluated in various culture media either added with 2% fetal bovine serum (FBS) or 1 ng/mL basic fibroblast growth factor plus 1 ng/mL transforming growth factor or both serum and growth factors supplementation in comparison with medium added with 10%FBS. Chondrocytes cultured in medium added with 2% fetal bovine serum and growth factors either supplemented with or without ITS were then mixed with pluronic F-127 hydrogel for in vivo tissue engineered cartilage formation in nude mice model. Engineered tissues were removed after 8 weeks of implantation and evaluated with histological staining, immunohistochemistry, transmission electron microscopy and quantitative gene expression analysis. ITS promoted human chondrocytes proliferation and reduced chondrocytes dedifferentiation in media supplemented with serum and growth factors. ITS with 2% FBS and growth factors provided 15-fold increased in chondrocytes number by the end of the culture period compared to the standard culture medium used in chondrocytes culture (medium added with 10% FBS). Engineered tissue resulted from ITS supplementation demonstrated higher quality of cartilage formation. In conclusion, our study has demonstrated the benefits of ITS supplementation in human chondrocytes monolayer culture and tissue engineering cartilage formation.

Adult↗

PubMed2000

Long-term follow-up of tissue-engineered intestine after anastomosis to native small bowel.

BACKGROUND: Our laboratory has investigated the fabrication of a tissue-engineered intestine using biodegradable polymer scaffolds. Previously we reported that isolated intestinal epithelial organoid units on biodegradable polymer scaffolds formed cysts and the neointestine was successfully anastomosed to the native small bowel. The purpose of this study was to observe the development of tissue-engineered intestine after anastomosis and to demonstrate the effect of the anastomosis over a 9-month period. METHODS: Microporous biodegradable polymer tubes were created from polyglycolic acid. Intestinal epithelial organoid units were harvested from neonatal Lewis rats and seeded onto the polymers, which were implanted into the abdominal cavity of adult male Lewis rats followed by 75% small bowel resection (n=24). Three weeks after implantation, the unit/polymer constructs were anastomosed to the native jejunum in a side-to-side fashion. The anastomosed tissue-engineered intestine was measured by laparotomy 10, 24, and 36 weeks after the implantation (n= 14). During the laparotomy, all rats with an obstruction in their anastomosis were killed and excluded from the statistical analysis. Another five rats were also killed at 10 and 36 weeks for histological and morphometric studies. RESULTS: All analyzed rats survived this study and significantly increased their body weight by 36 weeks. Obstruction of the anastomosis was observed in one rat at 24 weeks and in two rats at 36 weeks; however, the anastomosis was patent in the other 11 rats by 36 weeks. The tissue-engineered intestine of these 11 rats increased in length and diameter at 10, 24, and 36 weeks after anastomosis; there were statistically significant differences between each time point except between the length of 10 and 24 weeks (P<0.016 by Wilcoxon signed rank test). Histologically the inner surface of the tissue-engineered intestine was lined with well-developed neomucosa at 10 and 36 weeks; however, there were small bare areas lacking neomucosa in the tissue-engineered intestine at 36 weeks. Morphometric analysis demonstrated no significant differences in villus number, villus height, and surface length of the neomucosa at 10 and 36 weeks. CONCLUSIONS: Anastomosis between tissue-engineered intestine and native small bowel resulted in no complications after operation and maintained a high patency rate for up to 36 weeks. The tissue-engineered intestine increased in size and was lined with well-developed neomucosa for the duration of the study.

Anastomosis, Surgical↗

PubMed2000

[Short tandem repeat loci examination after repair of coracoclavicular ligament injury by tissue engineered tendon].

OBJECTIVE: To evaluate the result of clinical application in the repair of coracoclavicular ligament injury by tissue engineered tendon using the technique of short tandem repeat loci examination. METHODS: In september 1999, human embryonic tendon cells and artificial materials were co-cultured in vitro to construct tissue engineered tendon, which repaired coracoclavicular ligament injury. After 6 months of operation, micro-tissue were sampled during the operation of removal of internal fixation, and morphological characteristics were examined by HE staining, DNA of tissues were extracted to examine D3S1754 and Cyar04 gene loci. RESULTS: The shoulder function of the patient was recovered well after operation, and no local or systemic immunological rejection were occurred. The electrophoresis typing showed 13/14 at D3S1754 and 8/9 at Cyar04 in the tissue of tissue engineered tendon, while the autogenous ligament were 13/13 and 8/8 at D3S1754 and Cyar04 loci respectively, which suggested that the tissue engineered tendon was survived in vivo. CONCLUSION: The examination of short tandem repeat loci is a better index to evaluate the survival situation of tissue engineered tissue after transplantation in clinical application.

Acromioclavicular Joint↗

PubMed2005

A three-dimensional nonlinear finite element analysis of the mechanical behavior of tissue engineered intervertebral discs under complex loads.

The use of tissue-engineering method holds great promise for treating degenerative disc disease [Gan JC, Ducheyne P, Vresilovic E, Shapiro IM. J Biomed Mater Res 2000; 51(4): 596-604]. This concept typically implies that nucleus pulposus (NP) cells are seeded on a scaffold, while the NP tissue is regenerated. Such hybrid implant is inserted into the host intervertebral disc. Because the success of a tissue engineering approach depends on maintenance or restoration of the mechanical function of the intervertebral disc, it is useful to study the initial mechanical performance of the disc after implantation of the hybrid. A three-dimensional finite element model (FEM) of the L2-L3 disc-vertebrae unit has been analyzed. The model took into account the material nonlinearities and it imposed different and complex loading conditions. In this study, we validated the model by comparison of its predictions with several sets of experimental data; we determined the optimal Young's modulus as well as the failure strength for the tissue-engineered scaffold under different loading conditions; and we analyzed the effects of implanted scaffold on the mechanical behavior of the intervertebral disc. The results of this study suggest that a well-designed tissue-engineered scaffold preferably has a modulus in the range of 5-10 MPa and a compressive strength exceeding 1.67 MPa. Implanted scaffolds with such properties can then achieve the goal of restoring the disc height and distributing stress under different loading conditions.

Biomechanical Phenomena↗

PubMed2003

A tissue-engineered stomach as a replacement of the native stomach.

BACKGROUND: Despite recent advances in reconstruction techniques, total gastrectomy is still accompanied by various complications. As an alternative treatment, we propose a tissue-engineered stomach that replaces the mechanical and metabolic functions of a normal stomach. The objective of this study was to demonstrate the function of a tissue-engineered stomach as a replacement of the native stomach. METHODS: Tissue-engineered stomachs were formed in recipient rats from stomach epithelium organoid units isolated from neonatal donor rats. After 12 weeks, the animals underwent a second operation for replacement of the native stomachs. RESULTS: Tissue-engineered stomachs were successfully used as a substitute of the native stomach in a rat model. An upper gastrointestinal tract study revealed no evidence of bowel stenosis or obstruction at both anastomosis sites. Histologically, the tissue-engineered stomachs had well-developed vascularized tissue with a neomucosa continuously lining the lumen and stratified smooth muscle layers. Immunohistochemical staining for alpha-actin smooth muscle showed that the smooth muscle layers were arranged in a regular fashion. Scanning electron microscopy showed that the surface topography of the tissue-engineered stomachs resembled that of native stomachs. CONCLUSIONS: It has been demonstrated that a tissue-engineered stomach can replace a native stomach in a rat model. Replacement of the native stomach by a tissue-engineered stomach had beneficial effects on the formation of neomucosa and smooth muscle layers in the tissue-engineered stomach.

Animals↗

PubMed2004

Microtia chondrocytes as a donor source for tissue-engineered cartilage.

OBJECTIVES/HYPOTHESIS: Current surgical techniques for the correction of microtia are challenging. Research in the field of tissue engineering is providing insight into chondrocyte behavior for a possible future treatment of microtia. The authors wished to evaluate the biological potential of chondrocytes isolated from microtia cartilage as compared with normal auricular cartilage as a source of tissue-engineered cartilage. STUDY DESIGN: A comparative research design to study the potential of microtia cartilage chondrocytes with normal auricular chondrocytes as a source of tissue-engineered cartilage. METHODS: Cartilage specimens from 12 pediatric patients (six normal auricular specimens and six auricular specimens with microtia) were obtained. The chondrocytes were isolated and cultured in vitro; chondrocyte number was increased by passaging. Each type of cell was implanted in nude mice to generate tissue-engineered cartilage. Eight weeks after implantation the specimens were dissected and removed. Results were compared between the normal auricular and microtia specimens in regard to cell number expansion in vitro and generation of tissue-engineered cartilage in vivo. RESULTS: An initial mean cell number of 150,000 cells in each group (normal and microtia) increased to an average cell number of 120 million cells/mL in the normal and 130 million cells in the microtia subgroups, respectively, at the end of the second passage. Histologically, both types of chondrocytes generated normal elastic cartilage. CONCLUSION: The study demonstrated the potential of cells isolated from microtia cartilage to generate tissue-engineered cartilage. Microtia cartilage represents an important additional donor source for the possible generation of a human tissue-engineered auricle.

Case-Control Studies↗

PubMed2002

Towards tissue engineering of a composite aortic valve.

A tissue-engineered valve needs to incorporate the complex microstructure of the native aortic valve if it is to be as durable as existing bioprosthetic valves. Native aortic valve cusps contain large collagen fiber bundles surrounded by tubes of elastin, linked together by elastin sheets and struts. They also contain glycosaminoglycans (GAGs) that bind water and give the valve cusp a gelatinous consistency. Our approach to tissue engineering the aortic valve is to fabricate the cusp from the building blocks described above. We have developed collagen fiber bundles using the principle of directed collagen gel shrinkage, a GAG matrix by crosslinking high molecular weight hyaluronan with divinyl sulfone, and elastin sheets and tubes by culturing neonatal aortic fibroblasts on the appropriate substrates. To make collagen fiber bundles, cells are mixed with solubilized fibrillar collagen and cast into silicon rubber wells fitted with microporous holders to entrap the gel and hold it in place. As the cells interact with the collagen fibrils, they contract and compact the gel. Since the gel is constrained in the longitudinal direction, it can contract only laterally, forming well-aligned, strong (> 1 MPa) collagen fiber bundles. Elastin sheaths from naturally around the collagen fiber bundles and atop the hyaluronan gel when the neonatal aortic fibroblasts are cultured for more than 4 weeks. The individual building blocks of the aortic valve cusp, designed and fabricated according to patterns dictated by the microstructure of the native aortic valve, will be stacked together to make the final composite, tissue-engineered aortic valve cusp.

Absorbable Implants↗

PubMed2000

Tissue engineering of the vascular system: from capillaries to larger blood vessels.

Tissue engineering is a novel approach to the repair of wounded tissues. Application of this technology to the vascular system is important because of the fundamental nutritional role of the vasculature. This perspective is currently being applied to the first tissue-engineered organ: the skin. Knowledge of capillary constitution and factors inducing their formation has led to attempts to induce their formation in reconstructed skin. Such vascular conduits grown in vitro could also benefit the nutrition of tissues and organs in vivo. The paper reviews recent progress in the in-vitro development of vascularised skin and tissue-engineered blood vessels. It points out the necessity of obtaining pure and well-characterised cultures of the different cell populations that are the basic building blocks of the reconstructions. The importance of an adequate cell-culture environment (nutrients and bi- or tri-dimensional scaffolds for cells) for success in elaborating a reconstructed living tissue able to replace the original is emphasised. Engineered tissues can serve not only as tissue replacements but also as in-vitro models for research in organ physiology and physiopathology. These tissues are also attractive vehicles for gene therapy, one of the more promising new methods of disease treatment.

Blood Vessels↗

PubMed2006

Heart valve tissue engineering: concepts, approaches, progress, and challenges.

Potential applications of tissue engineering in regenerative medicine range from structural tissues to organs with complex function. This review focuses on the engineering of heart valve tissue, a goal which involves a unique combination of biological, engineering, and technological hurdles. We emphasize basic concepts, approaches and methods, progress made, and remaining challenges. To provide a framework for understanding the enabling scientific principles, we first examine the elements and features of normal heart valve functional structure, biomechanics, development, maturation, remodeling, and response to injury. Following a discussion of the fundamental principles of tissue engineering applicable to heart valves, we examine three approaches to achieving the goal of an engineered tissue heart valve: (1) cell seeding of biodegradable synthetic scaffolds, (2) cell seeding of processed tissue scaffolds, and (3) in-vivo repopulation by circulating endogenous cells of implanted substrates without prior in-vitro cell seeding. Lastly, we analyze challenges to the field and suggest future directions for both preclinical and translational (clinical) studies that will be needed to address key regulatory issues for safety and efficacy of the application of tissue engineering and regenerative approaches to heart valves. Although modest progress has been made toward the goal of a clinically useful tissue engineered heart valve, further success and ultimate human benefit will be dependent upon advances in biodegradable polymers and other scaffolds, cellular manipulation, strategies for rebuilding the extracellular matrix, and techniques to characterize and potentially non-invasively assess the speed and quality of tissue healing and remodeling.

Animals↗

PubMed2004

Synthetic extracellular matrices for tissue engineering and regeneration.

The need for replacement tissues or organs requires a tissue supply that cannot be satisfied by the donor supply. The tissue engineering and regeneration field is focused on the development of biological tissue and organ substitutes and may provide functional tissues to restore, maintain, or improve tissue formation. This field is already providing new therapeutic options to bypass the limitations of organ?tissue transplantation and will likely increase in medical importance in the future. This interdisciplinary field accommodates principles of life sciences and engineering and encompasses three major strategies. The first, guided tissue regeneration, relies on synthetic matrices that are conductive to host cells populating a tissue defect site and reforming the lost tissue. The second approach, inductive strategy, involves the delivery of growth factors, typically using drug delivery strategies, which are targeted to specific cell populations in the tissues surrounding the tissue defect. In the third approach, specific cell populations, typically multiplied in culture, are directly delivered to the site at which one desires to create a new tissue or organ. In all of these approaches, the knowledge acquired from developmental studies often serves as a template for the tissue engineering approach for a specific tissue or organ. This article overviews the development of synthetic extracellular matrices (ECMs) for use in tissue engineering that aim to mimic functions of the native ECM of developing and regenerating tissues. In addition to the potential therapeutic uses of these materials, they also provide model systems for basic studies that may shed light on developmental processes.

Blood Vessels↗

PubMed2003

Motivation, characterization, and strategy for tissue engineering the temporomandibular joint disc.

The purpose of this review is to serve as the standard point of reference in guiding researchers investigating the tissue engineering of the temporomandibular joint (TMJ) disc. Tissue engineering of the TMJ disc is in its infancy, and currently there exists a gap between the tissue engineering community and the TMJ characterization community. The primary goal is to help bridge that gap by consolidating the characterization studies here as a reference to researchers attempting to tissue engineer the TMJ disc. A brief review of TMJ anatomy is provided, along with a description of relevant pathology, current treatment, and a rationale for engineering the TMJ disc. The biochemical composition and organization of the disc are reviewed, including glycosaminoglycan (GAG) and collagen content. The collagen of the disc is almost exclusively type I and primarily runs anteroposteriorly through the center and in a ringlike fashion around the periphery. The GAG content is approximately an order of magnitude less than that of hyaline cartilage, and although the distribution is not entirely clear, it seems as though chondroitin and dermatan sulfate are by far the primary GAGs. Cellular characterization and mechanical properties under compression, tension, and shear are reviewed as well. The cells of the disc are not chondrocytes, but rather resemble fibrocytes and fibrochondrocytes and may be of the same lineage. Mechanically, the disc is certainly anisotropic and nonhomogeneous. Finally, a review of efforts in tissue engineering and cell culture studies of the disc is provided and we close with a description of the direction we envision/propose for successful tissue engineering of the TMJ disc.

Animals↗