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Results for “Tissue Engineering”

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PubMed2002

[A tissue-engineered strain scaffold for three-dimensional cell cultures].

This article introduces a three-dimensional scaffold which is used to perform three-dimensional cell culture under mechanical stretch from the point of construction of tissue-engineered tissue. The composition, structure, surface characteristics, mechanical property, and cell compatibility of the scaffold have been studied by using surface chemistry and material mechanics testing methods. The results indicate that the polyvinyl alcohol (PVA) sponge, which is water-tolerant, coated with Poly-DL-lactic-co-glycolic acid (PLGA) possesses a good nature in appropriate surface feature, porosity, elastic recoil, and cell compatibility. These features provide wide options for using this scaffold to study the effects of mechanical stretch on cells maintained in three-dimensional culture to provide a three-dimensional matrix.

Biocompatible Materials↗

PubMed2005

Bone tissue engineering with porous hydroxyapatite ceramics.

The main principle of bone tissue engineering strategy is to use an osteoconductive porous scaffold in combination with osteoinductive molecules or osteogenic cells. The requirements for a scaffold in bone regeneration are: (1) biocompatibility, (2) osteoconductivity, (3) interconnected porous structure, (4) appropriate mechanical strength, and (5) biodegradability. We recently developed a fully interconnected porous hydroxyapatite (IP-CHA) by adopting the "form-gel" technique. IP-CHA has a three-dimensional structure with spherical pores of uniform size that are interconnected by window-like holes; the material also demonstrated adequate compression strength. In animal experiments, IP-CHA showed superior osteoconduction, with the majority of pores filled with newly formed bone. The interconnected porous structure facilitates bone tissue engineering by allowing the introduction of bone cells, osteotropic agents, or vasculature into the pores. In this article, we review the accumulated data on bone tissue engineering using the novel scaffold, focusing especially on new techniques in combination with bone morphogenetic protein (BMP) or mesenchymal stem cells.

Animals↗

PubMed2002

[Tissue engineering--Quality and safety control of cultured human cells].

Tissue Engineering Research Center (TERC) at Ikeda city, Osaka has been established in April, 2001 and functions as Cell Processing Center (CPC) having biological clean rooms. At the center, many biomedical researchers as well as clinicians work to develop human cell-based medical devices. In the CPC, Medical Device Team in TERC deals with differentiated osteoblasts derived from cultured human bone marrow cells to create tissue-engineered implantable bone. We are focusing on patients treatments by direct application of the tissue engineered bone, therefore, we should manipulate the human cells under more restricted and controlled culture condition than ordinal cases. Here we introduce environment and technology of human bone marrow cell culture, and show quality control and safety evaluation of culture processes in TERC.

English Abstract↗

PubMedDate not supplied

A model of tissue-engineered ventral hernia repair.

We have developed a tissue-engineered ventral hernia repair system using our novel aligned collagen tube and autologous skeletal muscle satellite cells. In this model system, skeletal muscle satellite cells were isolated from a biopsy, expanded in culture, and incorporated into our collagen tube scaffold, forming the tissue-engineered construct. We characterized the results of the repaired hernias on both the gross and microscopic scales and compared them to an unrepaired control, an autologous muscle repair control, and a collagen-tube-only repair. Untreated animals developed a classic hernia sac, devoid of abdominal muscle and covered only with a thin layer of mesothelial tissue. Significant muscle, small-diameter blood vessels, and connective tissue were apparent in both the autologous control and the engineered muscle repairs. The engineered muscle repairs became cellularized, vascularized, and integrated with the native tissue, hence becoming a "living" repair. A tissue-engineered construct repair of ventral hernias with subsequent incorporation and vascularization could provide the ultimate in anterior wall myofascial defect repair and would further the understanding of striated muscle engineering. The knowledge gained from our model system would have immediate application to mangled extremities, maxillofacial reconstructions, and restorative procedures following tumor excision in other areas of the body.

Animals↗

PubMed1999

Human-based tissue-engineered implants for plastic and reconstructive surgery.

The emerging field of tissue engineering focuses on the creation of living tissues and organs for use in tissue repair and transplantation. Human cells are seeded onto biocompatible scaffolds and grown under physiologic conditions to produce all-human biointeractive implants. Tissue-engineered skin implants have shown efficacy in a variety of wound applications. Near term products, including injectable human matrix for contour defects and tissue-engineered cartilage, are proving to be important tools for plastic and reconstructive surgery.

Biotechnology↗

PubMed2002

[Application of tissue engineering in bioartificial renal tubule].

Tissue engineering is a discipline involving both materials science, engineering and life science. It has found successful application in Bioartificial renal tubule assist device RAD which is still under development. Experiments have proved that RAD can serve as renal tubule to perform its transport, metabolic and endocrine functions in patients with acute or chronic renal failure.

Animals↗

PubMedDate not supplied

Noninvasive measurement of viable cell number in tissue-engineered constructs in vitro, using 1H nuclear magnetic resonance spectroscopy.

Noninvasive monitoring of tissue-engineered constructs is of critical importance for accurate characterization of constructs and their remodeling in vitro and in vivo. This study investigated the utility of (1)H NMR spectroscopy to noninvasively quantify viable cell number in tissue-engineered substitutes in vitro. Agarose disk-shaped constructs containing betaTC3 cells were employed as the model tissue-engineered system. Two construct prototypes containing different initial cell numbers were monitored by localized, water-suppressed 1H NMR spectroscopy over the course of 13 days. (1)H NMR measurements of the total choline resonance at 3.2 ppm were compared with results from the traditional cell viability assay MTT and with insulin secretion rates. Results show a strong linear correlation between total choline and MTT (R (2) = 0.86), and between total choline and insulin secretion rate (R (2) = 0.90). Overall, this study found noninvasive measurement of total choline to be an accurate and nondestructive assay for monitoring viable betaTC3 cell numbers in tissue-engineered constructs. The applicability of this method to in vivo monitoring is also discussed.

Algorithms↗

PubMed2006

Elastin biosynthesis: The missing link in tissue-engineered blood vessels.

Nearly 20 years have passed since Weinberg and Bell attempted to make the first tissue-engineered blood vessels. Following this early attempt, vascular tissue engineering has emerged as one of the most promising approaches to fabricate orderly and mechanically competent vascular substitutes. In elastic and muscular arteries, elastin is a critical structural and regulatory matrix protein and plays an important and dominant role by conferring elasticity to the vessel wall. Elastin also regulates vascular smooth muscle cells activity and phenotype. Despite the great promise that tissue-engineered blood vessels have to offer, little research in the last two decades has addressed the importance of elastin incorporation into these vessels. Although cardiovascular tissue engineering has been reviewed in the past, very little attention has been given to elastin. Thus, this review focuses on the recent advances made towards elastogenesis and the challenges we face in the quest for appropriate functional vascular substitutes.

Arteries↗

PubMed2002

[First successful clinical application of tissue engineered blood vessel].

With this tissue engineering (TE) technique, the peripheral pulmonary artery was successfully reconstructed, using the patient's own venous cells in a 4-year-old girl, 2 years after Fontan procedure. A 4-year-old girl was given a diagnosis of single right ventricle, double-outlet right ventricle and pulmonary atresia. She underwent left modified Blalock-Taussig shunt at a month old, pulmonary artery angioplasty at a year and 3 months old, and bidirectional cavopulmonary shunt at 2 years and a month old. She underwent again pulmonary artery angioplasty and Fontan operation at 3 years and 3 months. An angiographical examination 7 months after the operation revealed total occlusion of the right intermediate pulmonary artery. TE technique using autologous cells was indicated. The application of this procedure was approved by the ethical committee in Tokyo Women's Medical University. The patient's parents were thoroughly informed and signed a consent form. Approximately 2 cm of the peripheral vein was explanted under sterile conditions. The tissue was minced, placed in tissue culture dishes and cultured at 37 degrees C, 100% humidity and a 5% CO2 atmosphere for almost a month. The number of cells substantially increased to reach 12 millions for almost a month. The culture medium was changed every 3 days. The polymer tube that served as a scaffold for cells was composed of the copolymer of PCL-PLA (50:50) with reinforcement by woven PGA. The polymer conduit, 10 mm in diameter, 20 mm in length and 1 mm in thickness, was designated to biodegradate within 8 weeks. The number of seeded cells was approximately a million/cm2. The graft transplantation was performed 10 days after seeding cells. The occlusive right intermediate pulmonary artery was reconstructed with the TE vessel graft under extracorporeal circulation with a pump-oxygenator. The patient followed a satisfactory postoperative course. The postoperative angiography demonstrated that the graft was not constricted and dilated but that it preserved good patency. Long-term follow-up are necessary. We plan to continue to use the TE technique using autologous cells in the low pressure system like venous or pulmonary circulation. Because our results even in early experimental phase were valuable and promising, we believe that the TE approach may play an important role in the near future as an another alternative, together with transplantation and artificial organ, especially in the field of cardiovascular surgery that mostly needs replants.

Blood Vessel Prosthesis Implantation↗

PubMed2003

Collagen/chitosan porous scaffolds with improved biostability for skin tissue engineering.

Porous scaffolds for skin tissue engineering were fabricated by freeze-drying the mixture of collagen and chitosan solutions. Glutaraldehyde (GA) was used to treat the scaffolds to improve their biostability. Confocal laser scanning microscopy observation confirmed the even distribution of these two constituent materials in the scaffold. The GA concentrations have a slight effect on the cross-section morphology and the swelling ratios of the cross-linked scaffolds. The collagenase digestion test proved that the presence of chitosan can obviously improve the biostability of the collagen/chitosan scaffold under the GA treatment, where chitosan might function as a cross-linking bridge. A detail investigation found that a steady increase of the biostability of the collagen/chitosan scaffold was achieved when GA concentration was lower than 0.1%, then was less influenced at a still higher GA concentration up to 0.25%. In vitro culture of human dermal fibroblasts proved that the GA-treated scaffold could retain the original good cytocompatibility of collagen to effectively accelerate cell infiltration and proliferation. In vivo animal tests further revealed that the scaffold could sufficiently support and accelerate the fibroblasts infiltration from the surrounding tissue. Immunohistochemistry analysis of the scaffold embedded for 28 days indicated that the biodegradation of the 0.25% GA-treated scaffold is a long-term process. All these results suggest that collagen/chitosan scaffold cross-linked by GA is a potential candidate for dermal equivalent with enhanced biostability and good biocompatibility.

Animals↗

PubMedDate not supplied

New cell-based technologies in bone and cartilage tissue engineering. I. Bone reconstruction.

A tissue engineering, cell-based therapeutic approach could be essential for extensive bone or cartilage reconstruction. This article is divided in two chapters and describes new cell-based surgical techniques for cartilage and bone reconstruction. In the first part on bone reconstruction, marrow-derived osteogenic progenitor cells combined with hydroxyapatite were utilized. The validity of this model has been shown for the repair of critical size bone defects in large size animal models. We used this cell-based therapeutic approach to treat 3 patients with large bone defects, achieving bone reconstruction.

Adolescent↗

PubMed2001

[The influence of tissue engineered tendon on subgroup of T lymphocytes and its receptor in roman chickens].

OBJECTIVE: To investigate the influence of tissue engineered tendon on subgroup of T lymphocytes and its receptor in Roman chickens. METHODS: The flexor digitorum profundus of the third toes of right feet in 75 Roman chickens were resected and made 2.5 cm defects as experimental model. They were randomly divided into five groups according to five repair methods: no operation (group A), autograft (group B), fresh allograft (group C), polymer combined with allogenous tendon cells (group D), derived tendon materials combined with allogenous tendon cells (group E). The proliferation and transformation of lymphocytes and contribution of CD4+, CD8+, CD28 and T cell receptor (TCR) were detected to study the immune response. RESULTS: The CD4+, CD8+ and TCR of group D and E were increased slightly than that of group B after 7 days, while after 14 days, those data decreased gradually and no significant difference between tissue engineered tendon and autografts (P > 0.05), and there was significant difference between fresh allograft and tissue engineered tendon (P < 0.05). Lymphocytes transformation induced by conA also showed no significant difference between tissue engineered tendon and autografts (P > 0.05). CONCLUSION: Tendon cells are hypoantigen cells, there are less secretion of soluble antigen or antigen chips dropped out from cells. Tissue engineered tendon has excellent biocompatibility.

Animals↗

PubMed2003

Characterization of cellular carriers for use in injectable tissue-engineering composites.

Injectable composite tissue-engineering scaffolds are systems that incorporate individual cell carriers within a gel delivery matrix. This study assessed low-temperature casting as a possible method to produce synthetic cell-carrier beads. Porous poly-L-lactide beads were manufactured by low-temperature casting. Two porogens, either glucose or sodium chloride, were incorporated into the beads and subsequently leached. Beads were seeded with primary culture aortic smooth muscle rat cells and were evaluated over a 13-day period using a series of chemical, biochemical, and histological assays. Results indicate that low-temperature casting is a viable technique to produce injectable beads on the order of 1.5-2.0 mm. The manufactured beads supported smooth muscle cell attachment and proliferation; where the beads formed with sodium chloride allowed enhanced proliferation. Differences in physical qualities, namely buoyancy and topography, were dependent on porogen selection and may provide a mechanism for bead and composite customization.

Animals↗

PubMed2006

Macroporous bioactive glass-ceramic scaffolds for tissue engineering.

Highly bioactive scaffolds for tissue engineering were synthesized using a glass belonging to the SiO2-CaO-K2O (SCK) system. The glass SCK was prepared by a traditional melting-quenching route and its bioactivity was assessed by in vitro tests in a simulated body fluid (SBF). The glass was ground and sieved to obtain powders of specific size that were subsequently mixed with polyethylene particles of two different dimensions. The powders were then uniaxially pressed to obtain a crack free green compact that was thermally treated to remove the organic component and to sinter the inorganic phase. The obtained biomaterial was characterised by means of X-ray Diffraction, SEM equipped with EDS, mercury intrusion porosimetry, density measurements, image analysis, mechanical tests and in vitro evaluations. A glass-ceramic macroporous scaffold with a homogenously distributed and highly interconnected porosity was obtained. The amount and size of the introduced porosity could be tailored using various amounts of polyethylene powders of different size.

Biocompatible Materials↗

PubMed2004

Functional tissue engineering parameters toward designing repair and replacement strategies.

Abnormal joint kinematics and loads induced after soft tissue injuries are assumed to contribute to long-term degenerative joint disease and osteoarthritis. Controlling abnormal kinematics after repair and reconstruction of these injured structures would seem to be important for limiting wear of the articular cartilage surfaces. In this paper, we propose to expand the paradigm of functional tissue engineering to more fully characterize normal joint function and to establish design parameters for soft tissue repair and reconstruction to ultimately protect joint surfaces after surgery. Structure-function relationships are examined for tissues of increasing complexity, from tendons to menisci. Emphasis is placed on understanding normal in vivo function of tissues by conducting biomechanical experiments in vitro that better mimic in vivo conditions. This process yields nine classes of functional tissue engineering parameters: differential fiber length, in vivo force and displacement, variations in relative attachment site locations, loading from adjacent structures, fiber interactions, types of insertion, regional variations in material properties, nonparallel fiber orientations, and complex loading within the structure. These functional tissue engineering parameters are useful not only for understanding the function of normal tissues but for more effectively designing their repair and replacement. This paper concludes with a discussion of research directions that investigators might take to establish tissue-specific functional tissue engineering parameters for improving joint function and reducing articular surface degradation and osteoarthritis.

Humans↗

PubMed1999

Engineering tissues and organs.

Genitourinary tissues can be engineered in-vitro and in-vivo for reconstruction using selective cell transplantation in combination with acellular matrices. This technology involves an interdisciplinary approach combining techniques of cell biology and materials sciences towards the development of functional tissues or organs. Tissues and organs in urology, such as the bladder, clitoris, corpus cavermosum, kidney, testis, ureter and urethra have been created in the laboratory, with varying degrees of functionality. Cells have also been recently used in patients as bulking agents for the treatment of vesicoureteral reflux and urinary incontinence. As the science of tissue engineering evolves, one can expect a wider application of this technology to the armamentarium of urologic surgery.

Animals↗

PubMed2006

Tissue engineering for the hand surgeon: a clinical perspective.

Hand surgeons may be faced with tissue shortages for reconstruction after trauma, tumor resection, or congenital deficiency. Tissue engineering is a developing scientific field that combines the principles of life sciences and engineering in developing biologic substitutes that will restore, maintain, or improve tissue function. This article reviews the general principles of tissue engineering as applied to musculoskeletal tissues including nerve, bone, tendon, skin, vessels, and cartilage and focuses on the application of tissue engineering that is relevant to clinical hand surgery.

Blood Vessel Prosthesis↗

PubMed2002

[Ocular surface reconstruction by tissue engineering].

Ocular surface reconstruction by tissue engineering using somatic stem cells is a second-generation modality. In order to treat bilaterally affected, severe ocular surface disorders, we investigated the transplantation of two types of cultivated mucosal epithelia: allogenic corneal epithelial stem cells, and autologous oral mucosal epithelial cells. For this, first, we summarized the clinical results of allogenic keratoepithelioplasty and limbal transplantation. In addition, we showed that the immunological shift from Th1 to Th2 by using keyhole limpet hemocyanin was effective in suppressing the incidence of immunological rejection. Second, we investigated the transplantation of cultivated human corneal epithelial stem cells onto amniotic membrane. The cultivated sheet was created by co-culture with 3T3 fibroblasts, using the air-lift method, in cultivating the corneal epithelial stem cell on the amniotic membrane. These cultivated cells demonstrated positive keratin 3 and 12 specific to in vivo corneal epithelium, tight junction related proteins, and telomerase activity. The transplanted allogenic human corneal epithelial sheet survived on the corneal surface in all cases, and was quite effective for achieving ocular surface stability in the acute phase of Stevens-Johnson syndrome, ocular cicatricial pemphigoid, or chemical injury. However, a few cases developed immunological rejection or opportunistic infection. Third, to establish the transplantation of the autologous cultivated oral mucosal epithelial sheet, we performed animal experiments using rabbits. In vitro oral mucosal epithelial sheet showed histology similar to that of in vivo corneal epithelial sheet. It expressed positive keratin 3 as well. Since the autologous transplantation of this sheet survived on the ocular surface with the recovery of corneal transparency, a cultivated oral mucosal epithelium may become a substitute for corneal epithelium. Fourth, we created a cultivated human corneal endothelial cell sheet on amniotic membrane using a similar technique, and transplanted it to a rabbit eye as a xenograft. The transplanted corneal endothelial cell density was over 3,000 cells/mm2, and it was actively functioning even after the transplantation. Lastly, to explore cell markers for corneal epithelial stem cells, we established a technique using laser micro-capture, and introduced amplified fragment length polymorphism (AFLP), identifying several candidate molecules as stem cell markers.

Animals↗