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Encyclopedia > Tissue engineering
Engineering Portal

Tissue engineering is the use of a combination of cells, engineering and materials methods, and suitable biochemical and physio-chemical factors to improve or replace biological functions. While most definitions of tissue engineering cover a broad range of applications, in practice the term is closely associated with applications that repair or replace portions of or whole tissues (i.e., bone, cartilage, blood vessels, bladder, etc...). Often, the tissues involved require certain mechanical and structural properties for proper function. The term has also been applied to efforts to perform specific biochemical functions using cells within an artificially-created support system (e.g. an artificial pancreas, or a bioartificial liver). The term regenerative medicine is often used synonymously with tissue engineering, although those involved in regenerative medicine place more emphasis on the use of stem cells to produce tissues. Image File history File links Portal. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... Engineering is the applied science of acquiring and applying knowledge to design, analysis, and/or construction of works for practical purposes. ... The Materials Science Tetrahedron, which often also includes Characterization at the center Materials science or Materials Engineering is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering. ... Biochemistry is the study of the chemical processes and transformations in living organisms. ... Biology studies the variety of life (clockwise from top-left) E. coli, tree fern, gazelle, Goliath beetle Biology (from Greek: βίος, bio, life; and λόγος, logos, knowledge), also referred to as the biological sciences, is the study of living organisms utilizing the scientific method. ... This article is about the skeletal organs. ... Cartilage is a type of dense connective tissue. ... The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... In anatomy, the urinary bladder is a hollow, muscular, and distensible (or elastic) organ that sits on the pelvic floor in mammals. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... The artificial pancreas is a technology in development to help diabetic persons automatically control their blood glucose level by providing the substitute endocrine functionality of a healthy pancreas. ... A bioartificial liver device (BAL) is an artificial extracorporeal supportive device for an individual who is suffering from acute liver failure. ... Medical researchers believe that stem cell treatments have the potential to change the face of human disease and alleviate suffering. ... Mouse embryonic stem cells with fluorescent marker. ...


In 2003, the NSF published a report entitled "The Emergence of Tissue Engineering as a Research Field" [2], which gives a thorough description of the history of this field. The logo of the National Science Foundation The National Science Foundation (NSF) is an independent United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. ...

Micromass cultures of C3H-10T1/2 cells at varied oxygen tensions stained with Alcian blue.
Micromass cultures of C3H-10T1/2 cells at varied oxygen tensions stained with Alcian blue.

Contents

Image File history File links Size of this preview: 800 × 400 pixelsFull resolution (1243 × 622 pixel, file size: 615 KB, MIME type: image/jpeg) Alcian blue stained micromass cultures of C3H-10T1/2 cells at different oxygen tensions. ... Image File history File links Size of this preview: 800 × 400 pixelsFull resolution (1243 × 622 pixel, file size: 615 KB, MIME type: image/jpeg) Alcian blue stained micromass cultures of C3H-10T1/2 cells at different oxygen tensions. ... The chemical formula of Alcian blue Alcian blue is a phthalocyanine dye which contains copper. ...

Definitions

A commonly applied definition of tissue engineering, as stated by Langer and Vacanti, is "an interdisciplinary field that applies the principles of engineering and life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function or a whole organ".[1] Tissue engineering has also been defined as "understanding the principles of tissue growth, and applying this to produce functional replacement tissue for clinical use."[2] A further description goes on to say that an "underlying supposition of tissue engineering is that the employment of natural biology of the system will allow for greater success in developing therapeutic strategies aimed at the replacement, repair, maintenance, and/or enhancement of tissue function."[citation needed] Categories: Possible copyright violations ... Interdisciplinary work is that which integrates concepts across different disciplines. ... Biological tissue is a collection of interconnected cells that perform a similar function within an organism. ...


Powerful recent developments in the multidisciplinary field of tissue engineering have yielded a novel set of tissue replacement parts and implementation strategies. Scientific advances in biomaterials, stem cells, growth and differentiation factors, and biomimetic environments have created unique opportunities to fabricate tissues in the laboratory from combinations of engineered extracellular matrices ("scaffolds"), cells, and biologically active molecules. Among the major challenges now facing tissue engineering is the need for more complex functionality, as well as both functional and biomechanical stability in laboratory-grown tissues destined for transplantation. The continued success of tissue engineering, and the eventual development of true human replacement parts, will grow from the convergence of engineering and basic research advances in tissue, matrix, growth factor, stem cell, and developmental biology, as well as materials science and bioinformatics.


Cells

Stained cells in culture
Stained cells in culture

Tissue engineering utilizes living cells as engineering materials. Examples include using living fibroblasts in skin replacement or repair, cartilage repaired with living chondrocytes, or other types of cells used in other ways. Cultured MDCK epithelial cells were stained for keratin, desmoplakin, and DNA. The stained cells were visualized by scanning laser confocal microscopy. ... Cultured MDCK epithelial cells were stained for keratin, desmoplakin, and DNA. The stained cells were visualized by scanning laser confocal microscopy. ... Mouse Embryonic Fibroblasts (MEF) A fibroblast is a type of cell that synthesizes and maintains the extracellular matrix of many animal tissues. ... Beyond overall skin structure, refer below to: See-also. ... Cartilage is a type of dense connective tissue. ... Chondrocytes (< Greek chondros cartilage + kytos cell) are the only cells found in cartilage. ...


Cells became available as engineering materials when scientists at Geron Corp. discovered how to extend telomeres in 1998, producing immortalized cell lines. Before this, laboratory cultures of healthy, noncancerous mammalian cells would only divide a fixed number of times, up to the Hayflick limit. A telomere is a region of highly repetitive DNA at the end of a chromosome that functions as a disposable buffer. ... Biological immortality can be defined as the absence of a sustained increase in rate of mortality as a function of chronological age. ... The Hayflick limit was discovered by Leonard Hayflick in 1965. ...


Extraction

From fluid tissues such as blood, cells are extracted by bulk methods, usually centrifugation or apheresis. From solid tissues, extraction is more difficult. Usually the tissue is minced, and then digested with the enzymes trypsin or collagenase to remove the extracellular matrix that holds the cells. After that, the cells are free floating, and extracted using centrifugation or apheresis.
Digestion with trypsin is very dependent on temperature. Higher temperatures digest the matrix faster, but create more damage. Collagenase is less temperature dependent, and damages fewer cells, but takes longer and is a more expensive reagent. Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... Centrifugation is a process that involves the use of the centrifugal force for the separation of mixtures. ... Whole blood enters the centrifuge on the left and separates into layers so that selected components can be drawn off on the right. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Trypsin (EC 3. ... Collagenases are enzymes that break the peptide bonds in collagen. ... Illustration depicting extracellular matrix (basement membrane and interstitial matrix) in relation to epithelium, endothelium and connective tissue In biology, the extracellular matrix (ECM) is the extracellular part of animal tissue that usually provides structural support to the cells in addition to performing various other important functions. ...


Types of cells

Cells are often categorized by their source:

  • Autologous cells are obtained from the same individual to which they will be reimplanted. Autologous cells have the fewest problems with rejection and pathogen transmission, however in some cases might not be available. For example in genetic disease suitable autologous cells are not available. Also very ill or elderly persons, as well as patients suffering from severe burns, may not have sufficient quantities of autologous cells to establish useful cell lines. Moreover since this category of cells needs to be harvested from the patient, there are also some concerns related to the necessity of performing such surgical operations that might lead to donor site infection or chronic pain. Autologous cells also must be cultured from samples before they can be used: this takes time, so autologous solutions may not be very quick. Recently there has been a trend towards the use of mesenchymal stem cells from bone marrow and fat. These cells can differentiate into a variety of tissue types, including bone, cartilage, fat, and nerve. A large number of cells can be easily and quickly isolated from fat, thus opening the potential for large numbers of cells to be quickly and easily obtained. Several companies have been founded to capitalize on this technology, the most successful at this time being Cytori Therapeutics.
  • Allogenic cells come from the body of a donor of the same species. While there are some ethical constraints to the use of human cells for in vitro studies, the employment of dermal fibroblasts from human foreskin has been demonstrated to be immunologically safe and thus a viable choice for tissue engineering of skin.
  • Xenogenic cells are those isolated from individuals of another species. In particular animal cells have been used quite extensively in experiments aimed at the construction of cardiovascular implants.
  • Syngeneic' or isogenic cells are isolated from genetically identical organisms, such as twins, clones, or highly inbred research animal models.
  • Primary cells are from an organism.
  • Secondary cells are from a cell bank.
  • Stem cells (see main article: stem cell) are undifferentiated cells with the ability to divide in culture and give rise to different forms of specialized cells. According to their source stem cells are divided into "adult" and "embryonic" stem cells, the first class being multipotent and the latter mostly pluripotent; some cells are totipotent, in the earliest stages of the embryo. While there is still a large ethical debate related with the use of embryonic stem cells, it is thought that stem cells may be useful for the repair of diseased or damaged tissues, or may be used to grow new organs.

A genetic disorder, or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. ... Mesenchymal cells, also known as mesenchymal stem cells or marrow stromal cells (MSC), are stem cells that can differentiate into osteoblasts, chondrocytes, myocytes, adipocytes, neuronal cells, and, as decribed lately, into beta-pancreatic islets cells. ... Mouse embryonic stem cells. ... This article does not cite any references or sources. ... For other uses, see FAT. Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. ... This article is about the skeletal organs. ... Cartilage is a type of dense connective tissue. ... For other uses, see FAT. Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. ... Nerves (yellow) Nerves redirects here. ... Image File history File links Mouse_embryonic_stem_cells. ... Image File history File links Mouse_embryonic_stem_cells. ... Binomial name Mus musculus Linnaeus, 1758 Mus musculus is the common house mouse. ... Mammalian embryogenesis is the process of cell division and cellular differentiation which leads to the development of a mammalian embryo. ... Mouse Embryonic Fibroblasts (MEF) A fibroblast is a type of cell that synthesizes and maintains the extracellular matrix of many animal tissues. ... Mouse embryonic stem cells with fluorescent marker. ... Multipotent progenitor cells can give rise to several other cell types, but those types are limited in number. ... Pluripotency in the broad sense refers to having more than one potential outcome. In biological systems, this can refer either to cells or to biological compounds. ... Totipotency is the ability of a single cell, usually a stem cell, to divide and produce all the differentiated cells in an organism, including extraembryonic tissues. ...

Engineering materials

Cells are often implanted or 'seeded' into an artificial structure capable of supporting three-dimensional tissue formation. These structures, typically called scaffolds, are often critical, both ex vivo as well as in vivo, to recapitulating the in vivo milieu and allowing cells to influence their own microenvironments. Scaffolds usually serve at least one of the following purposes: 2-dimensional renderings (ie. ... Scaffold may refer to: scaffolding as used in construction A gallows The Scaffold, UK musical group Scaffold - GNOME Development Environment Scaffold (Protein ECM) This is a disambiguation page — a navigational aid which lists pages that might otherwise share the same title. ... Ex vivo is a term used in reference to the study or assay of living tissue in an artificial environment outside the living organism. ... In vivo (Latin for (with)in the living). ...

  • Allow cell attachment and migration
  • Deliver and retain cells and biochemical factors
  • Enable diffusion of vital cell nutrients and expressed products
  • Exert certain mechanical and biological influences to modify the behaviour of the cell phase
This animation of a rotating Carbon nanotube shows its 3D structure. Carbon nanotubes are among the numerous candidates for tissue engineering scaffolds since they are biocompatible, resistant to biodegredation and can be functionalized with biomolecules. However, the possibility of toxicity with non-biodegradable nano-materials is not fully understood.
This animation of a rotating Carbon nanotube shows its 3D structure. Carbon nanotubes are among the numerous candidates for tissue engineering scaffolds since they are biocompatible, resistant to biodegredation and can be functionalized with biomolecules. However, the possibility of toxicity with non-biodegradable nano-materials is not fully understood.

To achieve the goal of tissue reconstruction, scaffolds must meet some specific requirements. A high porosity and an adequate pore size are necessary to facilitate cell seeding and diffusion throughout the whole structure of both cells and nutrients. Biodegradability is often an essential factor since scaffolds should preferably be absorbed by the surrounding tissues without the necessity of a surgical removal. The rate at which degradation occurs has to coincide as much as possible with the rate of tissue formation: this means that while cells are fabricating their own natural matrix structure around themselves, the scaffold is able to provide structural integrity within the body and eventually it will break down leaving the neotissue, newly formed tissue which will take over the mechanical load. Injectability is also important for clinical uses. Image File history File links Kohlenstoffnanoroehre_Animation. ... Image File history File links Kohlenstoffnanoroehre_Animation. ... 3D model of three types of single-walled carbon nanotubes. ... Biocompatible is the adjectival form of biocompatibility and is often used to characterise a biomaterial. ... Biodegradation is the decomposition of organic material by microorganisms. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Biodegradation is the process by which organic substances are broken down by living organisms. ...


Many different materials (natural and synthetic, biodegradable and permanent) have been investigated. Most of these materials have been known in the medical field before the advent of tissue engineering as a research topic, being already employed as bioresorbable sutures. Examples of these materials are collagen or some linear aliphatic polyesters. It has been suggested that suture material be merged into this article or section. ... Tropocollagen triple helix. ... In chemistry, non-aromatic and non-cyclic (acyclic) organic compounds are called aliphatic. ... SEM picture of a bend in a high surface area polyester fiber with a seven-lobed cross section Polyester is a category of polymers, or, more specifically condensation polymers, which contain the ester functional group in their main chain. ...


New biomaterials have been engineered to have ideal properties and functional customization: injectability, synthetic manufacture, biocompatibility, non-immunogenicity, transparency, nano-scale fibers, low concentration, resorption rates, etc. PuraMatrix, originating from the MIT labs of Zhang, Rich, Grodzinsky and Langer is one of these new biomimetic scaffold families which has now been commercialized and is impacting clinical tissue engineering.


A commonly used synthetic material is PLA - polylactic acid. This is a polyester which degrades within the human body to form lactic acid, a naturally occurring chemical which is easily removed from the body. Similar materials are polyglycolic acid (PGA) and polycaprolactone (PCL): their degradation mechanism is similar to that of PLA, but they exhibit respectively a faster and a slower rate of degradation compared to PLA. It has been suggested that this article or section be merged into polylactic acid. ... For the production of milk by mammals, see Lactation. ... Polyglycolide or Polyglycolic acid (PGA) is a biodegradable, thermoplastic polymer and the simplest linear, aliphatic polyester. ... Polycaprolactone (PCL) is a biodegradable polyester with a low melting point of around 60°C. It must be raised to melting point to biodegrade, and so must be composted. ...


Scaffolds may also be constructed from natural materials: in particular different derivatives of the extracellular matrix have been studied to evaluate their ability to support cell growth. Proteic materials, such as collagen or fibrin, and polysaccharidic materials, like chitosan or glycosaminoglycans (GAGs), have all proved suitable in terms of cell compatibility, but some issues with potential immunogenicity still remains. Among GAGs hyaluronic acid, possibly in combination with cross linking agents (e.g. glutaraldehyde, water soluble carbodiimide, etc...), is one of the possible choices as scaffold material. Functionalized groups of scaffolds may be useful in the delivery of small molecules (drugs) to specific tissues. Illustration depicting extracellular matrix (basement membrane and interstitial matrix) in relation to epithelium, endothelium and connective tissue In biology, the extracellular matrix (ECM) is the extracellular part of animal tissue that usually provides structural support to the cells in addition to performing various other important functions. ... Fibrin is a protein involved in the clotting of blood. ... Chitosan is a linear polysaccharide composed of randomly distributed ß-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). ... Chondroitin sulfate Hyaluronan Glycosaminoglycans (GAGs) or mucopolysaccharides are long unbranched polysaccharides consisting of a repeating disaccharide unit. ... The repeating disaccharide unit of hyaluronan Hyaluronan (also called hyaluronic acid or hyaluronate) is a non-sulfated glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues. ... Glutaraldehyde is a colourless liquid with a pungent odor used to sterilize medical and dental equipment. ... A carbodiimide is a functional group consisting of the formula N=C=N. Carbodiimides hydrolyze to form ureas, which makes them rarely found in nature. ...


Synthesis of tissue engineering scaffolds

A number of different methods has been described in literature for preparing porous structures to be employed as tissue engineering scaffolds. Each of these techniques presents its own advantages, but none is devoid of drawbacks.

  • Nanofiber Self-Assembly: Molecular self-assembly is one of the few methods to create biomaterials with properties similar in scale and chemistry to that of the natural in vivo extracellular matrix (ECM). Moreover, these hydrogel scaffolds have shown superior in vivo toxicology and biocompatibility compared with traditional macroscaffolds and animal-derived materials.
  • Textile technologies: these techniques include all the approaches that have been successfully employed for the preparation of non-woven meshes of different polymers. In particular non-woven polyglycolide structures have been tested for tissue engineering applications: such fibrous structures have been found useful to grow different types of cells. The principal drawbacks are related to the difficulties of obtaining high porosity and regular pore size.
  • Solvent Casting & Particulate Leaching (SCPL): this approach allows the preparation of porous structures with regular porosity, but with a limited thickness. First the polymer is dissolved into a suitable organic solvent (e.g. polylactic acid could be dissolved into dichloromethane), then the solution is cast into a mold filled with porogen particles. Such porogen can be an inorganic salt like sodium chloride, crystals of saccharose, gelatin spheres or paraffin spheres. The size of the porogen particles will affect the size of the scaffold pores, while the polymer to porogen ratio is directly correlated to the amount of porosity of the final structure. After the polymer solution has been cast the solvent is allowed to fully evaporate, then the composite structure in the mold is immersed in a bath of a liquid suitable for dissolving the porogen: water in case of sodium chloride, saccharose and gelatin or an aliphatic solvent like hexane for paraffin. Once the porogen has been fully dissolved a porous structure is obtained. Other than the small thickness range that can be obtained, another drawback of SCPL lies in its use of organic solvents which must be fully removed to avoid any possible damage to the cells seeded on the scaffold.
  • Gas Foaming: to overcome the necessity to use organic solvents and solid porogens a technique using gas as a porogen has been developed. First disc shaped structures made of the desired polymer are prepared by means of compression molding using a heated mold. The discs are then placed in a chamber where are exposed to high pressure CO2 for several days. The pressure inside the chamber is gradually restored to atmospheric levels. During this procedure the pores are formed by the carbon dioxide molecules that abandon the polymer, resulting in a sponge like structure. The main problems related to such a technique are caused by the excessive heat used during compression molding (which prohibits the incorporation of any temperature labile material into the polymer matrix) and by the fact that the pores do not form an interconnected structure.
  • Emulsification/Freeze-drying: this technique does not require the use of a solid porogen like SCPL. First a synthetic polymer is dissolved into a suitable solvent (e.g. polylactic acid in dichloromethane) then water is added to the polymeric solution and the two liquids are mixed in order to obtain an emulsion. Before the two phases can separate, the emulsion is cast into a mold and quickly frozen by means of immersion into liquid nitrogen. The frozen emulsion is subsequently freeze-dried to remove the dispersed water and the solvent, thus leaving a solidified, porous polymeric structure. While emulsification and freeze-drying allows a faster preparation if compared to SCPL, since it does not require a time consuming leaching step, it still requires the use of solvents, moreover pore size is relatively small and porosity is often irregular. Freeze-drying by itself is also a commonly employed technique for the fabrication of scaffolds. In particular it is used to prepare collagen sponges: collagen is dissolved into acidic solutions of acetic acid or hydrochloric acid that are cast into a mold, frozen with liquid nitrogen then liophylized.
  • Thermally Induced Phase Separation (TIPS): similar to the previous technique, this phase separation procedure requires the use of a solvent with a low melting point that is easy to sublime. For example dioxane could be used to dissolve polylactic acid, then phase separation is induced through the addition of a small quantity of water: a polymer-rich and a polymer-poor phase are formed. Following cooling below the solvent melting point and some days of vacuum-drying to sublime the solvent a porous scaffold is obtained. Liquid-liquid phase separation presents the same drawbacks of emulsification/freeze-drying.
  • CAD/CAM Technologies: since most of the above described approaches are limited when it comes to the control of porosity and pore size, computer assisted design and manufacturing techniques have been introduced to tissue engineering. First a three-dimensional structure is designed using CAD software, then the scaffold is realized by using ink-jet printing of polymer powders or through Fused Deposition Modeling of a polymer melt.

Non-woven textiles are those which are neither woven nor knit, for example felt. ... A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... Polyglycolide or Polyglycolic acid (PGA) is a biodegradable, thermoplastic polymer and the simplest linear, aliphatic polyester. ... Porosity is a measure of the void spaces in a material, and is measured as a fraction, between 0–1, or as a percentage between 0–100%. The term porosity is used in multiple fields including manufacturing, earth sciences and construction. ... Dichloromethane or Methylene chloride is a chemical compound widely used as a solvent for organic materials. ... Sodium chloride, also known as common salt, table salt, or halite, is a chemical compound with the formula NaCl. ... This article needs cleanup. ... Gelatin (also gelatine, from French gélatine) is a translucent brittle solid substance, colorless or slightly yellow, nearly tasteless and considered foul smelling, extracted from the collagen inside animals connective tissue. ... This article or section is in need of attention from an expert on the subject. ... the 3rd ingredient in big mac ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... A. Two immisicible liquids, not emulsified; B. An emulsion of Phase B dispersed in Phase A; C. The unstable emulsion progressively separates; D. The surfactant (purple outline) positions itself on the interfaces between Phase A and Phase B, stabilizing the emulsion An emulsion is a mixture of two immiscible (unblendable... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Freeze drying (also known as Lyophilization) is a dehydration process typically used to preserve a perishable material, or to make the material more convenient for transport. ... Acetic acid, also known as ethanoic acid, is an organic chemical compound with the formula CH3COOH best recognized for giving vinegar its sour taste and pungent smell. ... The chemical compound hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride gas (HCl). ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... 1,4-Dioxane, often just called dioxane, is a clear, colorless organic compound which is a liquid at room temperature and pressure. ... “CAD” redirects here. ... Computer-aided manufacturing (CAM) is the use of a wide range of computer-based software tools that assist engineers and CNC machinists in the manufacture or prototyping of product components. ... Fused deposition modeling, which is often referred to by its initials FDM, is a type of rapid prototyping or rapid manufacturing (RP) technology commonly used within engineering design. ...

Assembly methods

One of the continuing, persistent problems with tissue engineering is mass transport limitations. Engineered tissues generally lack an initial blood supply, thus making it difficult for any implanted cells to obtain sufficient oxygen and nutrients to survive, and/or function properly.


Self-assembly may play an important role here, both from the perspective of encapsulating cells and proteins, as well as creating scaffolds on the right physical scale for engineered tissue constructs and cellular ingrowth.


It might be possible to print organs, or possibly entire organisms. A recent innovative method of construction uses an ink-jet mechanism to print precise layers of cells in a matrix of thermoreversable gel. Endothelial cells, the cells that line blood vessels, have been printed in a set of stacked rings. When incubated, these fused into a tube.[3]


Tissue culture

In many cases, creation of functional tissues and biological structures in vitro requires extensive culturing to promote survival, growth and inducement of functionality. In general, the basic requirements of cells must be maintained in culture, which include oxygen, pH, humidity, temperature, nutrients and osmotic pressure maintenance. Epithelial cells in culture, stained for keratin (red) and DNA (green) Cell culture is the process by which either prokaryotic or eukaryotic cells are grown under controlled conditions. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... For other uses, see PH (disambiguation). ... This article or section is not written in the formal tone expected of an encyclopedia article. ... For other uses, see Temperature (disambiguation). ... Link title {{portal|Food} A nutrient is either a chemical element or compound used in an organisms metabolism or physiology. ... This article or section does not adequately cite its references or sources. ...


Tissue engineered cultures also present additional problems in maintaining culture conditions. In standard cell culture, diffusion is often the sole means of nutrient and metabolite transport. However, as a culture becomes larger and more complex, such as the case with engineered organs and whole tissues, other mechanisms must be employed to maintain the culture. diffusion (disambiguation). ...


Another issue with tissue culture is introducing the proper factors or stimuli required to induce functionality. In many cases, simple maintenance culture is not sufficient. Growth factors, hormones, specific metabolites or nutrients, chemical and physical stimuli are sometimes required. For example, certain cells respond to changes in oxygen tension as part of their normal development, such as chondrocytes, which must adapt to low oxygen conditions or hypoxia during skeletal development. Others, such as endothelial cells, respond to shear stress from fluid flow, which is encountered in blood vessels. Growth factor is a protein that acts as a signaling molecule between cells (like cytokines and hormones) that attaches to specific receptors on the surface of a target cell and promotes differentiation and maturation of these cells. ... Norepinephrine A hormone (from Greek όρμή - to set in motion) is a chemical messenger from one cell (or group of cells) to another. ... Chondrocytes (< Greek chondros cartilage + kytos cell) are the only cells found in cartilage. ... Hypoxia may refer to: Hypoxia (medical), the lack of oxygen in tissues Hypoxia or Oxygen depletion, a reduced concentration of dissolved oxygen in a water body leading to stress or even death in aquatic organisms This is a disambiguation page: a list of articles associated with the same title. ... Shear stress is a stress state where the stress is parallel or tangential to a face of the material, as opposed to normal stress when the stress is perpendicular to the face. ...


Bioreactors

Main article: Bioreactor

In many cases, bioreactors are employed to maintain specific culture conditions. The devices are diverse, with many purpose-built for specific applications. Bioreactors allow for precise and continuous control of culture conditions and also allow for introduction of different stimuli to tissue cultures. A bioreactor may refer to any device or system that supports a biologically active environment. ... A bioreactor may refer to any device or system that supports a biologically active environment. ...


Examples of tissue engineering technologies

  • Bioartificial liver device - several research efforts have produced hepatic assist devices utilizing living hepatocytes.
  • Artificial pancreas - research involves using islet cells to produce and regulate insulin, particularly in cases of diabetes.
  • Artificial bladders - Anthony Atala (Wake Forest University) has successfully implanted artificially grown bladders into seven out of approximately 20 human test subjects as part of a long-term experiment.[4]
  • Cartilage - lab-grown tissue was successfully used to repair knee cartilage.[5]

A bioartificial liver device (BAL) is an artificial extracorporeal supportive device for an individual who is suffering from acute liver failure. ... Hepatocytes make up 60-80% of the cytoplasmic mass of the liver. ... The artificial pancreas is a technology in development to help diabetic persons automatically control their blood glucose level by providing the substitute endocrine functionality of a healthy pancreas. ... A porcine islet of Langerhans. ... Insulin (from Latin insula, island, as it is produced in the Islets of Langerhans in the pancreas) is an anabolic polypeptide hormone that regulates carbohydrate metabolism. ... This article is about the disease that features high blood sugar. ... In anatomy, the urinary bladder is a hollow, muscular, and distensible (or elastic) organ that sits on the pelvic floor in mammals. ... Anthony Atala, M.D., is the Director of the Wake Forest Institute for Regenerative Medicine, and Chair of the Department of Urology at the Wake Forest University School of Medicine in the state of North Carolina in the United States. ... Wake Forest University is a private, coeducational university located in Winston-Salem, North Carolina. ... Cartilage is a type of dense connective tissue. ...

See also

The AbioCor artificial heart, an example of a biomedical engineering application of mechanical engineering with biocompatible materials for Cardiothoracic Surgery using an artificial organ. ... Biological engineering (a. ... In surgery, a biomaterial is a synthetic material used to replace part of a living system or to function in intimate contact with living tissue. ... An example of a molecular self-assembly through hydrogen bonds reported by Meijer and coworkers in Angew. ...

Agencies that support tissue engineering research

National Institutes of Health Building 50 at NIH Clinical Center - Building 10 The National Institutes of Health (NIH) is an agency of the United States Department of Health and Human Services and is the primary agency of the United States government responsible for biomedical research. ... The logo of the National Science Foundation The National Science Foundation (NSF) is an independent United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. ... The National Research Council of Canada (NRC) is Canadas leading organization for scientific research and development. ...

References

  1. ^ Langer, R & Vacanti JP, Tissue engineering. Science 260, 920-6; 1993.
  2. ^ MacArthur, B. D. & Oreffo, R.O.C. (2005). "Bridging the gap". Nature 433, 19.
  3. ^ Mironov, V., Boland, T., Trusk, T., Forgacs, G. & Markwald, R.R., Organ printing: computer-aided jet-based 3D tissue engineering. Trends in Biotechnology 21, 157-61; 2003.
  4. ^ Doctors grow organs from patients' own cells, CNN, April 3, 2006
  5. ^ [1]
  • Davis, M.E., et al., Injectable Self-Assembling Peptide Nanofibers Create Intramyocardial Microenvironments for Endothelial Cells. Circulation 111:442-450 (2005).
  • Ma, Peter X.: Scaffolds for tissue fabrication - Materials Today, May 2004, 30-40.
  • Holmes, T.C., et al., Extensive neurite outgrowth and active synapse formation on self-assembling peptide scaffolds. PNAS USA 97 :6728 (2000).
  • Semino, C.E., et al., Entrapment of migrating hippocampal neural cells in 3D peptide nanofiber scaffold. Tissue Engineering 10:643 (2004).
  • Mikos, A. G. & Temenoff J. S. (2000). "Formation of highly porous biodegradable scaffolds for tissue engineering". Electronic Journal of Biotechnology 3, 114-119. URL accessed on April 28, 2006.

The Cable News Network, commonly known as CNN, is a major cable television network founded in 1980 by Ted Turner. ...

External links

Organizations

Directories and Repositories

Research Initiatives

  • Institute for Chemical Process and Environmental Technology Tissue engineered (TE) corneas
  • Organ Printing Multi-site NSF-funded initiative

tissue engineering is crazy By the mid 20th century humans had achieved a mastery of technology sufficient to leave the surface of the Earth for the first time and explore space. ... For the song by 311, see Grassroots Applied science is the exact science of applying knowledge from one or more natural scientific fields to practical problems. ... Bold text[[Link title]] “AI” redirects here. ... Ceramic engineering is the technology of manufacturing and usage of ceramic materials. ... A processors core Computing is a very broad topic that has become pandemic to modern uses of technology. ... This article is about the engineering discipline. ... Energy storage is the storing of some form of energy that can be drawn upon at a later time to perform some useful operation. ... Engineering physics (EP) is an academic degree, usually at the level of Bachelor of Science. ... Environmental technology or green technology is the application of the environmental sciences to conserve the natural environment and resources, and by curbing the negative impacts of human involvement. ... The Materials Science Tetrahedron, which often also includes Characterization at the center Materials science is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering. ... Microtechnology is technology with features near one micrometre (one millionth of a metre, or 10-6 metre, or 1&#956;m). ... Buckminsterfullerene C60, also known as the buckyball, is the simplest of the carbon structures known as fullerenes. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Optical engineering is the field of study which focuses on applications of optics. ... The ASCII codes for the word Wikipedia represented in binary, the numeral system most commonly used for encoding computer information. ... Communication is a process that allows organisms to exchange information by several methods. ... Communication is a process that allows organisms to exchange information by several methods. ... This article needs additional references or sources for verification. ... Music Technology is a term that refers to all forms of technology involved with the musical arts, in particular the use of electronic devices and computer software to facilitate playback, recording, composition, storage, performance, search and retrieval. ... Speech recognition (in many contexts also known as automatic speech recognition, computer speech recognition or erroneously as Voice Recognition) is the process of converting a speech signal to a sequence of words, by means of an algorithm implemented as a computer program. ... Visual technology is the engineering discipline dealing with visual representation. ... This article does not cite any references or sources. ... Computational finance (also known as financial engineering) is a cross-disciplinary field which relies on mathematical finance, numerical methods and computer simulations to make trading, hedging and investment decisions, as well as facilitating the risk management of those decisions. ... Manufacturing (from Latin manu factura, making by hand) is the use of tools and labor to make things for use or sale. ... This article is about devices that perform tasks. ... Chuquicamata, the second largest open pit copper mine in the world, Chile. ... For other uses, see Bomb (disambiguation). ... It has been suggested that Last Call Poker be merged into this article or section. ... Boxes of ammunition clog a warehouse in Baghdad Ammunition is a generic military term meaning (the assembly of) a projectile and its propellant. ... This article lists military technology items, devices and methods. ... Marine Engineers are the officers of a ship which operate and maintain the propulsion and electrical generation systems onboard a ship. ... For other uses, see Home (disambiguation). ... A major appliance is a large machine which accomplishes some routine housekeeping task, which includes purposes such as cooking, food preservation, or cleaning, whether in a household, institutional, commercial or industrial setting. ... Domestic technology is the incorporation of applied science into the home. ... Educational technology is the use of technology in education to improve learning and teaching. ... The food technology room at Marling School in Stroud, Gloucestershire. ... Engineering is the applied science of acquiring and applying knowledge to design, analysis, and/or construction of works for practical purposes. ... Aerospace engineering is the branch of engineering that concerns aircraft, spacecraft, and related topics. ... An architectural engineer applies the skills of many engineering disciplines to the design, construction, operation, maintenance, and renovation of buildings while paying attention to their impacts on the surrounding environment. ... Biological engineering (also biosystems engineering and bioengineering) is a broad-based engineering discipline that deals with bio-molecular and molecular processes, product design, sustainability and analysis of biological systems. ... Unser Nachbar hat ein neues Auto. ... The AbioCor artificial heart, an example of a biomedical engineering application of mechanical engineering with biocompatible materials for Cardiothoracic Surgery using an artificial organ. ... Ceramic engineering is the technology of manufacturing and usage of ceramic materials. ... Chemical engineering is the branch of engineering that deals with the application of physical science (e. ... The Falkirk Wheel in Scotland. ... Computer engineering (also called electronic and computer engineering) is a discipline that combines elements of both electrical engineering and computer science. ... Construction engineering concerns the planning and management of the construction of structures such as highways, bridges, airports, railroads, buildings, dams, and reservoirs. ... Cryogenics is a branch of physics (or engineering) that studies the production of very low temperatures (below –150 °C, –238 °F or 123 K) and the behavior of materials at those temperatures. ... Electrical Engineers design power systems… … and complex electronic circuits. ... Electronic engineering is a professional discipline that deals with the behavior and effects of electrons (as in electron tubes and transistors) and with electronic devices, systems, or equipment. ... Environmental engineering[1][2] is the application of science and engineering principles to improve the environment (air, water, and/or land resources), to provide healthy water, air, and land for human habitation and for other organisms, and to remediate polluted sites. ... Materials engineering is a discipline related to materials science which focusses on materials design, processing techniques (casting, rolling, welding, ion implantation, crystal growth, thin film deposition, sintering, glassblowing, etc. ... Mechanical Engineering is an engineering discipline that involves the application of principles of physics for analysis, design, manufacturing, and maintenance of mechanical systems. ... Mechatronics is the synergistic combination of mechanical engineering (mecha for mechanisms, i. ... Metallurgical engineering- Designing, creating, or producing metals by various methods, for various applications, from metallic elements described on the Chemical Periodic Table of the Elements. ... Mining Engineering is a field that involves many of the other engineering disciplines as applied to extracting and processing minerals from a naturally occurring environment. ... Steamer New York in c. ... Nuclear engineering is the practical application of the breakdown of atomic nuclei and/or other sub-atomic physics, based on the principles of nuclear physics. ... Petroleum engineering is involved in the exploration and production activities of petroleum as an upstream end of the energy sector. ... Software engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software. ... Taipei 101, the worlds tallest building as of 2004. ... Systems engineering techniques are used in complex projects: from spacecrafts to chip design, from robotics to creating large software products to building bridges, Systems engineering uses a host of tools that include modeling & simulation, requirements analysis, and scheduling to manage complexity Systems Engineering (SE) is an interdisciplinary approach and means... This article or section does not adequately cite its references or sources. ... Warning signs, such as this one, can improve safety awareness. ... The AbioCor artificial heart, an example of a biomedical engineering application of mechanical engineering with biocompatible materials for Cardiothoracic Surgery using an artificial organ. ... Map of the human X chromosome (from the NCBI website). ... The structure of insulin Biotechnology is technology based on biology, especially when used in agriculture, food science, and medicine. ... Cheminformatics (also known as chemoinformatics and chemical informatics) is the use of computer and informational techniques, applied to a range of problems in the field of chemistry. ... Fire protection engineering is the practice of application of science and engineering principles and experience to protect people and their environments from the destructive effects of fire. ... Health Sciences are the group of disciplines of applied science dealing with human and animal health. ... Pharmacology (in Greek: pharmakon (φάρμακον) meaning drug, and lego (λέγω) to tell (about)) is the study of how drugs interact with living organisms to produce a change in function. ... Safety engineering is an applied science strongly related to systems engineering and the subset System Safety Engineering. ... Sanitary engineering is the application of scientific or mathematical principles with to the field of sanitation, especially in regards to its affect on public health. ... Look up aerospace in Wiktionary, the free dictionary. ... Aerospace engineering is the branch of engineering that concerns aircraft, spacecraft, and related topics. ... The Engine room of Argonaute, a French supply vessel. ... Space technology is a term that is often treated as a category. ...


  Results from FactBites:
 
Tissue engineering - Wikipedia, the free encyclopedia (2428 words)
Tissue engineering is the use of a combination of cells, engineering materials, and suitable biochemical factors to improve or replace biological functions.
Probably the first definition of tissue engineering was by Langer and Vacanti who stated it to be "an interdisciplinary field that applies the principles of engineering and life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function or a whole organ".
Usually the tissue is minced, and then digested with the enzymes trypsin or collagenase to remove the extracellular matrix that holds the cells.
Tissue Engineering (1194 words)
Tissue engineering uses synthetic or naturally derived, engineered biomaterials to replace damaged or defective tissues, such as bone, skin, and even organs.
Among the potential economic benefits from advanced tissue engineering technologies, reduced costs due to the availability of less expensive treatments for major medical problems is obvious, but indirect savings and dramatic improvements in treatment outcomes and quality of life for patients may prove to be even more important.
An "artificial pancreas" created by tissue engineering that reproduces the instantaneous response of the normal pancreas to changing glucose levels would dramatically lower the occurrence of these secondary illnesses and, not incidentally, dramatically improve the lives of diabetes sufferers.
  More results at FactBites »

 
 

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