Tissue Engineering | Wikipedia audio article
Tissue. Engineering is, the use of a combination, of cells engineering. And materials, methods and suitable, biochemical. And physicochemical, factors. To improve or replace biological. Tissues, tissue. Engineering, involves, the use of a tissue scaffold, for the formation, of new viable, tissue for a medical purpose, while. It was once categorized, as a subfield of biomaterials. Having grown in scope and importance, it can be considered as a field in its own, 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, IE bone cartilage blood, vessels bladder skin, muscle, etc, often. The tissues involved, require certain, mechanical, and structural properties. For proper functioning, the. Term has also been, applied to efforts, to perform specific biochemical. Functions, using cells within an artificially. Created support system, eg an artificial, pancreas or a bio artificial. 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 or progenitor cells, to produce tissues. Topic. Overview. A. Commonly. Applied definition, of tissue engineering as stated, by Langer and vacant E is an interdisciplinary. Field, that, applies the principles. Of engineering and, life sciences. Toward, the development, of biological, substitutes, that restore, maintain. Or improve, biological. Tissue function, or a whole organ. Tissue. Engineering, has also been defined as, understanding. The principles. Of tissue growth, and applying, this to produce functional, replacement tissue. For clinical, use 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. Or enhancement. Of tissue function. Powerful. 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, and vascularization 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.
In. 2003. The NSF, published, a report entitled, the emergence. Of tissue engineering as, a research, field, which. Gives a thorough description of the history of this field. Topic. Examples. Bio. Artificial. Windpipe the first procedure of regenerative, medicine of an implantation, of a bio, artificial. Organ. In. Vitro, meat edible, artificial, animal muscle tissue cultured, in vitro. Bio. Artificial. 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. Cartilage. Lab-grown tissue, was successfully, used to repair knee cartilage. Scaffold. Free cattle cartilage generated. Without the use of exogenous, scaffold. Material, in, this, methodology, all material. In the construct, is cellular or material, produced, directly, by the cells themselves. Doris. Taylor's heart in a jar. Tissue-engineered. Airway. Tissue. Engineered, vessels. Artificial. Skin constructed, from human skin cells embedded in a hydrogel, such as in the case of bioprinted. Constructs, for battlefield, burn repairs. Artificial. Bone marrow. Artificial. Bone. Laboratory. Ground penis. Oral. Mucosa, tissue engineering. For. Skin. Topic. Cells, as building, blocks. 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. Cells. Became available as engineering, materials, when scientists, at Jurong corp discovered, how to extend, telomeres, in 1998. Producing. Immortalized, cell lines, before. This laboratory, cultures, of healthy non cancerous mammalian, cells would only divide a fixed, number of times up to the hayflick limit before, dying. Topic. Extraction. From. Fluid tissues such as blood cells, are extracted by bulk methods, usually centrifugation. Or a phoresis. From. Solid tissues extraction. Is more difficult, usually. The tissue is minced and then digested, with the enzymes trypsin, or collagen A's to remove the extracellular matrix, ECM that, holds the cells after, that the cells are free-floating and extracted, using centrifugation. Or a phoresis. Digestion. With trypsin, is very dependent on temperature higher. Temperatures, digest, the matrix faster, but create more damaged collagen.
A's Is less temperature, dependent, and damages, fewer cells but takes longer, and is a more expensive. Agent. Topic. Types, of cells. Cells. Are often categorized by, their source. Autologous. Cells are obtained from the same individual, to which they will be re implanted. 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. Allogeneic. 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, Zener, genic cells are these isolated, from individuals, of another species, in, particular animal. Cells have been used quite extensively, in experiments. Aimed at the construction, of cardiovascular. Implants. Sen, genacore 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 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 another alternative, source induced, stem cells may be useful for the repair of diseased or damaged tissues, or may be used to grow new organs. Topic. Scaffolds. Scaffolds. Are materials, that have been engineered to cause desirable. Cellular interactions to, contribute, to the formation of new functional, tissues, for medical purposes. Cells. Are often seeded, into these structures capable, of supporting three-dimensional.
Tissue Formation. Scaffolds. Mimic the extracellular, matrix of the native tissue, recapitulating. The in vivo Miglia and allowing cells to influence, their own micro, environments. They. Usually serve, at least one of the following purposes 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 behavior of the cell phase, in. 2009. An interdisciplinary, team, led, by the thoracic surgeon, Torsten wellies implanted, the first bio artificial, transplant, that provides an innate vascular, network for post transplant, grafts apply successfully. Into a patient, awaiting, Trickle reconstruction. 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 scaffold 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 newly formed tissue which will take over the mechanical, load, inject. Ability, is also important, for clinical, uses. Recent. Research on organ printing is showing how crucial a good control of the 3d environment is, to ensure reproducibility. Of experiments. And offer better results. Topic. Materials. Many. Different, material. 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 by resorbable sutures. Examples. Of these materials, are collagen, and some polyesters. New. Biomaterials. Have been engineered to have ideal properties, and functional, customization. Inject, ability, synthetic. Manufacture. Biocompatibility. Non immunogenicity. Transparency. Nano scale fibers low concentration. Resorption, rates etc pure, matrix, originating. From the MIT labs, of Jang rich grodd's in ski 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 poly glycolic 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, while. These materials, have well maintained, mechanical, strength and structural, integrity they, exhibit a hydrophobic, nature this. Hydrophobicity. Inhibits. Their biocompatibility. Which, makes them less effective for in vivo uses tissue scaffolding.
In Order. To fix the lack of biocompatibility. Much, research has been done to combine these hydrophobic. Materials, with hydrophilic, and more biocompatible hydro. Gels while. These hydro, gels have a superior, biocompatibility. They lack the structural, integrity of PLA, PCL. And PGA. By. Combining, the two different types of materials, researchers, are trying to create a synergistic. Relationship, that produces, a more biocompatible. Tissue scaffolding. 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 polysaccharide. Ik materials, like kite San 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, eg 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, another. Form of scaffold, under investigation, is decellularized. Tissue extracts. Whereby the remaining, cellular, remnants extracellular, matrices, act as the scaffold. Recently. A range of nano composites, biomaterials. Are fabricated, by incorporating nano, materials, within polymeric, matrix, to engineer, bioactive, scaffolds, a 2009. Study by dota @al aim to improve in vivo like conditions, for 3d tissue via, stacking. Understand, layers, of paper impregnated with, suspensions. Of cells in extracellular, matrix, hydrogel. Making, it possible, to control oxygen. And nutrient, gradients, in 3d, and to analyze molecular. And genetic responses. It. Is possible, to manipulate gradients. Of soluble, molecules, and to characterize cells in these complex, gradients, more effectively, than conventional, 3d cultures, based on hydro gels cell spheroids, or 3d, / fusion reactors. Different. Thicknesses, of paper and types of medium can support a variety of experimental, environments. Upon. Deconstruction. These sheets can be useful, in cell based high-throughput, screening, and drug discovery. Topic. Synthesis. A. Number. Of different methods have 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 of three are drawbacks. Topic. Nanofibers. Self-assembly. Molecular. Self-assembly is, one of the few methods for creating biomaterials. With properties, similar in scale and chemistry, to that of the natural in vivo extracellular, matrix, ECM a, crucial, step toward tissue engineering, of complex, tissues. Moreover. These hydrogel. Scaffolds, have shown superiority. In in vivo toxicology. And biocompatibility. Compared. To traditional macro. Scaffolds, and animal derived materials. Topic. Textile. Technologies. These. Techniques, include, all the approaches, that have been successfully, employed for the preparation of nonwoven meshes, of different polymers in. Particular, nonwoven. Polyglot, colloid 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, in obtaining high, porosity and, regular pore size. Topic. Solvent. Casting, and particulate. Leaching. Solvent. Casting, and particulate, bleaching, SCP, L allows for the preparation of structures, with regular, porosity but, with limited thickness. First. The polymer is dissolved, into a suitable organic, solvent eg poly lactic acid, could be dissolved, into dichloromethane, then, the solution, is cast into a mold filled with porridge and particles. Such. Porridge n' can be an inorganic salt, like sodium chloride crystals. Of Sakura's gelatin, spheres or paraffin, spheres, the. Size of the porridge in particles, will affect the size of the scaffold, pause while the polymer, - porridge in 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 porridge in water in the case of sodium chloride sac, arose and gelatin or an aliphatic solvent, like hexane, for use with paraffin, once. The porridge in has been fully dissolved, a porous, structure is obtained, other. Than the small thickness range, that can be obtained another, drawback of as Cpl lies in its use of organic, solvents which must be fully removed to avoid any possible, damage to the cells seated on the scaffold. Topic. Gas foaming. To. Overcome the need to use organic solvents, and solid porridge ins a technique, using gas as a porridge in has been developed, first. Disk shaped structures, made of the desired polymer, are prepared by means of compression, molding using, a heated mold the. Disks are then placed in a chamber where, they 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, resulting, from 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 pause do not form an interconnected. Structure. Topic. Emulsification. Freeze-drying. This. Technique, does not require, the use of a solid porridge enlike SCP L first. A synthetic, polymer is dissolved, into a suitable solvent eg, poly lactic 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 allow for a faster, preparation, when compared, to SCP, L 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. And then lyophilized. Topic. Thermally. Induced phase, separation. Similar. To the previous technique, the tips phase separation. Procedure requires. The use of a solvent with a low melting point, that is easy to sublime. For. Example, dioxin, could be used to dissolve poly lactic acid, then phase separation. Is induced through the addition of a small quantity, of water a polymer, rich in a polymer pour 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. Topic. Electra, spinning. Electro, spinning is a highly, versatile, technique that can be used to produce continuous, fibers, from sub micrometer to nanometer. Diameters. In. A typical, electrospinning, setup a solution, is fed through a spinneret, and the high voltage is applied to the tip the. Buildup of electrostatic. Repulsion within, the charged solution, causes, it to reject a thin fibrous stream, a mounted. Collector, plate or rod with an opposite or grounded, charge draws in the continuous, fibers which arrive to form a highly porous Network, the. Primary, advantages, of this technique, are its simplicity, and ease of variation. And a. Laboratory, level a typical, electro spinning setup, only requires, a high-voltage power supply, up to 30 kilo, volts a syringe, a flat tip needle and a conducting, collector, for. These reasons, electro, spinning has become a common method of scaffold, manufacture. In many labs by. Modifying, variables. Such as a distance, to collector, magnitude. Of applied voltage or, solution, flow rate researchers. Can dramatically, change the overall scaffold. Architecture. Historically. Research, on electro, spun fibrous scaffolds, dates back to at least the late 1980s. When Simon, showed that electro spinning could be used to produce Nano and sub micron scale fibrous, scaffolds, from polymer solutions, specifically. Intended, for users in vitro cell and tissue substrates. This. Early use of electro, spon lattices, for cell culture and tissue engineering, showed that various, cell types would, adhere to and proliferate, upon polycarbonate.
Fibers, It. Was noted that as opposed to the flattened morphology, typically, seen in 2d culture, cells, grown on the electro spun fibers, exhibited, a more rounded, three-dimensional. Morphology, generally, observe of tissues, in vivo. Topic. CAD, cam technologies. Because. Most of the above techniques, 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 the. Porosity can, be, using algorithms within, the software the, scaffold, is then realized, by using inkjet, printing, of polymer powders or through fused deposition modeling, of, a polymer melt a 2011, study, by Liu be a towel investigated. 3d. Plotting, technique, to produce, biocompatible. And biodegradable poly. L lactide, macroporous. Scaffolds. With two different pore sizes. Via. Solid, freeform, fabrication SSF, with computer-aided, design CAD, to explore therapeutic, articular, cartilage, replacement as an alternative. To conventional tissue. Repair. The. Study found the smaller the pore size paired with mechanical, stress in a bioreactor, to induce in vivo light conditions, the higher the cell viability in, potential, therapeutic, functionality. Via decreasing. Recovery, time and increasing, transplant, effectiveness. Topic. Laser, assisted, bio, printing. In. A 2012, study kasha talc focused, on whether laser assisted bio printing, la BP can be used to build multicellular. 3d patterns, in natural, matrix and whether the generated, constructs, are functioning, and forming tissue, la. BP arranges, small volumes, of living cell suspensions, in set high resolution, patterns, the. Investigation. Was successful, the researchers, foresee that generated. Tissue constructs, might be used for in vivo testing, by implanting, them into animal, models. 14. As of, this study only human skin tissue has been synthesized. Though researchers, project that by, integrating further, cell types eg melanocytes. Schwann cells hair, follicle, cells into, the printed, cell construct. The behavior, of these cells in, a 3d in vitro, micro, environment, similar to their natural one, can be analyzed. Useful. For drug discovery and toxicology. Studies. Topic. 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 or function, properly. Topic. Self-assembly. Self-assembly. Methods have been shown to be promising methods for tissue engineering. Self-assembly. Methods have the advantage, of allowing tissues, to develop their own extracellular. Matrix, resulting, in tissue that better recapitulates. Biochemical. And biomechanical. Properties of, native tissue. Self-assembling. Engineered, articular, cartilage, was introduced, by Jerry who and kiriakos, a Afanasy Oh in 2006. And applications, of the process, have resulted, in engineered, cartilage, approaching, the strength of native tissue. Self-assembly. Is a prime technology, to get cells grown in a lab to assemble, into three-dimensional shapes. To. Breakdown tissues, into cells researchers. First have to dissolve the extracellular, matrix, that normally binds them together once. Cells are isolated they must form the complex, structures, that make up our natural, tissues. Topic. Liquid, based template, assembly. The. Air liquid surface, established, by faraday, waves is explored, as a template, to assemble, biological. Entities, for bottom-up tissue engineering, this. Liquid based template, can be dynamically, reconfigured. In a few seconds, and the assembly on the template, can be achieved, in a scalable and parallel, manner, Assembly, of microscale hydrogels cells neurons seeded, micro carrier beads cell, spheroids, into various symmetrical, and periodic, structures, was demonstrated. With good cell viability. Formation. Of 3d, neural network was achieved after 14, day tissue culture. Topic. Additive. Manufacturing. It. Might be possible to print organs or possibly, entire, organisms. Using additive manufacturing techniques. A recent. Innovative, method of construction, uses an inkjet mechanism. To print precise layers of cells in a matrix of thermo reversible, 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 the field of three-dimensional. And highly accurate models, of biological systems. Is pioneered, by multiple, projects, and technologies including. A rapid method for creating tissues, and even whole organs involves, a 3d printer that can print the scaffolding, and cells layer by layer into, a working, tissue sample, or organ the. Device is presented, in a TED talk by dr. Anthony, Atala MD. The director, of the Wake Forest, Institute for, regenerative, medicine and, the WH, Boyce professor, and chair of the department, of urology at, Wake Forest University in. Which a kidney is printed on stage during the seminar, and then presented, to the crowd it is. Anticipated that this technology will enable the production of livers in the future for transplantation. And theoretically, for toxicology, and other biological studies. As well. Recently. Multiphoton, processing. MPP, was employed for in vivo experiments by, engineering, artificial. Cartilage, constructs, an ex. Vivo histological. Examination showed. That certain pore geometry, and the pre growing of chondrocytes, cho prior to implantation, significantly. Improves, the performance of the created, 3d scaffolds. The. Achieved, biocompatibility. Was, comparable, to the commercially, available collagen. Membranes, the. Successful, outcome of this study supports, the idea that hexagonal. Pore shaped hybrid, organic, inorganic micro, structured scaffolds, in combination, with cho seeding, may be successfully. Implemented, for cartilage, tissue engineering. Topic. Scaffolding. In, 2013. Using a 3d scaffolding, of matrigel, in various configurations. Substantial. Pancreatic, organoids was produced, in vitro. Clusters. Of small numbers of cells proliferated. In 240, thousand cells within one week, the, clusters, transform, into cells that make either digestive, enzymes or hormones like insulin. Self-organizing. Into branch pancreatic. Organoids that resemble, the pancreas, the cells are sensitive to the environment such as gel stiffness, and contact, with other cells. Individual. Cells do not thrive a minimum, of four proximate, cells was required for subsequent organoid, development.
Modifications. To the medium composition. Produced, either hollow spheres, mainly, composed of pancreatic, progenitors. Or complex, organs, that spontaneously. Undergo, pancreatic. Morphogenesis. And differentiation. Maintenance. And expansion, of pancreatic, progenitors. Require, active notch and fgf, signaling, recapitulating. In vivo niche signaling interactions. The organoids, were seen as potentially, offering, many organs, for drug testing and for spare insulin, producing, cells. Topic. 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. Tissue, engineered cultures, also present, additional problems, in maintaining, cultural 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 a case with engineered, organs and whole tissues, other mechanisms, must be employed to maintain the culture such as a creation of capillary, networks, within the tissue. 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 converse, i'ts 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. Mechanical. Stimuli, such as pressure pulses, seem to be beneficial, to all kind of cardiovascular. Tissues, such as heart valves blood vessels, or pericardium. Topic. Bioreactors. A bioreactor. In tissue engineering, as opposed, to industrial. Bio reactors, is a device, that attempts, to simulate a physiological. Environment in order to promote cell or tissue growth, in vitro a. Physiological. Environment can, consist, of many different parameters, such as temperature and oxygen or carbon dioxide, concentration. But can extend to all kinds of biological chemical. Or mechanical stimuli. Therefore. There are systems that may include the application, of forces or stresses to, the tissue or even of electric, current in two or three dimensional. Setups, in. Academic, and industry research facilities. It is typical, for bio reactors to be developed, to replicate, the specific, physiological, environment. Of the tissue being grown eg, flex and fluid shearing for heart tissue growth. Several. General use and application, specific, bio reactors, are also commercially. Available and, may provide static, chemical, stimulation. Or combination. Of chemical, and mechanical stimulation. There. Are a variety of bio reactors designed, for 3d, cell cultures, there. Are small plastic, cylindrical, chambers as well as glass chambers, with regulated, internal, humidity and moisture specifically. Engineered for the purpose of growing cells in three dimensions, the.
Bioreactor, Uses. Bioactive, synthetic, materials, such as polyethylene. Terephthalate membranes. To surround the spheroid cells in an environment, that maintains, high levels of nutrients, they. Are easy to open and close so that cell spheroids, can be removed for testing yet the chamber is able to maintain 100%. Humidity. Throughout this. Humidity, is important, to achieve maximum, cell growth and function, the, bioreactor, chamber. Is part of a larger device that rotates to ensure equal cell growth in each direction across. Three dimensions, quintal technologies, from Singapore, has developed, a bioreactor, known, as the tizzle biaxial, bioreactor. Which is specially, designed for the purpose of tissue engineering, it is, the first bioreactor. In the world to have a spherical glass chamber with biaxial rotation specifically. To mimic the rotation, of the fetus in the womb which, provides a conducive environment, for the growth of tissues, mc2. Biotech, has also developed a bioreactor known, as prototype, that uses gas, to maintain high oxygen levels within the cell chamber improving, upon previous bioreactors. Because the higher oxygen, levels help the cell grow and undergo normal cell respiration. Topic. Long, fibre generation. In. 2013. A group from the university, of tokyo developed. Cell Laden fibers up to a meter in lengthen, on the order of 100, micrometers. In size, these. Fibers, were created, using a microfluidic. Device that forms a double coaxial. Laminar flow each. Layer of the microfluidic. Device cells, seeded in ECM, a hydrogel. Sheath and finally, a calcium, chloride solution, the. Seeded cells culture, within the hydrogel. Sheath for several days and then the sheath is removed with viable, cell fibers. Various. Cell types were inserted, into the ECM core including myocytes. Endothelial. Cells nerve, cell fibers, and epithelial. Cell fibers this. Group then showed that these fibers can be woven together to fabricate, tissues, or organs in, a mechanism, similar to textile, weaving. Fibrous. Morphologies, are advantageous, in that they provide an alternative, to traditional scaffold.
Design And many organs such as muscle, are composed, of fibrous, cells. Topic. Bio, artificial. Organs. An artificial. Organ is a man-made device that is implanted or, integrated, into a human, to replace a natural, organ for the purpose of restoring, a specific, function, or a group of related functions, so the patient, may return to a normal life as soon as possible, the. Replaced function, doesn't necessarily. Have to be related to life support but often is the. Ultimate, goal of tissue engineering as, a discipline, is to allow both off-the-shelf, bio artificial. Organs and regeneration, of injured tissue in the body in order. To successfully, create bio artificial, organs from a patient stem cells researchers. Continue to make improvements, in the generation, of complex, tissues by tissue engineering. For. Example much. Research, is aimed at understanding, nanoscale, cues present in a cell's micro environment. Topic. Constructing. Neural networks, in soft material. In. 2018. Scientists. At Brandeis University reported. Their research on soft material, embedded with chemical, networks which can mimic the smooth and coordinated, behavior, of neural tissue this. Research, was funded by the US Army, Research Laboratory the researchers. Presented an experimental system, of neural networks theoretically. Modeled as reaction, diffusion systems. Within. The networks was an array of patterned, reactors, each performing, the bellows of Jabotinsky, Baird, reaction, these. Reactors, could function on a Nano lighter scale the researchers, state that the inspiration for their project, was the movement of the blue ribbon eel the. Eels movements, are controlled by electrical. Impulses, determined, by a class of neural networks called the central, pattern generator. Central. Pattern generators. Function, within the autonomic nervous system to control bodily, functions, such as respiration, movement. And peristalsis, qualities. Of the reactor, that were designed with a network topology boundary. Conditions, initial conditions, reactor, volume coupling. Strength and the synaptic polarity, of the reactor, whether its behavior is inhibitory, or excitatory. Abby. Said emulsion, system with a solid elastomer, polydimethylsiloxane. PDMS. Was designed, both. Light and bro, permeable. PDMS. Have been reported, as viable methods to create a pacemaker for, neural networks. Topic. See, also. Equals. Equals notes.