Presentation tissue engineering

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Presentation 2009 :

Presentation 2009 Self Introduction Bishal Khatiwada BSC. BT 3 rd sem (2009) Lord Buddha Education Foundation


contents Topic Introduction Examples of tissue engineering Extraction Types of cells Scaffold and it’s synthesis Computer aided tissue engineering Basic principle of tissue engineering Emergence of tissue engineering Injectable tissue engineering Cryopreservation of Vascular Umbilical Cord Goal of tissue engineering Conclusion Reference

Introduction to topic Tissue engineering:

Introduction to topic Tissue engineering

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Tissue Engineering 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". It 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. Tissue engineering has also been defined as "understanding the principles of tissue growth, and applying this to produce functional replacement tissue for clinical use."

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Examples…… Bioartificial Liver Device — several research efforts have produced hepatic assist devices utilizing living Hepatocytes. Artificial Pancreas — research involves using 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. Doris Taylor’s heart in a jar Tissue-engineered airway Artificial Skin constructed from human skin cells embedded in Collagen. Artificial bone marrow. Artificial Bone.

Cells as Building Blocks:

Cells as Building Blocks Tissue engineering utilizes living cells as engineering materials. Examples include using living fibroblast in skin replacement or repair, cartilage repaired with living chondrocytes , or other types of cells used in other ways. Fig: Stained cells in culture


Extraction From fluid tissues such as blood, cells are extracted by bulk methods, usually centrifugation. 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.

Types of cells:

Types of cells 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. Allogeneic cells come from the body of a donor of the same species Xenogenic cells are these isolated from individuals of another species Syngenic 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 are undifferentiated cells with the ability to divide in culture and give rise to different forms of specialized cells


Scaffold Cells are often implanted or 'seeded' into an artificial structure capable of supporting 3 dimensional tissue formation. These structures, typically called scaffolds, are often critical, both ex vivo as well as in vivo Scaffolds 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 nutrients and expressed products . Exert certain mechanical and biological influences to modify the behaviour of the cell phase This animation of a rotating Carbon nanotubes shows its 3D structure. Carbon nanotubes are among the numerous candidates for tissue engineering scaffolds since they are biocompatible , resistant to biodegradation and can be functionalized with biomolecules.


Synthesis A number of different methods has been described in literature for preparing porous structures to be employed as tissue engineering scaffolds. Nanofiber Self-Assembly : Textile technologies : Solvent Casting & Particulate Leaching (SCPL) : Gas Foaming Emulsification/Freeze-drying Thermally Induced Phase Separation (TIPS) : CAD/CAM Technologies

Some of the potentialities of tissue engineering Strategies:

Some of the potentialities of tissue engineering Strategies From the triad Cells – Signal molecules- Scaffolds , both in vivo tissue regeneration and in vitro tissue engineering can be achieved. For the tissue regeneration, three different combinations ( Signal Molecules, Signal Molecules+Cells , and Signal Molecules+Cells+Scaffold ) can lead to tissue regeneration. The combination Signal Molecules+Cells leads to Cell therapy.

The tissue engineered tooth Tissue Engineered Teeth Grown in Rat Jaw and Omentum :

The tissue engineered tooth Tissue Engineered Teeth Grown in Rat Jaw and Omentum In a recent work, it has been demonstrated that a full tooth could be produced by using the techniques of tissue engineering. This is still more a curiosity than a practical development, but the authors had a clear aim : to create by tissue engineering techniques a viable biological substitute of a tooth.

Computer aided tissue engineering :

Computer aided tissue engineering The 3D Bioplotter offers the solution for computer aided Tissue Engineering. The Bioplotter technology - invented at the Freiburg Materials Research Centre - is based on a 3D Dispenser and allows to process a magnitude of materials including various biochemical systems and even living cells. CAD data handling and machine/process control is done via a system specific 2½D CAD/CAM software .

Basic principles of tissue engineering:

B asic principles of tissue engineering Basic principle of Tissue engineering is illustrated in the following figure. Cells can be isolated from the patient’s body, and expanded in a petridish in laboratory. Once we have enough number of cells, they can be seeded on a polymeric scaffold material, and cultured in vitro in a bioreactor or incubator. When the construct is matured enough, then it can be implanted in the area of defect in patient’s body. .

University Start-ups in Tissue Engineering:

University Start-ups in Tissue Engineering

New Tissue Engineering Companies by Year (1994 and earlier):

New Tissue Engineering Companies by Year (1994 and earlier)

Tissue Engineering Patent Families :

Tissue Engineering Patent Families As the adjoining figure shows, the earliest patenting activity occurred in the mid-to-late 80's with a more dramatic increase in the 1990s; consistent with the overall growth in awareness of the field. As the Figure shows, patenting in tissue engineering has been trending up since 1980 and has not yet peaked. In particular, in the last 5 years, patenting has increased 226% over the previous 5 years, which in turn was an increase of 138% over the prior 5 years

Priority (Inventor) Country of Worldwide Tissue Engineering Patents (1980-2001)::

Priority (Inventor) Country of Worldwide Tissue Engineering Patents (1980-2001): Given that most of the invention is coming from the US, it is not surprising to see that most of the patent assignees are US institutions as well

The institutions holding the most highly cited patents:

The institutions holding the most highly cited patents Assignees with 4 or more TE Global Patent Families (1980-2001)

Injectable tissue engineering (Intro):

Injectable tissue engineering (Intro) Breakthroughs in the regeneration of basic human cells now make it possible to repair cartilage and bone without intrusive surgery. Injectable Tissue, a new development by: Genzyme soon to hit the market, can repair damaged cartilage in the knee. This procedure will swap knee replacement and arthroscopic surgery with a new-fangled process that injects new tissue and growth hormones into the knee in order for the body to then repair itself. It has a great potential to cut down on costs, recovery time, and risk to patients.

Future projected plans for Injectable tissue are to Involve cartilage and bone repair, cosmetic surgeries, genetic disorders, then on to soft tissue regeneration:

Future projected plans for I njectable tissue are to I nvolve cartilage and bone repair, cosmetic surgeries, genetic disorders, then on to soft tissue regeneration

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A sheet of small intestinal sub mucosal scaffold. Animal gut is enzymatically treated to render an acellular wafer thin tissue that can act as a scaffold in a wide range of TE applications including arterial conduits, bladder reconstruction and the regeneration of small intestine itself .

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A collagen sponge scaffold. Collagen is extracted from pig skins, homogenised and enzymatically treated to produce a collagen solution free of antigenic material. It can be molded and freeze-dried before reinforcement over the base with polyglycolic acid felt to produce a robust scaffold.

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Collagen sponge scaffold being tested in a small intestine model. A 5cm length of jejunum has been resected and a silicone stent interposed to maintain a patent tube. A sheet of collagen sponge (arrow) is waiting to be wrapped around the tube to mimic the serosal layers. After 4 weeks the silicone tube is removed endoscopically and the neointestine exposed to gut content.

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The microscopic findings of regenerated small intestine after 16 weeks (Masson- Tricrom staining; 100x magnification). Intestinal mucosa with a villous pattern has covered the surface of the regenerated submucosal tissue. A thin muscular layer is also evident (arrow).

Slide 26:

Engineering of heart valve prostheses using autologous cells

Slide 27:

Cryopreservation of vascular umbilical cord cells Since it is not possible to use cells from heart valves themselves, cells must be utilized that are as similar as possible to heart valve cells. In the past few years human vascular umbilical cord cells have been evaluated as a source of autologous cells for cardiovascular tissue engineering. It has several long blood vessels and can be used to harvest a very large number of vascular cells without the patient undergoing any harvesting procedure. These cells can be stored in liquid nitrogen until required

Slide 28:

Development of cell culture systems and “bioreactors” in which the heart valve construct is conditioned by mechanical means.

Slide 29:

Tissue Engineered Skin: From the Lab to the Patient


GOAL OF TISSUE ENGINEERING The goal of tissue engineering is to replace many of the currently used prostheses (shown in this picture) with degradable tissue scaffolds that support the regeneration of lost or damaged tissue.


CONCLUSION Hence, the Tissue Engineering is to replace lost or damaged tissue with degradable tissue scaffolds that support the regeneration of lost or damaged tissue. Tissue engineering has made enormous advances in the last decade. There are still significant hurdles to overcome before the general surgeon will be able to use a tissue engineering solution for a problem in everyday practice. It is almost inevitable, however, that the surgeon of 2030 will be widely versed in the application of the results of tissue engineering. Tissue Engineering certainly has the advantage over the other options in its low cost, small recovery time, non-intrusiveness, and as a permanent fix to the problem. With the studies to come in the future, it will be able to be proven to be the most effective and longest lasting procedure. Tissue Engineering does not end here, but will have a future in many aspects of the medical field and each of our lives. Tissue Engineering is ‘the science of generating tissue, using laboratory molecular biological techniques and the principles of material engineering, to treat a functional or anatomical defect in vivo’.


refrences Bisceglie V. Uber die antineoplastische Immunitat; heterologe Einpflanzung von Tumoten in Huhner-Embryonen. Ztschr Krebsforsch 1933; 40: 122-40. Menasché P, Scorsin M, Hagege A et al. Myoblast transplantation for heart failure. Lancet 2001; 357: 279-80. Langer, R & Vacanti JP, Tissue engineering. Science 260, 920-6; 1993. MacArthur, B. D. & Oreffo, R.O.C. (2005). "Bridging the gap". Nature 433, 19. Ma, Peter X., and Jennifer Elisseeff, eds. Scaffolding in Tissue Engineering. New York: C R C P LLC, 2005. [Back to text]

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