Tissue Engineering

Department of Medical Engineering
presentation entitled
Tissue Engineering
prepared by: Raneem Mounir Al-Dubali

List of contents
 Introduction
 Examples
 Process Of Tissue Engineering
 Types of Cells
 Materials
 Methods Used For Synthesis Of Tissue Engineered Scaffolds
 Applications
 Pros and Cons

INTRODUCTION :
 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 functions.
 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 bio artificial liver).
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 [Biological tissue] function or
a whole organ”
EXAMPLES :
Bioartificial windpipe
Bioartificial liver device
· Artificial pancreas
Cartilage
Doris Taylor ‘s heart in a jar
Tissue engineered airway
Tissue engineered vessels
Artificial skin
Artificial bone marrow
Artificial bone
Oral mucosa tissue engineering
· Foreskin
STEPS
FOLLOWED
PROCESS OF TISSUE ENGINEERING
(1)Start building material (e.g., extracellular matrix, biodegradable

polymer).
(2) Shape it as needed.
(3) Seed it with living cells .
(4) Bathe it with growth factors.
(5) Cells multiply & fill up the scaffold & grow into three-dimensional
tissue.
(6) Implanted in the body.
(7) Cells recreate their intended tissue functions.
(8) Blood vessels attach themselves to the new tissue.
(9) The scaffold dissolves.
(10) The newly grown tissue eventually blends in with its
surroundings.
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 (ECM)
that holds the cells. After that, the cells are free floating, and
extracted using centrifugation or apheresis
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.
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.
 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.
 Xenogenic 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.
 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 multipotent, pluripotent& totipotent.
SCAFFOLDS
Cells are often implanted or 'seeded' into an artificial structure capable of supporting
three-dimensional tissue formation. These structures, typically called scaffolds
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 cell nutrients and expressed products
 Exert certain mechanical and biological influences to modify the behavior of the cell phase
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.
MATERIALS
 Many different materials (natural and synthetic, biodegradable and permanent) have
been investigated. Examples of the materials are collagen and some polyesters.
 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.
 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.
 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.
 Functionalized groups of scaffolds may be useful in the delivery of small molecules
(drugs) to specific tissues.
METHODS USED FOR SYNTHESIS OF TISSUE
ENGINEERED SCAFFOLDS
 Nanofiber Self-Assembly
 Textile technologies
 Solvent Casting & Particulate Leaching (SCPL)
 Gas Foaming
 Emulsification/Freeze-drying
 Thermally Induced Phase Separation (TIPS)
 ElectroSpinning
 CAD/CAM Technologies
 Laser-assisted BioPrinting (LaBP)
 Nanofiber Self-Assembly
 Textile technologies
 Solvent Casting & Particulate Leaching (SCPL) CAD/CAM Technologies
 Emulsification/Freeze-drying
 Thermally Induced Phase Separation (TIPS)

 Electrospinning
 Laser-assisted Bioprinting (LaBP)

APPLICATIONS
 Tissue engineering covers a broad range of applications, in practice the term has
come to represent applications that repair or replace structural tissues (i.e., bone,
cartilage, blood vessels, bladder, etc). These are tissues that function by virtue of their
mechanical properties.
 A closely related (and older) field is cell transplantation.
This field is concerned with the transplantation of cells that perform a specific biochemical
function (e.g., an artificial pancreas, or an artificial liver).
 Tissue engineering solves problems by using living cells as engineering materials.
 These could be artificial skin that includes living fibroblasts, cartilage repaired with living
chondrocytes, or other types of cells used in other ways.
 Tissue engineered heart valves offer a promising alternative
for the replacement of diseased heart valves avoiding the
limitations faced with currently available bioprosthetic and
mechanical heart valves.
 Tissue-engineered skin is a significant advance in the field of wound healing and was
developed due to limitations associated with the use of autografts.
End of presentation
Thanks for listing

Tissue Engineering

Uploaded by

Copyright:

Available Formats

Tissue Engineering

Uploaded by

Document Information

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Tissue Engineering

Uploaded by

Copyright:

Available Formats

Department of Medical Engineering

prepared by: Raneem Mounir Al-Dubali

 Process Of Tissue Engineering

 Methods Used For Synthesis Of Tissue Engineered Scaffolds

 Pros and Cons

(1)Start building material (e.g., extracellular matrix, biodegradable

• From fluid tissues such as blood, cells are extracted by

• From solid tissues, extraction is more difficult. Usually the

Tissue engineering utilizes living cells as engineering

Cells are often categorized by their source:

 Thermally Induced Phase Separation (TIPS)

 Laser-assisted Bioprinting (LaBP)

You might also like