This document discusses tissue engineering and its applications in artificial skin and cartilage. It begins by defining tissue engineering as applying engineering and life science principles to develop biological substitutes that restore or improve tissue function. It then discusses the goals of tissue engineering, including restoring biomechanical and physiological function. The document outlines different types of cells used, including autologous, allogeneic, xenogeneic and stem cells. It provides details on different tissue culture techniques and goes on to describe artificial skin and cartilage, including their history, manufacturing processes, cell sources and advantages/disadvantages.

1. Tissue Engineering
By- Sanju Sah
St. Xavier’s college, Maitighar
Department of Microbiology

4. Unit 5. Tissue Engineering
5.1 Introduction to Tissue Engineering
5.2 Technical goals of Tissue
Engineering
5.3 Tissue culture Preparation
Slide or cover slip cultures
Flask cultures
Test tube cultures
5.4 Artificial Skin
5.5 Artificial Cartilage

5. Types of cells
• Autologous
– Harvested from the patient
• Allogeneic cells
– Come from the body of a donor of the same species
• Xenogeneic cells
– Isolated from individuals of another species
• Isogenic cells
– Isolated from genetically identical organisms such as twins,
clones
• Stem cells
– Undifferentiated cells with the ability to divide in cult

6. Introduction to Tissue Engineering
• Tissue Engineering: A branch of Biomedical
Engineering
• Unification of Molecular Biology, Engineering
and Medicine
• Applied to restore or replace defected tissues
and organs

7. • As defined by Dr. Langer and Dr.
Vacanti, tissue engineering 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."

10. Technical Goals of TE
• The goal of tissue engineering is to assemble
functional constructs that restore, maintain,
or improve damaged tissues or whole organs.
– To fulfill a biomechanical role
– To replace physiological function
– To deliver secretary products
– A combination of above

11. Tissue culture
• Tissue culture is the growth of tissue or cells
separated from the organism.
• Types
– Slide or cover slip cultures
The coverslip method as used by Carrel (1912) and by Lewis
and Lewis (l911a,b) is the simplest and has signal advantages
for the beginner. The fragment of tissue is placed in a drop
of medium on a coverslip, covered with a depression slide,
sealed and incubated at body temperature. The cells migrate
and multiply and may be studied under the high powers of
the microscope. This provides the basic requirement for
acquisition of familiarity with the appearance of living,
proliferating cells in tissue culture.

12. – Flask cultures
This methods is used for maintenance of cultures for
longer periods without transfer, developed several
types of culture flasks. In -these ample nutriment and
oxygen are provided, growth of the numerous tissue
fragments is more nearly uniform under identical
conditions
– Test tube cultures
Ordinary Pyrex test tubes are used as the culture
container which is mechanically rotated to expose the
tissues alternately to a fluid nutrient and to oxygen.

13. Artificial Skin

14. • When and Why is Skin/ Skin Substitute
Needed?
– When skin is damaged or lost due to severe injury
or burns, bacteria and other microorganisms have
easy access to body.
– To treat a severe burn
– Patients with diabetes will have difficulties in
wound healing, Inflammation will occur, Chronic
Wound will be formed

15. Skin Autograft
• Transplantation of skin from a donor site to a
receiver site in the same individual

16. Artificial skin
• Artificial skin is a synthetic equivalent to human skin
which can increase the chance of survival of severely
burned patients by protecting the underlying tissues.
Aims
1. Protection from bacteria
2. Wound healing texture

17. History of Burns
• Before artificial skin was
developed, burns covering 50%
of the body were considered to
be fatal.
• In 2000, artificial skin cut death
rates in people with over 70%
burns from 100% to 40%.
• Skin is the body’s largest
organs and protects us from
physical damage, disease, and
controls our body’s
temperature.

18. How Artificial Skin is Made
• Skin is usually donated by other
donors.
• Fibroblasts are removed from
the donated skin and are frozen
until they are needed.
• The fibroblasts are placed on a
polymeric mesh scaffolding,
gather oxygen, and grow new
cells.
• The cells are then transferred to
a culture system.

19. Artificial Skin cont.
• After 4 weeks the polymer mesh dissolves and leaves behind a new
layer of dermal skin.
• When the growth cycle is completed, they add more nutrients.
• Keratinocytes are added to the collagen and are exposed to air to
form epidermal layers.
• The skin is now completed and is stored in sterile contains until
ready to use.

20. How Artificial Skin is Used
• Artificial skin is already being
used for burn victims and soon
will be available for other skin
disorders.
• The skin is not used for a
permanent replacement, but to
temporary cover the skin until
your skin can grow back
naturally.

22. There are two methods to produce
artificial skin. Both of them use fibroblasts
to make it

23. • Integra Dermal Regeneration Template®
– Semi -synthetic approach to skin regeneration
– Researchers develop a bi-layer membrane system called the
Dermal Regeneration Template
– The first and only FDA approved tissue engineered
product for burn and reconstructive surgery
– Dermal replacement layer is constructed of a porous,
biodegradable matrix of cross-linked bovine tendon collagen
and the glycos-aminoglycan chondroitin 6-sulfate.
• Allows a the wound to establish a new tissue base
– Second layer acts as a temporary replacement
(Epidermal ) – made from silicone polymer
 Following completion of the dermal layer physicians replace
the temporary epidermal with an epidermal auto-graft.

25. Artificial Cartilage
• Current strategies in human medicine for
treatment of diffuse joint degeneration rely
on replacement of the whole degenerated
joint with inert implants.
• Excellent treatment outcome has been
achieved for up to 15 years or more, but
approximately 20% of treated patients
require revision procedures after this time
(Steadman et al., 2001).
• For younger patients this current state-of-
the-art may translate to two or more
revision surgeries during their lifetime.
• A biological solution to repair damaged
cartilage that would provide life-long pain
relief would be a major medical
achievement.

26. • Hyaline articular cartilage is a complex
structure, developed and progressively refined
over hundreds of millions of years.
• Cartilage tissue engineered using this triad of
components often exhibit hyaline cartilage
morphology, but the tissue has inferior
mechanical properties when compared to
native joint cartilage

27. Cells of cartilage tissue engineering
• Articular hyaline cartilage is a very specialized
tissue characterized by low cellularity
extensive extracellular matrix, lack of vascular,
lymphatic, and nervous supply.
• Obvious choice of cell for cartilage repair is
the chondrocyte from hyaline cartilage.

28. BUT
• Chondrocytes unfortunately tend to dedifferentiation
towards the fibroblast cell lineage when expanded in
culture making them less suitable for transplantation
• the use of autologous chondrocytes is the need for two
surgical procedures, weeks apart to harvest and later
implant the cells, which adds time, cost, anesthetic risk
and risks of donor site morbidity
SO
• Stem cells or cells with chondrogenic potential from
various tissue sources have been investigated for
cartilage repair

29. Manufacturing process
• Unique building block of articular cartilage matrix is made of
Type II collagen.
• Middle architectural zone called “the netting” is made of
aggregates of proteoglycans called glycosamino- glycans (GAG’s):
This netting holds water i.e.: gives this zone its hydrophilic
character that yields the low friction, fluid wave enabling smooth
joint motion
• Scaffolds are region specific and includes chitosan/ fibrinoger for
bioreplacement.

30. Advantage and disadvantage
• Advantage
– Can prevent total knee replacement
– Can correct birth defects
– Bring hope and confidence in patient
• Disadvantage
– The risk of complication and infection
– It could be rejected by patient’s body
– expensive

32. Thank You