Despite advances in organ transplantation, thousands still die each year waiting for donor organs. Tissue engineering aims to construct artificial organs and tissues in vitro by combining cells, biomaterials, and growth factors to replace diseased organs. Some key challenges include developing scaffolds that mimic the extracellular matrix, integrating multiple cell types, and applying mechanical and chemical signals to direct tissue development. While tissue engineering has shown promise for tissues like bone and skin, fully regenerating complex organs that do not naturally regenerate has yet to be achieved. Further research is still needed to meet clinical and patient expectations for safety, effectiveness and cost.

3. Medical Students
Union
Faculty of Medicine

4. Introduction :
Despite recent technological advances,
thousands die each year while waiting for
organ transplants due to :
lack of organ donors or efficient organ
substitutes
So this lack of donor organs has caused many to
consider “tissue engineering” methods or
“regenerative medicine” as means to replace
diseased or damaged organs.

6. Is an emerging technology where artificial organs
and tissues are constructed in vitro and transplanted in
vivo for the recovery of lost or malfunctioned organs or
tissues.
It is the use of a combination of cells, engineering
methods and materials, and suitable biochemical and physico-
chemical factors to improve or replace biological functions.

7.  Congenital abnormalities require tissue
reconstruction.
 Most tissues cannot regenerate following a
disease or injury.
 Even tissues that regenerate spontaneously
(e.g. skin , bone …) may not completely do so.
 Transplantation is limited by the scarcity of
donor tissue.
 Permanent implants have a lot of success , but
also a lot of problems.

9. Does the same concept apply to
understanding the structure of biological
tissues?
If one sure approach to
understand the complex
structure of a device is to
take apart its components
and reassemble them into
a functional unit,

10. • Cells • Extracellular
matrix (ECM)
• Growth factors

11.  Autologous
donor back to donor , immune acceptable
 Allogeneic
donor to recipient, same species
 Syngeneic
genetically identical donor ,
such as homozygous twin
 Xenogeneic
cross-species,
such as animal cells in a human patient
 Stem cells
undifferentiated cells with the ability to divide
in culture and give rise to different forms of
specialized cells

13. •They are very large molecules and therefore have
very low diffusion ability
•They often have cell binding domains as well as
domains to bind other ECM molecules
•Many of critical binding domains identified can
be mimicked by small peptides
•They can regulate cell fates including :
differentiation , apoptosis and migration

15. Integrins - interactions

16. Hormones or other materials that direct
and regulate cell growth and differentiation

17. • Isolated cells are taken to culture system and cultivated
to selective cell differentiation time
• Different biomaterials are used for constructing
scaffolds
• Different techniques are used for scaffold fabrication
• For in vitro tissue engineering tissue culture is done
either on petri dishes or bioreactors

19. It is an artificial structure capable of
supporting three-dimensional tissue
formation

20. 1. Biocompatible
2. Bioabsorbable
3. Degrade with healing
4. Highly porous
5. Correct pore size for cell penetration and tissue
impregnation

21. 6. Permeable for nutrient delivery and gas exchange
7. Provide appropriate stress environment
8. Surface conducive to cell attachment
9. Promote extracellular matrix production and
deposition
10. Carry and transmit biomolecular signals

22. 1.collagen
2.gelatin
3.hyaluronan
4.poly(glycolic acid) (PGA)
5.poly(L-lactic acid) (PLLA)
6. poly(DL-lactic-co-glycolic acid) (PLGA)

23. 5.4 5.4 3.5 mm scaffold

24. collagen Polyglycolic a.

26. • Nanofiber Self-Assembly
• Solvent Casting & Particulate Leaching (SCPL)
• Gas Foaming
• Emulsification/Freeze-drying
• Thermally Induced Phase Separation (TIPS)
• CAD/CAM Technologies

27. • This may be done either on :
• Petri dishes :simple method commonly
used in tissue cultures
• Bioreactor :simulate the body
conditions like gas , temperature, pH
and dissolved oxygen levels

28. Bioreactor
• It is any device or system that supports a
biologically active environment.
• A bioreactor may also refer to a device or
system meant to grow cells or tissues in the
context of cell culture.

29. Some types of bioreactors

35. 1. Engineered cartilage:
Objectives:
Immediate functionality (mechanical; metabolic) Capacity
for further development and integration
Culture requirements:
High initial cell density
Nutrient and gas exchange
Growth factors (TGFβ. IGF I..sequential application)
Hydrodynamically active environment

36. 2.Engineered bone:
Objectives:
Immediate functionality (mechanical; metabolic)
Capacity for further development and integration
Structural hierarchy
Culture requirements:
Nutrient and gas exchange Regulatory molecules (dex,
BMP-2...) Hydrodynamically active environment
(interstitial flow)

37. 3. Engineered ligament:
Objectives:
Immediate functionality (mechanical:
metabolic)
Capacity for bonding with adjacent bone
Culture requirements:
High initial cell density
Nutrient and gas exchange
Physical signals
Perfusion
Mechanical stimulation (ligament - like)

38. 4. Engineered arteries:
Objective:
Mechanical competence
Nonthrombogenic surfaces
Requirements:
Tubular scaffold
Two cell types Regulatory molecules
Physical factors
• stretch
• pulsatile pressure

40. Current Status
• full regeneration of tissues that do not regenerate
spontaneously has not yet been achieved
• A lot of success with bone
• Skin has no glands and hair
• Engineered cartilage is not articular
Limited Success

41. Requirements for Successful
Tissue Engineered Products
• Basic science
• Expectations of clinicians/surgeons – how much
success rate?
• Expectations of patients – what criteria?
• Cost vs Benefits