Authors: Abdulaziz Rajeh Alanzi Meshari Muteb Almutairi Abdullah Riyadh Aljandal

1. Regenerative Medicine Essay3122
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Regenerative
Medicine Essay
Keele university – Guy Hilton Research Center
Abdulaziz Rajeh Alanzi
Meshari Muteb Almutairi
Abdullah Riyadh Aljandal 25 – Jul - 2011
Abstract
- Regenerative Medicine aim to repair damaged organs,
most often by using stem cells to replace damaged cells.
- Stem Cells are biological cells have a unique capacity to
renew itself or to give rise to specialized cell type.
- Major Types of stem cells are embryonic and adult stem
cells, or there is another classification of stem cells :
totipotent, pluripotent and unipotent.
- Major characteristics of stem cells are Self-renewal,
unspecialized and differentiation.
- Major applications of stem cells are treating leukemia ,
Parkinson's Disease , Heart disease and thalassemia.
- Tissue Engineering uses principles from chemistry ,
biology , materials science and engineering to develop
biological substitutes that can compensate for body
functions that have been lost or impaired as a result of
ageing, disease or accident.
- Tissue Engineering cells are categorized by their
source into : autologous , allogenic , cell lines and
xenogenic cells.
- There are many research areas linked with tissue
engineering such as some biomaterials ,
biomolecules ,engineering design aspects ,
biomechanical aspects of design and informatics
that support tissue engineering.

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 Introduction :
Regenerative medicine is a wide spired filed holds the promise
of regenerating damaged tissues and organs in the body by
stimulating previously irreparable organs to heal themselves , and
we can define regenerative medicine as "Medical interventions that
aim to repair damaged organs, most often by using stem cells to
replace damaged cells."
Another definition is :"seeks to devise new therapies for patients
with severe injuries or chronic diseases"
We can also define stem cells as :
"Cells that have both the capacity to self-renew ,make more stem
cells by cell division, as well as to differentiate into mature and
specialized cells."(3)
So we can say stem cell is the future of regenerative medicine that
has ability to recover and healing a multi-factorial disease such as
congestive heart failure , osteoporosis , Alzheimer’s , Parkinson’s
diseases , severe burns , spinal cord injuries , birth defects , diabetes
mellitus ...etc.
 Stem Cells :
First , let us define stem cells as :
biological cells have a unique capacity to renew itself (self- renew)
to produce more stem cells or to give rise to specialized
cell types.
o Characteristics of stem cells :
1- Self-renewal : so it can make copies of its self .
2- Unspecialized : so it remain without any function.
3- Differentiated : to any type of cell in human body .
o The major types of stem cells:
1- Embryonic stem cells :
Embryonic stem cells is found in the inner cell mass
that is located in early stages of embryo that called
blastocyst .
2- Adult stem cells :
we can find it in many places in the human body such
as bone marrow , kidney , liver , umbilical cord ,
brain , skin , salivary gland and muscle .

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o Another classification of stem cells:
totipotent : embryonic stem cell that can give rise to all
the tissue in the embryo including the extra embryonic
tissues, placenta, and umbilical cord.
Pluripotent : also embryonic stem cell that can give rise
to cells derived from all embryonic germ layers
mesoderm , endoderm and ectoderm .
Unipotent : it is adult stem cell that give rise to just one
cell type , however if the tissue in a compromised
situation and the replacement is must be required ,
pluripotent stem cells may become activated to repair the
damage.
o Why stem cells is important ?
1- Stem cells allow us to know how simple cells grow
and develop to become a mature cell.
2- Stem cells have the ability to regenerate and heal any
loss or damaged any cell or tissue that can not renew
themselves
3- As well as one of the importance of the stem cells
they can be used as treatment for different disease
such as Parkinson's disease , Leukemia and skin
graft used in severe burns.
4- Moreover , stem cells have the potential to regenerate
tissue and cure some of the disease like diabetes and
multiple sclerosis.
o Properties of embryonic stem cells :-
• Derived from the inner cell mass/epiblast of the
blastocyst.
• Capable of undergoing an unlimited number
of symmetrical divisions without differentiating
(long-term self-renewal).

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• Pluripotent ES cells can give rise to differentiated
cell types that are derived from all three primary
germ layers of the embryo (endoderm, mesoderm,
and ectoderm).
• Capable of integrating into all fetal tissues
during development. (Mouse ES cells maintained
in culture for long periods can still generate any
tissue when they are reintroduced into an
embryo to generate a chimeric animal.)
• Capable of colonizing the germ line and
giving rise to egg or sperm cells.
• Clonogenic, that is a single ES cell can give
rise to a colony of genetically identical cells, or
clones, which have the same properties as the
original cell.
• Expresses the transcription factor Oct-4, which
then activates or inhibits a host of target genes
and maintains ES cells in a proliferative,
nondifferentiating
state.
• Can be induced to continue proliferating or to
differentiate.
• Lacks the G1 checkpoint in the cell cycle. ES
cells spend most of their time in the S phase of
the cell cycle, during which they synthesize DNA.
Unlike differentiated somatic cells, ES cells do not
require any external stimulus to initiate DNA
replication.
o Properties of adult stem cells :-
• Adult stem cells can proliferate without differentiating
for a long period (a characteristic referred
to as long-term self-renewal), and they can give
rise to mature cell types that have characteristic
shapes and specialized functions.
• Some adult stem cells have the capability to
differentiate into tissues other than the ones from
which they originated; this is referred to as
plasticity.
• To date, published scientific literature indicates
that adult stem cells have been derived from
brain, bone marrow, peripheral blood, dental
pulp, spinal cord, blood vessels, skeletal muscle,
epithelia of the skin and digestive system,
cornea, retina, liver, and pancreas; thus, adult
stem cells have been found in tissues that
develop from all three embryonic germ layers.
• Hematopoietic stem cells from bone marrow are
the most studied and used for clinical applications
in restoring various blood and immune

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components to the bone marrow via transplantation.
There are at least two other populations of adult stem cells that
have been identified from bone marrow and blood.
• Several populations of adult stem cells have been identified in
the brain, particularly the hippocampus. Their function is
unknown. Proliferation and differentiation of brain stem cells
are influenced by various growth factors.
• There are now several reports of adult stem cells
in other tissues (muscle, blood, and fat) that
demonstrate plasticity. Very few published
research reports on plasticity of adult stem cells
have, however, included clonality studies. That is,
there is limited evidence that a single adult stem
cell or genetically identical line of adult stem
cells demonstrates plasticity.
• Rarely have experiments that claim plasticity
demonstrated that the adult stem cells have
generated mature, fully functional cells or that
the cells have restored lost function in vivo.
o Application :
1- Treating Leukemia :
Leukemia occur when white blood cells which made in
bone marrow begin to grow abnormally .
So , we can treat patient with leukemia by transplant
stem cells from bone marrow .
2- Parkinson's Disease :
Parkinson's disease is movement disorder result from
degenerative of central nervous system because of lack
in amount of dopamine which act as neurotransmitter.
Treating this disease by using cells that secrete
dopamine.
3- Heart disease :
Cardiologists and heart surgeons use vesCell adult
stem cell therapy to treat patients suffering from
coronary artery disease, cardiomyopathy, and
congestive heart failure.
4- Thalassemia :
Thalassemia is a genetic defect that is result from
decrease in the synthesis of globin chain that make
hemoglobin.
The only cure is done by transplant hematopoietic stem
cells .
 Tissue Engineering And Biomaterials :
Tissue engineering uses principles from chemistry , biology ,
materials science and engineering to develop biological substitutes

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that can compensate for body functions that have been lost or
impaired as a result of ageing, disease or accident. So we could say
that the main purpose of tissue engineering is to repair or enhance
biological function at the tissue or organ level
)etc.skin,bladder,blood vessels,lagecarti,bone(i.e.
So when we compare traditional medicine with regenerative
medicine ,traditional medicine is based on replacement of the organ
when there is a destructive disease but regenerative medicine can
cure this disease without giving patients entirely new organs.
Types of Tissue Engineered Implants
ExamplesMood of ActionType
Bone
Blood Vessels
Graft performs
primarily a
biomechanical
role.
Physical
Liver , KidneyGraft perform a
physiological
role
Physiological
Pancreatic
Islets
Use of cells to
produce soluble,
diffusible
components
Chemical
SkinGraft performs
more than one
role
Combination
Figure 1 : Types of Tissue Engineered Implants , www.biomed.drexel.edu
o Types of Cells :
Source of Cells
Harvested from patientAutologous
Cells from donorAllogenic
Cells which have
undergone genetic
mutation which allows
adaptation to indefinite
proliferation
Cell Lines:
Cells from different speciesXenogenic
Figure 2 : Source of Cells , www.biomed.drexel.edu
Cells are often categorized by their source :
- Autologous cells : are obtained from same patient and then
they are re-implanted to the body. But in some cases , these
cells are not available such as with very ill patients or elderly
patients, as well as patients suffering from severe burns, may
not have adequate quantities of autologous cells to create useful
cell lines. The main advantages of these cells are that the
autologous cells have the fewest problems in term of pathogen
transmission problems and they are always compatible. But
actually there are some disadvantages as well such as its very
costly and take a time to harvest , expand and construct implant.

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- Allogeneic cells : are obtained from a body of donor of the
same species.
- Cell Lines : Cells which have undergone genetic mutation
which allows adaptation to indefinite proliferation.
- Xenogenic cells : are obtained from individuals of another
species.
:
o Some areas of Tissue Engineering Research:
1) Biomaterials: including new biomaterials that are
designed to guide the growth, differentiation and
organization of cells in the process of forming functional
tissue by providing both physical and chemical cues.
2) Cells: including enabling methodologies for the
differentiation and proliferation of cells, getting the
appropriate source of cells such as autologous cells,
allogeneic cells, xenogeneic cells, stem cells,
3) Biomolecules: including angiogenic factors,
differentiation factors, growth factors and bone
morphogenic proteins.
4) Engineering Design Aspects: including 2-d cell
expansion, 3-d tissue growth, bioreactors, vascularization,
cell and tissue storage and shipping (biological packaging).
5) Biomechanical Aspects of Design: including properties
of native tissues, identification of minimum properties
required of engineered tissues, mechanical signals
regulating engineered tissues, and safety of engineered
tissues
6) Informatics to support tissue engineering: gene and
protein sequencing, gene expression analysis, protein
expression and interaction analysis, quantitative cellular
image analysis, quantitative tissue analysis, in silico tissue
and cell modeling, digital tissue manufacturing, automated
quality assurance systems, data mining tools, and clinical
informatics interfaces.
 Conclusion :
At the present and probably the future also the stem cells
are the future of regenerative medicine by its two major
types adult and embryonic stem cells. More ever , by its
properties and important characteristics such as
unspecialized , differentiated and self-renewal. Therefore ,
we can apply it in many application and treatment as well
such as treating leukemia , Parkinson's disease , heart disease
, diabetes and thalassemia.

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On the other hand , tissue engineering also used in many
applications by obtaining autologous , allogenic , cell lines or
xenogenic cells. Therefore , there are many Research areas
linked with tissue engineering such as some biomaterials ,
biomolecules ,engineering design aspects , biomechanical
aspects of design and informatics that support tissue
engineering.
References :
1. Ruth Kirschstein, Lana R. Skirboll (June 2001). "Stem Cells
scientific progress and future research direction". Chapter 1-4.
Pages :1-42
2. David M. Panchision (2006)." Regenerative Medicine".
Pages :4-11
3. Mason C, Dunnill P (January 2008). "A brief definition of
regenerative medicine".
4. W. W. Minuth, R. Strehl, K. Schumacher (2005). "Tissue
Engineering". Pages:132-136.
5. http://www.tissue-engineering.net – accessed at 19-jul-2011
6. www.biomed.drexel.edu – accessed at 21-jul-2011