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From RICE to Restoration
The Evolution of Tissue Engineering in Muscular Regeneration
By:
Shari Hawker
And
Charles Armstrong
Five hottest jobs for the
next millennium will be
bioengineering/biomedical
related.
Tissue
Engineering
Hottest job for the 21st
Century
Normal Wound Repair
Requires a Balance of
Processes
The Basic Three Rs
of Tissue Engineering
Right
Hormones
Matrices
Right
ECM
Cells
Healing
Signaling
Molecules
Right
Cells
What about the cells?
Adult stem cells
look promising
for some applications
Embryonic stem cells
great potential,
controversial
The right hormones can induce
these cells to become
a variety of cell types
Other Factors for
Stem Cell
Determination
Adult Muscle-derived Stem Cell
(MDSC) Isolation
Tissue Specific Growth
Factors Added (BMP, IGF
VEGF, TGF, NGF…)
MDSC expanded in culture
Muscle Biopsy
Multi-lineage Differentiation
Myogenic
Osteogenic
and
Hematopoetic
Neurogenic
Chondrocytic
Adiposity
adipocyte
osteoblast
hematopoetic/endothelial
cells
muscle cell
chondrocyte
Adult MuscleDerived Stem Cells
(MDSCs)
nerve cells/neurons/glial cell
hepatocyte/urinary bladder cells
Pancreatic islets??
What do all of these have in
common?
Muscle Tissue Issues
Rhabdomyolysis
Trauma
Myocardial Necrosis
Muscular
Dystrophy
A Breakdown of Muscular
Breakdown
Muscular Dystrophy
A degenerative muscular disease in which the body has a
defect in dystrophin, a muscle tissue regulator. As a result, muscle
grows improperly, or barely even at all.
Trauma (aka boo boos)
Sprains, twists, bruises etc. can all result in the destruction of
muscular tissue. When the muscle attempts to heal, it often does
what is call fibrosis. It creates scar tissue in the place of regular
tissue, obstructing muscle growth.
Myocardial Necrosis
When ischemia, or lack of metabolically accessible oxygen, occurs in
a region of muscular tissue; it undergoes necrosis, or cellular death.
The heart is no exception. When myocardium, or heart muscle, dies
off, it can even obstruct the function of living heart tissue. This is
called a myocardial infarction or a heart attack.
A Breakdown of Muscular
Breakdown (cont.)
Rhabodomyolysis
A big term for the excessive decomposition of muscular tissue,
there are various factors attributed to this disease including drugs,
excessive muscular strain, and genetics. When the muscles
breakdown a host of other problems arise: the products of muscle
degeneration, such as proteins, electrolytes and other metabolites
stored in the sarcoplasm of muscular cells, can flood the excretory
system and cause serious renal (kidney) damage.
Current Research in
Muscle Healing
Current
Treatments
Conservative treatment
•
•
•
•
•
RICE principle
NSAIDS
Mobilization
Therapeutic ultrasound
Hyperbaric oxygen
Surgical treatment
Slow progress in research
for muscle injury
Gene Therapy and Muscle
Healing
• Could potentially be used to deliver
genes to an individual for the
production of structural and bioactive
proteins
– Physical Trauma (IGF-1, Decorin, Suramin…)
• Would eliminate need for multiple injection of expensive,
easily degraded molecules in order to deliver long-term
doses of the desired compound
– Use of an inducible promoter to turn gene off (Tet ON)
– Biological Injury (Dystrophin, Sarcoglycan,
Decorin…)
• Could theoretically be introduced to all tissues of an
affected individual
Gene Therapy
• Types:
– Naked DNA transfection
– Lyposome transfection
– Viral transduction (Adenovirus, AAV,
Retrovirus, Herpes simplex)
• Delivery
– In vivo
– Ex vivo
WHAT IS THIS!?!?!?!?!
(Genetic Mootations?)
Myostatin
• A growth factor
(hormone) that
suppresses muscle
growth.
– Slows down development
of muscle stem cells
• In 2002, researchers at
the University of
Pennsylvania showed that
monoclonal antibody
specific to myostatin
improves the condition of
mice with muscular
dystrophy, presumably by
blocking myostatin's
action.
Muscle Injury Treatments
Biological Injury
Far more difficult to overcome since
the defect is global and not typically
localized as in a physical trauma,
hence cell and gene therapies are
rigorously being investigated
because of their potential to treat at
a cellular or molecular level the
entire organism.
Myoblast Transplantation
• Utilizes an unpurified muscle cell
population of satellite cells and other
muscle derived cell types isolated from
skeletal muscle in the hope that the cells
will fuse with myofibers lacking
dystrophin and restore this structural
protein to the muscle of DMD patients.
Clinical trials have been attempted
several times since the mid-90s.
Growth factor effect on:
myoblasts
Effect of growth factors in vitro
IGF-1, b-FGF, NGF
• Stimulate the proliferation and fusion
of myoblasts and is concentration
dependent.
___________________________________________________
Effect of growth factors in vivo
IGF-1, b-FGF, NGF
• Are potent stimulators of muscle growth in vivo
IGF-1
• Can enhance muscle recovery in vivo
The Preplate Technique
Enzymatic
digestion
Muscle Derived
Stem Cells
Muscle biopsy
(mice)
Pre-plate 6
After 1 h
Pre-plating
technique
After 24 h
(repeated 4 times)
MDSCs display an improved
transplantation capacity in skeletal muscle
when compared to myoblasts
MDSC’s have also been shown to participate
in forming new blood vessels, peripheral
nerves, bone, cartilage and cardiomyocytes.
Summary
• Treatment regimes vary between injury
types depending if it is congenital or acute
in nature.
• Standard treatments for physical traumas
include: RICE, NSAIDS, mobilization…
• Treatment of biological muscle trauma is
far more complicated.
• Innovative new strategies for aiding in
muscle regeneration include:
– 1)
– 2)
– 3)
– 4)
growth factor treatment
antifibrosis treatments
cellular therapies
gene therapy