An Introduction to Tissue Engineering

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An Introduction to Tissue Engineering

• Cindy Handley, PhD, MT(ASCP)
• SCCC Biology Instructor

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Acknowledgements
Pittsburg Tissue Engineering Initiative a
network strategy to promote regional economic
growth through the advancement and creation of
biomedical and related technologies associated
with engineered tissues, Including cell
culturing, gene therapy, organ transplantation
and regeneration, biomaterials, and
computer-assisted analysis and design.
http//www.ptei.org/ Mark Krotec, BS, MS
facilitator for the summer teachers workshop
and major contributor of data for this
presentation via the Education Outreach Manual
in Tissue Engineering and the summer workshop.
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Overview

• Tissue engineering defined
• Stem cell research
• Tissue model constructs
• and lab techniques
• IV. Ethics

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Tissue Engineering Defined
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According to the Pittsburgh Tissue Engineering
Initiative,

• Tissue engineering is an emerging
• interdisciplinary field that applies
• the principles of biology and
• engineering to the development of
• viable substitutes that restore,
• maintain, or improve the function of
• human tissues.

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What are viable substitutes?

• On a large scale, certain surgical interventions,
  like castration of a bull, have led to alteration
  of tissue function.
• On a molecular level, gene therapy is has been
  very successful with plants and animals
• On a cellular level, the research is currently
  focused on stem cells.

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Stem cells

• According to the Merriam-Webster Online
  Dictionary, a stem cell is,
• an unspecialized cell that gives rise to
  differentiated cells
• Two basic types
• Embryonic pluripotential
• Adult multipotential

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Embryonic stem cells

• According to Richard Mollard, Ph.D., of the
  International Society for Stem Cell Research,
  Human embryonic stem (ES) cells are cultured
  cell lines derived from the inner cell mass of
  the blastocyst that can be grown indefinitely in
  their undifferentiated state, yet also are
  capable of differentiating into all cells of the
  adult body.

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http//www.time.com/time/2001/stemcells/
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• Animation Stem cells

http//www.dnalc.org/stemcells.html
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Embryonic stem cells (cont)

• Two sources
• Fertilized egg from in vitro fertilization
• Ovum that has had nucleus removed and nuclear
  material injected from intended recipient of
  final tissue product
• (reproductive/therapeutic cloning)
• Very controversial

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Adult stem cells

• Found in
• Umbilical cord blood/tissue
• Adult brain, blood cornea, retina, heart, fat,
  skin, dental pulp, bone marrow, blood vessels,
  skeletal muscle and intestines

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II. Stem cell research
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What progress has been madeto date?

• Autologous stem cells have been injected into
  heart to regenerate damaged cardiac tissue
• Corneal autologous stem cell grafts have been
  used to treat eye disease trauma
• Skin replacement has been grown with stem cells
  for transplant in burn victims

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Progress

• Autologous stem-cell cartilage grafts have been
  used to treat joint disease
• Leukemia other cancers have been treated with
  stem cells from bone marrow and umbilical cord
  blood
• A human mandible has been produced using a
  titanium mesh and autologous bone-marrow stem
  cells

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The future?
According to the Stem Cell Research Center Half
Of All Americans Could Benefit From Stem Cell
Research Experts are predicting that stem cell
research has the potential to help up to half of
all Americans, who suffer from some form of
presently incurable disease, injury or birth
defect. Some of Those conditions includeOne
million children with juvenile diabetes 8.2
million people with cancer 58 million with heart
disease Four million suffering from Alzheimer's
disease 10 million with osteoporosis 43 million
arthritis sufferers 250,000 people paralyzed by
spinal cord injuries 30,000 victims of Lou
Gehrig's disease 500,000 with Parkinson's
disease
www.stemcellresearchfoundation.org/WhatsNew/Benefi
t.htm
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III. Tissue model constructs lab techniques
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Tissue engineering requires three things
Cells
Signals
Scaffold
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• Weve already discussed different types of cells
  that may be used
• The scaffold refers to the tissue model construct
• The signals refer to molecular signaling
  molecules, also known as growth factors

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Basic scaffold criteria

• Portions must be biodegradable
• Usually designed in the shape of the tissue
  product the researcher is working on

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www.eng.nus.edu.sg/ EResnews/0210/rd/rd_10.html
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Biomimetic Scaffold Fabrication
                                                  
                                                  
                                   
bms.dent.umich.edu/research/malab.html
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www.millenium-biologix.com/Html/00_ScientificInfor
mationCartiGraft.htm
Autologous de novo cartilage formed on Skelite
tissue engineering scaffold (grown in vitro),
illustrating the configuration of the implant
that provides functional cartilage tissue at the
articular surface. The presence of functional
cartilage tissue represents a major advance over
current cell therapy techniques. Cell therapy
involves the implantation of cells that still
have to make new cartilage in vivo at the defect
site under very challenging conditions. The
histology image on the right shows that cells
are healthy and growing, while attaching
themselves to the Skelite and beginning to
differentiate into mature cartilage.
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V. Ethics
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Now that we see that we CAN, the question
is should we??????
Pair up with a colleague and brainstorm ethical
concerns you can identify with this technology.
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ETHICS

• The great divide over stem cells
  (www.mtulode.com/index.php?issuedatesection12a
  rtid4540)
• The Ethics of Human Embryonic Stem Cell Research
  (www.isscr.org/public/ethics.htm)
• Guidelines for Human Embryonic Stem Cell
  Research(www.iom.edu/report.asp?id26661)

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Ethics (cont)

• Stem Cell Research All sides to the dispute
  (www.religioustolerance.org/res_stem.htm)
• Research Ethics and Stem Cells
  (stemcells.nih.gov/info/ethics.asp)

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SUMMARY
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Selected References Cited

• Carmichael, Mary. (2005). Organs under
  construction. Newsweek, Summer 2005, 46-48.
• Lanza, R., Rosenthal, N. (2004). The Stem Cell
  Challenge. Scientific American, June 2004,
  93-99.
• Pittsburgh Tissue Engineering Initiative (2001).
  An Education Outreach manual in Tissue
  Engineering, updated through June 2005.
  Pittsburg, PA, PTEI Author.
• Weiss, Rick (2005). The power to divide.
  National Geographic. July 2005, 3-27.