Neuroendocrine Tissue Engineering in Rotating Wall Vessel Bioreactors

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Neuroendocrine Tissue Engineering in Rotating
Wall Vessel Bioreactors
CELLULAR TISSUE ENGINEERING RESEARCH
P R O G R A M O V E R V I E W
In the Tissue Engineering Laboratory, our
researchers use a microgravity simulating
bioreactor environment to generate nueroendocrine
tissues with the future goal of using them as
replacement parts for neurodegenerative
conditions, such as Parkinsonss and Alzheimer's
diseases.
Innovative Cardiac Tissue Engineering
Using electrically conductive polymers scaffolds
to differentiate cardiac progenitor (stem) cells)
into beating cardiac myocytes, our researchers
aim is to fabricate myocardial patches that can
surgically replace the damaged myocardium.
Nueronal Tissue Engineering
Similar to the efforts in the area of cardiac
tissue engineering, research is also focused on
the use of electrically conductive polymers as
scaffolds to differentiate neuronal progenitor
(stem) cells into neurons, with the hope of
establishing functional neuronal networks.
Hemodynamic Etiology of Atherosclerosis
Here we are trying to define the molecular
mechanisms to discover why atherosclerotic
regions always occur in areas of hemodynamic
disturbances, such as bifurcations or arterial
branching points.
Cellular Responses to Mechanical Activation
Under the direction of Dr. Kenneth Barbee, we are
investigating the role of mechanical forces in
the control of cell growth and differentiation,
as well as the development of tissue structure.
By engineering the structure and biochemistry of
extra-cellular matrices, as well as
pre-conditioning with physiological loading
regimes, we will optimize cellular tissue
constructs based on initial functional properties
and the acquisition of adaptive behaviors that
will allow long-term replacement of tissue. A
major goal is the development of a vascular graft
capable of adapting to hemodynamic stresses lumen
such that size and wall structure are maintained
as in normal tissue.
Cellular Adhesion and Molecular Mechanisms
We are researching how cell function is regulated
by physicochemical environmental signals. Our aim
is to use this knowledge for synthesizing tissue
constructs, such as bone.
Vascularizing Tissues
Blood vessels are a part of almost all
tissues/organs. Endothelial cells are the cells
involved in formation of blood vessels.
"Angiogenic" factors, which activate endothelial
cells to invade the surrounding matrix and form
"blood vessels," are mainly released by bystander
cells, such as myocytes.
Faculty Fred Allen, Ph.D., Ken Barbee, Ph.D.,
Frank Ko, Ph.D., Cato Laurencin, Ph.D., Peter
Lelkes, Ph.D. (Director of Cellular Tissue
Engineering Initiative), Michele Marcolongo,
Ph.D., Yen Wei, Ph.D. Collaborating Researchers
Yasha Kresh, Ph.D., MCP Hahnemann University,
Alan G. MacDiarmid, Ph.D., University of
Pennsylvania Graduate Students Paul Bidez,
Seykyo Chung, Franziska Dietrich, Milind Ghandi,
Elizabeth Guterman, Amir Rezvan, Gulyter Serbest,
Eric Troop.
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NEUROENDOCRINE TISSUE ENGINEERING IN ROTATING
WALL VESSEL BIOREACTORS
P R O J E C T O N E P A G E R
In the Tissue Engineering Laboratory, our
researchers use a microgravity simulating
bioreactor environment to generate nueroendocrine
tissues with the future goal of using them as
replacement parts for neurodegenerative
conditions, such as Parkinsonss and Alzheimer's
diseases.
Faculty/Contact P. Lelkes, Ph.D., Director of
Cellular Tissue Engineering Laboratory, Drexel
University. E-mail pilelkes_at_drexel.edu Collaborat
ing Researchers F. Allen, Ph.D., Drexel
University K. Barbee, Ph.D., Drexel
University. Graduate Students E. Troop, Drexel
University F. Dietrich, Drexel
University. Funding NASA Laboratories Cellular
Tissue Engineering Laboratory MCP Hahnemann
University.
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INNOVATIVE CARDIAC TISSUE ENGINEERING
Using electrically conductive polymers as
scaffolds to differentiate cardiac progenitor
(stem) cells) into beating cardiac myocytes, our
aim is to fabricate myocardial patches that can
surgically replace the damaged myocardium.
P R O J E C T O N E P A G E R

• Cardiac Tissue Hypothesis
• Our working hypothesis states that
  tissue-specific differentiation and function of
  pluripotent stem cells into cardiac myocytes can
  be fine-tuned by the molecular structure/compositi
  on of 3-D scaffolds on the nano-scale.
• Specifically, we hypothesize that 3-D scaffolds,
  composed of nanofibers made of, or doped with,
  electrically conductive polymers will, in
  conjunction with advanced RWV Bioreactor
  Biotechnology, facilitate the
• differentiation of cultured pluripotent
  mesenchymal stem cells into cardiac myocytes.
  Moreover, the application   of controlled levels
  of electrical current will enhance/accelerate the
  formation of functional (beating) 3-D cardiac
  tissues.

• Cardiac Tissue Aims
• Specific aim 1 Generate 3-D nanoscale scaffolds
  composed of electrically conductive polymers,
  alone or composite,  and to optimize adhesion,
  growth, and differentiation of pluripotent stem
  cells and cardiac myocytes (isolated from adult
  or neonatal rats) on these scaffolds.
• Specific aim 2 Compare tissue-specific
  differentiation into functional cardiac tissues
  by exposing the cells to electrical current in
  conventional cultures and in RWV Bioreactors.
• Specific aim 3 Generate a functional vasculature
  within the tissue constructs.

e-Pan We are currently testing new techniques to
increase the biocompatibility of the
electroactive PAN(e-PAN). A serial dedoping
technique yields a substrate with improved cell
adhesion and proliferation. As seen in figures 5
and 6, H9C2 myoblasts adhere and form confluent
monolayers on the e-PAN.
Faculty/Contact P. Lelkes, Ph.D., Director of
Cellular Tissue Engineering Laboratory, Drexel
University. E-mail pilelkes_at_drexel.edu Collaborat
ing Researchers Y. Kresh, Ph.D., Drexel
University Y. Wei, Ph.D., Drexel University F.
Ko, Ph.D., Drexel University Alan MacDiarmid,
Ph.D., University of Pennsylvania. Graduate
Students P. Bidez, Drexel University F.
Dietrich, Drexel University. Funding NASA,
Synergy Grant. Laboratories Cellular Tissue
Engineering Laboratory MCP Hahnemann University.
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NEURONAL TISSUE ENGINEERING
P R O J E C T O N E P A G E R
To be successful, tissue engineering attempts to
recapitulate some of the fundamental steps in
organ development, such as electrical
current-driven differentiation in the nervous
system. Application of conducting polymers in
biotechnology remains a challenge because of the
supposedly poor biocompatibility of these
materials. We hypothesize that the
biocompatibility of electroactive polymers, such
as polyaniline (PANI), can be improved by
covalently linking bioactive peptides onto the
surfaces of prefabricated conducting polymer
films/fibers. Our long-term goal is to generate
3-D scaffolds from biocompatible conductive PANI
that exhibit enhanced adhesion, proliferation,
and differentiation of cells seeded onto them.
In this study, we demonstrated the feasibility
of our approach by covalently linking a model
amino acid, tryptophan, to the chloromethylated
PANI backbone. The structure of the modified PANI
was assessed using UV-VIS, IR, and NMR
spectroscopy. The fluorescence properties of
tryptophan allow for quantitative validation of
its covalent attachment to the polymer. In
assessing the biocompatibility of this modified
conductive PANI, we are currently testing
attachment, proliferation and differentiation of
a cellular model for neuronal differentiation,
PC-12 pheochromcytoma cells. In comparison to
unmodified PANI, PC-12 cells seeded onto films
prepared from the modified polymers exhibit
enhanced attachment and proliferation, in
addition to remaining responsive to nerve growth,
factor-induced neuronal differentiation. This
significantly improved PANI is now available for
3-D scaffold formation (e.g. by electrospinning
of nanofibers) and for a variety of biomedical
engineering applications, such as generating
replacement tissues in neurodegenerative
diseases, as well as spinal cord injury.
Faculty/Contact P. Lelkes, Ph.D., Director of
Cellular Tissue Engineering Laboratory, Drexel
University. E-mail pilelkes_at_drexel.edu Collaborat
ing Researchers Y. Kresh, Ph.D., Drexel
University Y. Wei, Ph.D., Drexel University F.
Ko, Ph.D., Drexel University Alan MacDiarmid,
Ph.D., University of Pennsylvania. Graduate
Students Shan Cheng, Paul Bidez, and Kolby
Palouian (Undergraduate Student) - Drexel
University. Funding NASA, US Army Research
Office, Synergy Grant, and The Nanotechnology
Institute. Laboratories Cellular Tissue
Engineering Laboratory MCP Hahnemann University.
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HEMODYNAMIC ETIOLOGY OF ATHEROSCLEROSIS
P R O J E C T O N E P A G E R
Disturbed Hemodynamic Forces Predispose
Endothelial Cells to Atherosclerotic Lesions
In Vitro System Models Events at Sites of
Atherosclerotic Predilection
Enhanced monocyte adhesion First step towards
developing atherosclerotic lesions.
Atherosclerotic injury occurs at sites of
hemodynamic disturbances (e.g., at branching
points or bifurcations).
Model chamber for exposing cultured endothelial
cells to disturbed flow.
Altered gene expression Analysis by cDNA
micro-arrays.
Faculty/Contact P. Lelkes, Ph.D., Director of
Cellular Tissue Engineering Laboratory, Drexel
University. E-mail pilelkes_at_drexel.edu Collaborat
ing Researchers F. Allen, Ph.D., Drexel
University K. Barbee, Ph.D., Drexel
University. Graduate Students P. Bidez, E.
Troop, A. Rezvan - all from Drexel
University. Funding Berlex Biosciences,
Richmond, CA. Laboratories Cellular Tissue
Engineering Laboratory MCP Hahnemann University.
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CELLULAR RESPONSES TO MECHANICAL ACTIVATION
P R O J E C T O N E P A G E R
The promise of tissue engineering lies in the
prospect of replacing tissue that has become
dysfunctional due to trauma or disease with new
tissue capable of responding and adapting to
environmental stimuli. Of primary importance in
tissues that serve a mechanical or structural
function is the ability to sense and respond to
mechanical forces in order to adapt to the
changing physical demands on the tissue. Previous
in vivo and in vitro studies suggest that the
structure and mechanical properties of blood
vessel walls develop in response to the stress
history of the tissue. The endothelium mediates
vascular tone and structural remodeling in
response to changes in blood flow, while the
vascular smooth muscle (VSM) cells sense and
respond to changes in stress within the vessel
wall itself. These responses are essential to the
maintenance of structural integrity and the
regulation of blood flow. The central
hypothesis of this research is that in normal
development, structural relationships in vascular
tissue are optimized for efficient sensing and
transduction of the mechanical environment by the
cells of the vessel wall. To engineer a tissue
structure intended to acquire the property of
adaptability present in normal tissue, we must
first understand the salient features of the
cells interaction with their surrounding
structures that allow appropriate
mechano-transduction to occur. The structure and
biochemistry of engineered matrices, as well as
pre-conditioning with physiological loading
regimes, will be analyzed and optimized based on
initial functional properties and the acquisition
of adaptive behaviors that will allow long-term
replacement of tissue.
Faculty/Contact P. Lelkes, Ph.D., Director of
Cellular Tissue Engineering Laboratory, Drexel
University. E-mail pilelkes_at_drexel.edu Collaborat
ing Researchers K. Barbee, Ph.D., Drexel
University F. Allen, Ph.D., Drexel
University. Graduate Students A. Rezvan, Drexel
University E. Troop, Drexel University. Funding
Berlex Biosciences, Richmond, CA. Laboratories
Cellular Tissue Engineering Laboratory MCP
Hahnemann University.
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CELLULAR ADHESION AND MOLECULAR MECHANISMS
P R O J E C T O N E P A G E R
We are researching how cell function is regulated
by physicochemical environmental signals. Our
aim is to use this knowledge for synthesizing
tissue constructs, such as bone.

• We use time-lapse and fluorescence
• mcroscopy to study the biophysical
• and biochemical function of cells, such
• as
• Cell Adhesion
• Cell Migration
• Intracellular Signaling

Faculty/Contact P. Lelkes, Ph.D., Director of
Cellular Tissue Engineering Laboratory, Drexel
University. E-mail pilelkes_at_drexel.edu Collaborat
ing Researchers F. Allen, Ph.D., Drexel
University. Graduate Students Amir Rezvan,
Drexel University. Funding Laboratories
Cellular Tissue Engineering Laboratory MCP
Hahnemann University.
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VASCULARIZING TISSUES
P R O J E C T O N E P A G E R
Faculty/Contact P. Lelkes, Ph.D., Director of
Cellular Tissue Engineering Laboratory, Drexel
University. E-mail pilelkes_at_drexel.edu Collaborat
ing Researchers Franziska Dietrich, Graduate
Student, Drexel University. Funding
Laboratories Cellular Tissue Engineering
Laboratory MCP Hahnemann University.