Transcript Stem Cells and Their Environment 11_deepika

CHEMICAL AND PHYSICAL
REGULATION OF STEM CELLS AND
PROGENITOR CELLS: POTENTIAL
FOR CARDIOVASCULAR TISSUE
ENGINEERING (REVIEW)
NGAN F. HUANG, RANDALL J. LEE,
SONG LI
By Deepika Chitturi
BIOE 506
Spring 2009
WHY CARDIOVASCULAR TISSUE
ENGINEERING?
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Leading Cause of Mortality
(every 34 sec)
Expensive ($250 billion)
Myocardial Infarction (MI aka
heart-attacks)
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Coronary Artery Occlusion
Cardiomyocyte Cell Death
Non-generation
Formation of Scar Tissue
Dilation of Chamber Cavities
Aneurysmal Thinning of Walls
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REDUCED
PUMPING
CAPACITY
Driving Force:
Shortage of Donors
POTENTIAL STEM & PROGENITOR CELLS
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MSCs: Mesenchymal Stem
Cells
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HSCs: Hematopoietic Stem
Cells
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ESCs: Embryonic Stem
Cells
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EPCs: Endothelial
Precursor Cells
Skeletal Myoblasts
Resident Cardiac Stem Cells
PERFECT TISSUE ENGINEERED
CONSTRUCT
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CELL SOURCE
SOLUBLE CHEMICAL
FACTORS
EXTRACELLULAR MATRIX
(ECM)
CARDIOVASCULAR TISSUE ENGINEERING
(I)
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Cell Source
Embryonic Stem Cells
 Adult Stem Cells
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Soluble Chemical Factors
VEGF (ESCs, HSCs, EPCs)
 TGF-β (ESCs, MSCs, HSCs,
EPCs)
 BMP (ESCs)
 5-azacytidine (MSCs)
 FGF (ESCs, HSCs, EPCs)
 IGF (HSCs, EPCs)
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CARDIOVASCULAR TISSUE ENGINEERING
(II)
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Extracellular Matrix
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Natural Polymers
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Matrigel: In vivo injection for MI, ESC differentiation
Collagen: In vivo injection for MI, Vascular grafts
Hyalinuric Acid: Vascular grafts
Alginate: ESC differentiation
Fibrin: In vivo injection for MI, Vascular conduits
Decellularized Vessel: Vascular conduits
Synthetic Polymers
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Poly-L-lactic Acid (PLLA): ESC differentiation
Poly-lactic-co-glycolic acid (PLGA): ESC differentiation
Polyglycotic Acid (PGA): Vascular grafts
Peptide Nanofibers: In vivo injection for MI
Poly-diol-citrates and Poly-glycerol-sebacate: General tissue
engineering
EXTRACELLULAR MATRIX
Matrigel Angiogenesis
Effects of Cordyceps militaris extract on
angiogenesis and tumor growth1 Hwa-seung YOO,
Jang-woo SHIN2, Jung-hyo CHO, Chang-gue SON, Yeonweol LEE, Sang-yong PARK3, Chong-kwan CHO4
Department of East-West Cancer Center, College of
Oriental Medicine, Daejeon University, Daejeon 301-724;
PLLA Angiogenesis
Dr. Vasif Harsirci- Middle East Technical University
(Biomedical Unit)
ROLE OF MATRIX MATERIALS FOR
STRUCTURAL SUPPORT
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hESCs cultured in porous PLGA/PLLA scaffolds coated
with Matrigel or Fibronectin vs. Matrigel alone or
fibronectin-coated dishes (Levenberg et al)
3-D polymer structure promoted differentiation (neural tissue,
cartilage, liver and blood vessels)
 Formation of 3-D blood vessels
 Fibronectin-coated dishes:
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Matrigel:
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Failure to organize into 3-D structure
Organization into 3-D structure
No cell differentiation
Conclusion:
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Large inter-connected pores: cell colonization
Pores smaller than 100 nm: limit diffusion of nutrients and gases
3-D: great surface area, higher expression of integrins
ROLE OF MATRIX TOPOGRAPHY AND
RIGIDITY
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Topography: Cell Organization, alignment and
differentiation
Nano-scale and micro-scale matrix topography affects
organization and differentiation of stem cells
 hMSCs undergo skeletal reorganization and orient
themselves in the direction of microgrooves and nano-fibers
(Patel et al)
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Stiffness/Rigidity: Cells tend to migrate toward morerigid surfaces and cells on soft matrix have a low rate
of DNA synthesis and growth (Engler et al)
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Assembly of focal adhesions and contractile cytoskeleton
structure depend on rigidity
CARDIOVASCULAR TISSUE ENGINEERING
MODELS
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In vitro differentiation method: engineering
constructs with structural and functional
properties as native tissues before
transplantation
In situ method: relies on host environment to
remodel the chemical and physical environment
for cell growth and function
Ex vivo approach: excision of native tissues and
remodeling them in culture
CARDIOVASCULAR TISSUE ENGINEERING
PROPOSED MODELS
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Injectable Stem Cells and Progenitor Cells for in
situ cardiac tissue engineering
Vascular Conduits
INJECTABLE STEM CELLS AND PROGENITOR
CELLS FOR IN SITU CARDIAC TISSUE
ENGINEERING
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Delivery modes for myocardial constructs:
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Cardiac patching
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Cell Injection
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Cell-polymer injection
Less invasive than solid scaffolds
 Adopt shape and form of host environment
 Delivery vehicles (with cells and GFs)
 Polymers: Collagen I, Matrigel, Fibrin, Alginate and
Peptide Nanofibers
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INJECTABLE DELIVERY OF POLYMERS
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Collagen I, Matrigel and Fibrin
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Fibrin + MSCs (Huang et al)
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Promotes angiogenesis
ESCs + Matrigel (Kofidis et al)
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Higher capillary density than saline control treatment
Migration of vascular cells into infarcted region for neovascularization
Greater improvements in contractility after 2 weeks
Rat bone marrow mononuclear cells (MNCs) + Fibrin (Ryu et al)
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Enhanced neovascularization
Development of larger vessels
Extensive tissue regeneration
Graft survival: 8 weeks
TREATMENT USING STEM AND
PROGENITOR CELLS ALONE
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TGF-β-treated CD117+ rat MNCs (Li et al)
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Retrovirally transduced Akt1-overexpressing MSCs (Mangi et
al, Laflamme et al)
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Differentiation into myogenic lineage
Enhanced vascular density
Reduced intramyocardial inflammation
80% of lost myocardial volume regeneration
Normal systolic and diastolic functions restoration
Cardiac enriched hESCs in athymic rats (Laflamme et al)
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Cardiomyocyte growth
No teratomas
7-fold increase in graft size in 4 weeks
Potential regeneration of human myocardium in rat heart
VASCULAR CONDUITS
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Goal: To create functional
conduit as a bypass graft (small,
non-thrombogenic, native
mechanical properties)
Limitations to vein grafts:
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Availability
35% 10-year failure
Synthetic Vascular Grafts:
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Poly-ethylene-terephthalate
Expanded poly-tetrafluoroethylene
Polyurethane
Limitation:
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Inside diameter larger than 5 mm
Frequent thrombosis and occlusions
in smaller grafts
VASCULAR CONDUITS—PROPOSED
MODELS
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ECs + SMCs in a tubular PGA porous scaffold (Niklason et al)
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EPC-seeded grafts (Kaushal et al)
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In vivo implantation: patent for 2 weeks; development of histological
features consistent with vascular structures
Remained patent for more than 130 days
Acellular control grafts occluded in 15 days
Vessel-like characteristics: contractility and nitric-oxide mediated
vascular relaxation
EPCs derived from umbilical cord blood using 3D porous
polyurethane tubular scaffolds in a biomimetic flow system
(Schmidt et al)
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In 12 days, EPCs lined lumen of VGs and formed endothelial
morphology
VASCULAR CONDUITS—PROPOSED
MODELS
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MSC seeded nanofibrous vascular grafts (Hashi
et al)
Patent for at least 8 weeks
 Synthesis and organization of collagen and elastin
 EC monolayer formed on lumen surfaces
 SMCs were recruited and formed
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CONCLUSION
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Understanding the effect of chemical and
physical cues for regulation of stem-cell survival,
differentiation, organization and morphogenesis
into tissue-like structures: most important!!
Cardiovascular repair, Cardiac therapies after
MI and engineering of vascular conduits