Chemical and Physical Regulation of Stem Cells and Progenitor Cells: Potential for Cardiovascular Tissue Engineering (Review) Ngan F. Huang, Randall J. Lee, Song Li

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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

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Why Cardiovascular Tissue Engineering?

• Leading Cause of Mortality (every 34 sec)
• Expensive (250 billion)
• Myocardial Infarction (MI aka heart-attacks)
• Coronary Artery Occlusion
• Cardiomyocyte Cell Death
• Non-generation
• Formation of Scar Tissue
• Dilation of Chamber Cavities
• Aneurysmal Thinning of Walls
• REDUCED PUMPING CAPACITY
• Driving Force Shortage of Donors

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Potential Stem Progenitor Cells

• MSCs Mesenchymal Stem Cells
• HSCs Hematopoietic Stem Cells
• EPCs Endothelial Precursor Cells
• ESCs Embryonic Stem Cells
• Skeletal Myoblasts
• Resident Cardiac Stem Cells

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Perfect Tissue Engineered Construct

• CELL SOURCE
• SOLUBLE CHEMICAL FACTORS
• EXTRACELLULAR MATRIX (ECM)

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Cardiovascular Tissue Engineering (I)

• Cell Source
• Embryonic Stem Cells
• Adult Stem Cells
• Soluble Chemical Factors
• VEGF (ESCs, HSCs, EPCs)
• TGF-ß (ESCs, MSCs, HSCs, EPCs)
• BMP (ESCs)
• 5-azacytidine (MSCs)
• FGF (ESCs, HSCs, EPCs)
• IGF (HSCs, EPCs)

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Cardiovascular Tissue Engineering (II)

• Extracellular Matrix
• Natural Polymers
• 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
• 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

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Extracellular Matrix

• Matrigel Angiogenesis

• PLLA Angiogenesis

• Dr. Vasif Harsirci- Middle East Technical
  University (Biomedical Unit)

Effects of Cordyceps militaris extract on
angiogenesis and tumor growth1 Hwa-seung YOO,
Jang-woo SHIN2, Jung-hyo CHO, Chang-gue SON,
Yeon-weol LEE, Sang-yong PARK3, Chong-kwan CHO4
Department of East-West Cancer Center, College
of Oriental Medicine, Daejeon University, Daejeon
301-724
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Role of Matrix Materials for Structural Support

• 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
• Failure to organize into 3-D structure
• Matrigel
• Organization into 3-D structure
• No cell differentiation
• Conclusion
• 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

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Role of Matrix Topography and Rigidity

• 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)
• Stiffness/Rigidity Cells tend to migrate toward
  more-rigid surfaces and cells on soft matrix have
  a low rate of DNA synthesis and growth (Engler et
  al)
• Assembly of focal adhesions and contractile
  cytoskeleton structure depend on rigidity

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Cardiovascular Tissue Engineering Models

• 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

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Cardiovascular Tissue Engineering Proposed Models

• Injectable Stem Cells and Progenitor Cells for in
  situ cardiac tissue engineering
• Vascular Conduits

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Injectable Stem Cells and Progenitor Cells for in
situ cardiac tissue engineering

• Delivery modes for myocardial constructs
• Cardiac patching
• Cell Injection
• 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

• Collagen I, Matrigel and Fibrin
• Higher capillary density than saline control
  treatment
• Migration of vascular cells into infarcted region
  for neovascularization
• Fibrin MSCs (Huang et al)
• Promotes angiogenesis
• ESCs Matrigel (Kofidis et al)
• Greater improvements in contractility after 2
  weeks
• Rat bone marrow mononuclear cells (MNCs) Fibrin
  (Ryu et al)
• Enhanced neovascularization
• Development of larger vessels
• Extensive tissue regeneration
• Graft survival 8 weeks

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Treatment using Stem and Progenitor Cells alone

• TGF-ß-treated CD117 rat MNCs (Li et al)
• Differentiation into myogenic lineage
• Enhanced vascular density
• Retrovirally transduced Akt1-overexpressing MSCs
  (Mangi et al, Laflamme et al)
• Reduced intramyocardial inflammation
• 80 of lost myocardial volume regeneration
• Normal systolic and diastolic functions
  restoration
• Cardiac enriched hESCs in athymic rats (Laflamme
  et al)
• Cardiomyocyte growth
• No teratomas
• 7-fold increase in graft size in 4 weeks
• Potential regeneration of human myocardium in rat
  heart

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Vascular Conduits

• Goal To create functional conduit as a bypass
  graft (small, non-thrombogenic, native mechanical
  properties)
• Limitations to vein grafts
• Availability
• 35 10-year failure
• Synthetic Vascular Grafts
• Poly-ethylene-terephthalate
• Expanded poly-tetrafluoroethylene
• Polyurethane
• Limitation
• Inside diameter larger than 5 mm
• Frequent thrombosis and occlusions in smaller
  grafts

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Vascular ConduitsProposed Models

• ECs SMCs in a tubular PGA porous scaffold
  (Niklason et al)
• In vivo implantation patent for 2 weeks
  development of histological features consistent
  with vascular structures
• EPC-seeded grafts (Kaushal et al)
• 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)
• In 12 days, EPCs lined lumen of VGs and formed
  endothelial morphology

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Vascular ConduitsProposed Models

• 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

• 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