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SYNTHETIC EXTRACELLULAR MATRICES FOR PROMOTING ANGIOGENESIS. Eduardo A. Silva Harvard University, Cambridge, MA, USA and Faculdade de Engenharia da Universidade do Porto, Porto, Portugal December 2004 Porto, Portugal. MOTIVATION. Cardiovascular Diseases: - PowerPoint PPT Presentation
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SYNTHETIC EXTRACELLULAR MATRICES FOR PROMOTING ANGIOGENESIS
Eduardo A. SilvaEduardo A. Silva
Harvard University, Cambridge, MA, USAHarvard University, Cambridge, MA, USAandand
Faculdade de Engenharia da Universidade do Porto, Porto, PortugalFaculdade de Engenharia da Universidade do Porto, Porto, Portugal
December 2004December 2004Porto, PortugalPorto, Portugal
MOTIVATION
Cardiovascular Diseases:
- Principal cause of mortality in western countries
Current Approaches to treat Ischemic Heart Diseases:
Pharmacologic
Invasive Surgical
Therapeutic Angiogenesis
ISCHEMIA
Carmeliet & Jain Nature, 2000
Ischemia - isch- is restriction, hemia or haemia is blood
ANGIOGENESISSprouting of new blood vessels from
pre-existent vessels
VASCULAR ENDOTHELIAL GROWTH FACTOR
VEGF
Is a key regulator of blood vessels formation and function
Endothelial Cells are the primary target of VEGF
45 kDa homodimer
Four isoforms obtained by alternative splicing:
VEGF121, VEGF165, VEGF189, VEGF206
Muller et al., Structure, 5:1325-1338 (1997)Muller et al., Structure, 5:1325-1338 (1997) Fairbrother et al., Structure, 6:637-648 (1998)
AIM I: Investigate VEGF signaling in cardiac cells under hypoxia.
AIM I
VEGF SECRETION UNDER HYPOXIA
TISSUE ENGINEERING STRATEGY
Localized, sustained delivery from bioactive polymeric systems
Constant local concentration
Protection from degradation
Minimal side effects
AIM II
Development of an injectable polymeric system for controlled and defined delivery of angiogenic molecules
VEGF incorporated in an injectable polymer
POLYMERIC SYSTEMAlginate
OOH
CO2-
O
O
OH
-O2C
OH
O
HO
CO2- OH
OHO
CO2-
OHO
O
OOH
OHO
CO2-
O
OH
G G MM G
Ca2+
-L- Guluronic acid
-D- Mannuronic acid
Gelation process
Hydrogel
MODEL SYSTEM Distinct approach used to incorporate VEGF
Simple mixing VEGF and alginate
Pre-incorporation of VEGF in polymeric microspheres and immobilization in the alginate
+ +Ca2+
Angiogenic moleculesAlginate
+ + Microspheres
Polymeric system
Bioactive moleculesBioactive molecules
ALGINATE MODIFICATIONSCombination of binary molecular weight distribution and partial oxidation
Oxidation with NaIOOxidation with NaIO44
Irradiation (5 Mrad)Irradiation (5 Mrad)
CHOCHO
Solution Properties
Gel Properties
VEGF RELEASE
BIOACTIVITY OF VEGF RELEASED
0
5000
10000
15000
20000
25000
0 1 4
Time (days)
Cell number
MediaMedia/VEGFMedia/VEGF released
ANGIOGENESIS
PDGF RELEASE
VEGF/PDGF RELEASE
In vivo evaluation of VEGF releasing materials
Model: Ischemic hind limb of Apo E null (Apo E -/-)
LDPI image
In vivo evaluation of VEGF releasing materials
Blank
VEGF&PDGF
VEGF
Week 2 Week 4 Week 6
In vivo evaluation of VEGF releasing materials
CONCLUSIONS
Sustainable and controlled angiogenic molecules delivery can be achieved with
binary alginate
Blood vessel formation and perfusion can be significantly improved by using binary
alginate as local dual delivery vehicle
FUTURE WORKVEGF 121 AND VEGF 165 PLAY DISTINCT ROLES IN THE STIMULATION OF COLLATERAL VESSEL AND BLOOD FLOW RE-ESTABLISHMENT IN AN ISCHEMIC HEART
VEGF 121
µmµm
VEGF 165
-+
ACKNOWLEDGMENTSProfessor David J. Mooney
Professor Mário Barbosa
Department of RadiologyDivision of Cardiovascular DiseasesDepartment of Internal MedicineUniversity of Michigan
Paul M. Grossman
Sanjay Rajagopalan
Qinghua Sun
Mooney Lab
2nd PGDB
FCT - Fundação para a Ciência e a Tecnologia
IGC/FCG - Fundação Calouste Gulbenkian
NIH - National Institutes of Health
Harvard University/University of Michigan & Universidade do Porto
Thinking about Curia 2005
A - Alginate; B - New tissue; C - Blood Vessel; D - Inflammatory cells