Stimulation of In Vivo Angiogenesis Through Dual Growth Factor Loaded Hyaluronic Acid Hydrogels

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Stimulation of In Vivo Angiogenesis Through Dual
Growth Factor Loaded Hyaluronic Acid Hydrogels

• Celeste Riley
• Mentor Dr. Robert Peattie
• Department of Chemical Engineering

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Importance

• Engineered tissues
• Organ transplants
• Ischemic Pathologies
• (Diabetes)

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Components of the Project

• Preparation of Hydrogels
• Surgery on living mouse models
• Count formed blood vessels and analyze data

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Hydrogel Preparation
What is a hydrogel?

• Natural or Synthetic
• Biocompatible
• Crosslinked to form a gel-like substance
• Dehydration

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Hydrogel Preparation
What is Hyaluronic Acid?

• Glycosaminoglycan
• Complexes H20 molecules
• Chief component of extracellular matrix
• Contributes to cell proliferation and migration

Chemical structure of hyaluronic acid
http//www.hyalogic.com/aboutha.htm
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Addition of Growth Factors
What are growth factors?
Diagram of Growth Factor Binding

• Signaling proteins
• Bind receptors of target cells
• Promote differentiation and maturation

http//www.grahamstudios.net/medcon.html
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Addition of Growth Factors
Which Growth Factors?
Model of VEGF

• Vascular Endothelial Growth Factor (VEGF)
• Angiopoietin 1 (Ang-1)

http//kerrins.net/ud/proteins.html
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Goal of Project

• Make hydrogel from hyaluronic acid
• Impregnate hydrogel with growth factors Ang-1 and
  VEGF
• Dehydrate and implant hydrogel into mouse ear
• Determine if implant, loaded with growth factors,
  stimulates angiogenesis

GFs

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Project Setup
Conditions to consider

• Spontaneous Growth
• Original Vessels
• Individual combinations control cases (chart)

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Treatment Cases

• 6 animals per treatment group

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Determining Blood Vessel Growth

• Thin-section both surgical and contralateral ear
• Count blood vessels under 400X magnification

Contralateral Ear
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Data Analysis
What do we want to measure?
How do we measure it?

• Define a statistical index to account for
• effect of sham surgery
• number of vessels present before surgery

Additional vessels due only to the particular
surgical treatment
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Neovascularization Index
NI (treatment-CL) (sham-CL)
mean CL

• (treatment-CL) average of additional blood
  vessels in the implanted ear of treatment group
• (sham-CL) average of additional vessels due
  to the surgical procedure itself
• mean CL average vessel count in all
  contralateral ears effectiveness measure

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Results
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Conclusion

• Currently, data collection is still ongoing
• When calculated, compare NI of experimental case
  to NIs of control cases
• At this point, no definite conclusion can be
  drawn about the effect of Ang-1 and VEGF
  delivered through HA hydrogel on angiogenesis

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Acknowledgments
Dr. Robert Peattie
Dr. Kevin Ahern
Howard Hughes Medical Institute
Co-researcher Peter Fuegy