Stimulation of In Vivo Angiogenesis
Through Dual Growth Factor Loaded
Hyaluronic Acid Hydrogels
Celeste Riley
Mentor: Dr. Robert Peattie
Department of Chemical Engineering

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

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

What is a hydrogel?

Natural or Synthetic

Biocompatible

Crosslinked to form a gel-like substance

Dehydration

What is Hyaluronic Acid?

Glycosaminoglycan

Complexes H molecules
2
0
Chemical structure of hyaluronic acid

Chief component of extracellular matrix

Contributes to cell proliferation and migration http://www.hyalogic.com/aboutha.htm

What are growth factors?

Signaling proteins
Diagram of Growth
Factor Binding

Bind receptors of target cells

Promote differentiation and maturation http://www.grahamstudios.net/medcon.html

Which Growth Factors?
Model of VEGF

Vascular
Endothelial Growth
Factor (VEGF)

Angiopoietin 1
(Ang-1) http://kerrins.net/ud/proteins.html


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

Conditions to consider

Spontaneous Growth

Original Vessels

Individual combinations: control cases (chart)

• 6 animals per treatment group
Treatment 1 2 3 4 5 6
HA gel -
VEGF -
Ang-1 -
+
-
-
-
+
-
-
-
+
-
+
+
+
+
-
7
+
-
+
8
+
+
+

Determining Blood Vessel Growth

Thin-section both surgical and contralateral ear

Count blood vessels under
400X magnification Contralateral Ear

What do we want to measure?
Additional vessels due only to the particular surgical treatment
How do we measure it?
Define a statistical index to account for o effect of sham surgery o number of vessels present before surgery

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

Sham
Treatment
HA gel only
VEGF only
Ang-1 only
Ang-1 + VEGF
HA gel + Ang-1
HA gel + VEGF
HA gel + Ang-1 + VEGF
7 day NI 14 day NI
-
0.12
0.95
1.80
1.30
2.97
6.74


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

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