Implementation of a Device for Assessing Dosage for Platelet Glycoprotein Inhibitors Steven A. Jones, Yuri Lvov, Tianhong Cui, Bruce Walters Sachin Sah, Kanvasri Jonnalagada, Jeremy Klein
Jan 07, 2016
Implementation of a Device for Assessing Dosage for Platelet
Glycoprotein Inhibitors
Steven A. Jones, Yuri Lvov, Tianhong Cui,Bruce Walters
Sachin Sah, Kanvasri Jonnalagada, Jeremy Klein
PLATELETS
• Blood Coagulation• Vasoconstriction, vessel repair, immune
response• Defects lead to bleeding disorders• Can enhance atherosclerosis, heart attack,
unstable angina, diabetes, stroke, eclampsia
Platelet Anatomy
The Idea
AgonistReservoirs
Substrates
Separator
Channels
PressureFeed
AssayReserAssayReservoir
WasteReservoir
What Does the Cardiologist Want?
• Glycoprotein Inhibitors (e.g. abciximab).
• What is the proper dose for this heart patient?
• Has an appropriate dose been reached?
• Does this patient need GP Inhibitors?
Analysis of Need
• "It is not possible to use in vitro assays for more direct measurement of platelet viability and hemostatic function on a regular basis, because they are difficult to perform, expensive, and time-consuming”
Holme et al., Transfusion, V. 38, 1998
The Current ImplementationInlet Outlet
Plexiglass Plates PDMSChannel
Nano Coating
Fabrication of channels
UV Mask
Silicon Substrate
Thermal Oxide
Negative Photoresist
Develop
Silicon Oxide
Etch Silicon Oxide
Etch Silicon to 150 μm
Cast PDMS mold
Flow Experiment
Early Images of Platelet Adhesion on Fibrinogen
385/s 2091/s
3990/s 6000/s
147/s
7000/s
Platelet Coverage vs. Shear
0
5
10
15
20
0 20 40 60 80
Shear Stress (dynes/cm2)
Per
cen
tag
e C
ove
rag
e
No Fibrinogen
Fibrinogen
Adhesion Patterns at 20 dynes/cm2
vWf
Fibronectin
Fibrinogen
Fibrinogen Vs Fibronectin Vs vWF
0
0.5
1
1.5
2
2.5
3
3.5
4
150 400 1000 2000 4000 6000
Shear Rate ( /sec )
Perc
enta
ge C
over
age
(%)
Fibrinogen
Fibronectin
vWF
Poly. (Fibrinogen)
Poly. (Fibronectin)
Poly. (vWF)
Conclusions
• Adhesion over various proteins can be observed.– LbL Assembly– Fluorescent Staining/Microscopy
• Adhesion is shear dependent.
• Adhesion patterns depend on the protein substrate used.
Future Work
• Other substrates
• Varieties of platelets
• Quantification of adhesion patterns
• In vivo testing
Acknowledgements
• Sachin Sah• Kanvasri Jonnalaggada• Ameya Kantak• Bruce Gale• David Mills• James Spaulding• Mike McShane• Hua Ai• IfM Staff