Jeffrey Fontenot, REU Student

To seal off any broken or leaking blood vessels

Protecting damaged tissue while it heals

http://biomed.brown.edu/Courses/BI108/BI108_2005_Groups/10/webpages/plateletslink.htm

Over-activity◦ Clots and thrombi

form in unnecessary places or situations

◦ Thrombi may become larger than needed

◦ Heart attack and stroke may result

Under-activity◦ Clots do not form

when needed◦ Excessive bleeding◦ Wounds not healing

quickly or properly

The end goal ◦ Develop processes and devices that

can measure platelet activity◦ Diagnose platelet problems or

dysfunction in the clinical setting Intermediate goal

◦ Show that L-arginine decreases platelet adhesion

◦ Show that higher shear stress will increase platelet adhesion

Reproducing previous results◦ Positive control◦ Constant flow rate◦ Change L-arginine

concentrations from 0 to 25 µM/L

New work◦ Use different shear

stresses ranging from 1 to 15 dynes/cm2

◦ Use two different concentrations of L-arginine, 0 and 20 µM/L

Cut out micro channels Layer-by-Layer self

assembly Manifold and syringe

pump Calculate flow rate from

the desired shear stress◦   

Bovine blood is collected and spun down to separate the Platelet Rich Plasma (PRP) which settles on the top

PRP travels down through the channel for one minute. The channels are rinsed with PBSEach channel is dyed with acridine orange

Each channel is photographed 22 times

The images are processed through a MatLab code

The average percent coverage is calculated in Excel

The positive control results

The current work results

Shear stress and L-arginine do have effects on platelet adhesion

Increasing shear stress appears to decrease adhesion◦ Possibly due to sodium citrate,

Yasuo et al. Source of errors

Correct the errors The results appear to

be opposite of the expected

There are more factors than originally expected◦ The anticoagulant may

play a role◦ Is there a delay between

activation and adhesion◦ Is the thrombus forming

and breaking up

Dr. Steven JonesMelanie GroanLouisiana Tech UniversityNational Science Foundation