Summary
Approximately nine out of 10 cerebrovascular attacks are due to atherosclerosis. Additionally, endothelial
dysfunction is currently accepted as the first pathophysiological step toward atherosclerosis. Endothelial cell
homeostasis and gene expression is highly regulated via shear stress, which is directly associated with blood
flow changes. Aerobic exercise (AX) has been associated with improved cardiovascular (CV) health. However,
only ~50% of the beneficial effects of AX are explained via improvements on traditional CV risk factors (e.g.,
hypertension, hypercholesterolemia, obesity). The remainder ~50% of the beneficial effects of AX are
unknown. Moreover, traditionally controlled AX does not provide personalized medicine, which could account
for a high number of non-responders. Therefore, the main purpose of this proposal is to develop a 3D
synthetic model of the human carotid artery using 3D bio-printing technology to simulate in vivo
personalized AX-induced blood flow patterns and endothelial shear stress and to determine gene
expression/transcription and molecular changes in endothelial cultured cells in vitro. Based on previous
reports and our preliminary data we hypothesize that a 3D synthetic model of the carotid artery will respond to
exercise-induced blood flow patterns as a normal carotid artery. In addition, we hypothesize that endothelial
cultured cells under similar blood flow patterns and shear stress will increase the expression of
atherosclerosis-protective mRNA/proteins (e.g., eNOS, PGI2, and SOD) and structural mRNA/proteins (e.g.,
actin, heparin sulfate proteoglycan [glycocalyx], and a-actinin-bundled stress fibers), and a decrease of pro-
atherosclerosis and pro-inflammatory mRNA/protein expression (e.g., ICAM-1, VCAM-1, and ET-1) in a similar
intensity-dependent manner. First, we will determine biomechanical properties (e.g., vessel distensibility and
compliance) of the carotid artery in vivo during resting conditions and at 3 AX intensities in healthy, young
subjects, patients with stroke, and age-matched controls. Then, subjects will undergo a magnetic resonance
imaging (MRI) study to determine the exact shape (e.g., length and contour) of same tested carotid artery and
the images will be used to build a 3D synthetic model via 3D bio-printing. The 3D synthetic model will mimic
more anatomical and hemodynamic conditions, which will allow for more physiological in vitro experiments.
Secondly, we will perform several flow patterns in endothelial cultured cells seeded on the 3D synthetic model.
Flow patterns will be similar to those patterns observed during in vivo studies. After applying the different flow
patterns, cells will be collected and processed to determine changes in specific gene transcription factors and
protein expression. By characterizing blood flow patterns during different intensities of AX and determining the
gene expression/transcription and molecular changes in endothelial cells under these same blood flow
patterns, using a ‘reverse’ translation approach, we will explain the mechanisms of the cardiovascular
protective factors associated with AX as personalized medicine, especially in stroke survivors.
