Ultrasound standing wave fields are generated in a tissue-culture plate containing endothelial cells embedded in collagen. Endothelial cells form the insides of blood vessels. Pressure from ultrasound standing wave fields nudges the cells into predetermined positions. The frequency and intensity of the waves organize the cells and control the density and spacing of cell bands. Samples are then polymerized in an incubator and locked into place. Their close positioning encourages cells to signal to each other and sprout three-dimensional blood vessels.
Tissue constructs are visualized with multiphoton microscopy, a technique that captures specimens in three-dimensional sections.
“Distinct and interesting formations can be seen depending on the frequency and intensity of the ultrasound stationary wave fields,” Helguera said. “We decided to quantitatively analyze these three-dimensional data sets to extract parameters characteristic of each exposure regime.”
Imaging science Ph.D. student Mohammed Yousefhussien developed an image-processing tool for evaluating the structures of the blood sprouts. Third-year imaging science student Amy Becker is modifying the tool to capture details that will help manipulate the sprouts’ growth. Determining the preferred direction in which the vessels branch outward will lead to networks resembling the vascular system within an organ.
“The goal is to design a quantitative protocol that will allow us to create a more complicated structure that is closer to a real system,” Helguera said.