Tissue engineering and vascular biology expert Guohao Dai, assistant professor in the Department of Biomedical Engineering at Rensselaer Polytechnic Institute, recently won a Faculty Early Career Development Award (CAREER) from the National Science Foundation (NSF).

Dai will use the five-year, $440,000 grant to advance his research into bio-fabricating human tissues with 3-D cell printing technology. Adult neural stem cells are known to hold a great potential for treating disease and damage to the nervous system. However, these cells are both rare and difficult to use in a laboratory setting. The cells lose their potency quickly upon being removed from their native environment, making it difficult to study them.

With his CAREER Award, Dai seeks to design and develop a new way of using 3-D cell printing technology to create a "vascular niche" that replicates the native environment of adult neural stem cells. With the ability to prolong the potency of the cells and precisely control the parameters and components of its vascular niche, researchers would be better positioned to study the cells and their role in treating treat spinal cord injury and neurodegenerative diseases.

"Adult neural stem cells hold so much promise for treating injury and disease, but they are extremely difficult to work with," Dai said. "We believe that we can apply 3-D tissue printing technology to create a vascular niche that will prolong the life of the cells and, in turn, enable new opportunities for studying how they may be used to treat injury and fight disease."

The CAREER Award is given to faculty members at the beginning of their academic careers and is one of NSF's most competitive awards, placing emphasis on high-quality research and novel education initiatives. Dai will collaborate on his CAREER project with two stem cells experts, Rensselaer Associate Professor of Biomedical Engineering Deanna Thompson and Neural Stem Cell Initiative Scientific Director Sally Temple.

Most laboratory cell cultures are 2-D. This is significantly different from the human body, where most cells are in a 3-D environment. A major challenge in creating and studying 3-D tissues is the diffusion limit in the tissues, which quickly lose potency or die without a flow of blood to provide oxygen and nutrients.

To help overcome this challenge, Dai and his collaborators have spent years developing a 3-D tissue printer -- both the hardware and the software. The unique device prints biological tissue by carefully depositing cells, hydrogels, and other materials one layer at a time. Using this platform, Dai developed the technology to create perfused vascular channels, which provide nutrients and oxygen to the printed tissues.

"Blood vessels run throughout almost every part of our bodies, bringing the oxygen and nutrients that allow our cells to survive. The same is true of 3-D cell cultures. They need a vascular system in order to survive," Dai said. "Our device can print 3-D tissues with small channels that function as blood vessels. This enables us to print cells with extracellular matrices that closely replicate those found within the body."

Dai's research team used the 3-D tissue printing technology to help study how the functions of the vascular endothelium -- a thin layer of cells that line entire circulatory system -- are affected by environmental factors such as interactions with blood and smooth muscle cells. A dysfunctional endothelium is known to be a contributor to many vascular diseases including inflammation, thrombosis, and atherosclerosis.

With his CAREER Award, Dai is applying his expertise and unique 3-D tissue printing technology to replicate the native environment of adult neural stem cells. If successful, the project could significantly expand the potency and life span of the cells in laboratory settings, and lead to a better understanding of how this extracellular environment influences the behavior of the cells.

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3-D-printed tissues advance stem cell research