Most stem cell researchers handle their samples very delicately. Chemical and Biological Engineering Associate Professor Sean Palecek prefers to pull them, add chemicals or pulse them with current.
Palecek is using embryonic and induced pluripotent stem cells to study how cells differentiate and how to guide that differentiation. Induced pluripotent stem cells are adult human cells that have been reverted back to an embryonic state via a method pioneered by renowned UW-Madison stem cell scientist James Thomson.
Cells in an embryonic state can divide an unlimited number of times and can differentiate into any type of cell in the body. These are special characteristics, as every other healthy cell in the body can make only a certain number of division.
Palecek is working to guide stem cell differentiation into endothelial (blood vessel) cells, epithelial (skin) cells and cardiomyocytes (heart cells). He places stem cells in various micro-environments to see which factors in those environments best facilitate cell growth. For example, endothelial cells have fluid flowing across them, so Palecek tests whether that fluid flow is necessary for the cells to develop. Epithelial cells develop well in a matrix and respond to particular chemical cues.
One of Palecek’s unique discoveries is that culturing stem cells in three-dimensional arrays stimulates cell-cell communication, significantly improving the yield of cardiomyocytes. The variety of micro-environments means Palecek’s work encompasses a range of bioengineering issues. “We get pulled a lot into the mechanical side because the extracellular matrix that surrounds the cells ties into cell surface proteins,” he says. “The matrix allows the cells to attach to their environment and provides chemical signaling to the cells, so you can’t decouple mechanics from chemistry. We have to look at both.”
While producing whole human tissues and organs for medical treatment is a long way off, stem cell research also yields rare insight into early human development and produces tissues for pharmaceutical research to complement animal testing.