BS, Agronomy, Beijing Agricultural University
MS, Plant Genetics and Breeding, Beijing Agricultural University
PhD, Molecular and Biochemistry, Rutgers University and the University of Medicine and Dentistry of New Jersey
When Investigator Ting Xie, PhD, joined the Stowers Institute in 2000, he established a research program that examines the mechanisms by which stem cells maintain themselves and differentiate to become specialized cells. Xie has continued his exploration of stem cell microenvironments called niches and the relationships of stem cells within the niche. “Like siblings in a family, stem cells sometimes work together and other times compete for their parent’s attention,” he says.
Xie didn’t set out to discover what governs the fate of stem cells—or to show how these cells might be harnessed to treat disease. Instead, growing up in rural China, his first big interest was the plant world. That’s why Xie entered the Beijing Agricultural University to learn how to create new varieties of crops, and came to the US to continue his training in plant science at Rutgers University. But his interest changed after being exposed to developmental genetics and cell biology. “In less than a year, I realized that creating new crops wasn’t for me,” he says. “I was more attracted to mechanisms—how things happen.”
Then Xie discovered the growing body of research using the fruit fly, Drosophila, to investigate development—how a single-celled embryo can give rise to a complex creature with a heart, eyes, and wings. He joined the laboratory of Richard Padgett, PhD, at Rutgers and began exploring the biological signals that govern the patterns of development. “Once I started on fly research, I decided to pursue science as a career. That was my true interest,” he says.
When Xie moved to the Carnegie Institution of Washington to work with Allan Spradling, PhD, as a postdoc, he began studying stem cells—those cells that are capable of transforming into many types of tissues and organs. He focused on the Drosophila ovary as an adult stem cell system to experimentally demonstrate the existence of the stem cell niche. In 2000, Xie moved to the newly established Stowers Institute, and continues to make fundamental discoveries about stem cell regulation that hold promise for the treatment of human disease.
The Xie Lab is interested in a combination of molecular, genomic, developmental, and cell biological approaches to understand how adult stem cells are regulated using fruit flies and mice. Xie’s quest is to enable future therapies by revealing key aspects of stem cell regulation in animal model systems and determining what’s similar in humans.
Stem cells are those cells that are capable of transforming into many types of tissues and organs. They live together in tiny cylindrical structures known as germaria, in which niches are located at their tip. Each of these niches contains two or three stem cells and looks like a hat made up of “cap” cells. As a stem cell divides, one daughter cell moves out of the niche to generate mature oocytes, or egg cells. The remaining daughter cell stays put and retains its stem cell identity.
While at the Carnegie Institution of Washington as a postdoc in the late 1990s, Xie and Spradling were the first to demonstrate that a stem cell’s fate was determined by its proximity to the cap cells or niche, a finding that changed the field. Other labs quickly showed that this time of niche control was the rule, not the exception. Over the years, Xie pinpointed the chemical signals that the cap cells use to tell the stem cells what to do, and many intrinsic factors that are important for stem cells to respond to niche instructions and prevent differentiation.
Xie is applying his stem cell expertise to tackle human diseases. The mechanisms governing stem cell regulation are also of great interest to understanding tissue regeneration and aging, and developing treatments for degenerative diseases and cancer. The great promise of stem cells is that, injected into patients, the cells could fix an ailing heart or repair a broken spinal cord by differentiating into the right kind of cells. While that promise has yet to be realized, Xie is testing the potential of stem cells in treating degenerative eye diseases, including glaucoma, retinitis pigmentosa, and macular degeneration, in mice. “We first need to prove the approach in mice, and then we can start working with human cells and, eventually, patients,” says Xie.