By Bekah McBride
Researchers are one step closer to understanding the cellular mechanisms underlying stem cell aging in the brain thanks to a new tool developed at the University of Wisconsin–Madison. The tool allows scientists to use autofluorescence, or the natural emission of light by a biological specimen, to study adult neural stem cells in their different cell states, previously limited by available techniques.
The new tool combines autofluorescence and single-cell RNA sequencing to study neural stem cell behavior. Autofluorescence is often considered a negative feature of cells as it obscures the fluorescent labels researchers use to track specific signals within a cell. In this case, however, researchers have determined that autofluorescence signatures can be used to better study the substates of neural stem cells including the key stage of quiescence, also known as the stem cell’s dormant state.
“Our goal was to create a new tool that could identify if an adult neural stem cell was quiescent and its different substates (dormant or resting quiescence) or if the cell is activated, entering into the cell cycle,” says Darcie Moore, the senior author on the study, an associate professor in the Department of Neuroscience, and a member of the Stem Cell and Regenerative Medicine Center. “The quiescent state is very important because the exit from quiescence is the rate-limiting step in making newborn neurons in the adult brain. Aging and neurological diseases limit this exit from quiescence, so we have a great need to study adult neural stem cells in their different cell states.”
Moore partnered with Melissa Skala, a professor at the Morgridge Institute for Research and the Department of Biomedical Engineering, and also a member of the Stem Cell and Regenerative Medicine Center, to develop this tool. Skala’s lab has been developing fluorescence lifetime imaging, which is used to detect the autofluorescent signatures associated with each single cell.
“I was excited by the high rigor of this study, which relates an experimental measurement (autofluorescence lifetimes) to standard measurements of cell function and identity,” says Skala. “I was also excited that these natural signals within the cell can reliably identify cell function and identity. It’s like nature is trying to tell us all the secrets of life.”
By identifying and decoding these autofluorescence signatures, Moore and Skala have developed a tool that will not only aid in the study of adult neurological diseases and aging, but potentially expand beyond neuroscience.
“We have many projects that we will use with this new system,” says Moore.
For example, they’ve already begun working with Colin Crist, an associate professor in the Department of Human Genetics at McGill University to investigate the unique autofluorescent signatures present in muscle stem cells.
While the study, which was published in Cell Stem Cell on March 22, has resulted in a key discovery that will impact the future of biomedical research, the original research was so novel that it was considered high-risk in terms of its ability to bring a discovery forward. As such, Moore is thankful for the support of the Vallee Scholar Award from the Vallee Foundation, which provided her with flexible, unrestricted funding.
“As a high-risk project, their support was critical to allow us to perform this work,” says Moore, who also received additional support from the National Institutes of Health. “Trying new approaches is always risky but can also provide unexpected knowledge and high reward. Today’s general funding schemes from government-funded agencies are typically very risk-averse, and that limits innovation. I’m so happy we were funded and supported in this work by the Vallee Foundation, and that we can show how stepping outside of one’s scientific comfort zone can reap great benefits.”
Additionally, Skala was supported through the Carol Skornicka Chair at the Morgridge Institute for Research and the Retinal Research Foundation Daniel M. Albert Chair.
In addition to the funding, Moore notes that this discovery would not have been possible without collaboration across campus.
“This work could never have been done without the amazing collaboration of Melissa Skala. She provided us with ideas and opportunities to play and try different things that led to these findings,” says Moore. “It’s important to surround yourself with people who, when you have a crazy idea say “yes! let’s try it!” Melissa is one of those people, and working together we have found exciting ways our expertise can work together to move science forward. This work is an example of what I love about science – the discovery and the collaboration.”
Skala echoed those sentiments, “As an engineer, I was excited to learn about neuroscience and work with a talented team of dedicated scientists. It makes the whole process fun and exciting. I enjoy Darcie’s energy and her big picture vision. She can understand and solve engineering problems while still focusing on the important mysteries of neuroscience. It has been a rewarding collaboration with a long runway to keep making progress. Fearless science at its best!”
Moving forward, Moore and Skala plan to explore how this discovery can further biomedical research.
“Now that we’ve discovered that this research created not only a tool but gave us unique insight to cellular processes that are different between quiescent and activated neural stem cells, I feel even more strongly that identifying a cell based on how they act versus how they express one protein will shift studies from studying static systems to dynamic systems,” says Moore. “That we can study these cells as they change throughout time without destroying them, while also seeing how these functional measures change is very exciting.”
A version of this story was also published on wisc.edu
This research was supported in part by grants from the National Institutes of Health (P30 CA014520, 1S10RR025483-01, T32GM008688 and 1DP2OD025783) as well as the Vallee Foundation, Morgridge Institute for Research and Retina Research Foundation.