How does the skin develop follicles and eventually sprout hair? A USC-led study, published in the Proceedings of the National Academy of Sciences (PNAS), addresses this question using insights gleaned from organoids, 3D assemblies of cells possessing rudimentary skin structure and function–including the ability to grow hair.
In the study, first author Mingxing Lei, a postdoctoral scholar in the USC Stem Cell laboratory of Cheng-Ming Chuong, and an international team of scientists started with dissociated skin cells from a newborn mouse. Lei then took hundreds of timelapse movies to analyze the collective cell behavior. They observed that these cells formed organoids by transitioning through six distinct phases: 1) dissociated cells; 2) aggregated cells; 3) cysts; 4) coalesced cysts; 5) layered skin; and 6) skin with follicles, which robustly produce hair after being transplanted onto the back of a host mouse.
In contrast, dissociated skin cells from an adult mouse only reached phase 2–aggregation–before stalling in their development and failing to produce hair.
To understand the forces at play, the scientists analyzed the molecular events and physical processes that drove successful organoid formation with newborn mouse cells.
“We used a combination of bioinformatics and molecular screenings, and the core facilities at the Health Sciences Campus have facilitated my analyses,” said Lei.
At various time points, they observed increased activity in genes related to: the protein collagen; the blood sugar-regulating hormone insulin; the formation…