Cell Types Promoting Goosebumps Form a Niche to Regulate Hair Follicle Stem Cells

The document from August 1, 2020, details a study that explored the relationship between hair follicle stem cells (HFSCs), arrector pili muscles (APMs), and sympathetic nerves. The study found that APMs and sympathetic nerves form a niche that regulates HFSC activity, with sympathetic nerves directly influencing HFSCs through norepinephrine and synapse-like structures. Without norepinephrine signaling, HFSCs become deeply quiescent, altering their cell cycle and metabolism. The study also discovered that HFSC progeny secretes Sonic Hedgehog (SHH) to direct the formation of the APM-sympathetic nerve niche, which is crucial for hair follicle regeneration in adults. The sympathetic nervous system's role in modulating stem cells suggests a mechanism by which environmental factors, such as cold, can stimulate hair growth. The study involved mice, with sample sizes ranging from 3 to 10 mice per condition, and used techniques like immunofluorescent staining, RNA sequencing, and electron microscopy. The findings indicate a potential target for treating hair loss conditions like androgenetic alopecia by manipulating the sympathetic nerve-HFSC interaction.