Fig. 1. Skin stem cells and niches orchestrate the hair growth cycle, encompassing the telogen, anagen, and catagen phases.

Hair follicle stem cells can generate various cell types within the HF. The immune system, including T cells, macrophages, dendritic cells, and Treg cells, undergoes fluctuations during the hair growth cycle and plays an important role in HF regeneration. Blood vessels play a crucial role in HF regeneration by providing oxygen, nutrients, and growth factors essential for hair growth and maintenance. The surrounding vasculature enables the delivery of these vital components. The interactions among lymphatic vessels, sympathetic nerves, sensory nerves, and HFs are complex and interconnected, collectively contributing to HF function regulation, including nutrient supply, immune surveillance, and responses to environmental cues.