TLDR  Exosomes from human skin cells can stimulate hair growth and could potentially be used for treating hair loss.   
  In 2019, Prof. Young-Kwan Sung led a study that discovered exosomes derived from human dermal papilla cells (DP cells) can stimulate hair growth and regeneration. The research showed that these exosomes, when derived from 3D cultured DP cells, increased the proliferation of DP cells and outer root sheath cells, and boosted the expression of growth factors in DP cells. They also extended the length of the hair shaft in cultured human hair follicles and triggered the active growth phase of hair follicles in mice. When used in human DP spheres, these exosomes enhanced hair follicle neogenesis. The study concluded that these exosomes could potentially be used in therapeutic strategies for hair loss.
           
           87 citations
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  April 2018   in “Biochemical and Biophysical Research Communications”    Exosomes from dermal papilla cells can help grow hair and might treat hair loss.  
     
           5 citations
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  October 2016   in “Experimental Dermatology”    Activin A is important for creating new hair follicles.  
     
           256 citations
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  October 2013   in “Proceedings of the National Academy of Sciences of the United States of America”    Growing human skin cells in a 3D environment can stimulate new hair growth.  
     
           75 citations
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  August 2011   in “Journal of Investigative Dermatology”    Forming spheres boosts the ability of certain human cells to create hair follicles when mixed with mouse skin cells.  
     
           417 citations
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  September 2005   in “PLoS biology”    Understanding gene expression in hair follicles can reveal insights into hair growth and disorders.  
    
   
        
               5 citations
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  March 2022   in “Frontiers in Cell and Developmental Biology”    Colostrum-derived exosomes can promote hair growth and may be a promising treatment for hair loss.  
     
           October 2021   in “Research Square (Research Square)”    Hair follicle stem cells in hairpoor mice are disrupted, causing hair loss.  
     
           65 citations
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  July 2020   in “Science Advances”    Dermal exosomes with miR-218-5p boost hair growth by controlling β-catenin signaling.  
     
           58 citations
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  March 2019   in “Experimental Dermatology”    Exosomes from human skin cells can stimulate hair growth and could potentially be used for treating hair loss.  
               130 citations
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  December 1998   in “The journal of investigative dermatology/Journal of investigative dermatology”    Hair follicle melanocytes die during hair regression.