November 2001 in “PubMed” This research found that perming, combing, and stretching cause hair damage, leading to a significant reduction in keratin levels within a specific molecular weight range.
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April 2019 in “Nature Communications” This study found that mechanical skin stretching can stimulate hair stem cell proliferation and hair regeneration by activating a complex pathway involving WNT, BMP-2, and M2 macrophages.
October 2020 in “Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature” This study found that applying the right mechanical stretch to skin can activate hair stem cells and promote hair regeneration through a pathway involving WNT, BMP-2, and M2 macrophages.
September 2025 in “Cell Reports” This study found that a single instance of acute skin stretching can enhance immune surveillance and improve vaccine delivery by increasing skin permeability and promoting immune cell recruitment without causing tissue damage.
This study found that perming, combing, and stretching human hair lead to damage, as evidenced by a reduction in keratins with molecular weights between 67,000 to 43,000 daltons.