Researchers reveal new molecular mechanism for stimulating hair growth


Signalling by senescent melanocytes hyperactivates hair growth,

Nature (2023). DOI: 10.1038/s41586-023-06172-8

Niche signals maintain stem cells in a prolonged quiescence or transiently activate them for proper regeneration1. Altering balanced niche signalling can lead to regenerative disorders. Melanocytic skin nevi in human often display excessive hair growth, suggesting hair stem cell hyperactivity. Here, using genetic mouse models of nevi2,3, we show that dermal clusters of senescent melanocytes drive epithelial hair stem cells to exit quiescence and change their transcriptome and composition, potently enhancing hair renewal. Nevus melanocytes activate a distinct secretome, enriched for signalling factors. Osteopontin, the leading nevus signalling factor, is both necessary and sufficient to induce hair growth. Injection of osteopontin or its genetic overexpression is sufficient to induce robust hair growth in mice, whereas germline and conditional deletions of either osteopontin or CD44, its cognate receptor on epithelial hair cells, rescue enhanced hair growth induced by dermal nevus melanocytes. Osteopontin is overexpressed in human hairy nevi, and it stimulates new growth of human hair follicles. Although broad accumulation of senescent cells, such as upon ageing or genotoxic stress, is detrimental for the regenerative capacity of tissue4, we show that signalling by senescent cell clusters can potently enhance the activity of adjacent intact stem cells and stimulate tissue renewal. This finding identifies senescent cells and their secretome as an attractive therapeutic target in regenerative disorders.

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A cure for baldness

With Koehler’s hairy skin organoids, we are talking about growing new hairs, which is quite the breakthrough. You could easily imagine it being used to reverse baldness. “We’re definitely thinking about this,” says Koehler. There will, however, be hurdles, like growing the skin larger and overcoming graft rejection – the skin would probably have to be grown from stem cells taken from the transplant recipient. “It’s going to be hugely expensive and not fast – not on the timescale some balding men might like,” says Koehler. But perhaps there is an easier option.

At the root of each hair there is a group of dermal papilla cells, which are involved in regulating hair growth. We know that in some hair follicles, such as those on the head, these crucial cells are lost with each successive hair growth cycle, until they are all gone. As a result, the signals telling hairs to grow cease and hairs miniaturise. So why not replace dermal papilla cells? That is what Colin Jahoda at Durham University, UK, thought several decades ago. He took these cells from the coat hair of mice and injected them into the rodents’ ears, which have much finer hair. The ear hair quickly grew longer and thicker.

full article


As long as i dont get alot of moles on my scalp :stuck_out_tongue_winking_eye: