LB1792 CCL2 restores adult cells to regenerate hair follicles by microenvironmental regulation

Aged cells have a reduced ability to regenerate tissues. Thus, it is intriguing to reactivate the adult cells to regenerate. Here, we used hair follicles as a model to study how mechanical stimuli induce hair regeneration using hair plucking and organoid culture approaches in adult mice. We observed that skin organoid cultures using cells derived from day 3 post-plucking (PPD3) skin had the highest hair regeneration capacity. The regenerated hair follicles had normal morphology. By RNA-sequencing, single-cell RNA-sequencing analysis, and in situhybridization, we identified that the chemokine signaling pathway genes including Ccl2 are significantly increased in the hair follicle and surrounding dermal microenvironment at PPD3, as well as in skin organoid cultures. Immunostaining shows that the PPD3 skin epithelial cells have increased multipotency. Under organoid culture, these skin cells can self-organize to form epidermal aggregates. By adding CCL2 recombinant protein to the skin organoid culture using an environmental reprogramming protocol, we observed the adult cells which lose their regenerative ability can self-organize in organoid culture and regenerate hair follicles upon transplantation. In summary, we elucidate the mechanism by which mechanical stimulus induces hair regeneration at the microenvironmental regulation level using the hair plucking and organoid culture models. Our study reinforces the concept of immune regulation in hair regeneration under mechanical stimuli. The immune modulation in the skin organoid culture system also provides therapeutic potential for future clinical application.