709 Stem cell niche architecture dictates hair progenitor distribution and differentiation

Stem cells and their nearby niche generate an organ architecture essential to its function. For hair production, the follicle remodels epithelial through stem cell behaviors under instruction of a juxtaposed fibroblast -- dermal papilla. Although papilla’s signaling crosstalk with epithelium is well-characterized, little known about how physical organized support cells. Here, we leveraged live mice imaging, 3D reconstruction, genetic manipulations understand papilla fibroblasts remodel in orchestration progeny progenitors. We find that develop broad membrane protrusions form upward polarized enclosed by Importantly, this remodeling process strengthens niche’s architectural integrity such retained even after depletion. Furthermore, discovered TGFβ required actively maintain architecture. Dermal could not receive signals relocated from within precociously while retaining identity. Orchestrated relocating fibroblasts, progenitors redistributed inside out concurrently. Interestingly, still perform regenerative as proliferation differentiation, yet normal differentiation generated shorter shafts. Altogether, our work reveals cellular molecular mechanisms organize It further highlights dictates distribution differentiation. propose shape functional diversity may result transformable architectures scalable mechanic-chemical