Valentina Greco: Got Hair?

Valentina Greco's research focuses on tissue regeneration and regression in the hair follicle and its parallels with cancer. Her work has revealed that the positioning of stem cells within the hair follicle's niche influences their activity and contribution to tissue regeneration. Greco's team at Yale has developed new conditional expression mouse lines and utilized intravital microscopy to observe live cell division in hair follicles. They discovered that hair germ and bulge stem cells have different functions, with hair germ cells primarily giving rise to differentiated cells and bulge stem cells becoming new hair germ cells in the next cycle. Surprisingly, they found that both hair germ and bulge stem cells are dispensable, as nearby epithelial cells can replace their functions if removed. However, when the mesenchymal niche is removed, regeneration stalls, highlighting the importance of the stem cell niche over the stem cells themselves. Greco's lab is also investigating tumor biology, specifically keratoacanthoma, a type of tumor that can spontaneously regress or give rise to malignant squamous tumors. They have identified a signaling cascade through which retinoic acid can induce regression in these tumors and are exploring the differences between benign and malignant forms. Greco's work has implications for understanding tissue regeneration, stem cell niches, and tumor biology.