Basement Membrane Components Define the Microenvironment of Aggregated Fibroblasts in the Skin and Support Their Aggregation In Vitro

The study investigates the role of the basement membrane (BM)-like extracellular matrix (ECM) in the organization of dermal papilla (DP) cells, which are crucial for hair follicle development and regeneration. It reveals that DP cells are embedded in a BM-like ECM, characterized by a mesh-like structure with minimal cell-cell adhesion, rather than in a conventional interstitial fibrillar ECM like collagen I. The interaction of DP cells with specific laminin isoforms via integrin α7β1 results in weak adhesiveness. In vitro experiments show that a BM extract-based matrix, Matrigel, supports the formation and maintenance of DP aggregates and enhances DP-marker gene expression, whereas collagen I gel leads to their dispersion. These findings underscore the importance of a BM-like ECM niche in maintaining DP cohesion.