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) in maintaining the structure of dermal papilla (DP) fibroblast aggregates, which are crucial for hair follicle development and regeneration. Unlike conventional interstitial fibrillar ECM, DP cells are embedded in a BM-like ECM that forms a diffuse, mesh-like structure with minimal cell-cell adhesion. The interaction with specific laminin isoforms via integrin α7β1 results in weak adhesiveness. In vitro experiments showed that DP spheroids remained aggregated in a BM extract-based matrix but dispersed in collagen I gel. These findings highlight the BM's unconventional role as an adhesive microenvironment that supports fibroblast aggregation, offering insights into mesenchymal tissue organization and potential in vitro culture substrates for DP cells.