Cultured dermal papilla cells of the rat vibrissa follicle. Proliferative activity, adhesion properties and reorganization of the extracellular matrix in vitro

The study investigated the distribution of fibronectin, laminin, and type IV collagen during the rat vibrissa follicle growth cycle, focusing on their role in basement membrane restructuring. Laminin and type IV collagen were consistently present at the dermal-epidermal junction and within the dermal papilla, with changes in their distribution observed during different hair cycle phases. Fibronectin was abundant in the anagen phase but showed heterogeneous staining at telogen. These changes in extracellular matrix distribution were linked to modifications in basement membrane ultrastructure, suggesting that the lower vibrissa follicle can rapidly remodel its basement membrane, facilitating dermal-epidermal signaling. The findings indicated that dermal papilla cells might contribute to basement membrane formation and that fibronectin could regulate cellular activities within the follicle, highlighting dynamic cellular activity throughout the hair cycle.

The study demonstrated that adult vibrissa follicle dermal papillae could induce hair growth and follicle formation when implanted into small incisional cuts on rat ear pinnae. The resulting hair fibers were abnormally large and exhibited vibrissa-type characteristics, indicating that the papillae interacted with the wound epidermis to produce new follicles. Histological and immunohistochemical analyses showed that early follicle construction involved a significant presence of laminin and type IV collagen in the dermis. These findings suggested that adult rat papillae retained the ability to determine vibrissa specificity in induced follicles, similar to embryonic dermis.

The study examined the in vitro properties of dermal papilla cells from human hair follicles, comparing them to dermal fibroblasts from the same source. Dermal papilla cells showed a polygonal morphology and formed multi-layered aggregates, especially on collagen gels, unlike the spindle-shaped, monolayer growth of dermal fibroblasts. Papilla cells had a shorter in vitro survival time and their properties were similar to rat vibrissa papilla cells.