Morphogenetic Events in Hair Follicle Heterotypic Spheroids

The study aimed to create human hair follicle (HF) germ-like structures in vitro and investigated the formation of aggregates using dermal papilla cells (DPCs) and keratinocytes (KCs). The researchers found that mixed aggregates of DPCs and KCs showed upregulation of HF markers and proper self-assembly initiation, which was essential for morphogenesis. In contrast, coated aggregates did not exhibit morphogenetic events. The size and number of proliferative cells in mixed aggregates were influenced by the hair-inducing abilities of the DPCs. The structure and morphology of mixed aggregates were characterized, with DPCs forming round-shaped structures and KCs generating multilayered trabeculae. The addition of hyaluronic acid (HA) to the cell suspension before aggregate formation increased the size of aggregates and the number of proliferative cells, but did not maintain DPC-specific markers during 2D cultivation. CD44 staining revealed microvillus-type plasma membrane protrusions on DPCs in mixed aggregates, which are involved in HA metabolism. The study concluded that HA has a significant impact on aggregate formation, self-organization, and HF development.