Expansion Culture of Hair Follicle Stem Cells through Uniform Aggregation in Microwell Array Devices

Large-Scale Preparation of Hair Follicle Germs Using a Microfluidic Device

Hair follicle morphogenesis during embryonic development is driven by the formation of hair follicle germs (HFGs) via interactions between epithelial and mesenchymal cells. Bioengineered HFGs are potential tissue grafts for hair regenerative medicine because they can replicate interactions and hair follicle morphogenesis after transplantation. However, a mass preparation approach for HFGs is necessary for clinical applications, given that thousands of de novo hair follicles are required to improve the appearance of a single patient with alopecia. In this study, we developed a microfluidics-based approach for the large-scale preparation of HFGs. A simple flow-focusing microfluidic device allowed collagen solutions containing epithelial and mesenchymal cells to flow and generate collagen microbeads with distinct Janus structures. During the 3 days of culture, the collagen beads contracted owing to cellular traction forces, resulting in collagen- and cell-dense HFGs. The transplantation of HFGs into nude mice resulted in highly efficient de novo hair follicle regeneration. This method provides a scalable and robust tissue graft preparation approach for hair regeneration.

iPSC-based approach for human hair follicle regeneration

Hair follicles (HFs) are a multifunctional structure involved in physical protection, thermoregulation, sensational detection, and wound healing. Formation and cycling of HFs require dynamic interaction between different cell types of the follicles. Although the processes have been well studied, the generation of human functional HFs with a normal cycling pattern for clinical utilization has yet to be achieved. Recently, human pluripotent stem cells (hPSCs) serve as an unlimited cell source for generating various types of cells including cells of the HFs. In this review, HF morphogenesis and cycling, different cell sources used for HF regeneration, and potential strategies for HF bioengineering using induced pluripotent stem cells (iPSCs) are depicted. Challenges and perspectives toward the therapeutic use of bioengineered HFs for hair loss disorder are also discussed.