We're another step closer to finding a real cure for baldness. For the first time, scientists have created functional hair follicles in the lab that naturally cycle through periods of growth.
To make it work, a team of researchers from the US and Japan identified a missing essential link: a cell type that supports regeneration and triggers full hair growth and tissue attachment.
Before we get ahead of ourselves, we should point out that this research was carried out in mice. With human tests still pending, we're still a long way from translating the findings into a new treatment for hair loss.
However, the discovery does support new approaches to restore follicle growth where hair is no longer being produced naturally.
In particular, it defines a core, three-cell 'recipe' that's required to produce a completely functional hair follicle in the lab.
"This study provides significant contributions to the basic and medical science of adult organ-inductive potential stem cells and their niches in organ morphogenesis and the adult hair cycle," write the researchers in their published paper.
The initial 'seed' for the hair follicle begins with epithelial stem cells (which make the hair itself) and dermal papilla cells (which send growth signals) – two cell types that have previously been used to grow hair follicles in laboratory conditions.
Crucially, hair follicles produced by those previous efforts failed to grow or connect with underlying tissue while in the lab, functioning as intended only when transplanted into living mouse skin.
That's where the third cell type comes in, a helper tissue known as an accessory mesenchymal cell that provides scaffolding and structure, particularly around the follicle's 'bulge' and as part of a covering called the dermal sheath.
Adding this third stem cell type at the earliest stage of follicle formation was enough to encourage the follicles to progress through growth cycles and connect to tissues under laboratory conditions.
"In future studies, we aim to elucidate the lineage around bulge mesenchymal cells and their roles in hair follicle development and the hair cycle in vivo and to pave the way toward hair follicle regeneration through humanized models," write the researchers.
In recent years, scientists have continued to get closer to growing hair follicles outside of the human body and have them function like the real thing. Future success will involve scaling this kind of technology and figuring out how lab-grown follicles can be safely transplanted onto human heads.
The researchers also believe this latest work could be used to develop other organs in the lab, by looking beyond the most commonly used stem cells in the earliest stages of bioengineering, to cells that play a less obvious but still vital role.
Some of the study team are part of a company called OrganTech, which partially funded this research and is looking to develop in vitro hair follicle production further along these same lines – eventually, perhaps, to full treatments for hair restoration.
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Lab-grown hair may also be used to assess therapies for hair loss and to take a closer look at how hair growth starts and stops, without any animal or human testing.
"This work defines a foundational cellular configuration for functional hair follicle regeneration," says Yoshio Shimo, the CEO of OrganTech, who wasn't directly involved in the study.
"Beyond hair biology, it reinforces our broader strategy of organ-level regenerative medicine, where precisely orchestrated epithelial and mesenchymal interactions enable stable and functional tissue reconstruction."
The research has been published in Biochemical and Biophysical Research Communications.