SCIENCE: Scientists grow first fully functional hair follicles in the lab

Sci­en­tists have suc­cess­ful­ly grown func­tion­al mouse hair fol­li­cles in vit­ro in the lab.

For the first time, the research team suc­ceed­ed in cre­at­ing hair fol­li­cle organoids, which are minia­ture ver­sions of the organs that grow hair, using cells obtained from embry­on­ic mice.

Fur­ther­more, when these hair fol­li­cles were trans­plant­ed into liv­ing hair­less mice, they were able to main­tain their func­tion while repeat­ed­ly grow­ing hair.

The research team said the study could help treat hair loss and pro­vide an alter­na­tive mod­el to ani­mal test­ing and drug screening.

Hair fol­li­cles are formed dur­ing embryo­ge­n­e­sis. The out­er lay­er of the skin, the epi­der­mis, and the next lay­er of con­nec­tive tis­sue, the mes­enchyme, inter­act to trig­ger a mor­phogenic process in which cells begin to join togeth­er to form organs.

These epi­der­mal-mes­enchy­mal inter­ac­tions that give rise to hair fol­li­cles are poor­ly under­stood. In the lab­o­ra­to­ry, we were able to cul­ture mouse and human skin organoids con­tain­ing hair fol­li­cles, but it was dif­fi­cult to cul­ture hair fol­li­cles alone.

There­fore, a research team led by Pro­fes­sor Tat­su­to Kageya­ma of Yoko­hama Nation­al Uni­ver­si­ty decid­ed to con­duct research using organoids.

The research began with two types of cells, epithe­lial (skin) and mes­enchy­mal, col­lect­ed from embry­on­ic mice.

Some of these cells were cul­tured with a mouse-derived mem­brane prepa­ra­tion called Matrigel, a sub­stance that helps the cells form struc­tures, while oth­ers were cul­tured with­out Matrigel.

The dif­fer­ence was stark. Two types of cells clumped togeth­er, and with­in the clumps spon­ta­neous­ly sep­a­rat­ed to form an orga­nized structure.

With­out Matrigel, or when it was added lat­er, these struc­tures were bell-shaped and did not devel­op into func­tion­al follicles.

How­ev­er, when Matrigel was added with­in 6 hours after seed­ing the cells, a lay­er of mes­enchy­mal cells sur­round­ed the nuclei of the epithe­lial cells.

This arrange­ment increas­es the con­tact area between the two types of cells, mak­ing it eas­i­er for the chro­mo­somes to devel­op into hair follicles.

In fact, this is the result of their obser­va­tion. This core spot grew into a fol­lic­u­lar organoid that pro­duced mature hairs with a suc­cess rate of near­ly 100%, grow­ing 2 mm hairs after 23 days.

This process allowed us to study at the mol­e­c­u­lar lev­el how hair fol­li­cles devel­op and gen­er­ate hair.

He also tried drugs that stim­u­late the pro­duc­tion of melanocytes, the cells involved in pigmentation.

When cul­tured with this drug, the hair grown from the hair fol­li­cle organoids became dark­er in pig­ment than the hair with­out the drug.

Final­ly, they trans­plant­ed the cul­tured fol­li­cles into immune-sup­pressed nude mice to see if the organoids could be inte­grat­ed into the body.