Small technology, big insights?
The advanced technology used by Dr. Ito and colleagues in the study included 3D-intravital imaging and single-cell RNA sequencing to track the stem cells in almost real time as they aged and moved within each hair follicle.
“This paper uses a nice mix of classic and modern techniques to help answer a question that many in the field of pigmentation biology have suspected for a long time. Not all dormant melanocyte stem cells are created equal,” Dr. Harris said.
“The one question not answered in this paper is how to reverse the dysfunction of the melanocyte stem cell ‘stuck’ in the hair bulge,” Dr. Harris added. “There are numerous clinical case studies in humans showing medicine-induced hair repigmentation, and perhaps these cases are examples of dysfunctional melanocyte stem cells becoming ‘unstuck.’ ”
‘Very interesting’ findings
The study and its results “are very interesting from a mechanistic perspective and basic science view,” said Anthony M. Rossi, MD, a private practice dermatologist and assistant attending dermatologist at Memorial Sloan Kettering Cancer Center in New York, when asked to comment on the results.
The research provides another view of how melanocyte stem cells can pigment the hair shaft, Dr. Rossi added. “It gives insight into the behavior of stem cells and how they can travel and change state, something not well-known before.”
Dr. Rossi cautioned that other mechanisms are likely taking place. He pointed out that graying of hair can actually occur after a sudden stress event, as well as with vitamin B12 deficiency, thyroid disease, vitiligo-related autoimmune destruction, neurofibromatosis, tuberous sclerosis, and alopecia areata.
The “standout concept” in this paper is that the melanocyte stem cells are stranded and are not getting the right signal from the microenvironment to amplify and appropriately migrate to provide pigment to the hair shaft, said Paradi Mirmirani, MD, a private practice dermatologist in Vallejo, Calif.
It could be challenging to find the right signaling to reverse the graying process, Dr. Mirmirani added. “But the first step is always to understand the underlying basic mechanism. It would be interesting to see if other factors such as smoking, stress … influence the melanocyte stem cells in the same way.”
Grants from the National Institutes of Health and the Department of Defense supported the study. Dr. Ito, Dr. Harris, Dr. Mirmirani, and Dr. Rossi had no relevant disclosures.
A version of this article first appeared on Medscape.com.