The relation between skin regeneration and body hair regeneration is very closely connected. I previously discussed it in detail in my post on skin regeneration, wound healing and hair growth. If you want to regenerate damaged human skin, you also need to regenerate skin appendages such as hair follicles, sweat glands, pigment cells, fat cells, sebaceous glands and more.

Full Skin Regeneration by Unblocking Nerves

An interesting new study from Harvard scientists has found that it may be possible to fully regenerate skin without any scars (not the current norm). And the process of doing this might be just a simple Botox-like nerve blocking.

The scientists found that when embryonic mice skin was intentionally damaged three days before birth, the skin regenerated diverse cell types and closely resembled unwounded skin. However, when postnatal mice skin was wounded at five days after birth, the site was “covered by epithelial cells and became packed with collagen scar tissue and abnormally dense nerve fibers and immune cells”.

The densely packed nerves (“hyperinnervation”) are caused by fibroblasts in postnatal wounds upregulating the gene Cxcl12. It recruits excessive nerves to the injured area and impairs the regrowth of other skin-cell types. Basically, nerves are blocking your skin from healing like an embryo.

When the Harvard researchers depleted Cxcl12 in wounds in postnatal mice, this “hyperinnervation” was curtailed. Subsequently, the healing skin regrew diverse cell types. Of most interest, blocking the local nerve signaling with botulinum toxin A (Botox) produced similar effects. According to senior author Ya-Chieh Hsu, professor of stem cell and regenerative biology at the Harvard Stem Cell Institute:

“Before the study, I expected that the key to wound healing would be recreating a series of regeneration-promoting factors to mimic embryonic healing. The solution turned out to be much simpler. I didn’t think that we’d have to retract a brake, which actually is good news — it’s a lot easier. It gives me hope that this might be applicable to improving wound healing in humans.”

The potential for full skin regeneration has positive implications towards full hair regeneration (both body hair and head hair). Perhaps the concept of intentional scalp wounding to regenerate scalp hair may currently be ineffective for many people due to “hyperinnervation”?

Intentional Wounding to Regenerate Hair

Intentional scalp injury when done correctly via microneedling can theoretically also regrow head hair as a side effect of wound healing. However, anecdotal online forums reported results have been mixed and very inconsistent.

But the fact that a 2018 medical case report mentioned how an 80-year old man grew a new pigmented hair after wound healing is very encouraging. As is the famous case of a 78-year old man who grew new hair after accidentally burning his frontal scalp bald region. Also of note, the stimulation of hair growth during wound healing is a phenomenon that was already noted in the 1950s.

The following quote from Dr. George Cotsarelis from the old Follica website is also very encouraging:

“Following skin disruption, cells that migrate to help healing are forced to make a decision: Should I make epidermis, or should I make a hair? There is a window of opportunity in which we can potentially push them to choose the latter, and we believe there are multiple biological pathways to target to enhance this outcome. This regenerative effect is called hair follicle neogenesis.”

Prior to its hibernation, Follica said that its technology is based on the creation of an “embryonic window” in adult skin, allowing new follicles and new hair to form from epithelial stem cells.

Make sure to read my post from last year regarding skin injury, adipocyte lipolysis and subsequent hair growth. Intentional skin wounding is also thought to lead to hair growth via an increase in various fibroblast growth factors and interleukin-1 (IL-1).