Krystal Jacques completed her Master’s degree in the Institute of Medical Science department at the University of Toronto. For her Master’s she studied the embryonic origin of pancreatic stem cells under the supervision of Dr. Derek van der Kooy, where she developed an interest in both photography and science communication. She is currently building her own business as an artist. As a scientist turned artist, she hopes that she can tell stories through visual and written media. You can find her on Instagram @krystaljacques
Photo courtesy of Towfiqu Barbhuiya for Unsplash
I was talking to a 28-year-old male friend of mine one day and he told me that he “could not wait to be rich so he can get a hair transplant!” Another friend of mine (age 30), after I ranted about my life problems to him, rubbed his bald scalp and told me jokingly, “when you start feeling bad about yourself…just remember…I’m bald.” Losing one’s hair is a deeply emotional and psychological burden. For many, it seems to be the worst thing that could happen.
Of course, hair loss doesn’t just affect men after twenty, it also affects women as they get older (female-pattern baldness), and both sexes at younger ages due to contributing factors such as obesity, and polycystic ovarian syndrome (for women), disorders such as alopecia areata (autoimmune disease), as well as chronic stress and thyroid disorders. In the case of male- and female-patterned baldness, these conditions may often be referred to as androgen-induced or androgenetic alopecia, as androgen hormones (such as testosterone) play a key role by binding to the surface of hair follicle cells and attacking them. Balding men tend to have hair remaining at the back of the head because the hair follicle cells in this area lack sensitivity to the androgen hormone.
The hair follicle is the source of hair growth. Stem cells reside in the bulge of the hair follicle and the stem cell state (activated or inactivated) maps well with the hair cycle: telogen (resting state for the stem cell and no hair growth), anagen (proliferation for the stem cell and hair growth) and catagen (resting state for the stem cell and hair fall). The hair cycle, being relatively short for mice, offers the opportunity to observe follicle stem cell behaviour over the course of an entire cycle, making HF’s a great model for studying stem cell biology.
In a recent study by Zhang et al (here’s an alternative read if you can’t access the study) the authors, who used intravital imaging (two photon imaging for live animals) visualized live follicle stem cells within their native tissue environment in vivo, and followed their position (in relation to hair bulge, or upper dermis) during all stages of the hair cycle and hair regeneration.
According to Zhang et al., the young hair follicle in stem cells surrounding the hair bulge are tightly packed. However, during aging, the pool of stem cells located at the bulge eventually lose the glue (the cell adhesion molecules and extracellular matrix) that anchors them in this location. As a result, they “escape” from their original niche and migrate to the outer layers of the dermis, making them unable to contribute to growing hair.
Old stem cells that have escaped, and have migrated towards the skin surface, differentiate and lose their stem cell identity. This process is not only associated with the lack of glue, but a loss of the stem cells’ collagen production. For androgenic alopecia specifically, this is thought to be largely due to testosterone, which after being converted into dihyrdrotestosterone (DHT), binds to the hair follicle’s dermal papilla receptors leading to cell death.
Besides androgenic alopecia, a recent study by Morinaga et al. highlighted that obesity, due to its underlying cause of insulin resistance, triggers inflammation, reactive oxygen species and several signalling pathways that lead to accelerated hair follicle shrinking and stem cell differentiation. Obesity, along with repetitive hair cycles over time, diminishes hair follicle stem cell pools, and self-renewal capabilities, which leads to hair thinning.
During normal hair growth, the hair bulge shrinks, but eventually cycles back to expansion. For those who are balding, the progression of hair follicle miniaturization continues until the hair follicle disappears permanently. To restore hair loss aesthetically, many men resort to expensive hair transplantations. However, in this procedure new hairs aren’t created, they are just moved around. Entire hair follicles are plucked from the thicker patch of hair that remains at the back of the head and are transplanted to where the hair is thinning. Women affected by female-pattern hair loss unfortunately don’t have the same thick back patch of “donor hair” to work with.
Popular products Rogain and Propecia may slow hair loss but won’t regrow lost hair. However, in the last few years, a promising innovative alternative has appeared: Vancouver-based Replicel™.
As it states on their website, RepliCel™ is a regenerative medicine company focused on developing cell therapies for aesthetic and orthopedic conditions by using your own (autologous) cells. Their baldness treatment involves taking a few hair follicles from the head and subsequently isolating the dermal sheath cup cells (DSCs). DSCs are considered to be stem-like cells that support all the cell populations in the hair follicle that are directly related to hair growth. People who suffer from androgenetic alopecia experience a loss of these DSCs in the hiar follicle (due to the androgen hormone’s attack) and, consequently, their hair producing cells lose their ability to regrow hair. Fortunately, the particular DSCs that are initially isolated for treatment are naturally immune to the androgen hormone’s attack and they maintain this immunity throughout manufacturing. In the initial safety trial and the subsequent dosing clinical trial, these cells were injected in areas of hair loss, which helped to replace lost DSCs and resulted in significant improvements in restoring hair growth in the remaining existing follicles of the scalp.
What’s also interesting is that RepliCel has two other products: one for skin rejuvenation and one for tendon repair. The cells isolated here are also from the hair follicle, but instead of DSCs, fibroblast-like cells are isolated. These fibroblast-like cells produce collagen and the end cellular product helps to reverse collagen degeneration when introduced into aging tendons or skin. Each patented product is currently undergoing approved clinical trials, with the hair loss product being farthest along.
Hair is tied to deeply ingrained societal ideas about beauty, power and vitality, and has a significant impact on how we see ourselves. What’s more, going through hair loss can be devastating. As we wait for companies such as RepliCel to commercialize and release their product for regrowing hair, reducing your stress, being your healthiest self, and re-focusing your attention away from the problem goes a long way in managing the physical and psychological impacts of hair loss.
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