There are various conditions which cause excessive shedding or loss of hair, but a particular concern of trans women is hair loss due to male pattern baldness (MPB). Hair follicles in the scalp get affected by DHT which causes their growth cycle to decrease and miniaturizes them each cycle. The follicle does not regrow to its full capacity and if the muscle which erects hairs becomes detached the loss of hair may become permanent.[1]
When DHT is reduced and blocked and estrogen is introduced with HRT, the blueprint for the hair follicle reverts to a pattern which elongates the growth cycles and promotes thicker, longer hair. Promoting hair growth cycle by various methods is necessary to restore hair previously lost to miniaturization, although the effect may vary between people due to length of time and progression of MPB and the sensitivity of hormone receptors.
In general you want increase stem cell activity of the dermal papilla by improving scalp blood flow, promoting cell regeneration through targeted wound healing and upregulating the factors involved in follicular cell growth and differentiation.
DHT Blocker
Finasteride and Dutasteride are 5α-Reductase inhibitors which are agents that inhibit the enzyme 5α-reductase, which is involved in the metabolic transformations of a variety of endogenous steroids. 5-ARIs are known for preventing conversion of testosterone to dihydrotestosterone (DHT) thereby reducing its circulating level and effect on hair follicles and other tissues.
Vasodilators
Minoxidil is a medication which widens blood vessels and promotes blood flow around the capillaries which connect to parts of the hair follicular unit, enabling those cells to receive nutrients and grow more.
Dermarolling
Microneedling with a dermaroller is a way to create a series of dense, small and shallow punctures in the epidermis which triggers a wound healing response that is beneficial for angiogenesis and stem cell activation. This over time supports regrowth of hair follicles which were dormant due to miniaturization. [2]
Microneedling also causes certain topical medications to penetrate into the skin more effectively to exert a greater effect. Although it is not recommended to use Minoxidil the same day as dermaroller treatment.
Hair Growth Factors
There are certain pathways which regulate hair restoration potential which may be upregulated to increase the effect.
Lef1: These fibroblasts are defined by the expression of a canonical Wnt transcription factor Lef1 and using gain- and loss of function genetic mouse models, we demonstrate that Lef1 expression in fibroblasts primes the adult skin macroenvironment to enhance skin repair, including regeneration of hair follicles with arrector pili muscles in healed wounds.[3]
Wnt⁄b-catenin: As we observed that DHT inhibited the canonical Wnt signalling, we further investigated whether the DHT effect on hair differentiation is mediated by a canonical Wnt signalling blockage. For this purpose we collected the conditioned media from DPC cultured in the presence of both LiCl and DHT. Lithium inhibits the activity of GSK-3b, leading to b-catenin stabilization and an increase of the Wnt canonical signalling pathway.[4]