I have been watching the research VERY closely since the original. The original ended up being more effective at slowing/preventing loss in most users, though quite a few reports of excellent growth.
I used the wrong TRPV1 agonist, IMO, and found a better one for the new version, as well as quite a few new angles.
A Hot New Twist to Hair Biology
Involvement of Vanilloid Receptor-1 (VR1/TRPV1) Signaling in Human Hair Growth Control
Enikő Bodó, Tamás Bíró, [...], and Ralf Paus
The vanilloid receptor-1 (VR1, or transient receptor potential vanilloid-1 receptor, TRPV1) is activated by capsaicin, the key ingredient of hot peppers. TRPV1 was originally described on sensory neurons as a central integrator of various nociceptive stimuli. However, several human skin cell populations are also now recognized to express TRPV1, but with unknown function. Exploiting the human hair follicle (HF) as a prototypic epithelial-mesenchymal interaction system, we have characterized the HF expression of TRPV1 in situ and have examined TRPV1 signaling in organ-cultured human scalp HF and outer root sheath (ORS) keratinocytes in vitro. TRPV1 immunoreactivity was confined to distinct epithelial compartments of the human HF, mainly to the ORS and hair matrix.
In organ culture, TRPV1 activation by capsaicin resulted in a dose-dependent and TRPV1-specific inhibition of hair shaft elongation, suppression of proliferation, induction of apoptosis, premature HF regression (catagen), and up-regulation of intrafollicular transforming growth factor-β2. Cultured human ORS keratinocytes also expressed functional TRPV1, whose stimulation inhibited proliferation, induced apoptosis, elevated intracellular calcium concentration, up-regulated known endogenous hair growth inhibitors (interleukin-1β, transforming growth factor-β2), and down-regulated known hair growth promoters (hepatocyte growth factor, insulin-like growth factor-I, stem cell factor). These findings strongly support TRPV1 as a significant novel player in human hair growth control, underscore the physiological importance of TRPV1 in human skin beyond nociception, and identify TRPV1 as a promising, novel target for pharmacological manipulations of epithelial growth disorders.
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TRPV1 antagonist, PAC-14028, can accelerate hair growth in vivo
JA Seo, I-H Bae, MY Park, K-W Lee, Y-H Park and K-M Lim Medical Beauty Research Institute, AmorePacific Corporation R&D Center, Yongin, Republic of Korea
Transient receptor potential vanilloid type 1 (TRPV1) is a cation channel activated by diverse noxious stimuli like capsaicin, low pH, or heat. TRPV1 is expressed not only in peripheral sensory nerve fibers (C and Aδ) but also in the skin epidermal cells, including hair follicle. Recently, it was revealed that TRPV1 might be associated with hair growth control. Here we aimed to investigate if the blockade of TRPV1 might affect hair growth, by employing a new TRPV1 antagonist, PAC-14028. The effect of PAC-14028 on hair growth was evaluated in vivo using an anagen induction and a catagen induction model in C57BL/6 mice. In macroscopic evaluation, PAC-14028 accelerated the onset of anagen hair cycle (14 days after treatment) compared to vehicle (27–28 days after treatment). Mice treated with 1% PAC-14028 showed significantly increased hair weight in a dose-dependent manner (101.25±16.51 and 56.81±10.58 mg for PAC-14028 1% and vehicle control, respectively). In the catagen induction model, the 1% PAC-14028-treated group showed darker skin as determined by a skin chromameter, which was comparable to 2% minoxidil. In addition, 1% PAC-14028 increased the skin thickness, confirming the delay of catagen induction. These results demonstrate that TRPV1 antagonist could be useful for hair growth based on anagen elongation and induction in vivo.