The topical penta-peptide Gly-Pro-Ile-Gly-Ser increases the proportion of thick hair in Japanese men with androgenetic alopecia

An epidermis-permeable dipeptide is a potential cosmetic ingredient with partial agonist/antagonist activity toward fibroblast growth factor receptors

BACKGROUND

Fibroblast growth factors (FGFs) are promising agents with which to treat problems of skin and hair. But their inability to penetrate into the skin due to their large size and hydrophilic nature prevents their topical application as effective cosmetic ingredients.

AIMS

To identify small peptide(s) with FGF-like activity and epidermis permeability.

METHODS

Several peptides deduced from our earlier studies were tested for their ability to promote keratinocyte growth and to activate FGF receptors (FGFRs). Permeability was assessed using HPLC after derivatization.

RESULTS

A dipeptide, prolyl-isoleucine (Pro-Ile), not only stimulated growth of human keratinocytes, it also moderately activated FGFR3c and FGFR4, and activated FGFR1c to a lesser extent. This receptor specificity of Pro-Ile is similar to that of FGF18. The activity of Pro-Ile toward FGFR/BaF3 cells was enhanced by heparin and was inhibited by an FGFR inhibitor, PD173074. Pro-Ile enhanced the activity of 5 ng/mL FGF18, but suppressed the activity of 50 ng/mL FGF18 toward FGFR3c and FGFR4. Pro-Ile was found to permeate through validated model human epidermis.

CONCLUSIONS

These results indicate that the dipeptide Pro-Ile acts as a partial agonist/antagonist for FGFR signaling, that it has receptor specificity similar to FGF18, and that it is able to penetrate into the model epidermis. Because FGFs expressed in the cutaneous system are physiological regulators, these results suggest the potential utility of this peptide as a topically applicable cosmetic ingredient for the regulation of skin physiology, hair growth, and wound healing.

Efficacy of Off-Label Topical Treatments for the Management of Androgenetic Alopecia: A Review

Androgenetic alopecia (AGA) is characterized by non-scarring follicle miniaturization. Despite the success of approved therapies, commonly reported side effects and the need for continual use has led to the investigation of alternative therapies. The aim of this paper is to critically review the success of off-label, topical monotherapies for treatment of AGA in men. A literature search was conducted to obtain randomized, controlled and blinded studies that investigated off-label, topical, monotherapies in male patients. Hair density, hair diameter and hair growth were used to evaluate treatment success. Fourteen off-label topical therapies were investigated among the 16 studies that met inclusion criteria. Nine off-label therapies were reported to produce a significantly greater improvement in hair restoration parameters (e.g. mean change from hair count and hair diameter) as compared to placebo (p < 0.05 for all treatments). In two studies, procyanidin oligomers exhibited greater efficacy over vehicle with response to mean change in hair density (hairs/cm²) (p_s < 0.0001 at Week 24). In conclusion, prostaglandin analogs and polyphenols, such as latanoprost and procyanidin oligomers, can improve hair restoration parameters in male AGA patients, possibly through targeting mechanisms proposed in the etiology of AGA. The current evidence suggests short-term (24 weeks) use may provide benefit for hair loss patients; however, long-term efficacy and safety data are required.