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Background A penta-peptide, Gly-Pro-Ile-Gly-Ser ( GPIGS), promotes proliferation of mouse hair keratinocytes and accelerates hair growth in mice. Aim of this study This study focused on the ability of the peptide to promote human hair growth. Methods We used a human hair keratinocyte proliferation assay and organ cultures of human hair follicle as in vitro systems. The lotions with and without the penta-peptide were administered to 22 Japanese men with androgenetic alopecia (AGA) for 4 months in a double-blind and randomized clinical study. Results The penta-peptide significantly stimulated the proliferation of human hair keratinocytes at a concentration of 2.3 μ m ( P < 0.01), and 5.0 μ m of this peptide had a marked effect on hair shaft elongation in the organ culture ( P < 0.05). The change in the proportion of thick hair (≥60 μm) compared to baseline in patients that received the peptide was significantly higher than in the placebo ( P = 0.006). The change in the proportion of vellus hair (<40 μm) was also significantly lower in the peptide group than in the placebo ( P = 0.029). The penta-peptide also significantly improved the appearance of baldness ( P = 0.020) when blinded reviewers graded photographs of the participants according to a standardized baldness scale. No adverse dermatological effects due to treatment were noted during this clinical study. Conclusions This penta-peptide promotes proliferation of human hair keratinocytes and hair shaft elongation of human hair follicles, in vitro. This peptide increases thick hair ratio in vivo, and this compound is useful for the improvement of AGA. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the efficacy of oral administration of glucosylceramide (GC) in the improvement of skin barrier function and its contribution to the tight junction (TJ) formation of cultured keratinocytes. The study uses statistical analysis and microarray analysis to determine mRNA expression in mice skin and the effect of GC metabolites in TJ formation. Results show that oral administration of GC has improved the skin barrier function.

Flank organs of hamster are useful for studying androgen- dependent growth of hair follicles and sebaceous glands. To elucidate the mechanism of gene expression regulated by androgen, we constructed a cDNA library from flank organs of male hamsters and screened by a differential hybridization method using cDNA probes from normal and castrated males. We isolated a cDNA clone, termed FAR-17a, whose expression was found to be highly sensitive to androgen. FAR-17a mRNA of 1.8 kb was reduced after castration and reappeared after testosterone treatments. Among several tis- sues examined, FAR-17a gene was expressed at a high level in flank organ and a low level in testis and earlobe. FAR-17a probe detected a few fragments in genomic DNA of hamster, mouse, suncus, pig, and human, suggesting that this gene is phylogenetically conserved. The sequence of FAR-17a cDNA predicts a protein of 231 amino acids (27,216 daltons) having basic properties. The deduced protein has no significant homologies to proteins previously described. [ABSTRACT FROM AUTHOR]

Hair follicle regeneration involves epithelial–mesenchymal interactions (EMIs) of follicular epithelial and dermal papilla (DP) cells. Co-grafting of those cellular components from mice allows complete hair reconstitution. However, regeneration of human hair in a similar manner has not been reported. Here, we investigated the possibility of cell-based hair generation from human cells. We found that DP-enriched cells (DPE) are more critical than epidermal cells in murine hair reconstitution on a cell number basis, and that murine DPE are also competent for hair regeneration with rat epidermal cells. Co-grafting of human keratinocytes derived from neonatal foreskins with murine DPE produced hair follicle-like structures consisting of multiple epidermal cell layers with a well-keratinized innermost region. Those structures expressed hair follicle-specific markers including hair keratin, and markers expressed during developmental stages. However, the lack of regular hair structures indicates abnormal folliculogenesis. Similar hair follicle-like structures were also generated with cultured human keratinocytes after the first passage, or with keratinocytes derived from adult foreskins, demonstrating that epidermal cells even at a mature stage can differentiate in response to inductive signals from DP cells. This study emphasizes the importance of EMI in follicular generation and the differentiation potential of epidermal keratinocytes.Journal of Investigative Dermatology (2007) 127, 2106–2115; doi:10.1038/sj.jid.5700823; published online 12 April 2007 [ABSTRACT FROM AUTHOR]

Cells that constitute the dermal papillae of hair follicles might be derived from the dermal sheath, the peribulbar component of which is the dermal sheath cup. The dermal sheath cup is thought to include the progenitor cells of the dermal papillae and possesses hair inductive potential; however, it has not yet been well characterized. This study investigated the gene expression profile of the intact dermal sheath cup, and identified dermal sheath cup signature genes, including extracellular matrix components and bone morphogenetic protein-binding molecules, as well as transforming frowth factor beta 1 as an upstream regulator. Among these, gremilin-2, a member of the bone morphogenetic protein antagonists, was found by in situ hybridization to be highly specific to the dermal sheath cup, implying that gremlin-2 is a key molecule contributing to maintenance of the properties of the dermal sheath cup.