Gene expression in head hair follicles plucked from men and women.

Characterizing gene expression in hair follicles can help to elucidate the hair growth cycle by delineating the genes and pathways involved in follicular growth and degeneration. The objectives of this study were to determine whether intact RNA could be extracted from a small number of plucked, unstaged hair follicles in sufficient quantity to conduct gene expression profiling, and to conduct global gene expression profiling. To this end, RNA was extracted from 1 to 3 unstaged follicles plucked from the scalp of 36 volunteers. The average quantifiable yield of RNA/follicle was 112.5 ng. Ribosomal ratios were lower than normally expected, but investigation indicated the RNA was intact. Ten of the samples were amplified and hybridized to Affymetrix genechips. On average, 2,567 of the total probe sets (8,500) were expressed in each sample; 1,422 were expressed in all 10 samples; 97 were significantly changed in one gender compared to the other, and 41 had high levels of interindividual variability. This study demonstrates that RNA of sufficient quantity and quality to use in microarray hybridizations can be obtained from as little as a single plucked human hair follicle. Genes expressed in all individuals are probably related to follicular growth and could form a starting set for developing signatures of toxicant exposure. The differentially expressed genes could be involved in producing gender and interindividual differences in hair growth.