Yuko Miura

Organ culture of human hair follicles in serum-free medium

Human hair follicles were cultured in serum-free media at 31‡C in an atmosphere containing 95% O2 and 5% CO2. Results showed that the length of the cultured hair increased time dependently for 96 h. Histological findings revealed that the hair germinative cells maintained their normal morphology throughout the 96 h culture period. DNA synthesis in the hair bulb also increased time dependently for 96 h. Autoradiographs of 3H-thymidinelabelled follicles indicated that they were localized in the germinative cells below Aubers critical line. The effects of minoxidil sulphate on DNA synthesis in this culture system were concentration dependent. Minoxidil sulphate at concentrations of 10−10,10−9 and 10−8M significantly increased DNA synthesis compared with DNA synthesis in the control medium. Autoradiographs of the follicles cultured in 10−10M minoxidil sulphate showed that 3H-thymidine localized primarily in the germinative cells below Aubers critical line. These results suggest that this organ culture system may be useful for studying DNA synthesis by hair germinative cells in serum-free media.

Organ culture conditions of human hair follicles

Experimental results revealed that although [3H]thymidine uptake in the hair bulb increased time dependently for 12 days under normal culture conditions (95% air-5% CO2 at 37 degrees C), striking morphological changes occurred in the hair bulb cells as demonstrated by histological findings. As such, organ culture conditions applicable to human hair follicles were studied utilizing observations from both histology and DNA synthesis. We found that culture conditions of 95% O2-5% CO2 at 31 degrees C were superior when compared to normal culture conditions for cultures of human hair follicles when attempting to maintain the normal morphology of hair germinative cells. The hair bulb and the germinative cells successfully maintained their normal morphology throughout the 96 and 48 h culture period, respectively. Autoradiographs of [3H]thymidine-labeled follicles showed localization in the germinative cells below Aubers critical line. Hair bulb DNA synthesis increased time dependently for 96 h after culture initiation. Under conditions of 95% O2-5% CO2 at 31 degrees C, the synthesis of DNA in hair germinative cells was observed. Such an organ culture method may prove useful for studies on the human hair growth mechanism.

Is Improvement of Genetic Resolution at the VDR Locus Necessary

Peltekova et al. suggest that direct haplotyping at the VDR locus improves genetic resolution, based largely on the work from Uitterlinden and coworkers. It is certainly correct that a more precise haplotyping can be achieved without having to infer haplotypes from the more common allelic frequencies. However, as the authors point out, the frequency of incorrect assignment is very low due to the low frequency of the “less common” alleles. Although it is possible that the differing results reported from different geographic localities in relation to the gene alleles may relate to some of these haplotypic differences, this remains a conjecture and has yet to be demonstrated. Also, although the direct haplotyping method could potentially have some advantages, robustness of the longer range PCR and the multiple enzyme digestion in less experienced hands has yet to be demonstrated. Notwithstanding these concerns about the direct haplotyping methodology, allelic frequencies will differ between populations, and more precise assignment of haplotypes could yield additional information in some populations. However, virtually all the studies carried out in Japanese populations have demonstrated a predictive effect for the simple allelic polymorphisms as defined. Although direct haplotyping could be more relevant in individuals, the small number of incorrect assignments associated with inferred haplotyping seems unlikely to be of clinical significance in analytic studies in most populations.