Hair growth / Anti-hair loss efficacy is assessed using different techniques:
5-alpha-reductase is involved in hair loss mechanisms, therefore its activity quantification by biochemical assays is a useful tool to test the ability of products to moderate this process. Additional biological assays are also performed on human keratinocytes or skin fibroblasts and human hair follicle dermal papilla cells and allow to evaluate the amount of dihydrotestosterone (DHT), which is an indirect marker of 5-alpha-reductase activity.
Phototricogram. A transitional area of hair loss between normal hair and the balding area of 1.8 cm2 is defined using a stencil template and chosen for clipping. The clipped hairs within the target area are dyed for gray or fair hairs with a commercially available solution in order to enhance their contrast. Thereafter, the dyed hairs are cleansed using an alcoholic solution and digital images are taken while the area is still wet with a digital close-up camera. Images are taken at day 0, immediately after clipping, and 2 days after clipping. These two photographs are then examined by a software system that is able to recognize individual hair fibers in the photographs.
Pull test. Gentle traction is exerted on a cluster of hairs (approximately 60 hairs) on three different areas of the scalp (frontal, temporal and occipital), and the number of extracted hairs is counted. Normally, less than three telogen-phase hairs should come out with each pull. If at least three hairs are obtained with each pull or if more than ten hairs total are obtained, the pull test is considered positive and suggestive of telogen effluvium.
- Decrease of hair loss
- Digital images
- Clinical evaluations
- Self assesment