Cystine-Thiamin-Containing Hair-Growth Formulation Modulates the Response to UV Radiation in an In Vitro Model for Growth-Limiting Conditions of Human Keratinocytes

The study from December 2018 explored the impact of a cystine-thiamin-containing hair-growth formulation (P-IC) on the response of human keratinocytes to UV radiation in vitro. The research demonstrated that L-cystine and thiamin, components of P-IC, significantly increased the metabolic activity and proliferation of normal human epidermal keratinocytes (NHEKs) cultured in a minimal growth medium (MGM). The combination of ingredients in P-IC was more effective than individual components, leading to a four-fold increase in metabolic activity and a three-fold increase in proliferation. Furthermore, P-IC-treated cells showed a substantially lower reduction in metabolic activity after UV irradiation compared to cells in MGM alone, indicating a protective effect against UV-induced damage that was not due to UV filtering. The study concluded that P-IC could be beneficial for hair and scalp protection against environmental stressors like UV radiation, suggesting a potential UV-protective role for hair-growth formulations containing these ingredients. The document also notes the authors' affiliation with Merz Pharmaceuticals GmbH.