Hair Matrix Cell Kinetics: A Selective Review

In the 1978 review, Malkinson and Keane examined the dynamics of hair matrix cell division, noting the rapid division rate of human anagen hair matrix cells and the influence of various factors such as genetics, age, sex, disease, malnutrition, and environmental conditions on hair growth. They highlighted the lack of direct studies on hair matrix cell kinetics at the time and the reliance on indirect measures to infer changes. The review summarized that cell cycle times and growth rates are affected by factors like hair papilla size and nutrient availability, and discussed the cell division cycle phases. The complexity of hair matrix cell kinetics was emphasized, along with the need for more research to understand hair growth and loss mechanisms. Additionally, the review covered the dose-dependent impact of radiation on matrix cells, with higher doses causing more severe damage, and the temporary effects of chemotherapeutic drugs on hair matrix cells, contrasting with the more permanent effects of high-dose radiation. It also mentioned the "escape" phenomenon in hair damage with ongoing cytotoxic agent administration and the additive effects when drugs and radiation are combined. The review suggested that once cell replication begins, there are no significant differences in cell kinetics between stimulated and spontaneously dividing cells, although this may not apply to all in vivo observations.