BMI1 is required for melanocyte stem cell maintenance and hair pigmentation

Irradiation-induced hair graying in mice: an experimental model to evaluate the effectiveness of interventions targeting oxidative stress, DNA damage prevention, and cellular senescence

Hair graying, also known as canities or achromotrichia, is a natural phenomenon associated with aging and is influenced by external factors such as stress, environmental toxicants, and radiation exposure. Understanding the mechanisms underlying hair graying is an ideal approach for developing interventions to prevent or reverse age-related changes in regenerative tissues. Hair graying induced by ionizing radiation (γ-rays or X-rays) has emerged as a valuable experimental model to investigate the molecular pathways involved in this process. In this review, we examine the existing evidence on radiation-induced hair graying, with a particular focus on the potential role of radiation-induced cellular senescence. We explore the current understanding of hair graying in aging, delve into the underlying mechanisms, and highlight the unique advantages of using ionizing-irradiation-induced hair graying as a research model. By elucidating the molecular pathways involved, we aim to deepen our understanding of hair graying and potentially identify novel therapeutic targets to address this age-related phenotypic change.

Melanocyte stem cells in the skin: Origin, biological characteristics, homeostatic maintenance and therapeutic potential

Melanocyte stem cells (MSCs), melanocyte lineage-specific skin stem cells derived from the neural crest, are observed in the mammalian hair follicle, the epidermis or the sweat gland. MSCs differentiate into mature melanin-producing melanocytes, which confer skin and hair pigmentation and uphold vital skin functions. In controlling and coordinating the homeostasis, repair and regeneration of skin tissue, MSCs play a vital role. Decreased numbers or impaired functions of MSCs are closely associated with the development and therapy of many skin conditions, such as hair graying, vitiligo, wound healing and melanoma. With the advancement of stem cell technology, the relevant features of MSCs have been further elaborated. In this review, we provide an exhaustive overview of cutaneous MSCs and highlight the latest advances in MSC research. A better understanding of the biological characteristics and micro-environmental regulatory mechanisms of MSCs will help to improve clinical applications in regenerative medicine, skin pigmentation disorders and cancer therapy. KEY POINTS: This review provides a concise summary of the origin, biological characteristics, homeostatic maintenance and therapeutic potential of cutaneous MSCs. The role and potential application value of MSCs in skin pigmentation disorders are discussed. The significance of single-cell RNA sequencing, CRISPR-Cas9 technology and practical models in MSCs research is highlighted.

Effect of N-acetylcysteine on hair follicle changes in mouse model of cyclophosphamide-induced alopecia: histological and biochemical study

Chemotherapy-induced alopecia (CIA) represents one of the most severe side effects of chemotherapy, which forces some patients to reject cancer treatment. The exact pathophysiological mechanisms of CIA are not clearly understood, which makes it difficult to discover efficient preventive or therapeutic procedures for this adverse effect. N-acetylcysteine (NAC) has a strong antioxidant activity as it stimulates glutathione synthesis and acts as an oxygen radical scavenger. The current study tried to investigate the efficacy of NAC in preserving biochemical parameters and hair follicle structure against cyclophosphamide (CYP) administration. In total, 40 adult female C57BL/6 mice were induced to enter anagen by depilation (day 0) and divided into four groups: group I (control), group II (CYP) received a single dose of CYP [150 mg/kg body weight (B.W.)/intraperitoneal injection (IP)] at day 9, group III (CYP & NAC) received a single dose of CYP at day 9 as well as NAC (500 mg/kg B.W./day/IP) from day 6-16, and group IV (NAC) received NAC from day 6-16. CYP administration in group II induced an increase in malondialdehyde (MDA), decrease in superoxide dismutase (SOD), histological hair follicle dystrophy, disruption of follicular melanogenesis, overexpression of p53, and loss of ki67 immunoreactivity. NAC coadministration in group III reversed CYP-induced alterations in the biochemical parameters and preserved hair follicle structure, typical follicular melanin distribution as well as normal pattern of p53 and ki67 expression. These findings indicated that NAC could be used as an efficient and safe therapeutic option for hair loss induced by chemotherapy.