Background: Keloid is a common fibroproliferative disorder, often manifesting symptoms such as itching and pain. Given the unique characteristics of keloids, their occurrence is primarily limited to humans, posing difficulties for spontaneous keloid development in animals. Consequently, the creation of animal models has somewhat impeded the comprehensive investigation of keloids.Aims: The aim is to develop a keloid mouse model that mimics the formation process of human keloids, enabling researchers to gain a deeper understanding of their pathophysiological mechanisms and to explore effective therapeutic approaches.Methods: Human keloid fibroblasts were isolated, cultured, and subcutaneously injected with Matrigel into nude mice at four concentrations (1 × 10⁶, 3 × 10⁶, 5 × 10⁶, and 7 × 10⁶ cells). Subcutaneous nodules were transplanted into additional mice to validate stability. Histological and immunohistochemical analyses were performed to assess morphological and molecular features.Results: Keloid‐like nodules formed in a cell density‐dependent manner, with the highest concentration group (7 × 10⁶ cells) achieving nodule formation in 39.6 ± 3.2 days, significantly faster than lower concentrations (p < 0.001). The transplantation success rate reached 80%, with nodules exhibiting dense collagen deposition (72.7% ± 3.8%), CD34‐positive microvessels (23.1 ± 2.2 vessels/field), and α‐SMA expression (11.29% ± 3.7%), closely mirroring human keloid histopathology.Conclusion: The combination of human keloid fibroblasts and Matrigel provides a simple and rational approach for constructing a nude mouse model, offering a reliable animal model for experimental and clinical research on the pathogenesis and treatment strategies of keloids.

Human skin colour is determined mainly by the amount of melanin it contains. Melanin is a brown pigment whose main role is to protect the skin from the damaging effect of ultraviolet rays. Melanin is produced in the skin by melanocytes, which are specialised cells in the outer layer (epidermis). The production of melanin is a complex process called melanogenesis. It is influenced genetically (racial skin type), by ultraviolet exposure and also as a result of skin inflammation such as eczema or psoriasis. This occurs through interaction between melanocytes and surrounding cells both in the epidermis and the supporting tissues underneath (the dermis). These cells secrete many different messenger chemicals (cytokines) which affect melanocyte activity. This is known as a paracrine effect. This article from workers in Yanji, China, reviews the very complex chemical processes that influence melanin pigment production. Melanocyte activity is affected by cytokines derived from adjacent epidermal cells (keratinocytes), from nerve endings in the skin, and from soluble factors diffusing from fibroblasts, cells found in the dermis beneath the melanocytes. In addition, cells involved in skin inflammatory conditions produce various chemicals, e.g. histamine, which affect melanin production. This can lead to the skin becoming lighter or darker in colour after an episode of psoriasis, for example. Thirty‐one chemical messengers involved in regulating pigment production are discussed in this paper. No doubt more will be discovered in the future, adding to the complexity of our understanding of this vital function of the skin.