Tregs Expand the Skin Stem Cell Niche

The dual role of tissue regulatory T cells in tissue repair: return to homeostasis or fibrosis

Tissue resident regulatory T cells (tissue Tregs) are vital for maintaining immune homeostasis and controlling inflammation. They aid in repairing damaged tissues and influencing the progression of fibrosis. However, despite extensive research on how tissue Tregs interact with immune and non-immune cells during tissue repair, their pro- and anti-fibrotic effects in chronic tissue injury remain unclear. Understanding how tissue Tregs interact with various cell types, as well as their roles in chronic injury and fibrosis, is crucial for uncovering the mechanisms behind these conditions. In this review, we describe the roles of tissue Tregs in repair and fibrosis across different tissues and explore potential strategies for regulating tissue homeostasis. These insights hold promise for providing new perspectives and approaches for the treatment of irreversible fibrotic diseases.

Stem cells, niches and scaffolds: Applications to burns and wound care

The importance of skin to survival, and the devastating physical and psychological consequences of scarring following reparative healing of extensive or difficult to heal human wounds, cannot be disputed. We discuss the significant challenges faced by patients and healthcare providers alike in treating these wounds. New state of the art technologies have provided remarkable insights into the role of skin stem and progenitor cells and their niches in maintaining skin homeostasis and in reparative wound healing. Based on this knowledge, we examine different approaches to repair extensive burn injury and chronic wounds, including full and split thickness skin grafts, temporising matrices and scaffolds, and composite cultured skin products. Notable developments include next generation skin substitutes to replace split thickness skin autografts and next generation gene editing coupled with cell therapies to treat genodermatoses. Further refinements are predicted with the advent of bioprinting technologies, and newly defined biomaterials and autologous cell sources that can be engineered to more accurately replicate human skin architecture, function and cosmesis. These advances will undoubtedly improve quality of life for patients with extensive burns and difficult to heal wounds.

Regulatory T cells in skin

Foxp3⁺ CD4⁺ regulatory T (Treg) cells are a subset of immune cells that function to regulate tissue inflammation. Skin is one of the largest organs and is home to a large proportion of the body's Treg cells. However, relative to other tissues (such as the spleen and gastrointestinal tract) the function of Treg cells in skin is less well defined. Here, we review our understanding of how Treg cells migrate to skin and the cellular and molecular pathways required for their maintenance in this tissue. In addition, we outline what is known about the specialized functions of Treg cells in skin. Namely, the orchestration of stem cell-mediated hair follicle regeneration, augmentation of wound healing, and promoting adaptive immune tolerance to skin commensal microbes. A comprehensive understanding of the biology of skin Treg cells may lead to novel therapeutic approaches that preferentially target these cells to treat cutaneous autoimmunity, skin cancers and disorders of skin regeneration.