The process of tissue repair occurs after tissue damage and usually involves three stages: inflammation, proliferation, and remodelling. In each of these stages, different cells migrate to the wound area to provide protection and mediate the expression of pro-and anti-inflammatory proteins. Neutrophils are the first cells to arrive in the injured area, sending signals for the migration of macrophages that mediate the expression of cytokines, growth factors, and reactive oxygen (ROS) and nitrogen (RNS) species. These ROS and RNS generated during inflammation can lead to cell membrane disorganization and protein oxidation by altering cellular function. Therefore, the balance between ROS production and antioxidant defense is important for efficient tissue repair in organs such as the skin, liver, lungs, kidneys, heart, and testes. An increased oxygen consumption occurs during the process of tissue repair, resulting in an intense production of ROS and RNS. When the tissue is damaged by reactive species, it is common to observe lipid, protein, and DNA damage, leading to oxidative stress that impairs tissue repair.

Regarding the pivotal role played by antioxidant defences in maintaining morphological and functional integrity during tissue repair, the development of new drugs with antioxidant properties are potentially useful in accelerating tissue recovery. These new drugs act increasing enzymatic and non-enzymatic antioxidant defences, protecting against ROS and RNS, and attenuating the formation of biomarkers such as malondialdehyde, hydroperoxides, nitric oxide, and carbonyl protein at the tissue level. This antioxidant activity might favour tissue repair, thus contributing to tissue protection and accelerating the healing process. Besides, treatments that increase the levels of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) are shown to accelerate the healing process in different tissues. In this process, antioxidant molecules are potentially beneficial as they stimulate fibroblast migration, proliferation, increased collagen synthesis, and scar tensile strength; a process partially mediated by ROS and RNS catalysis. Accordingly, evidence from preclinical (in vitro and in vivo) and clinical studies opens new venues for the development of pharmacological strategies to accelerate tissue repair. These therapies usually stimulate the synthesis of antioxidant proteins and accelerate the completion of the inflammatory process, as well as decrease the oxidative stress in regenerating tissues.

The aim of this Special Issue is to bring together original research articles and review articles including morphological, physiological, and pathological issues to discuss the subcellular, cellular, and molecular basis of the metabolism redox associated with tissue repair at all levels. This Issue accepts articles containing primary research results (in silico, in vitro, and in vivo) as well as studies based on secondary data, such as comprehensive and systematic review articles, that will illustrate and stimulate the continuing effort to understand the redox systems in tissue repair metabolism, biomarkers, and treatments. Interdisciplinary work is highly encouraged.

Potential topics include but are not limited to the following:

• Inflammation and tissue repair
• Metabolism redox in tissue repair
• Biomarkers of oxidative stress and antioxidant defenses during tissue repair
• Therapies that act as antioxidants during the repair process
• Analytical methods and instrumentation applied to the analysis of redox metabolism in tissue repair
• Main redox mechanisms involved in inflammatory processes during tissue repair
• Main redox mechanisms involved in regeneration and tissue healing processes