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Fibrocytes were first described in 1994 as fibroblast-like, peripheral blood cells. These bone marrow-derived mesenchymal progenitor cells migrate into regions of tissue injury. They are unique in their expression of hematopoietic and monocyte lineage markers and extracellular matrix proteins. Several studies have focused on the specific role of fibrocytes in the process of wound repair and tissue regeneration. We discuss herein the biology and mechanistic action of fibrocytes in wound healing, scar formation, and maintenance of tissue integrity. Fibrocytes synthesize and secrete different cytokines, chemokines, and growth factors, providing a wound milieu that supports tissue repair. They further promote angiogenesis and contribute to wound closure via pathways involving specific cytokines, leukocyte-specific protein-1, serum amyloid P, and adenosine A(2A) receptors. Fibrocytes are involved in inflammatory fibrotic processes in such diseases as systemic fibrosis, atherosclerosis, asthma, hypertrophic scarring, and keloid formation. Accumulating literature has emphasized the important role of fibrocytes in wound healing and fibrosis. Detailed mechanisms nevertheless remain to be investigated to elucidate the full therapeutic potential of fibrocytes in the treatment of fibrosing disorders and the enhancement of tissue repair.

Publisher Summary The cumulating amount of data on the primary structure of cytochrome c oxidase obtained either from protein or DNA sequences of phylogenatically distant organisms allows first comparative analyses, which lead to conclusions concerning origin, structural arrangement, and functional sites of this enzyme. This chapter discusses the general structure of cytochrome c oxidase and special functions of subunits I and II. The eucaryotic cytochrome c oxidase in principal is made up from the two mitochondrial polypeptides I and II that bind all four metal centers and also contain the coupling site for e- and H+ translocation. These components are considered as true subunits of this enzyme. Possibly they are anchored together in one of the membrane domains of the complex and form a big part of the C-domain. The folding pattern of subunit II shows that the functional core of this protein is on the cytoplasmic side of the inner membrane. It also has been identified as the high affinity cytochrome c binding site.