Through Gap Junction Communications, Co-Cultured Mast Cells and Fibroblasts Generate Fibroblast Activities Allied with Hypertrophic Scarring
ABSTRACT : The prominent inflammatory cell identified in excessive scarring is the mast cell. Hypertrophic scar exhibits myofibroblasts derived from the transformation of fibroblasts, increased collagen synthesis, and stationary nonmigratory resident cells. The co-culture of fibroblasts with an established rat mast cell line (RMC-1) was used to explore the hypothesis of whether mast cells through gap junctional intercellular communications guide fibroblasts in promoting excessive scarring.
: Human dermal fibroblasts were cultured alone or co-cultured with RMC-1 cells as is or with either blocked gap junctional intercellular communications or devoid of cytoplasmic granules. Collagen synthesis was analyzed by dot blot analysis; immunohistology identified myofibroblasts, and a cell migration assay measured fibroblast locomotion.
: Fibroblasts co-cultured with RMC-1 cells transformed into myofibroblasts, had increased collagen synthesis, and showed retarded cell migration. In contrast, RMC-1 cells unable to form gap junctional intercellular communications were similar to fibroblasts alone, failing to promote these activities. Degranulated RMC-1 cells were as effective as intact RMC-1 cells.
: Mast cells induce fibroblast activities associated with hypertrophic scarring through gap junctional intercellular communications. Eliminating the mast cell or its gap junctional intercellular communications with fibroblasts may be a possible approach in preventing hypertrophic scarring or reducing fibrotic conditions.
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ABSTRACT: Most cutaneous wounds heal with scar formation. Ideally, an inconspicuous normotrophic scar is formed, but an abnormal scar (hypertrophic scar or keloid) can also develop. A major challenge to scientists and physicians is to prevent adverse scar formation after severe trauma (e.g. burn injury) and understand why some individuals will form adverse scars even after relatively minor injury. Currently many different models exist to study scar formation, ranging from simple monolayer cell culture to 3D tissue engineered models even to humanized mouse models. Currently these high/ medium throughput test models avoid the main questions referring to why an adverse scar forms instead of a normotrophic scar and what causes a hypertrophic scar to form rather than a keloid scar. Also, how is the genetic pre-disposition of the individual and the immune system involved. This information is essential if we are to identify new drug targets and develop optimal strategies in the future to prevent adverse scar formation. This viewpoint review summarizes the progress on in vitro and animal scar models, stresses the limitations in the current models and identifies the future challenges if scar free healing is to be achieved in the future. This article is protected by copyright. All rights reserved.Experimental Dermatology 04/2014; 23(6). DOI:10.1111/exd.12419 · 4.12 Impact Factor
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ABSTRACT: Dexamethasone, a common therapy for reducing hypertrophic scar, sometimes fails. However, in cell culture, all dexamethasone-treated fibroblasts die. In co-cultures, gap junction intercellular communications between mast cells and fibroblasts promote profibrotic activities. Does the co-culture of mast cells with fibroblasts prevent dexamethasone-induced fibroblast death? Survival of fibroblasts co-cultured with RMC-1 cells, a rat mast cell line, receiving dexamethasone was studied. RMC-1 cells pretreated with a secretagogue that degranulated mast cells and/or with a long-acting gap junction intercellular communications inhibitor were compared to untreated RMC-1 cells co-cultured with fibroblasts and dexamethasone. Fibroblasts alone treated with dexamethasone all died in 3 hours. Fibroblasts co-cultured with intact RMC-1 cells or with degranulated RMC-1 cells in dexamethasone all survived. No fibroblasts survived, co-cultured with RMC-1 cells unable to form gap junction intercellular communications with fibroblasts. Dexamethasone-treated fibroblasts, forming gap junction intercellular communications with mast cells, may explain why dexamethasone therapy sometimes fails. Gap junction intercellular communications between scar mast cells and fibroblasts or myofibroblasts apparently blocks the death of these cell populations. Preventing gap junction intercellular communications between mast cells and fibroblasts by including anti-gap junction intercellular communication agents may enhance the effectiveness of steroid therapy in treating excessive scarring.Plastic and Reconstructive Surgery 05/2014; 133(5):638e-44e. DOI:10.1097/PRS.0000000000000103 · 3.33 Impact Factor
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ABSTRACT: The repair of wounds usually terminates with a scar. The healing from a severe tissue loss can create a new clinical problem, excessive scarring. Approaches to prevent excessive scarring will optimize the repair process. Controlling gap-junction communications between cells and/or the transport of the proteins that form gap junctions offers new approaches for controlling this problem. Gap-junctional intercellular communication (GJIC) requires hemichannels, connexon structures, embedded in the plasma membrane of coupled cells. The connexon is composed of six proteins from the connexin (Cx) family. The docking of connexons between the neighboring cells forms a gated channel, where small molecules can pass directly between the cytoplasm of cells. In wound repair, GJIC between fibroblasts in granulation tissue advances wound repair. Also, the GJIC between mast cells and fibroblasts during the remodeling phase of repair may explain how mast cells promote excessive scarring. In addition, Cx can affect transforming growth factor beta (TGF-β) intracellular signaling through its shared binding site on microtubules within fibroblasts. Can excessive scarring be controlled through limiting the local amassing of mast cells or preventing their interactions with wound fibroblasts through GJIC? The prevention of the accumulation of mast cells in granulation tissue or interfering with their communications via GJIC with fibroblasts offers new approaches for preventing excess scarring. The association of Cx with microtubules altering TGF-β signaling presents a new target for improving the quality of repair as well as the deposition of unnecessary fibrosis.05/2013; 2(4):113-121. DOI:10.1089/wound.2012.0414