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A novel immune competent murine hypertrophic scar contracture model: A tool to elucidate disease mechanism and develop new therapies
Author(s) -
Ibrahim Mohamed Magdy,
Bond Jennifer,
Bergeron Andrew,
Miller Kyle J.,
Ehanire Tosan,
Quiles Carlos,
Lorden Elizabeth R.,
Medina Manuel A.,
Fisher Mark,
Klitzman Bruce,
Selim M. Angelica,
Leong Kam W.,
Levinson Howard
Publication year - 2014
Publication title -
wound repair and regeneration
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.847
H-Index - 109
eISSN - 1524-475X
pISSN - 1067-1927
DOI - 10.1111/wrr.12238
Subject(s) - hypertrophic scar , sirius red , vascularity , immune system , medicine , contraction (grammar) , pathology , contracture , anatomy , fibrosis , surgery , immunology
Hypertrophic scar ( HS c) contraction following burn injury causes contractures. Contractures are painful and disfiguring. Current therapies are marginally effective. To study pathogenesis and develop new therapies, a murine model is needed. We have created a validated immune‐competent murine HS c model. A third‐degree burn was created on dorsum of C 57 BL /6 mice. Three days postburn, tissue was excised and grafted with ear skin. Graft contraction was analyzed and tissue harvested on different time points. Outcomes were compared with human condition to validate the model. To confirm graft survival, green fluorescent protein ( GFP ) mice were used, and histologic analysis was performed to differentiate between ear and back skin. Role of panniculus carnosus in contraction was analyzed. Cellularity was assessed with 4′,6‐diamidino‐2‐phenylindole. Collagen maturation was assessed with Picro‐sirius red. Mast cells were stained with T oluidine blue. Macrophages were detected with F 4/80 immune. Vascularity was assessed with CD 31 immune. RNA for contractile proteins was detected by quantitative real‐time polymerase chain reaction (q RT ‐ PCR ). Elastic moduli of skin and scar tissue were analyzed using a microstrain analyzer. Grafts contracted to ∼45% of their original size by day 14 and maintained their size. Grafting of GFP mouse skin onto wild‐type mice, and analysis of dermal thickness and hair follicle density, confirmed graft survival. Interestingly, hair follicles disappeared after grafting and regenerated in ear skin configuration by day 30. Radiological analysis revealed that panniculus carnosus doesn't contribute to contraction. Microscopic analyses showed that grafts show increase in cellularity. Granulation tissue formed after day 3. Collagen analysis revealed increases in collagen maturation over time. CD 31 stain revealed increased vascularity. Macrophages and mast cells were increased. q RT ‐ PCR showed up‐regulation of transforming growth factor beta, alpha smooth muscle actin, and rho‐associated protein kinase 2 in HS c. Tensile testing revealed that human skin and scar tissues are tougher than mouse skin and scar tissues.