Abstract
Objective To investigate the biological changes after transplantation of expanded skin and discuss the mechanism of skin retraction for further improving the clinical efficacy.Methods Eight adult dogs were used.On the back of each animal,4 rectangular expanders were implanted beneath the skin and panniculus carnosus bilaterally.Final injection was terminated through weekly injection over an 8-week period.Dogs were divided into 4 groups (n =2 each).At 3rd week,6th week,3rd month and 6th month after inset of the flaps respectively,the skin-flap area was measured with histological examination stained with hematoxylin and eosin (HE),ultrastructural observation under transmission electron microscope,and the expression level of α-smooth muscle actin (α-SMA) mRNA and protein.Results The epidermis and dermis of expanded flap returned to normal 6 months after the flap inset.The ultrastructural study revealed the following changes.In the epidermis,the intracellular spaces in all layers of expanded epidermis were significantly reduced.The expanded dermis contained large bundles of compacted collagen fibers which lined in disordering fibroblasts.A few myofibroblasts were seen in deeper part of the dermis.Three months post-inset,the fibroblasts functioned normally.Collagens lined themselves regularly and myofibroblasts disappeared.The α-SMA mRNA expression in skin expansion was significant between high expression (1.204 ± 0.011) at 3rd week and low expression (0.910 ± 0.008) at 3rd month.The expression of protein was same between (1.533 ±0.012) at 3rd week and (0.519 ±0.007) at 3rd month.The change trend of α-SMA mRNA and protein was consistent (P ＜ 0.05).Conclusion The changes after skin expansion returned to normal after 6 months,expanded skin had certain degree of contraction after transplantation,which may be related to the appearance and persistence of myofibroblasts in dermis. Key words: Skin ; Tissue expansion ; Myofibroblast; Histology
Published Version
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