The Effects Of Continuous Elastic Outside Distraction On The Expression Of Basic Fibroblast Growth Factor And Transforming Growth Factor-beta1in The Nipple Of Minipig Model

Objective: To observe the effect of continuous elastic outside distraction on theexpression of basic fibroblast growth factor （b-FGF） and transforming growth factor-beta1（TGF-β₁） in the female porcine nipples. To further investigate the mechanism ofcontinuous elastic outside distraction stimulation the proliferation of supporting tissue innipples, so as to provide the theory basis for better using and improvement this techniqueto correct inverted nipples. Methods: Three3-month-old female minipigs were employed,each of them has12nipples （all to36nipples）. The nipples of each pig were numberedfrom1to12, four nipples of each minipig （from No.1to No.4） were used as controlgroup, while the other eight nipples were continuously distracted with prefabricatedinstruments. One nipple without distraction and two distracted nipples of each minipigwere excised at2,4,8, and12weeks after operation under general anesthesiarespectively. The excised nipples were fixed in10%neutral formaldehyde solution for48hours, and routinely prepared for embedding in paraffin. The samples were mounted onultramicrotome into4μm thickness sections for HE staining to observe the histologicalchange, and immunohistochemical staining to observe the expression of b-FGF andTGF-β₁. Image analysis software was employed for quantitative analysis. Results: Inhistology, fibroblasts and capillaries in distracted groups significantly proliferated thanthe control group and the fibroblasts arranged closer in directionality. Inimmunohistochemical staining, b-FGF and TGF-β₁expressions of all groups werepositive, but those of control groups were weaker than those of the distracted groups atany time. And the integral optical density of b-FGF and TGF-β₁in positive cellscompared with the control group at each time were significantly different （p＜0.01）. The expression of b-FGF increased gradually after tracted and reached the peak at4weeks,then it started to decrease, but it was still stronger than that in control group at each time.The expression of b-FGF was strongly positive in duct glandular epithelial cells andvascular smooth muscle cell, weaker but widespread in the area of fibroblasts, and washardly positive in the vascular endothelial cell. There are significant difference （p＜0.05）in the expression of b-FGF between4w and12w group. The expression of TGF-β₁wasincreased to the peak after2weeks, then to decrease, but it was still stronger than that incontrol group at each time. The expression of TGF-β₁was strong in duct glandularepithelial cells and fibroblasts, but weaker in vascular endothelial cells, while it washardly positive in vascular smooth muscle cells. The expression of TGF-β₁in8w and12w groups compared with2w group had statistical significance （p＜0.05）. Theexpressions of b-FGF and TGF-β₁had a positive correlation during the traction.Conclusion: Continuous elastic outside distraction can promote female minipig nipple tosynthesis and secrete b-FGF and TGF-β₁. The two growth factors interact with each otherto provoke the proliferation of supporting tissue by promoting the proliferations ofcollagen and blood vessels. This technique which is stably effective by providingcontinuous power is a good way to correct inverted nipple. It is worth popularizing.