Experimental And Clinical Research On The Effect Of Epidermal Growth Factor In Tissue Expansion

Tissue expansion as a means for providing additional tissue for soft-tissue reconstruction has been widely used in plastic surgery. Histological observations after tissue expansion have proved that epidermal hyperplasia, which is caused chiefly by cell layers in basal and suprabasal layers, contributes to creation of new tissue in tissue expansion. Therefore, the study was performed with a vitro model of expansion in which keratinocytes were cultured on a flexible-bottom membrane that could be mechanically deformed by vacuum, by which cell experience average 10% strain. We investigate the effect of cyclic (3 cycles/min,250mmHg) strain on human kerationocyte in vitro. Contorl cells were cultured on the same plates in the same incubator but not subjected to strain. Keratinocytes from passage 3-4 (5,000 cells/cm2 )were respectively seeded equally on flexible membranes coated with type I collagen of cyclic strain group and control group and were incubated at 37 C in a 5%CO2 incubator for 72hr which were cultured in serum-free medium.The medium were collected respectively after 12-72 h of stretch. EGF concentrations were determined using an enzyme-linked immunosorbent assay. We found that the secretion levels of EGF produced in keratinocyte varied between stretched and control cells. EGF levels after 36h increased significantly, reaching 16.03pg/ml after 36h, and couldExperimental and Clinical Research on the Effect of Epidermal Growth Factor in Tissue Expansionnot determined apart from 36h after stretch. Conversely, EGF levels could not determined during 12-72H in control group. Meanwhile, with all but mechanical strain there was a concomitant stimulation of EGF secretion. After 72h of strech keratinocytes grew well. Conversely keratinocytes in the control group had died after 72h.These findings suggest that cyclic pressure promotes proliferation and secreation of EGF of cultivated epidermal cells.EGF producted by mechanical stress in vivo may play an important part in tissue expansion. As we know that tissue expansion is a prolonged process, typically requiring at least 6 weeks to complete. Recently interst has focous on shortening the period. Some investigators have report several agents that speed up tissue expansion. In the current study we investigated the effect of rapid tissue expansion using topically epidermal growth factor (EGF) application. The experiment performed on domestic pig was designed to evaluate the effectiveness of EGF application. The pigs underwent rapid expansion as a model of tissue expansion. Experiment was divided into four groups: a base cream group and a group I and an experimental group II and an experimental group III. Each donor site on each pig was applied to the skin overlying the expander with different cream daily. The donor sites were photographed daily .The percent expansion and final volumes were calculated after expansion. At the same time, biopsies were stained with hematoxylin and eosin to observe the architecture of the stretching skin. A statistically significant difference was also found between the average total inflated volumes between each group. Theaverage inflated total volume was 195.5000 cc±51.61880 in control group, and 227.5000 cc±77.5134 in group I and 241.8333 cc±26.2421 in group II and 241.2000 cc±25.3515 in group III. The average expansion and volumn infused during 12 days in the experimental group I and the experimental group II significantly exceeded those of other groups. Cell proliferation was evident in the experimental group II and the experimental group III compared with other groups. Application topically with epidermal growth factor significantly facilitated the epidermal regeneration in tissue expansion. The function of EGF is independent to activation of mitogen activated protein kinases (MAPK). The study was to explore the molecular mechanisms through observing and analysising the distribution and expression of the phosphorylated extracellular signal- regulated kinase (ERK) as a branch of MAPK in expanded skin and non-...