The Expanded Prefabricated Adipose Tissue Constructed By External Volume Expansion

Objective:Soft tissue defect caused by congenital malformation,surgery,accidental trauma,or others reasons is a common problem in the clinical work in plastic surgery.Reconstructing the soft tissue defect has been a great challenge to plastic surgeons,therefore,to find suitable source of soft tissue is a tricky subject.More and more evidences show that mechanical force can produce tissue regeneration effect,and a series of device have been applied to clinic on the basis of this theory.Skin expander is used widely in plastic surgery under tissue expansion techniques,which demonstrate that mechanical force can promote cell proliferation and increase the area of skin tissue.In recent years,breast external expansion device via vacuum have been invented by an American plastic surgeon.Continuous using for a period of time can produce stable breast enlargement according to clinical application.The tissue growth produced by Brava device gives us a lot of inspiration,which offeres us a novel strategy to induce tissue regeneration with a noninvasive method,in view of this advantage,it has more value to clinic.In this study,we design a rat model that applies external volume expansion above groin fat flap to confirm the adipose tissue regeneration effect of mechanical force.Meanwhile,we also plan to investigate the change of adipose tissue after external volume expansion at a cellular and molecular level in the purpose of uncovering the possible mechanism of tissue regeneration by this way.Methods:There are two sections in this study.1.The histological studies of expanded prefabricated adipose tissue(EPAT)constructed by external volume expansionFirstly,we find the rat model and then investigate the change of fat flap volume after undergo different period of external volume expansion to confirm the tissue growth.Secondly,we investigate the histological change with HE-staining,immunofluorescence and PT-PCR.Finally,we collect the data and analyze it through appropriate statistical methods.2.The mechanism of adipose tissue regeneration by external volume expansionWe detect the expression of inflammatory cytokine in adipose tissue behind different duration of external volume expansion,and investigate the role of inflammatory in tissue growth by external volume expansion.Finally,collect the data and analyzing it through appropriate statistical methods.Results:1.The fat flap showed a normal appearance and structure after external volume expansion,and the volume of it also had a significant enlargement.The adipose tissue flap expanded from 1.633±0.163 ml to 2.15±0.350 ml after 4 weeks of expansion,and 2.917±0.365 ml at 8 weeks,3.717±0.337 ml at 12 weeks.However,we observed a bit of shrink after removing the expansion device for 4 weeks.After expansion,we also observed the increase of fiber connective tissue and microvascular density by HE-staining.Immunofluorescence analysis showed that both microvascular density and proliferative cells were increased after different duration of external volume expansion,and fell back when removing the expansion device.This results suggested that external volume expansion can induce vascular remodeling and cell proliferation.Meanwhile,the expression of PPAR? and CEBP? gene showed a similar change pattern,it suggested that external volume expansion can up-regulate the process of adipogenic differentiation.2.The expression of inflammatory cytokine such as IL-1?,IL-6,TNF-?,MIF in adipose tissue behind external volume expansion were up-regulated at 1 week,and dropped at 4,8,12 weeks.At last,it fell back to the baseline after stopping expansion.Combined with the result of the first section,inflammation may be involved in the regulation of adipose tissue regeneration.Conclusions:1.External volume expansion can activate the cell proliferation,angiogenesis and adipogenesis differentiation,therefore,inducing the growth of adipose tissue,and produced expanded prefabricated adipose tissue with a small fat flap.2.The growth of adipose tissue by external volume expansion is induced by a variety of mechanisms,inflammation may involved in the regulation of the adipose tissue regeneration through the inflammatory cytokine and inflammatory cells.