The construction of expanded prefabricated adipose tissue (EPAT) using an external volume expansion (EVE) device.

Background: Multiple studies have demonstrated that mechanical forces promote the growth of adipose tissue. However, the mechanism of adipose tissue regeneration induced by mechanical forces remains unclear. Methods: In an experiment using rats, prefabricated adipose tissue with a vessel pedicle was expanded using an external volume expansion (EVE) device. The volume of fat flaps was tested at different time points. Cell proliferation and angiogenesis were analyzed using immunofluorescence. The expression of adipogenic genes and inflammatory cytokines were evaluated using real-time polymerase chain reaction analysis and enzyme-linked immunosorbent assay, respectively. Results: There were more CD31+ cells and Ki67/CD34+ cells in the experimental group than in the control group. The number of Ki67/CD34+ cells peaked at 1-4 weeks. However, the expression levels of PPAR[gamma] and CEBP[beta] were highest from 4-12 weeks in the experimental group. Compared with the control group, the experimental group showed more pro-inflammatory cytokines: IL-1[beta], IL-6, TNF-[alpha], and macrophage migration inhibitory factor (MIF). Conclusions: The construction of expanded prefabricated adipose tissue by mechanical forces is a dynamic and complex process. Mechanical forces promoted cell proliferation and angiogenesis in the early stage of adipose tissue regeneration (before 4 weeks) and induced adipogenic differentiation at a later stage (after 4 weeks) through upregulation of MIF, which provided an adipogenic inductive microenvironment. (C)2017American Society of Plastic Surgeons

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