LAUSR

The optimal fat processing technique of fat grafting has not been determined. We have proved the importance of washing lipoaspirate to remove blood, but the necessity of washing when there is no obvious bleeding during liposuction is not clear. The purpose of this study is to further investigate the effect of washing on fat graft survival and the underlying mechanisms, from the perspective of inflammation, oxidative stress and apoptosis. To exclude the influence of blood, de-erythrocyte infranatant (dEI) isolated from lipoaspirate was obtained. Purified fat processed by cotton pad filtration mixed with dEIs after sedimentation (sedimentation group), washing (washing group) or phosphate buffer solution (control group) was transplanted to nude mice subcutaneously. Samples were harvested at 1 day and 1, 3, 8 weeks after transplantation. Volume and weight retention, histologic examination, immunostaining of perilipin-1, CD31, CD45 and Ly6g, mRNA expression of PPAR‐γ, C/EBPα, VEGF, bFGF, IL-6, IL10, TNF-α, TGF-β, Bax and Bcl-2, and protein contents of 8-iso-PGF2α, IL-6, IL10, TNF-α and TGF-β were all compared among groups. After transplantation, volume and weight retention, histologic scores, viable adipocytes and vascularization were all improved in the washing group, with increased expression of adipogenic and angiogenic genes. Compared with the sedimentation group, the washing group had milder inflammation, lower levels of oxidative stress and apoptosis. Washing lipoaspirate to eliminate mixed components can improve fat graft survival and promote adipogenesis and angiogenesis, possibly by relieving inflammation, reducing oxidative stress injury and inhibiting apoptosis. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of 47 these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266.