Mechanical Manipulation of Fat: From Lipoaspirate to SVF Concentrate.

Abstract

<h4>Background</h4>The adipose stromal vascular fraction (SVF) is a mesh of connective tissue, capillaries, stem cells and supportive cells which may have regenerative properties. Attention is shifting from enzymatic isolation and expansion of the stem cell population alone, to the benefit of preserving the SVF as a functional unit. Enzymatic breakdown of lipoaspirate is time consuming and involves use of foreign substances. We have established a simple procedure for perioperative mechanical isolation of SVF. This study investigates how mechanical fractionation and centrifugation changes the qualities of lipoaspirate.<h4>Methods</h4>Three derivatives of manipulated fat were defined: A: Washed and centrifuged lipoaspirate (Coleman fat), B: Mechanically fractionated Coleman fat (nanofat), and C: SVF concentrate obtained by hard centrifugation of nanofat. The end products were characterized by flow cytometry, proliferation capacity measured as time to confluence, and histological and cytological characteristics.<h4>Results</h4>Vigorous mechanical fractionation of dry lipoaspirate to nanofat still preserves viable stem cells. A sedimented SVF concentrate from centrifugated nanofat has a high stem cell concentration. A nanofat "mayonnaise problem" may need a salvage procedure to enable centrifugal separation. Proliferation is significantly but marginally delayed in SVF cells from fractionated fat versus non-manipulated lipoaspirate. Histology and cytology demonstrate the presence of micrografts in SVF concentrate, i.e. capillary fragments with SVF cells attached.<h4>Conclusion</h4>SVF concentrate manufactured by mechanical fractionation and centrifugation contains viable cells capable of proliferation. SVF concentrate contains vascular micrografts which may be injected alone for regenerative purposes or added to non-manipulated lipoaspirate for stem cell enriched fat transfer.