LIPOSUCTION-DERIVED HUMAN FAT USED FOR VASCULAR GRAFT SODDING CONTAINS ENDOTHELIAL-CELLS AND NOT MESOTHELIAL CELLS AS THE MAJOR CELL-TYPE

Purpose: Endothelial cell transplantation has been suggested as a meth od to improve the patency of prosthetic grafts used for vascular recon struction. A major technical concern of all cell transplantation studi es has been the purity of cells in the primary isolate used for subseq uent transplantation. Accordingly we have evaluated the cellular const ituents of liposuction-derived human fat with immunocytochemistry and scanning electron microscopy. Methods: Samples of liposuction-derived human fat were processed for immunohistochemistry and subsequently sta ined for the presence of von Willebrand factor (vWF), alpha-smooth mus cle cell actin, cytokeratin (peptide 18), and the endothelial cell-spe cific marker EN4. We also performed histochemistry studies on the cell s derived from this fat after collagenase dispersion of the liposuctio n fat. Results: Immunohistochemistry revealed that 86.1% of the cells in intact, liposuction-derived fat express vWF, whereas 5.7% of the ce lls exhibited alpha-smooth muscle cell actin, and 1.0% expressed the m esothelial cell-related antigen, cytokeratin peptide 18. Expression of EN4 was found in 89.6% of the cells counted in intact fat. After dige stion of fat with collagenase and centrifugal separation of adipocytes from vascular and stromal cells, the expression of vWF, alpha-smooth muscle cell actin, and cytokeratin was 77.5%, 5.8%, and 2.1%, respecti vely. EN4 expression was observed in 74.6% of the isolated cells. Thus most cells present in liposuction-derived fat, even before tissue dig estion and cell isolation, were characterized as endothelium. Although other cells common to mesodermally derived tissue were identified (e. g., adipocytes, smooth muscle cells, and mesothelium), they represente d a minor fraction of the total cells present. On isolation, the numbe r of cells expressing vWF- and EN4-specific antigens was less than tha t observed in intact fat. Conclusions: This finding suggests that a po rtion of cells reacting with antibodies in situ lose vWF and EN4 stain ing during the isolation procedure. Unlike omentum, liposuction-derive d fat predominantly contains adipocytes and endothelial cells. On dige stion of liposuction-derived fat and separation of cells, vascular end othelial cells represent the major cellular component.