Histological and Urodynamic Effects of Autologous Stromal Vascular Fraction Extracted from Fat Tissue with Minimal Ex Vivo Manipulation in a Porcine Model of Intrinsic Sphincter Deficiency

Abstract

To evaluate the healing abilities of autologous stem cell therapy (stromal vascular fraction) prepared from adipose tissue we used an automated system without an exvivo culture phase in a pig model of intrinsic sphincteric deficiency. A total of 15 pigs underwent endoscopic section of the urethral sphincter. Animals were then randomly assigned to 3 groups, including 1) controls without stromal vascular fraction injection, 2) early injection with stromal vascular fraction 2 to 3 days after section and 3) late stromal vascular fraction injection delivery 30 days after injury. Extraction and stromal vascular fraction injection were performed as a single procedure. The stromal vascular fraction was characterized by flow cytometry. Mesenchymal stem cell-like cells were enumerated by clonogenicity (cfufibroblast) assay. Study end points included histological assessment of the urethral injury surface and urodynamics to determine maximum urethral pressure. Flow cytometry analysis revealed a mesenchymal stem cell-like phenotype in a mean ± SD of 47.3% ± 11.8% of stromal vascular fraction cells. The cfu fibroblast frequency was 1.3 to 6.6/100 stromal vascular fraction cells (1.3% to 6.6%). Stromal vascular fraction injection was associated with a reduction of the urethral injury surface in the early and late injection groups compared with the respective controls (7% vs 17% and 1% vs 13%, p = 0.050 and 0.029, respectively). On day 30 after injection maximum urethral pressure wassignificantly higher in the injected groups than in the control group, that is 64% vs 50% of maximum urethral pressure on day 0 (p = 0.04). These data demonstrate the ability of an autologous stromal vascular fraction to improve the urethral healing process in a large animal model of intrinsic sphincteric deficiency.