Abstract / Summary
Background and Objectives: Stromal vascular fraction (SVF) is increasingly used for erectile dysfunction (ED), but published human data are very limited and no study has related the cellular composition of the administered product to clinical outcomes. We evaluated the outcomes of SVF added to phosphodiesterase type 5 inhibitors (PDE-5I) in patients unresponsive to PDE-5I alone, and identified factors associated with treatment response. Materials and Methods: Records of 93 consecutive patients with vasculogenic ED who underwent autologous SVF injection in addition to PDE-5I at a single andrology clinic were reviewed retrospectively. Total nucleated cell concentration and viability were measured in every product. International Index of Erectile Function-5 (IIEF-5), Erection Hardness Score (EHS) and penile colour Doppler ultrasonography were assessed at baseline and at 6 and 12 months. The primary outcome was an EHS of 3 or 4 at 6 months. Multivariate logistic regression and receiver operating characteristic (ROC) analysis were used to identify factors associated with response. Results: A total of 66 of 93 patients (71.0%, 95% CI 61.1–79.2) reached an EHS of 3 or 4 at 6 months; no patient had reached this threshold at baseline. Mean IIEF-5 rose from 10.1 at baseline to 16.2 at 6 months and 15.1 at 12 months (p = 0.001); peak systolic velocity and end-diastolic velocity both improved at 6 months (p = 0.001 for both). Non-responders were older (63.8 vs. 52.7 years), had longer ED duration (6.7 vs. 3.0 years), higher HbA1c (6.8 vs. 6.3) and more diabetes (66.7% vs. 42.4%). Product cell concentration (2.5 vs. 1.8) and viability (88.0% vs. 82.5%) were higher in responders (p = 0.001 for both). On multivariate analysis, older age (OR 1.88 per year, 95% CI 1.19–2.96), higher HbA1c (OR 13.23 per unit, 95% CI 1.65–105.87) and lower product cell viability (OR 0.38 per percentage point, 95% CI 0.20–0.73) were independently associated with non-response. On exploratory ROC analysis, cell viability discriminated responders from non-responders with an area under the curve of 0.925 (95% CI 0.872–0.977) at a threshold of 85.3%. Conclusions: In this uncontrolled retrospective series, SVF added to PDE-5I was associated with improved erectile function in approximately seven of ten patients. The cell viability of the administered product was independently associated with outcome, a finding that cannot be attributed to placebo response and that identifies product quality as a modifiable variable. These hypothesis-generating results require confirmation in controlled prospective studies.