Rat aortas were decellularized and the lumens were seeded with TSP2 KO fibroblasts and cultured before a second decellularization. SEM images show an unmodified graft (A) compared to TSP2 KO ECM in the lumen after 3 (B), 5 (C), 7 (D), and 10 (E) days in culture (Hitachi). While a complete, but thin ECM can be found as early as 3 days, the most mature modification is found after 10 days. Presence of TSP2 KO ECM was confirmed by immunofluorescent detection of fibronectin. Very little fibronectin was detectable on unmodified grafts (F, green color), while fibroncetin convered a significant portion of the TSP2 KO ECM modified grafts at 10 days (G). Quantification of fibronectin coverage at all time points was performed, showing significantly higher fibronectin coverage on ECM-modified grafts, with the highest percent coverage found at 10 days (H). *p < 0.05, **p < 0.01 compared to unmodified. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)