Cell-derived TSP2 KO ECM does not support platelet aggregation. DF-derived ECM was prepared in vitro following decellularization of long-term (7 days) cultures. Mouse platelets were exposed to either WT or TSP2 ECM for 30 minutes. (A-C) Representative images of platelets visualized by rhodamine-phalloidin (red color) on WT (A) or TSP2 KO ECM are shown. Detection of FN (green color) confirms the retention of ECM during the duration of the experiment (Zeiss). (C) Quantification of platelet area by ImageJ showed reduced platelet aggregation on TSP2 KO ECM. n = 5; *P < .05. (D) Incubation of TSP2 KO ECM with 5 μg/mL TSP2 (detected via immunofluorescence, green color) overnight did not appear to increase platelet aggregation on TSP2 KO ECM.