Abstract 285: Thrombospondin-5 Is Necessary For Males But Not Females In Hindlimb Ischemia Recovery

Introduction: Ameliorating critical limb ischemia (CLI), in part, relies on arteriogenesis and angiogenesis. We have shown thrombospondin-5 (TSP5) is proangiogenic in vitro. The role of TSP5 in CLI and the differences between males and females are unknown. Hypotheses: blood flow recovery, arteriogenesis and angiogenesis after limb ischemia is diminished (1) in TSP5 null mice compared to controls, and (2) in female compared to male TSP5 null mice. Methods: 14-16 week-old wild type (WT; C57Bl6) or TSP5 null male and female mice underwent left femoral artery ligation and transection (n=6-9/group). Laser Doppler data was collected preoperative, post ligation and at sacrifice (day 14). Blood flow recovery was expressed as a ratio of ischemic/non-ischemic limb. Immunohistochemistry was performed using anti-α-smooth-muscle-actin on the vastus lateralis to quantify arteriogenesis and anti-CD31 on the gastrocnemius to quantify angiogenesis. Arteriole and capillary density were determined by vessel counts/5HPF. Data was analyzed by ANOVA with post hoc testing, with p<0.05 being significant. Results: TSP5 null mice had decreased blood flow recovery in males (WT 0.85 ± 0.04 vs TSP5 0.48 ± 0.06, p<0.001) and females (WT 0.63 ± 0.07 vs TSP5 0.36 ± 0.04, p<0.01). No difference in flow recovery was seen between male and female TSP5 nulls (male 0.48 ± 0.06 vs female 0.36 ± 0.04 p<0.14). Arteriogenesis was impaired in male TSP5 null mice (WT 3.91 ± 0.24 vs TSP5 2.6 ± 0.42, p<0.02), but increased in females (WT 2.5 ± 0.26 vs TSP5 4.35 ± 0.73, p<0.01). Angiogenesis was decreased in TSP5 null males (WT 10.9 ± 0.93 vs TSP5 7.03 ± 0.84, p<0.01), but not females (WT 6.1 ± 0.50 vs TSP5 5.6 ± 0.80 p<0.9). In contrast, flow recovery, angiogenesis and arteriogenesis was decreased in WT females compared to WT males (p< 0.05). Conclusions: Our findings suggest TSP5 is relevant to vascular remodeling following hindlimb ischemia with a divergence in mechanism between males and females. TSP5 is necessary in males for arteriogenesis and angiogenesis. TSP5 in females may be supressive of arteriogenesis and has no effect on angiogenesis. Further investigation into these sexually dimorphic adaptive processes may lead to specific targeted CLI treatments.