Abstract Body: Background: Peripheral Artery Disease (PAD) is the leading cause of limb pain, non-healing ulcers and amputation, increasing the risk of heart attack and stroke. Diabetes is a major risk factor. Women with diabetes-associated PAD experience greater graft failure and limb loss, functional impairment, reduced long-term survival after revascularization and increased post-surgical mortality when compared to men. Why this is the case is unclear.

Aim: To identify whether sexual dimorphisms in endothelial cell (EC) function(s) impact diabetes-associated PAD pathophysiology.

Methods: Male and female Apoe^-/- mice were rendered diabetic with streptozotocin. Hindlimb ischemia (HLI) was performed 18 w later and blood flow to lower limbs monitored. Mice were euthanised 2w post-HLI. Plasma chemistries were measured. Angiogenesis, arterial relaxation, and oxidative stress were examined by histology, myography and qPCR, as measures of EC function. Gastrocnemius from mice was subjected to single cell RNA sequencing. ECs were exposed to high glucose over 14d to assess changes to respiration by sex. Diabetes-associated PAD patients undergoing below- or above-knee amputation were recruited; muscle, artery, and blood plasma collected. Stable microvessel numbers, arterial relaxation and gene changes in oxidative stress markers were assessed. Blood plasma F₂ isoprostane levels were measured.

Results: Plasma glucose levels and glucose tolerance were equivalent between sexes in mice. Diabetic female tissues had impaired angiogenesis and arterial relaxation. Limb tissues also had increased expression of NADPH-oxidases (NOXs) in response to HLI. Single cell RNA sequencing revealed 3 EC clusters. There was enriched suppression of Complex I mitochondrial genes in female ECs. ECs exposed to high glucose for 14 d had reduced respiration, associating with reduced mitochondrial gene expression and increased NOXs. Amputation tissues from female PAD patients had ~50% reduction in stable microvessel numbers and reduced arterial relaxation compared to males. Female patient tissues also had increased oxidative stress and reduced expression of Complex I genes.

Conclusions: EC mitochondrial dysfunction could be the driving force for poorer vascular health in female patients. This may explain why women with diabetes-associated PAD have worse outcomes to treatment. Improving EC mitochondrial function(s) could represent a target for sex-specific therapy in PAD.