Arterial and Venous Identity during Angiogenesis in Health and Diabetes

Background: Vascular complications of diabetes are due in part to impaired angiogenesis. The extent to which these problems are due to disturbed identification of newly formed endothelial cells (EC) as ‘arterial’ or ‘venous’ (i.e. AV specification), recruitment of perivascular cells (PVC), or perturbed growth factor expression, had not been addressed. Methods Results: Using microvascular preparations from type-I diabetes (T1D) and non-diabetic animals transplanted into T1D and non-diabetic hosts, we show that mice T1D have impaired vessel AV specification, displaying ubiquitous expression of arterial marker ephrin-B2, loss of hierarchical organization, and reduced PVC coverage. Blockage of PVC recruitment in normoglycemic mice did not affect blood flow, but recapitulated the vascular immaturity of T1D, implicating PVCs in AV-specification. The latter occurred with downregulated Jagged1 and Notch3, key modulators of EC-PVC interactions. Co-cultures showed that PVCs induce arterial identity by increasing ephrin-B2, while decreasing venous marker eph-B4. This was antagonized by hyperglycemia or by inhibiting Jagged1 in EC. Vessel sprouting and consequent loss of AV identity was also dependent on hepatocyte growth factor (HGF) secreted from PVCs, with HGF levels decreased in T1D. Vessel anastomosis and implant perfusion was delayed in T1D,suggesting a role for HGF in inosculation. Finally, EC exposed to pulsatile stretch (mimicking pulsatile flow) upregulated platelet-derived growth factor-b (PDGFb), which was blunted by hyperglycemia. Importantly, microvessels from mice with T1D displayed normal PVC coverage, hierarchical organization and Jagged1/Notch3 expression after implantation into non-diabetic hosts, indicating no ‘metabolic memory’. Conclusion: We show that AV identity is impaired in T1D, due to abnormal PVC recruitment, dysregulated expression of HGF (by PVC) and PDGFb (by EC). These findings are associated with disordered Jagged1-Notch3 signaling, and lead to ineffective vascular connections with the host, which can be normalized in non-diabetic hosts.Ph.D.2019-12-19 00:00:0