The leading cause of death in people with type 2 diabetes (T2D) and/or obesity is atherosclerotic cardiovascular disease (ASCVD). Arterial damage and repair are regulated by mechanisms of vessel homeostasis, which include vasculogenesis (de novo blood vessel synthesis), angiogenesis (vessel formation from pre-existing vessels), and arteriogenesis (re-modelling of collateral vessels). Key cellular modulators of these processes include hematopoietic stem/progenitor cells (HPC) and their myeloid progenies, together referred to as vascular regenerative cells.~An established and innovative multi-parametric flow cytometry assay that utilizes lineage-specific cell surface marker expression and aldehyde dehydrogenase (ALDH) activity will be used to characterize and quantify vascular regenerative cells from peripheral blood samples. Using this assay, we previously identified three distinct populations of vascular regenerative cells within the hematopoietic hierarchy:~ALDHhiSSClow (high ALDH activity, low side scatter/granular complexity) represent primitive progenitor cells, such as HPCs, that secrete chemo-attractant cytokines to recruit other circulating vascular regenerative cells to sites of vessel damage and ischemia.~ALDHhiSSCmid cells represent macrophage precursor cells (i.e. monocytes) classified along a spectrum of pro-inflammatory subtypes versus pro-vascular subtypes that remodel arterial occlusions.~ALDHhiSSChi cells represent granulocyte precursors, consisting of a heterogeneous group of pro-inflammatory subtypes that aggravate atherosclerosis and endothelial damage, along with pro-angiogenic subtypes that reduce inflammation and support vessel repair.~Using our multi-parametric flow cytometry assay, we previously reported that people with T2D presented lower frequencies of vascular regenerative cells in their peripheral blood compared to people without T2D. We also showed that these frequencies were increased in response to the antihyperglycemic agent empagliflozin and bariatric surgery, suggesting that this regenerative cell deficiency can be reversed. Specifically, three months after bariatric surgery, frequencies of ALDHhiSSClow primitive progenitor cells and pro-vascular ALDHhiSSCmid monocytes in the peripheral blood were increased, whereas frequencies of pro-inflammatory monocytes and ALDHhiSSChi granulocyte precursors were decreased. These studies established circulating vascular regenerative cells as key mechanistic constituents of vessel homeostasis that can be quantified from readily available blood samples, and highlighted the utility of our assay in providing high-throughput, real-time biological readouts of vascular repair potential or deficiency.~Semaglutide belongs to a drug class known as glucagon-like peptide-1 receptor agonists (GLP-1RA). Semaglutide mimics the actions of GLP-1, a gut hormone that is released after a meal and triggers a range of metabotropic effects such as elevating insulin release, reducing food motility, and increasing satiety. In landmark clinical trials, weekly semaglutide injections led to a 1.9% reduction in HbA1c, 16% weight loss in adults and teens, and a 26% reduction in major ASCVD events.~The precise mechanism(s) underlying the effect of semaglutide on ASCVD reduction remain poorly defined. In light of our previous observations (described above), we hypothesize that in people with T2D, semaglutide add-on to usual care will be superior to usual care alone in the restoration of vascular regenerative cell frequency. Specifically, we predict significantly greater baseline to 6 month increases in the frequency of ALDHhiSSClow primitive progenitor cells and pro-vascular ALDHhiSSCmid monocytes, along with decreases in pro-inflammatory monocytes and ALDHhiSSChi granulocyte precursors in the semaglutide-assigned group compared to the usual care group.~Findings from this study will reveal whether semaglutide affects the quantity of circulating vascular regenerative cells responsible for vessel repair, thereby providing a potential mechanism of action behind the reduction of ASCVD events observed in GLP-1RA cardiovascular outcome trials.
SEMA-VR is a prospective, randomized, 6-month long, open-label study of semaglutide. Approximately 100 participants with type 2 diabetes and/or obesity will be randomized (1:1) to receive semaglutide at escalating doses (up to 1.0 mg/week) or usual care without semaglutide for 6 months.~The goal of this trial is to understand how semaglutide exerts cardio-protective effects in people with type 2 diabetes and/or obesity. The main question it aims to answer is:~• Does semaglutide treatment preserve or increase the number of vessel-repairing cells circulating in the blood?~Participants will:~Be allocated to receive either semaglutide or usual care for 6 months~Provide a blood sample at the baseline visit and another blood sample at the 6-month visit~Researchers will compare participants receiving semaglutide to those receiving usual care for any differences in the 6-month change in the number of vessel-repairing cells in the blood.