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Small animal models have shown improved cardiac function with DPP-4 inhibition, but many human studies have shown worse outcomes or no benefit. We seek to bridge the gap by studying the DPP-4 inhibitor sitagliptin in a swine model of chronic myocardial ischemia using proteomic analysis. Thirteen Yorkshire swine underwent the placement of an ameroid constrictor on the left coronary circumflex artery to model chronic myocardial ischemia. Two weeks post-op, swine received either sitagliptin 100 mg daily (SIT, n = 5) or no drug (CON, n = 8). After 5 weeks of treatment, swine underwent functional measurements and tissue harvest. In the SIT group compared to CON, there was a trend towards decreased cardiac index (p = 0.06). The non-ischemic and ischemic myocardium had 396 and 166 significantly decreased proteins, respectively, in the SIT group compared to CON (all p < 0.01). This included proteins involved in fatty acid oxidation (FAO), myocardial contraction, and oxidative phosphorylation (OXPHOS). Sitagliptin treatment resulted in a trend towards decreased cardiac index and decreased expression of proteins involved in OXPHOS, FAO, and myocardial contraction in both ischemic and non-ischemic swine myocardium. These metabolic and functional changes may provide some mechanistic evidence for outcomes seen in clinical studies. [ABSTRACT FROM AUTHOR]

Human bone mesenchymal stem cell‐derived extracellular vesicles (HBMSC‐EV) have been used successfully in animal models of myocardial ischemia, yet have dampened effects in metabolic syndrome through unknown mechanisms. This study demonstrates the basal differences between non‐diabetic human coronary artery endothelial cells (HCAEC) and diabetic HCAEC (DM‐HCAEC), and how these cells respond to the treatment of HBMSC‐EV. HCAEC and DM‐HCAEC were treated with HBMSC‐EV for 6 h. Proteomics, western blot analysis, and tube formation assays were performed. Key metabolic, growth, and stress/starvation cellular responses were significantly altered in DM‐HCAEC in comparison to that of HCAEC at baseline. Proteomics demonstrated increased phosphorus metabolic process and immune pathways and decreased RNA processing and biosynthetic pathways in DM‐HCAEC. Similar to previous in vivo findings, HCAEC responded to the HBMSC‐EV with regenerative and anti‐inflammatory effects through the upregulation of multiple RNA pathways and downregulation of immune cell activation pathways. In contrast, DM‐HCAEC had a significantly diminished response to HBMSC‐EV, likely due to the baseline abnormalities in DM‐HCAEC. To achieve the full benefits of HBMSC‐EV and for a successful transition of this potential therapeutic agent to clinical studies, the abnormalities found in DM‐HCAEC will need to be further studied. [ABSTRACT FROM AUTHOR]

Dipeptidyl peptidase 4 inhibitors (DPP4i) may be cardioprotective based on several small animal and clinical studies, though randomized control trials have demonstrated limited benefit. Given these discrepant findings, the role of these agents in chronic myocardial disease, particularly in the absence of diabetes, is still poorly understood. The purpose of this study was to determine the effects of sitagliptin, a DPP4i, on myocardial perfusion and microvessel density in a clinically relevant large animal model of chronic myocardial ischemia. Normoglycemic Yorkshire swine underwent ameroid constrictor placement to the left circumflex artery to induce chronic myocardial ischemia. Two weeks later, pigs received either no drug (CON, n = 8) or 100 mg oral sitagliptin (SIT) daily (n = 5). Treatment continued for 5 weeks, followed by hemodynamic measurements, euthanasia, and tissue harvest of ischemic myocardium. There were no significant differences in myocardial function between CON and SIT as measured by stroke work (p > 0.5), cardiac output (p = 0.22), and end‐systolic elastance (p = 0.17). SIT was associated with increased absolute blood flow at rest (17% increase, IQR 12–62, p = 0.045) and during pacing (89% increase, IQR 83–105, p = 0.002). SIT was also associated with improved arteriolar density (p = 0.045) compared with CON, without changes in capillary density (p = 0.72). SIT was associated with increased expression of pro‐arteriogenic markers MCP‐1 (p = 0.003), TGFß (p = 0.03), FGFR1 (p = 0.002), and ICAM‐1 (p = 0.03), with a trend toward an increase in the ratio of phosphorylated/active PLCγ1 to total PLCγ1 (p = 0.11) compared with CON. In conclusion, in chronically ischemic myocardium, sitagliptin improves myocardial perfusion and arteriolar collateralization via the activation of pro‐arteriogenic signaling pathways. [ABSTRACT FROM AUTHOR]

In animal models, human bone marrow mesenchymal stem cell‐derived extracellular vesicles (MSC‐EV) have been found to have beneficial effects in cardiovascular disease, but only when administered via intramyocardial injection. The biodistribution of either intravenous or intramyocardial injection of MSC‐EV in the presence of myocardial injury is uncharacterized at this time. We hypothesized that intramyocardial injection will ensure delivery of MSC‐EV to the ischemic myocardium, while intravenous injection will not. Human bone marrow mesenchymal stem cells were cultured and the MSC‐EV were isolated and characterized. The MSC‐EVs were then labeled with DiD lipid dye. FVB mice with normal cardiac function underwent left coronary artery ligation followed by either peri‐infarct intramyocardial or tail vein injection of 3*106 or 2*109 particles of DiD‐labeled MSC‐EV or a DiD‐saline control. The heart, lungs, liver, spleen and kidneys were harvested 2 h post‐injection and were submitted for fluorescent molecular tomography imaging. Myocardial uptake of MSC‐EV was only visualized after intramyocardial injection of 2*109 MSC‐EV particles (p = 0.01) compared to control, and there were no differences in cardiac fluorescence after tail vein injection of MSC‐EV (p = 0.5). There was no significantly detectable MSC‐EV uptake in other organs after intramyocardial injection. After tail vein injection of 2*109 particles of MSC‐EV, the liver (p = 0.02) and spleen (p = 0.04) appeared to have diffuse MSC‐EV uptake compared to controls. Even in the presence of myocardial injury, only intramyocardial but not intravenous administration resulted in detectable levels of MSC‐EV in the ischemic myocardium. This study confirms the role for intramyocardial injection in maximal and effective delivery of MSC‐EV. Our ongoing studies aimed at developing bioengineered MSC‐EV for targeted delivery to the heart may render MSC‐EV clinically applicable for cardiovascular disease. [ABSTRACT FROM AUTHOR]

Cardiovascular disease has been associated with increased levels of reactive oxygen species (ROS). Recently, we have shown that a critical balance between cytosolic ROS and mitochondrial ROS is crucial in cardiovascular health and that modulation of mitochondrial ROS helps prevent detrimental effects of cytosolic ROS on endothelial cells (EC) in transgenic animals. Here, we report the development of a controlled delivery system for a mitochondria‐targeted antioxidant, JP4‐039, from an electrospun scaffold made of FDA‐approved biocompatible polymeric nanofibers. We demonstrate that the active antioxidant moiety was preserved in released JP4‐039 for over 72 h using electron paramagnetic resonance. We also show that both the initial burst release of the drug within the first 20 min and the ensuing slow and sustained release that occurred over the next 24 h improved tube formation in human coronary artery ECs (HCAEC) in vitro. Taken together, these findings suggest that electrospinning methods can be used to upload mitochondrial antioxidant (JP4‐039) onto a biocompatible nanofibrous PLGA scaffold, and the uploaded drug (JP4‐039) retains nitroxide antioxidant properties upon release from the scaffold, which in turn can reduce mitochondrial ROS and improve EC function in vitro. [ABSTRACT FROM AUTHOR]