The acute impact of high-dose lipid-lowering treatment on endothelial progenitor cells in patients with coronary artery disease-The REMEDY-EPC early substudy.

RATIONALE AND OBJECTIVE: Endothelial progenitor cells (EPCs) play a role in vascular repair, while circulating endothelial cells (CECs) are biomarkers of vascular damage and regeneration. Statins may promote EPC/CEC mobilization in the peripheral blood. We evaluated whether pre-procedural exposure to different lipid-lowering drugs (statins±ezetimibe) can acutely increase levels/activity of EPCs/CECs in patients with stable coronary artery disease (CAD). METHODS: In a planned sub-analysis of the Rosuvastatin For REduction Of Myocardial DamagE During Coronary AngioplastY (REMEDY) trial, 38 patients with stable CAD on chronic low-dose statin therapy were randomized, in a double-blind, placebo-controlled design, into 4 groups before PCI: i. placebo (n = 11); ii. atorvastatin (80 mg+40 mg, n = 9); iii. rosuvastatin (40 mg twice, n = 9); and iv. rosuvastatin (5 mg) and ezetimibe (10 mg) twice, (n = 9). At baseline and 24 h after treatment-before PCI-, patients underwent blinded analyses of EPCs [colony forming units-endothelial cells (CFU-ECs), endothelial colony-forming cells (ECFCs) and tubulization activity] and CECs in peripheral blood. RESULTS: We found no significant treatment effects on parameters investigated such as number of CECs [Median (IQR): i. 0(0), ii. 4.5(27), iii. 1.9(2.3), iv. 1.9(2.3)], CFU-ECs [Median (IQR): i. 27(11), ii. 19(31), iii. 47(36), iv. 30(98)], and ECFCs [Median (IQR): i. 86(84), ii. 7(84), iii. 8/(42.5), iv. 5(2)], as well as tubulization activity [total tubuli (well), Median (IQR): i. 19(7), ii. 5(4), iii. 25(13), iv. 15(24)]. CONCLUSIONS: In this study, we found no evidence of acute changes in levels or activity of EPCs and CECs after high-dose lipid-lowering therapy in stable CAD patients.

High glucose-induced hyperosmolarity contributes to COX-2 expression and angiogenesis: implications for diabetic retinopathy.

BACKGROUND: We tested the hypothesis that glucose-induced hyperosmolarity, occurring in diabetic hyperglycemia, promotes retinal angiogenesis, and that interference with osmolarity signaling ameliorates excessive angiogenesis and retinopathy in vitro and in vivo. METHODS AND RESULTS: We incubated human aortic (HAECs) and dermal microvascular endothelial cells (HMVECs) with glucose or mannitol for 24 h and tested them for protein levels and in vitro angiogenesis. We used the Ins2 Akita mice as a model of type 1 diabetes to test the in vivo relevance of in vitro observations. Compared to incubations with normal (5 mmol/L) glucose concentrations, cells exposed to both high glucose and high mannitol (at 30.5 or 50.5 mmol/L) increased expression of the water channel aquaporin-1 (AQP1) and cyclooxygenase (COX)-2. This was preceded by increased activity of the osmolarity-sensitive transcription factor Tonicity enhancer binding protein (TonEBP), and enhanced endothelial migration and tubulization in Matrigel, reverted by treatment with AQP1 and TonEBP siRNA. Retinas of Ins2 Akita mice showed increased levels of AQP1 and COX-2, as well as angiogenesis, all reverted by AQP1 siRNA intravitreal injections. CONCLUSIONS: Glucose-related hyperosmolarity seems to be able to promote angiogenesis and retinopathy through activation of TonEBP and possibly increasing expression of AQP1 and COX-2. Osmolarity signaling may be a target for therapy.

Transplantation of adipose tissue mesenchymal cells conjugated with VEGF-releasing microcarriers promotes repair in murine myocardial infarction.

RATIONALE: Engraftment and survival of transplanted stem or stromal cells in the microenvironment of host tissues may be improved by combining such cells with scaffolds to delay apoptosis and enhance regenerative properties. AIMS: We examined whether poly(lactic-co-glycolic acid) pharmacologically active microcarriers (PAMs) releasing vascular endothelial growth factor (VEGF) enhance survival, differentiation, and angiogenesis of adipose tissue-mesenchymal stromal cells (AT-MSCs). We analysed the efficacy of transplanted AT-MSCs conjugated with PAMs in a murine model of acute myocardial infarction (AMI). METHODS AND RESULTS: We used fibronectin-coated (empty) PAMs or VEGF-releasing PAMs covered with murine AT-MSCs. Twelve-month-old C57 mice underwent coronary artery ligation to induce AMI, and were randomized into five treatment groups: AMI control (saline 20 µL, n = 7), AMI followed by intramyocardial injection with AT-MSCs (2.5 × 10(5) cells/20 µL, n = 5), or concentrated medium (CM) from AT-MSCs (20 µL, n = 8), or AT-MSCs (2.5 × 10(5) cells/20 µL) conjugated with empty PAMs (n = 7), or VEGF-releasing PAMs (n = 8). Sham-operated mice (n = 7) were used as controls. VEGF-releasing PAMs increased proliferation and angiogenic potential of AT-MSCs, but did not impact their osteogenic or adipogenic differentiation. AT-MSCs conjugated with VEGF-releasing PAMs inhibited apoptosis, decreased fibrosis, increased arteriogenesis and the number of cardiac-resident Ki-67 positive cells, and improved myocardial fractional shortening compared with AT-MSCs alone when transplanted into the infarcted hearts of C57 mice. With the exception of fractional shortening, all such effects of AT-MSCs conjugated with VEGF-PAMs were paralleled by the injection of CM. CONCLUSIONS: AT-MSCs conjugated with VEGF-releasing PAMs exert paracrine effects that may have therapeutic applications.