The role of endothelial progenitor cells in diabetic patients with and without coronary disease

Purpose: Endothelial progenitor cells (EPCs) originating from the bone marrow playa significant role in neovascularization of ischemic tissues and in re-endotheliazationof injured blood vessels. The purpose of this study was to investigate if theadministration of pioglitazone or perindopril in diabetic patients can modify thenumber of EPCs in the peripheral blood and alter the endothelial function andinflammatory status of these patients.Methods: Fifty type 2 diabetic patients were recruited and were randomly assigned toreceive either pioglitazone (15mg/day) or perindopril (4mg/day) for a one-monthperiod. In both groups blood sample were drawn on admission (baseline) and afterone month of drug’s administration. Blood samples were taken in order to count EPCsand inflammation markers such as C-reactive protein (hsCRP), vascular endothelialgrowth factor (VEGF) and asymmetric dimethilarginine (ADMA). Circulating EPCswere defined by the surface markers CD34+/KDR/CD133 (CD34 and VEGFR2expressing cells) and analyzed by flow-cytometry. Moreover the endothelial functionof the patients was evaluated both on admission and after treatment with flowmediated dilation (FMD).Results: We have found that neither pioglitazone (p=0.09), nor perindopril (p=0.5)affected the number of EPCs. Importantly, we have shown that pioglitazone reducedCRP (p=0.04) and ADMA levels (p=0.002). In addition, pioglitazone improved FMD(p=0.04) and increased plasma concentrations of VEGF (p=0.01). On the contrary perindopril had no significant effect on CRP levels (p=0.07), FMD (p=0.23) as wellas on ADMA levels (p=0.09). However, perindopril administration increasedsignificantly plasma levels of VEGF (p=0.03). Moreover, in the present study weaimed to compare the effects of the different treatments on the aforementionedparameters (absolute changes, delta, Δ). Our results showed that although pioglitazonehad a significant beneficial effect on all the study markers, no significant differencewas observed in the absolute changes between the 2 agents. Moreover, both agentsdid not differ regarding to their effect on ΔEPCs (p=0.34), ΔFMD (p=0.70), ΔVEGF(p=0.27) and ΔCRP (p=0.85). Interestingly, we have found that perindopril had asuperior effect than that of pioglitazone considering ΔADMA levels (p=0.01), despitethe non significant (post administration) effect on ADMA levels resulting solely.Conclusions: Based on the existing data, it seems that both treatments did not affectsignificantly number of circulating endothelial cells. Importantly, pioglitazoneaffected beneficially all the study parameters. On the other hand, perindoprilincreased significantly only VEGF levels, while CRP, FMD and ADMA levels wereunaffected. Interestingly, we found that although perindopril had no significant effecton ADMA levels, this effect was greater when compared to that of pioglitazone.Considering our results, we provide also evidence for a possible addition ofperindopril to the conventional treatment with pioglitazone which could affect furtherthe neovascularization and reduce oxidative stress in these patients.Σκοπός: Τα αρχέγονα ενδοθηλιακά κύτταρα (ΑΕΚ) προέρχονται από το μυελό τωνοστών και διαδραματίζουν σημαντικό ρόλο στη νεοαγγειογένεση των ισχαιμικώνιστών και στην επανενδοθηλιοποίηση των τραυματισμένων αγγείων. Ο σκοπός τηςσυγκεκριμένης μελέτης είναι να διερευνήσει αν η χορήγηση πιογλιταζόνης ήπερινδοπρίλης στους διαβητικούς ασθενείς δύναται να τροποποιήσει τον αριθμό τωνΑΕΚ και να μεταβάλει την ενδοθηλιακή λειτουργία και τη φλεγμονώδη κατάστασητων αγγείων τους.Μέθοδοι: Πενήντα διαβητικοί ασθενείς τύπου 2 συμμετείχαν στη μελέτη καιεπιλέχθηκαν τυχαία να λαμβάνουν πιογλιταζόνη (15mg/day) ή περινδοπρίλη(4mg/day) για περίοδο ενός μήνα. Αιμοληψίες διενεργήθηκαν τόσο προ τηςχορήγησης της πιογλιταζόνης όσο και ένα μήνα μετά τη θεραπεία, προκειμένου ναμετρηθούν ο αριθμός των κυκλοφορούντων ΑΕΚ και δείκτες φλεγμονής όπως η C-αντιδρώσα πρωτεΐνη (CRP), ο αγγειακός ενδοθηλιακός αυξητικός παράγοντας(VEGF) και η ασύμμετρη διμεθυλαργινίνη (ADMA). Ο προσδιορισμός των ΑΕΚέγινε με τη μέθοδο της κυτταρομετρίας ροής χρησιμοποιώντας σαν αντιγόναεπιφανείας τα CD34+, CD133+ και KDR. Επιπλέον η εκτίμηση της ενδοθηλιακήςλειτουργίας πραγματοποιήθηκε με την υπερηχογραφική τεχνική τηςενδοθηλιοεξαρτώμενης διαμέσου της ροής αγγειοδιαστολής (flow-mediated dilation=FMD). Αποτελέσματα: Αποδείχθηκε ότι ούτε η πιογλιταζόνη (p=0.09) ούτε η περινδοπρίλη(p=0.5) επηρεάζουν σημαντικά τον αριθμό των ΑΕΚ. Είναι σημαντικό πως ηπιογλιταζόνη μείωσε σημαντικά τα επίπεδα πλάσματος CRP (p=0.04) και ADMA(p=0.002). Επιπρόσθετα, η πιογλιταζόνη βελτίωσε το FMD (p=0.04) και αύξησε ταεπίπεδα πλάσματος του VEGF (p=0.01). Αντίθετα, η περινδοπρίλη δεν είχεσημαντική επίδραση στα επίπεδα της CRP (p=0.07), στο FMD (p=0.23) καθώς καιστα επίπεδα της ADMA (p=0.09). Ωστόσο, η χορήγηση περινδοπρίλης αύξησεσημαντικά τα επίπεδα του VEGF (p=0.03). Επιπλέον, στόχος της παρούσας μελέτηςήταν να συγκρίνει τις επιδράσεις των δύο φαρμάκων στις προαναφερθείσεςπαραμέτρους (απόλυτες αλλαγές, delta, Δ). Τα αποτελέσματα της μελέτης απέδειξανότι παρόλο που η πιογλιταζόνη είχε σημαντικά ευεργετική επίδραση σε όλους τουςεξεταζόμενους δείκτες, δεν προέκυψε σημαντική διαφορά στις απόλυτες αλλαγέςμεταξύ των 2 φαρμάκων: ΔEPCs (p=0.34), ΔFMD (p=0.70), ΔVEGF (p=0.27) andΔCRP (p=0.85). Είναι ενδιαφέρον ότι η χορήγηση περινδοπρίλης αποδείχθηκε να έχειανώτερη επίδραση από ότι η πιογλιταζόνη στα επίπεδα ΔADMA (p=0.01), παρά τογεγονός ότι δεν είχε σημαντική επίδραση από μόνη της στα επίπεδα της ADMA.Συμπεράσματα: Βασιζόμενοι στα υπάρχοντα αποτελέσματα, και οι δύο θεραπείες δεφαίνεται αν επηρέασαν σημαντικά τον αριθμό των κυκλοφορούντων ΑΕΚ. Είναισημαντικό ότι η πιογλιταζόνη επηρέασε ευεργετικά όλες τις παραμέτρους τηςμελέτης. Αντίθετα, η περινδοπρίλη αύξησε σημαντικά μόνο τα επίπεδα του VEGF,ενώ τα επίπεδα CRP, FMD και ADMA παρέμειναν ανεπηρέαστα. Ένα ακόμαενδιαφέρον στοιχείο της μελέτης είναι ότι ενώ η περινδοπρίλη δεν επηρέασεσημαντικά τα επίπεδα της ADMA, η επίδραση αυτή ήταν σημαντικότερησυγκρινόμενη σε εκείνη της πιογλιταζόνης. Σύμφωνα με τα αποτελέσματα τηςμελέτης παρέχονται αποδεικτικά στοιχεία για την πιθανή ευεργετική προσθήκη της περινδοπρίλης στη συμβατική θεραπεία της πιογλιταζόνης που θα μπορούσε ναεπηρεάσει περαιτέρω την νεοαγγειοποίηση και να μειώσει το οξειδωτικό στρες στουςδιαβητικούς ασθενείς

Diabetes Mellitus and Vascular Endothelial Dysfunction: Current Perspectives

Patients with diabetes mellitus (DM) have a high prevalence of coronary artery disease (CAD), as diabetes is implicated in the formation of atherosclerotic plaque. Endothelial dysfunction is one of the precursor key steps in the development of atherosclerosis in diabetic subjects. Decreased nitric oxide (NO) production, increased oxidative stress and impaired function of endothelial progenitor cells are the main mechanisms involved in the accelerated atherosclerotic process observed in type 2 DM patients. Therapeutic approaches including classic agents such as statins, angiotensin-converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), antioxidants and novel agents such as tetrahydrobiopterin (BH4), asymmetric dimethylarginine (ADMA) and homocysteine (tHcy), have been implicated in order to ameliorate endothelial function of diabetic patients

Novel Agents Targeting Nitric Oxide

Nitric oxide (NO) is a soluble gas continuously synthesized from the amino acid L-arginine in endothelial cells by the constitutive calcium-calmodulin-dependent enzyme nitric oxide synthase (NOS). Endothelial dysfunction has been identified as a major mechanism involved in all the stages of atherogenesis. Evaluation of endothelial function seems to have a predictive role in humans, and therapeutic interventions improving nitric oxide bioavailability in the vasculature, may improve the long-term outcome in healthy individuals, high-risk subjects or patients with advanced atherosclerosis. Several therapeutic strategies (including statins, angiotensin converting enzyme inhibitors/angiotensin receptors blockers, insulin sensitizers, antioxidant compounds) are now available, targeting both the synthesis and oxidative inactivation of NO in human vasculature, reversing in that way endothelial dysfunction which is enhanced by the release of nitric oxide from the endothelium

The Role of Nitric Oxide on Endothelial Function

The vascular endothelium is a monolayer of cells between the vessel lumen and the vascular smooth muscle cells. Nitric oxide (NO) is a soluble gas continuously synthesized from the amino acid L-arginine in endothelial cells by the constitutive calcium-calmodulin-dependent enzyme nitric oxide synthase (NOS). This substance has a wide range of biological properties that maintain vascular homeostasis, including modulation of vascular dilator tone, regulation of local cell growth, and protection of the vessel from injurious consequences of platelets and cells circulating in blood, playing in this way a crucial role in the normal endothelial function. A growing list of conditions, including those commonly associated as risk factors for atherosclerosis such as hypertension, hypercholesterolemia, smoking, diabetes mellitus and heart failure are associated with diminished release of nitric oxide into the arterial wall either because of impaired synthesis or excessive oxidative degradation. The decreased production of NO in these pathological states causes serious problems in endothelial equilibrium and that is the reason why numerous therapies have been investigated to assess the possibility of reversing endothelial dysfunction by enhancing the release of nitric oxide from the endothelium. In the present review we will discuss the important role of nitric oxide in physiological endothelium and we will pinpoint the significance of this molecule in pathological states altering the endothelial function

Biomarkers of premature atherosclerosis

C-reactive protein (CRP) is an acute phase protein and a biochemical marker with important prognostic value for cardiovascular events. Interleukins IL-1 and IL-6 are implicated in the pathogenesis of atherosclerosis and are associated with CRP. Apolipoproteins ApoA-I and ApoB are the main lipid metabolic markers implicated in the development and progression of atherosclerosis. Fibrinogen has also been proposed to be a major independent risk factor for cardiovascular events. Because premature atherosclerosis precedes the development of cardiovascular disease, identification of the associated biomarkers is of great importance. However, further studies will be needed to determine whether or not these markers are useful predictors of future cardiovascular events. Here, we review the roles of specific biomarkers that have been implicated in premature atherosclerosis

The Impact of Diabetes Mellitus on Coronary Artery Disease: New Therapeutic Approaches

Patients with diabetes mellitus (DM) type 2 have a high prevalence of coronary artery disease ( CAD), as diabetes is implicated in the formation of atherosclerotic plaque. Hyperglycemia, elevated free fatty acid, increased amount of circulating end-glucosylated serum products and insulin resistance are the main mechanisms involved in the accelerated atherosclerotic process observed in type 2 DM patients. Novel treatments have been proposed to prevent and treat CAD in patients with diabetes, mainly in those with diabetes type 2. Several clinical trials have been designed in order to examine the effectiveness of these agents, such as angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers, glitazones, statins and antioxidants, but the results are still controversial

Paraneoplastic digital ischemia in clear-cell renal-cell carcinoma: Report of a case and review of the literature

Digital ischemia has been rarely associated, as a paraneoplastic syndrome, with renal cancer. Since it can severely compromise the patients' quality of life, early recognition is important, in order to optimally address it with currently available treatment options, such as tyrosine inhibitors. Digital ischemia may occur in the general population and it can be the result of other non-cancerous diseases; accordingly, a thorough and aggressive work-up is mandatory, together with appropriate therapeutic steps such as tyrosine kinase inhibitors, vasodilators, and antiaggregants. Herein, we report a 78-year-old male patient with a history of clear-cell renal-cell cancer, who presented in the emergency department with critical ischemia in the upper limbs

Potential Pathogenic Inflammatory Mechanisms of Endothelial Dysfunction Induced by Type 2 Diabetes Mellitus

Insulin resistance and the vascular complications of diabetes include activation of the inflammation cascade, endothelial dysfunction, and oxidative stress. The comorbidities of diabetes, namely obesity, insulin resistance, hyperglycemia, hypertension and dyslipidemia collectively aggravate these processes while antihyperglycemic interventions tend to correct them. Increased C-reactive protein, interleukin 6, tumor necrosis factor alpha and especially interstitial cellular adhesion molecule-1, vascular cellular adhesion molecule-1, and E-selectin are associated with cardiovascular and non-cardiovascular complications of both type 1 and type 2 diabetes. We sought to review the clinical implications of the inflammation theory, including the relevance of inflammation markers as predictors of type 2 diabetes in clinical studies, and the potential treatments of diabetes, inferred from the pathophysiology