Sitagliptin plus granulocyte colony-stimulating factor in patients suffering from acute myocardial infarction: A double-blind, randomized placebo-controlled trial of efficacy and safety (SITAGRAMI trial)

The effects of dipeptidyl peptidase-4 inhibitors on cardiac structure and function using cardiac magnetic resonance: a meta-analysis of clinical studies

Objective

The aim of the study was to evaluate the effect of dipeptidyl peptidase-4 inhibitors (DPP4i) on cardiac structure and function by cardiac magnetic resonance (CMR). Research Methods & Procedures: Database including PubMed, Cochrane library, Embase and SinoMed for clinical studies of DPP4i on cardiac structure and function by CMR were searched. Two authors extracted the data and evaluated study quality independently. Mean difference (MD) or standardized MD and 95% confidence intervals (CI) were used for continuous variables. Review Manager 5.3 was used to performed the analysis.

Results

Ten references (nine studies) were included in this meta-analysis. Most of the studies were assessed as well quality by the assessment of methodological quality. For clinical control studies, the merged MD values of △LVEF by fixed-effect model and the pooled effect size in favor of DPP4i was 1.55 (95% CI 0.35 to 2.74, P=0.01). Compared with positive control drugs, DPP4i can significantly improve the LVEF (MD=4.69, 95%CI=2.70 to 6.69), but no such change compared to placebo (MD=-0.20, 95%CI=-1.69 to 1.29). For single-arm studies and partial clinical control studies that reported LVEF values before and after DPP4i treatment, random-effect model was used to combine effect size due to a large heterogeneity (Chi2 = 11.26, P=0.02, I2 = 64%), and the pooled effect size in favor of DPP4i was 2.31 (95% CI 0.01 to 4.62, P=0.05). DPP4i significantly increased the Peak filling rate (PFR) without heterogeneity when the effect sizes of two single-arm studies were combined (MD=31.98, 95% CI 13.69 to 50.27, P=0.0006; heterogeneity test: Chi2 = 0.56, P=0.46, I2 = 0%).

Conclusions

In summary, a possible benefit of DPP4i in cardiac function (as measured by CMR) was found, both including ventricular systolic function and diastolic function.

Incretins-Based Therapies and Their Cardiovascular Effects: New Game-Changers for the Management of Patients with Diabetes and Cardiovascular Disease

Atherosclerosis is the leading cause of death worldwide, especially in patients with type 2 diabetes mellitus (T2D). GLP-1 receptor agonists and DPP-4 inhibitors were demonstrated to play a markedly protective role for the cardiovascular system beyond their glycemic control. Several cardiovascular outcome trials (CVOT) reported the association between using these agents and a significant reduction in cardiovascular events in patients with T2D and a high cardiovascular risk profile. Moreover, recent evidence highlights a favorable benefit/risk profile in myocardial infarction and percutaneous coronary revascularization settings. These clinical effects result from their actions on multiple molecular mechanisms involving the immune system, platelets, and endothelial and vascular smooth muscle cells. This comprehensive review specifically concentrates on these cellular and molecular processes mediating the cardiovascular effects of incretins-like molecules, aiming to improve clinicians' knowledge and stimulate a more extensive use of these drugs in clinical practice as helpful cardiovascular preventive strategies.

Effects of DPP4 Inhibitor in Platelet Reactivity and Other Cardiac Risk Markers in Patients with Type 2 Diabetes and Acute Myocardial Infarction

Background: The management of acute myocardial infarction (AMI) presents several challenges in patients with diabetes, among them the higher rate of recurrent thrombotic events, hyperglycemia and risk of subsequent heart failure (HF). The objective of our study was to evaluate effects of DPP-4 inhibitors (DPP-4i) on platelet reactivity (main objective) and cardiac risk markers. Methods: We performed a single-center double-blind randomized trial. A total of 70 patients with type 2 diabetes (T2DM) with AMI Killip ≤2 on dual-antiplatelet therapy (aspirin plus clopidogrel) were randomized to receive sitagliptin 100 mg or saxagliptin 5 mg daily or matching placebo. Platelet reactivity was assessed at baseline, 4 days (primary endpoint) and 30 days (secondary endpoint) after randomization, using VerifyNow Aspirin™ assay, expressed as aspirin reaction units (ARUs); B-type natriuretic peptide (BNP) in pg/mL was assessed at baseline and 30 days after (secondary endpoint). Results: Mean age was 62.6 ± 8.8 years, 45 (64.3%) male, and 52 (74.3%) of patients presented with ST-segment elevation MI. For primary endpoint, there were no differences in mean platelet reactivity (p = 0.51) between the DPP-4i (8.00 {−65.00; 63.00}) and placebo (−14.00 {−77.00; 52.00}) groups, as well in mean BNP levels (p = 0.14) between DPP-4i (−36.00 {−110.00; 15.00}) and placebo (−13.00 {−50.00; 27.00}). There was no difference between groups in cardiac adverse events. Conclusions: DPP4 inhibitor did not reduce platelet aggregation among patients with type 2 diabetes hospitalized with AMI. Moreover, the use of DPP-4i did not show an increase in BNP levels or in the incidence of cardiac adverse events. These findings suggests that DPP-4i could be an option for management of T2DM patients with acute MI.

Dipeptidyl peptidase-4 inhibitors, glucagon-like peptide 1 receptor agonists and sodium-glucose co-transporter-2 inhibitors for people with cardiovascular disease: a network meta-analysis

BACKGROUND

Cardiovascular disease (CVD) is a leading cause of death globally. Recently, dipeptidyl peptidase-4 inhibitors (DPP4i), glucagon-like peptide-1 receptor agonists (GLP-1RA) and sodium-glucose co-transporter-2 inhibitors (SGLT2i) were approved for treating people with type 2 diabetes mellitus. Although metformin remains the first-line pharmacotherapy for people with type 2 diabetes mellitus, a body of evidence has recently emerged indicating that DPP4i, GLP-1RA and SGLT2i may exert positive effects on patients with known CVD.

OBJECTIVES

To systematically review the available evidence on the benefits and harms of DPP4i, GLP-1RA, and SGLT2i in people with established CVD, using network meta-analysis.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and the Conference Proceedings Citation Index on 16 July 2020. We also searched clinical trials registers on 22 August 2020. We did not restrict by language or publication status.

SELECTION CRITERIA

We searched for randomised controlled trials (RCTs) investigating DPP4i, GLP-1RA, or SGLT2i that included participants with established CVD. Outcome measures of interest were CVD mortality, fatal and non-fatal myocardial infarction, fatal and non-fatal stroke, all-cause mortality, hospitalisation for heart failure (HF), and safety outcomes.

DATA COLLECTION AND ANALYSIS

Three review authors independently screened the results of searches to identify eligible studies and extracted study data. We used the GRADE approach to assess the certainty of the evidence. We conducted standard pairwise meta-analyses and network meta-analyses by pooling studies that we assessed to be of substantial homogeneity; subgroup and sensitivity analyses were also pursued to explore how study characteristics and potential effect modifiers could affect the robustness of our review findings. We analysed study data using the odds ratios (ORs) and log odds ratios (LORs) with their respective 95% confidence intervals (CIs) and credible intervals (Crls), where appropriate. We also performed narrative synthesis for included studies that were of substantial heterogeneity and that did not report quantitative data in a usable format, in order to discuss their individual findings and relevance to our review scope.

MAIN RESULTS

We included 31 studies (287 records), of which we pooled data from 20 studies (129,465 participants) for our meta-analysis. The majority of the included studies were at low risk of bias, using Cochrane's tool for assessing risk of bias. Among the 20 pooled studies, six investigated DPP4i, seven studied GLP-1RA, and the remaining seven trials evaluated SGLT2i. All outcome data described below were reported at the longest follow-up duration. 1. DPP4i versus placebo Our review suggests that DPP4i do not reduce any risk of efficacy outcomes: CVD mortality (OR 1.00, 95% CI 0.91 to 1.09; high-certainty evidence), myocardial infarction (OR 0.97, 95% CI 0.88 to 1.08; high-certainty evidence), stroke (OR 1.00, 95% CI 0.87 to 1.14; high-certainty evidence), and all-cause mortality (OR 1.03, 95% CI 0.96 to 1.11; high-certainty evidence). DPP4i probably do not reduce hospitalisation for HF (OR 0.99, 95% CI 0.80 to 1.23; moderate-certainty evidence). DPP4i may not increase the likelihood of worsening renal function (OR 1.08, 95% CI 0.88 to 1.33; low-certainty evidence) and probably do not increase the risk of bone fracture (OR 1.00, 95% CI 0.83 to 1.19; moderate-certainty evidence) or hypoglycaemia (OR 1.11, 95% CI 0.95 to 1.29; moderate-certainty evidence). They are likely to increase the risk of pancreatitis (OR 1.63, 95% CI 1.12 to 2.37; moderate-certainty evidence). 2. GLP-1RA versus placebo Our findings indicate that GLP-1RA reduce the risk of CV mortality (OR 0.87, 95% CI 0.79 to 0.95; high-certainty evidence), all-cause mortality (OR 0.88, 95% CI 0.82 to 0.95; high-certainty evidence), and stroke (OR 0.87, 95% CI 0.77 to 0.98; high-certainty evidence). GLP-1RA probably do not reduce the risk of myocardial infarction (OR 0.89, 95% CI 0.78 to 1.01; moderate-certainty evidence), and hospitalisation for HF (OR 0.95, 95% CI 0.85 to 1.06; high-certainty evidence). GLP-1RA may reduce the risk of worsening renal function (OR 0.61, 95% CI 0.44 to 0.84; low-certainty evidence), but may have no impact on pancreatitis (OR 0.96, 95% CI 0.68 to 1.35; low-certainty evidence). We are uncertain about the effect of GLP-1RA on hypoglycaemia and bone fractures. 3. SGLT2i versus placebo This review shows that SGLT2i probably reduce the risk of CV mortality (OR 0.82, 95% CI 0.70 to 0.95; moderate-certainty evidence), all-cause mortality (OR 0.84, 95% CI 0.74 to 0.96; moderate-certainty evidence), and reduce the risk of HF hospitalisation (OR 0.65, 95% CI 0.59 to 0.71; high-certainty evidence); they do not reduce the risk of myocardial infarction (OR 0.97, 95% CI 0.84 to 1.12; high-certainty evidence) and probably do not reduce the risk of stroke (OR 1.12, 95% CI 0.92 to 1.36; moderate-certainty evidence). In terms of treatment safety, SGLT2i probably reduce the incidence of worsening renal function (OR 0.59, 95% CI 0.43 to 0.82; moderate-certainty evidence), and probably have no effect on hypoglycaemia (OR 0.90, 95% CI 0.75 to 1.07; moderate-certainty evidence) or bone fracture (OR 1.02, 95% CI 0.88 to 1.18; high-certainty evidence), and may have no impact on pancreatitis (OR 0.85, 95% CI 0.39 to 1.86; low-certainty evidence). 4. Network meta-analysis Because we failed to identify direct comparisons between each class of the agents, findings from our network meta-analysis provided limited novel insights. Almost all findings from our network meta-analysis agree with those from the standard meta-analysis. GLP-1RA may not reduce the risk of stroke compared with placebo (OR 0.87, 95% CrI 0.75 to 1.0; moderate-certainty evidence), which showed similar odds estimates and wider 95% Crl compared with standard pairwise meta-analysis. Indirect estimates also supported comparison across all three classes. SGLT2i was ranked the best for CVD and all-cause mortality.

AUTHORS' CONCLUSIONS

Findings from both standard and network meta-analyses of moderate- to high-certainty evidence suggest that GLP-1RA and SGLT2i are likely to reduce the risk of CVD mortality and all-cause mortality in people with established CVD; high-certainty evidence demonstrates that treatment with SGLT2i reduce the risk of hospitalisation for HF, while moderate-certainty evidence likely supports the use of GLP-1RA to reduce fatal and non-fatal stroke. Future studies conducted in the non-diabetic CVD population will reveal the mechanisms behind how these agents improve clinical outcomes irrespective of their glucose-lowering effects.

Roles and Mechanisms of Dipeptidyl Peptidase 4 Inhibitors in Vascular Aging

Vascular aging is characterized by alterations in the constitutive properties and biological functions of the blood vessel wall. Endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are indispensability elements in the inner layer and the medial layer of the blood vessel wall, respectively. Dipeptidyl peptidase-4 (DPP4) inhibitors, as a hypoglycemic agent, play a protective role in reversing vascular aging regardless of their effects in meliorating glycemic control in humans and animal models of type 2 diabetes mellitus (T2DM) through complex cellular mechanisms, including improving EC dysfunction, promoting EC proliferation and migration, alleviating EC senescence, obstructing EC apoptosis, suppressing the proliferation and migration of VSMCs, increasing circulating endothelial progenitor cell (EPC) levels, and preventing the infiltration of mononuclear macrophages. All of these showed that DPP4 inhibitors may exert a positive effect against vascular aging, thereby preventing vascular aging-related diseases. In the current review, we will summarize the cellular mechanism of DPP4 inhibitors regulating vascular aging; moreover, we also intend to compile the roles and the promising therapeutic application of DPP4 inhibitors in vascular aging-related diseases.

"Protocol for a phase 2, randomized, double-blind, placebo-controlled, safety and efficacy study of dutogliptin in combination with filgrastim in early recovery post-myocardial infarction": study protocol for a randomized controlled trial

BACKGROUND

Regenerative therapies offer new approaches to improve cardiac function after acute ST-elevation myocardial infarction (STEMI). Previous trials using bone marrow cells, selected stem cell populations, or cardiac stem cell progenitors require invasive procedures and had so far inconclusive results. A less invasive approach utilizes granulocyte-colony stimulating factor (G-CSF) to mobilize stem cells to circulating blood and induce neovascularization and differentiation into endothelial cells and cardiomyocytes. Stromal cell-derived factor 1 alpha (SDF-1α) is an important chemokine for initiating stem cell migration and homing to ischemic myocardium. SDF-1α concentrations can be increased by inhibition of CD26/DPP4. Dutogliptin, a novel DPP4 inhibitor, combined with stem cell mobilization using G-CSF significantly improved survival and reduced infarct size in a murine model.

METHODS

We test the safety and tolerability and efficacy of dutogliptin in combination with filgrastim (G-CSF) in patients with STEMI (EF < 45%) following percutaneous coronary intervention (PCI). Preliminary efficacy will be analyzed using cardiac magnetic resonance imaging (cMRI) to detect > 3.8% improvement in left ventricular ejection fraction (LV-EF) compared to placebo. One hundred forty subjects will be randomized to filgrastim plus dutogliptin or matching placebos.

DISCUSSION

The REC-DUT-002 trial is the first to evaluate dutogliptin in combination with G-CSF in patients with STEMI. Results will lay the foundation for an appropriately powered cardiovascular outcome trial to test the efficacy of this combined pharmacological strategy.

TRIAL REGISTRATION

EudraCT no.: 2018-000916-75 . Registered on 7 June 2018. IND number: 123717.

Effects of antidiabetic drugs on left ventricular function/dysfunction: a systematic review and network meta-analysis

BACKGROUND

Although a variety of antidiabetic drugs have significant protective action on the cardiovascular system, it is still unclear which antidiabetic drugs can improve ventricular remodeling and fundamentally delay the process of heart failure. The purpose of this network meta-analysis is to compare the efficacy of sodium glucose cotransporter type 2 (SGLT-2) inhibitors, dipeptidyl peptidase-4 (DPP-4) inhibitors, glucagon-like peptide-1 (GLP-1) agonists, metformin (MET), sulfonylurea (SU) and thiazolidinediones (TZDs) in improving left ventricular (LV) remodeling in patients with type 2 diabetes (T2DM) and/or cardiovascular disease (CVD).

METHODS

We searched articles published before October 18, 2019, regardless of language or data, in 4 electronic databases: PubMed, EMBASE, Cochrane Library and Web of Science. We included randomized controlled trials in this network meta-analysis, as well as a small number of cohort studies. The differences in the mean changes in left ventricular echocardiographic parameters between the treatment group and control group were evaluated.

RESULTS

The difference in the mean change in LV ejection fraction (LVEF) between GLP-1 agonists and placebo in treatment effect was greater than zero (MD = 2.04% [0.64%, 3.43%]); similar results were observed for the difference in the mean change in LV end-diastolic diameter (LVEDD) between SGLT-2 inhibitors and placebo (MD = - 3.3 mm [5.31, - 5.29]), the difference in the mean change in LV end-systolic volume (LVESV) between GLP-1 agonists and placebo (MD = - 4.39 ml [- 8.09, - 0.7]); the difference in the mean change in E/e' between GLP-1 agonists and placebo (MD = - 1.05[- 1.78, - 0.32]); and the difference in the mean change in E/e' between SGLT-2 inhibitors and placebo (MD = - 1.91[- 3.39, - 0.43]).

CONCLUSIONS

GLP-1 agonists are more significantly associated with improved LVEF, LVESV and E/e', SGLT-2 inhibitors are more significantly associated with improved LVEDD and E/e', and DPP-4 inhibitors are more strongly associated with a negative impact on LV end-diastolic volume (LVEDV) than are placebos. SGLT-2 inhibitors are superior to other drugs in pairwise comparisons.

Bispecific Antibody Inhalation Therapy for Redirecting Stem Cells from the Lungs to Repair Heart Injury

Stem cell therapy is a promising strategy for cardiac repair. However, clinical efficacy is hampered by poor cell engraftment and the elusive repair mechanisms of the transplanted stem cells. The lung is a reservoir of hematopoietic stem cells (HSCs) and a major biogenesis site for platelets. A strategy is sought to redirect lung resident stem cells to the injured heart for therapeutic repair after myocardial infarction (MI). To achieve this goal, CD34-CD42b platelet-targeting bispecific antibodies (PT-BsAbs) are designed to simultaneously recognize HSCs (via CD34) and platelets (via CD42b). After inhalation delivery, PT-BsAbs reach the lungs and conjoined HSCs and platelets. Due to the innate injury-finding ability of platelets, PT-BsAbs guide lung HSCs to the injured heart after MI. The redirected HSCs promote endogenous repair, leading to increased cardiac function. The repair mechanism involves angiomyogenesis and inflammation modulation. In addition, the inhalation route is superior to the intravenous route to deliver PT-BsAbs in terms of the HSCs' homing ability and therapeutic benefits. This work demonstrates that this novel inhalable antibody therapy, which harnesses platelets derived from the lungs, contributes to potent stem cell redirection and heart repair. This strategy is safe and effective in a mouse model of MI.

Impact of sitagliptin on endometrial mesenchymal stem-like progenitor cells: A randomised, double-blind placebo-controlled feasibility trial

BACKGROUND

Recurrent pregnancy loss (RPL) is associated with the loss of endometrial mesenchymal stem-like progenitor cells (eMSC). DPP4 inhibitors may increase homing and engraftment of bone marrow-derived cells to sites of tissue injury. Here, we evaluated the effect of the DPP4 inhibitor sitagliptin on eMSC in women with RPL, determined the impact on endometrial decidualization, and assessed the feasibility of a full-scale clinical trial.

METHODS

A double-blind, randomised, placebo-controlled feasibility trial on women aged 18 to 42 years with a history of 3 or more miscarriages, regular menstrual cycles, and no contraindications to sitagliptin. Thirty-eight subjects were randomised to either 100 mg sitagliptin daily for 3 consecutive cycles or identical placebo capsules. Computer generated, permuted block randomisation was used to allocate treatment packs. Colony forming unit (CFU) assays were used to quantify eMSC in midluteal endometrial biopsies. The primary outcome measure was CFU counts. Secondary outcome measures were endometrial thickness, study acceptability, and first pregnancy outcome within 12 months following the study. Tissue samples were subjected to explorative investigations.

FINDINGS

CFU counts following sitagliptin were higher compared to placebo only when adjusted for baseline CFU counts and age (RR: 1.52, 95% CI: 1.32-1.75, P<0.01). The change in CFU count was 1.68 in the sitagliptin group and 1.08 in the placebo group. Trial recruitment, acceptability, and drug compliance were high. There were no serious adverse events. Explorative investigations showed that sitagliptin inhibits the expression of DIO2, a marker gene of senescent decidual cells.

INTERPRETATION

Sitagliptin increases eMSCs and decreases decidual senescence. A large-scale clinical trial evaluating the impact of preconception sitagliptin treatment on pregnancy outcome in RPL is feasible and warranted.

FUNDING

Tommy's Baby Charity.

CLINICAL TRIAL REGISTRATION

EU Clinical Trials Register no. 2016-001120-54.

Therapeutic strategies utilizing SDF-1α in ischaemic cardiomyopathy

Heart failure is rapidly increasing in prevalence and will redraw the global landscape for cardiovascular health. Alleviating and repairing cardiac injury associated with myocardial infarction (MI) is key to improving this burden. Homing signals mobilize and recruit stem cells to the ischaemic myocardium where they exert beneficial paracrine effects. The chemoattractant cytokine SDF-1α and its associated receptor CXCR4 are upregulated after MI and appear to be important in this context. Activation of CXCR4 promotes both cardiomyocyte survival and stem cell migration towards the infarcted myocardium. These effects have beneficial effects on infarct size, and left ventricular remodelling and function. However, the timing of endogenous SDF-1α release and CXCR4 upregulation may not be optimal. Furthermore, current ELISA-based assays cannot distinguish between active SDF-1α, and SDF-1α inactivated by dipeptidyl peptidase 4 (DPP4). Current therapeutic approaches aim to recruit the SDF-1α-CXCR4 pathway or prolong SDF-1α life-time by preventing its cleavage by DPP4. This review assesses the evidence supporting these approaches and proposes SDF-1α as an important confounder in recent studies of DPP4 inhibitors.

Stem Cell Homing: a Potential Therapeutic Strategy Unproven for Treatment of Myocardial Injury

Despite advances in the prevention and therapeutic modalities of ischemic heart disease, morbidity and mortality post-infarction heart failure remain big challenges in modern society. Stem cell therapy is emerging as a promising therapeutic strategy. Stem cell homing, the ability of stem cells to find their destination, is receiving more attention. Identification of specific cues and understanding the signaling pathways that direct stem cells to targeted destination will improve stem cell homing efficiency. This review discusses the cellular and molecular mechanism of stem cell homing at length in the light of literature and analyzes the problem and considerations of this approach as a treatment strategy for the treatment of ischemic heart disease clinically.

Impact of dipeptidyl-peptidase 4 inhibitors on cardiovascular diseases

Dipeptidyl peptidase 4 (DPP-4) inhibitor is a novel group of medicine employed in type 2 diabetes mellitus (T2DM),which improves meal stimulated insulin secretion by protecting glucagon-like peptide-1 (GLP-1) and glucose dependent insulinotropic polypeptide (GIP) from enzymatic degradation. Cardiovascular diseases are serious complications and leading causes of mortality among individuals with diabetes mellitus. Glycemic control per se seems to fail in preventing the progression of diabetic cardiovascular complications. DPP-4 has the capability to inactivate not only incretins, but also a series of cytokines, chemokines, and neuropeptides involved in inflammation, immunity, and vascular function. Pre-clinical studies suggested that DPP-4 inhibitors may have potential cardiovascular protective effects in addition to their antidiabetic actions. In recent years, a number of clinical trials have been conducted to evaluate the effect of different DPP-4 inhibitors on the cardiovascular system. We herein review the available clinical studies in cardiovascular effects played by each DPP-4 inhibitor and discuss the prospective application of DPP-4 inhibitors on cardiovascular diseases.

Sitagliptin Accelerates Endothelial Regeneration after Vascular Injury Independent from GLP1 Receptor Signaling

INTRODUCTION

DPP4 inhibitors (gliptins) are commonly used antidiabetic drugs for the treatment of type 2 diabetes. Gliptins also act in a glucose-independent manner and show vasoregenerative effects. We have shown that gliptins can remarkably accelerate vascular healing after vascular injury. However, the underlying mechanisms remain unclear. Here, we examined potential signaling pathways linking gliptins to enhanced endothelial regeneration.

METHODS AND RESULTS

We used wild-type and GLP1 receptor knockout (Glp1r-/-) mice to investigate the underlying mechanisms of gliptin-induced reendothelialization. The prototype DPP4 inhibitor sitagliptin accelerated endothelial healing in both animal models. Improved endothelial growth was associated with gliptin-mediated progenitor cell recruitment into the diseased vascular wall via the SDF1-CXCR4 axis independent of GLP1R-dependent signaling pathways. Furthermore, SDF1 showed direct proproliferative effects on endothelial cells. Excessive neointimal formation was not observed in gliptin- or placebo-treated Glp1r-/- mice.

CONCLUSION

We identified the SDF1-CXCR4 axis as a crucial signaling pathway for endothelial regeneration after acute vascular injury. Furthermore, SDF1 can directly increase endothelial cell proliferation. Gliptin-mediated potentiation of endothelial regeneration was preserved in Glp1r-/- animals. Thus, gliptin-mediated endothelial regeneration proceeds through SDF-1/CXCR4 in a GLP1R-independent manner after acute vascular injury.

Inhibiting DPP4 in a mouse model of HHT1 results in a shift towards regenerative macrophages and reduces fibrosis after myocardial infarction

AIMS

Hereditary Hemorrhagic Telangiectasia type-1 (HHT1) is a genetic vascular disorder caused by haploinsufficiency of the TGFβ co-receptor endoglin. Dysfunctional homing of HHT1 mononuclear cells (MNCs) towards the infarcted myocardium hampers cardiac recovery. HHT1-MNCs have elevated expression of dipeptidyl peptidase-4 (DPP4/CD26), which inhibits recruitment of CXCR4-expressing MNCs by inactivation of stromal cell-derived factor 1 (SDF1). We hypothesize that inhibiting DPP4 will restore homing of HHT1-MNCs to the infarcted heart and improve cardiac recovery.

METHODS AND RESULTS

After inducing myocardial infarction (MI), wild type (WT) and endoglin heterozygous (Eng+/-) mice were treated for 5 days with the DPP4 inhibitor Diprotin A (DipA). DipA increased the number of CXCR4+ MNCs residing in the infarcted Eng+/- hearts (Eng+/- 73.17±12.67 vs. Eng+/- treated 157.00±11.61, P = 0.0003) and significantly reduced infarct size (Eng+/- 46.60±9.33% vs. Eng+/- treated 27.02±3.04%, P = 0.03). Echocardiography demonstrated that DipA treatment slightly deteriorated heart function in Eng+/- mice. An increased number of capillaries (Eng+/- 61.63±1.43 vs. Eng+/- treated 74.30±1.74, P = 0.001) were detected in the infarct border zone whereas the number of arteries was reduced (Eng+/- 11.88±0.63 vs. Eng+/- treated 6.38±0.97, P = 0.003). Interestingly, while less M2 regenerative macrophages were present in Eng+/- hearts prior to DipA treatment, (WT 29.88±1.52% vs. Eng+/- 12.34±1.64%, P<0.0001), DPP4 inhibition restored the number of M2 macrophages to wild type levels.

CONCLUSIONS

In this study, we demonstrate that systemic DPP4 inhibition restores the impaired MNC homing in Eng+/- animals post-MI, and enhances cardiac repair, which might be explained by restoring the balance between the inflammatory and regenerative macrophages present in the heart.

Diagnostic and prognostic value of miR-1 and miR-29b on adverse ventricular remodeling after acute myocardial infarction - The SITAGRAMI-miR analysis

BACKGROUND

MicroRNAs (miRs) have shown to exert fibrotic and anti-fibrotic effects in preclinical models of acute myocardial infarction (AMI). The aim of this study was to evaluate miR-1, miR-21, miR-29b and miR-92a as circulating biomarkers for adverse ventricular remodeling (AVR) in post-AMI patients.

METHODS

Plasma levels of miR-1, miR-21, miR-29b and miR-92a were measured in 44 patients of the SITAGRAMI trial population at day 4, day 9 and 6month after AMI and in 18 matched controls (CTL). MiR expression patterns were correlated with magnetic resonance imaging (MRI) parameters for AVR (absolute change (Δ) in infarct volume (IV), left ventricular ejection fraction (LVEF) and left ventricular end-diastolic volume (LVEDV) between day 4 and 6months after AMI) and a combined cardiovascular endpoint.

RESULTS

Expression of miR-1, miR-21 and miR-29b but not miR-92a was increased in AMI vs. CTL cohort showing highest miR levels at d9. However, only miR-1 and miR-29b levels significantly correlated with ΔIV and showed a trend for correlation with ΔLVEF. Only miR-29b levels at day 9 correlated with ΔLVEDV at 6-month follow-up. There was no correlation of miR levels with an adverse outcome.

CONCLUSION

Mir-1 and miR-29b plasma levels post-AMI correlate with IV changes. In addition, miR-29b levels are associated with changes of LVEDV over time. These results provide insights into the role of miRs as diagnostic AVR surrogate markers. Further large scale clinical trials will be needed to evaluate the real prognostic relevance of these miRs with respect to a clinical implication in the future.

Concise Review: Perspectives and Clinical Implications of Bone Marrow and Circulating Stem Cell Defects in Diabetes

Diabetes mellitus is a complex systemic disease characterized by severe morbidity and excess mortality. The burden of its multiorgan complications relies on an imbalance between hyperglycemic cell damage and defective endogenous reparative mechanisms. Inflammation and abnormalities in several hematopoietic components are typically found in diabetes. The discovery that diabetes reduces circulating stem/progenitor cells and impairs their function has opened an entire new field of study where diabetology comes into contact with hematology and regenerative medicine. It is being progressively recognized that such rare circulating cell populations mirror finely regulated processes involved in hematopoiesis, immunosurveillance, and peripheral tissue homeostasis. From a clinical perspective, pauperization of circulating stem cells predicts adverse outcomes and death. Furthermore, studies in murine models and humans have identified the bone marrow (BM) as a previously neglected site of diabetic end-organ damage, characterized by microangiopathy, neuropathy, fat deposition, and inflammation. As a result, diabetes impairs the mobilization of BM stem/progenitor cells, a defect known as mobilopathy or myelokathexis, with negative consequences for physiologic hematopoiesis, immune regulation, and tissue regeneration. A better understanding of the molecular and cellular processes that govern the BM stem cell niche, cell mobilization, and kinetics in peripheral tissues may uncover new therapeutic strategies for patients with diabetes. This concise review summarizes the current knowledge on the interplay between the BM, circulating stem cells, and diabetes, and sets the stages for future developments in the field. Stem Cells 2017;35:106-116.