Showing papers by "Francis G. Spinale published in 2014"

Injectable and bioresponsive hydrogels for on-demand matrix metalloproteinase inhibition

Abstract: Excessive activity of matrix metalloproteinases (MMPs) occurs in many diseases; however, the systemic administration of MMP inhibitors can cause undesirable, off-target effects and hence, clinical translation has been hampered. Now, injectable polysaccharide-based hydrogels are shown to enable the localized delivery of an inhibitor of MMP following the hydrogels’ degradation in response to MMP activity. This targeted approach shows efficacy in a myocardial infarction model in large animals.

Local Hydrogel Release of Recombinant TIMP-3 Attenuates Adverse Left Ventricular Remodeling After Experimental Myocardial Infarction

Abstract: An imbalance between matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) contributes to the left ventricle (LV) remodeling that occurs after myocardial infarction (MI). However, translation of these observations into a clinically relevant, therapeutic strategy remains to be established. The present study investigated targeted TIMP augmentation through regional injection of a degradable hyaluronic acid hydrogel containing recombinant TIMP-3 (rTIMP-3) in a large animal model. MI was induced in pigs by coronary ligation. Animals were then randomized to receive targeted hydrogel/rTIMP-3, hydrogel alone, or saline injection and followed for 14 days. Instrumented pigs with no MI induction served as referent controls. Multimodal imaging (fluoroscopy/ echocardiography/magnetic resonance imaging) revealed that LV ejection fraction was improved, LV dilation was reduced, and MI expansion was attenuated in the animals treated with rTIMP-3 compared to all other controls. A marked reduction in proinflammatory cytokines and increased smooth muscle actin content indicative of myofibroblast proliferation occurred in the MI region with hydrogel/rTIMP-3 injections. These results provide the first proof of concept that regional sustained delivery of an MMP inhibitor can effectively interrupt adverse post-MI remodeling.

Targeted Overexpression of Tissue Inhibitor of Matrix Metalloproteinase-4 Modifies Post Myocardial Infarction Remodeling in Mice

Abstract: Rationale:Myocardial infarction (MI) causes an imbalance between matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases (TIMPs) and is associated with adverse left ventricular (LV) remodeling. A uniform reduction in TIMP-4 post-MI has been observed. Objective:To examine post-MI remodeling with cardiac-restricted overexpression of TIMP-4, either through a transgenic or viral delivery approach. Methods and Results:MI was induced in mice and then randomized to targeted injection of an adenoviral construct (10 μL; 8×109 plaque forming units/mL) encoding green fluorescent protein (GFP) and the full-length human TIMP-4 (Ad-GFP-TIMP4) or GFP. A transgenic construct with cardiac-restricted overexpression TIMP-4 (hTIMP-4exp) was used in a parallel set of studies. LV end-diastolic volume, an index of LV remodeling, increased by >60% from baseline at 5 days post-MI and by >100% at 21 days post-MI in the Ad-GFP only group. However, LV dilation was reduced by ≈50% in both the Ad-GFP-TIMP4 and hTI...

Quantitative Measurement of Dissection Resistance in Intimal and Medial Layers of Human Coronary Arteries

Abstract: The left anterior descending (LAD) coronary artery is the most frequently involved vessel in coronary artery dissection, a cause of acute coronary syndrome or sudden cardiac death. The biomechanical mechanisms underlying arterial dissection are not well understood. This study investigated the dissection properties of LAD specimens harvested from explanted hearts at the time of cardiac transplantation, from patients with primary dilated cardiomyopathy (n = 12). Using a previously validated approach uniquely modified for these human LAD specimens, we quantified the local energy release rate, G, within different arterial layers during experimental dissection events (tissue tearing). Results show that the mean values of G during arterial dissection within the intima and within the media in human LADs are 20.7 ± 16.5 J/m2 and 10.3 ± 5.0 J/m2, respectively. The difference in dissection resistance between tearing events occurring within the intima and within the media is statistically significant. Our data fall in the same order of magnitude as most previous measurements of adhesive strength in other human arteries, with the differences in measured values of G within the layers most likely due to histologically observed differences in the structure and composition of arterial layers.

Targeted Injection of a Biocomposite Material Alters Macrophage and Fibroblast Phenotype and Function following Myocardial Infarction: Relation to Left Ventricular Remodeling

Abstract: A treatment target for progressive left ventricular (LV) remodeling prevention following myocardial infarction (MI) is to affect structural changes directly within the MI region. One approach is through targeted injection of biocomposite materials, such as calcium hydroxyapatite microspheres (CHAM), into the MI region. In this study, the effects of CHAM injections upon key cell types responsible for the MI remodeling process, the macrophage and fibroblast, were examined. MI was induced in adult pigs before randomization to CHAM injections (20 targeted 0.1-ml injections within MI region) or saline. At 7 or 21 days post-MI (n = 6/time point per group), cardiac magnetic resonance imaging was performed, followed by macrophage and fibroblast isolation. Isolated macrophage profiles for monocyte chemotactic macrophage inflammatory protein-1 as measured by real-time polymerase chain reaction increased at 7 days post-MI in the CHAM group compared with MI only (16.3 ± 6.6 versus 1.7 ± 0.6 cycle times values, P < 0.05), and were similar by 21 days post-MI. Temporal changes in fibroblast function and smooth muscle actin (SMA) expression relative to referent control (n = 5) occurred with MI. CHAM induced increases in fibroblast proliferation, migration, and SMA expression—indicative of fibroblast transformation. By 21 days, CHAM reduced LV dilation (diastolic volume: 75 ± 2 versus 97 ± 4 ml) and increased function (ejection fraction: 48 ± 2% versus 38 ± 2%) compared with MI only (both P < 0.05). This study identified that effects on macrophage and fibroblast differentiation occurred with injection of biocomposite material within the MI, which translated into reduced adverse LV remodeling. These unique findings demonstrate that biomaterial injections impart biologic effects upon the MI remodeling process over any biophysical effects.

Mechanistic Relationship Between Membrane Type-1 Matrix Metalloproteinase and the Myocardial Response to Pressure Overload

Abstract: Background—Although matrix metalloproteinases (MMPs) were initially thought to result primarily in extracellular matrix degradation, certain MMP types, such as membrane type-1 (MT1) MMP, may also be involved in profibrotic cascades through hydrolysis of latency-associated transforming growth factor–binding protein (LTBP-1) and activation of transforming growth factor–dependent profibrotic signaling. The present study tested the hypothesis that MT1-MMP plays a direct role in the matrix remodeling response to a left ventricular (LV) pressure overload (PO) stimulus. Methods and Results—Wild-type (WT) and transgenic mice with cardiac-restricted MT1-MMP overexpression or MT1-MMP reduced expression underwent PO for 4 weeks. PO resulted in a 57% increase in LV mass (no change in LV end diastolic volume, resulting in an increase in the LV mass/volume ratio consistent with concentric remodeling), a 60% increase in MT1-MMP–mediated LTBP-1 hydrolysis and a 190% increase in collagen content in WT mice. Although LV ma...

Analyzing propensity matched zero-inflated count outcomes in observational studies

Abstract: Determining the effectiveness of different treatments from observational data, which are characterized by imbalance between groups due to lack of randomization, is challenging. Propensity matching is often used to rectify imbalances among prognostic variables. However, there are no guidelines on how appropriately to analyze group matched data when the outcome is a zero-inflated count. In addition, there is debate over whether to account for correlation of responses induced by matching and/or whether to adjust for variables used in generating the propensity score in the final analysis. The aim of this research is to compare covariate unadjusted and adjusted zero-inflated Poisson models that do and do not account for the correlation. A simulation study is conducted, demonstrating that it is necessary to adjust for potential residual confounding, but that accounting for correlation is less important. The methods are applied to a biomedical research data set.

Cardiac-restricted overexpression or deletion of tissue inhibitor of matrix metalloproteinase-4: differential effects on left ventricular structure and function following pressure overload-induced hypertrophy

Abstract: Historically, the tissue inhibitors of matrix metalloproteinases (TIMPs) were considered monochromatic in function. However, differential TIMP profiles more recently observed with left ventricular ...

Cyclosporin A in left ventricular remodeling after myocardial infarction.

Abstract: Recent studies suggest that an increase in apoptosis within the myocardium may be a contributing factor for the progression of late adverse left ventricular (LV) remodeling following myocardial infarction (MI). Given that apoptosis is often triggered by induction of the mitochondrial permeability transition (MPT) pore, the goal of this study was to evaluate the therapeutic efficacy of cyclosporin A (CsA), an MPT blocker, to prevent cells from undergoing apoptosis and consequently attenuate late LV remodeling post-MI. MI was induced in C57BL/6 mice and then randomized to either vehicle or CsA groups. Beginning 48 h after surgery after infarction had already occurred, mice were gavaged with CsA (2 mg/kg) or vehicle once daily. LV end-diastolic volume and LV ejection fraction were assessed by echocardiography before MI induction and terminally at either 7 days (n = 7) or 28 days (n = 8) post-MI. LV end-diastolic volume increased and LV ejection fraction decreased in all MI groups with no difference between the CsA-treated and untreated groups. After vehicle and CsA, areas of necrosis were present at 7 and 28 days post-MI with no difference between treatment groups. Caspase-3 activity and terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling in distal nonnecrotic LV both increased after MI but were lower in CsA-treated mice compared with vehicle (P < 0.05). In conclusion, CsA decreased apoptosis occurring late after MI, confirming involvement of a CsA-sensitive MPT in the cell death. However, CsA-mediated reduction in apoptosis in non-MI myocardium was not beneficial against late pump dysfunction occurring during post-MI remodeling.

Abstract 11612: Serial Changes in Specific Biomarkers Reflect Cardiac Resynchronization Therapy Response: Results From the SMART-AV Trial

Abstract: Background: Early identification of a favorable cardiac resynchronization therapy (CRT) response holds great clinical import These studies often utilized a single biomarker or were performed at one point in time The present study utilized an innovative approach whereby a panel of biomarkers were quantified in patients prior to CRT implant (Baseline) and then at 3 and 6 months post-CRT in a robust group of patients whereby CRT response had also been pre-specified Methods/Results: Plasma was collected from patients (SMART-AV trial), and a positive CRT response was pre-specified as a ≥15 mL reduction in LV end-systolic volume at 6 months post-CRT (Responders:n=390/Non-Responders:n=388) Through initial cohort testing and multivariate modeling, serial measures of a 12 biomarker cassette was selected using high sensitivity multiplex profiling, which consisted of C-reactive protein, soluble glycoprotein 130, soluble interleukin-2 receptor, soluble tumor necrosis factor receptor-II, interferon gamma, N-terminal brain natriuretic peptide (NT-proBNP), soluble suppressor of tumorgenicity-2 (sST-2), matrix metalloproteinases-2 and -9 (MMP-2, MMP-9), and tissue inhibitors of MMP (TIMP-1, -2, -4) Analysis of variance (ANOVA) for repeated measures identified that NT-proBNP, sST-2, and MMP-2 changed across time following CRT (by ANOVA, p Conclusion: The unique findings from this study identified that time dependent changes in a specific biomarker signature occur early in those patients likely to respond favorably to CRT, and as such, may be of potential utility for point of care testing and integration into the CRT evaluation algorithm

Reply to "letter to the editor: 'cyclosporin A in left ventricular remodeling after myocardial infarction'".

Abstract: reply: We thank Dr. Javadov (4) for providing feedback to our article published in American Journal of Physiology-Heart and Circulatory Physiology entitled “Cyclosporin A in left ventricular remodeling after myocardial infarction” (5). We set up our study to determine whether and to what degree administration of cyclosporin A (CsA) after coronary artery ligation would prevent left ventricular (LV) dilation and pump dysfunction after myocardial infarction (MI). Specifically, CsA administration was initiated 48 h after coronary artery ligation so as not to interfere with early inflammatory/necrotic responses to sustained ischemia, since the extent of LV remodeling is proportional to infarct size (2). Therefore, our study design examined the effects of CsA exclusively on the “late” phase of LV remodeling post-MI and intentionally made the size of the necrotic area the same for the CsA-treated and vehicle groups. Mitochondria isolated from cyclophilin D knockout (CypD−/−) mice are resistant to onset of the mitochondrial permeability transition (MPT), CsA does not inhibit MPT pores of CypD-deficient mitochondria, and myocardial necrosis after ischemia-reperfusion is diminished in CypD−/− mice (1, 9). In his letter, Dr. Javadov contends that the MPT can lead to only necrosis and not apoptosis. However, MPT onset is well established to cause large-amplitude mitochondrial swelling, rupture of outer membranes, and release of cytochrome c from the intermembrane space. Such cytochrome-c release leads to apoptotic protease activating factor-1 and caspase-9-dependent activation of the executioner caspase-3 as a committed step toward apoptotic cell death (8). Dr. Javadov is correct that caspase-3 activation by this mechanism requires ATP (or 2-deoxy-ATP), which becomes virtually completely depleted after severe ischemia-reperfusion. However, under less severe conditions, ATP may not become fully depleted, and enough ATP can remain to allow caspase-3 activation after cytochrome-c release, especially if glycolytic sources of ATP are available. Indeed, such glycolytic ATP prevents necrosis, but because of MPT onset, apoptosis occurs instead (6). The observation of increased apoptosis in cardiac myocytes of CypD-overexpressing mice provides further experimental support of MPT-initiated apoptosis (1). After an MI, the LV regions that were not originally ischemic undergo “reactive” remodeling, resulting in hypertrophy secondary to an increase of workload of the surviving cardiomyocytes. After several weeks, this hypertrophy can give way to a dilated cardiomyopathy with loss of cell mass, leading to heart failure and death. Accordingly, our study examined the hypothesis that increased work by surviving viable myocardium post-MI causes a concomitant increase in intracellular Ca2+ loading and respiration-dependent reactive oxygen species (ROS) formation. Increased Ca2+ and ROS then predispose to CsA-sensitive MPT pore opening, leading to dysfunction and death of cardiomyocytes (7). The MPT in these overworked myocytes need not occur in every mitochondrion of any particular cell, but only in a fraction of mitochondria large enough to release sufficient cytochrome c to initiate apoptotic signaling. The remaining intact mitochondria continue to provide ATP by oxidative phosphorylation, which is also supplemented by ATP generation from glycolysis. In this scenario, a vicious cycle develops of fewer cells doing progressively more work with further increases of intracellular Ca2+ concentrations and ROS generation, leading ultimately to substantial cell loss, LV pump dysfunction and LV dilation—the principal features of adverse post-MI remodeling (7). The question of apoptosis in ischemic myocytes raised by Dr. Javadov is moot as far as our study is concerned, because we measured apoptosis by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling and caspase-3 activation only in remote myocardium that had never experienced ischemia. Indeed, our aim was to determine whether CsA would alleviate apoptosis in remote myocardium and prevent LV dilation and pump dysfunction. However, contrary to the expectation of our hypothesis, even though CsA provided partial protection against apoptosis in remote nonischemic myocardium, CsA did not protect against LV dilation and pump dysfunction, which led us to the conclusion that a CsA-sensitive MPT was not an important pathophysiological mechanism in adverse postischemic remodeling in the weeks after an acute MI. Nonetheless, we cannot rule out that an unregulated, CsA-insensitive MPT was taking place to promote cell loss and adverse LV remodeling (3). The dose of CsA that we used was comparable with doses previously employed to protect acutely against necrotic infarction after ischemia-reperfusion (10). Protection by CsA against apoptosis observed in our study confirmed that CsA had been administered at a pharmacologically effective dose, which was important to document since higher CsA caused nephrotoxicity and could not be used. In our study, we suggested that protection against apoptosis by CsA could have been due to MPT inhibition, but we also indicated that CsA could be acting by other mechanisms, including cyclophilin A-dependent immune suppression as argued by Dr. Javadov. Dr. Javadov also suggested that in our experiments, CsA may not have been delivered to the border zone/MI region when administered after coronary occlusion. Although this may be true, our study focused on apoptosis and adverse remodeling in remote nonischemic myocardial regions where blood circulation was never compromised. Indeed, protection by CsA against apoptosis was strong evidence that CsA was effectively delivered to this tissue. Despite protection against apoptosis, CsA did not decrease ventricular dilation, pump dysfunction, and adverse LV remodeling at 4 wk post-MI. Thus we suggest that a CsA-sensitive MPT, although contributing to infarction in the early phase of ischemic injury, likely does not play a significant role in late adverse LV remodeling at 28 days post-MI.