Arthur C. Coffey

Proinflammatory Cytokine Effects on Mesenchymal Stem Cell Therapy for the Ischemic Heart

Mesenchymal stem cells (MSCs) hold great promise for improving myocardial recovery after ischemia. The cardiothoracic surgeon is uniquely positioned to be at the forefront of any clinical application of this therapy. As such, a basic understanding of stem cells and the cytokines that affect stem cell function will be an essential component of the surgeons ever-expanding knowledge base. This review provides: (1) a general overview of stem cells and MSCs in particular, (2) critically analyzes several cytokines known to alter MSC function, and (3) discusses methods to manipulate cytokine-activated MSCs to improve MSC function for potential clinical application.

Prospective Clinical Study of a Novel Left Atrial Appendage Occlusion Device

PURPOSEnThis Food and Drug Administration-approved investigational device exempt trial assessed the safety and efficacy of a novel device for external left atrial appendage (LAA) exclusion.nnnDESCRIPTIONnDelivery tool and implant consisting of connectors imbedded in a compliant, soft silicone applied to the base of the LAA flush with the external wall was assessed.nnnEVALUATIONnPatients in this prospective, multicenter trial were undergoing elective, nonendoscopic cardiac operations. A core laboratory independently assessed all intraprocedural and 90-day transesophageal echocardiograms. Sixty patients (37 men), aged 33 to 86 years, enrolled. The mean LAA application time was 27 seconds. Transesophageal echocardiograms at 90 days were available in 54 patients, and no leaks were detected. The residual LAA cavity exceeded 6 mm in 5 patients. One delivery device failed to close, and an adjunctive suture was required to complete LAA exclusion. One patient required adjunct sutures at a small tear site related to manual manipulation after fastener application.nnnCONCLUSIONSnThe study demonstrated safety and efficacy of this LAA exclusion device, offering an alternative to manual suturing or staples with or without reinforcement.

Gender dimorphisms in progenitor and stem cell function in cardiovascular disease

Differences in cardiovascular disease outcomes between men and women have long been recognized and attributed, in part, to gender and sex steroids. Gender dimorphisms also exist with respect to the roles of progenitor and stem cells in post-ischemic myocardial and endothelial repair and regeneration. Understanding how these cells are influenced by donor gender and the recipient hormonal milieu may enable researchers to further account for the gender-related disparities in clinical outcomes as well as utilize the beneficial effects of these hormones to optimize transplanted cell function and survival. This review discusses (1) the cardiovascular effects of sex steroids (specifically estradiol and testosterone); (2) the therapeutic potentials of endothelial progenitor cells, mesenchymal stem cells, and embryonic stem cells; and (3) the direct effect of sex steroids on these cell types.

Simultaneous noninvasive recording of skin sympathetic nerve activity and electrocardiogram

BACKGROUNDnSympathetic nerve activity is important to cardiac arrhythmogenesis.nnnOBJECTIVEnThe purpose of this study was to develop a method for simultaneous noninvasive recording of skin sympathetic nerve activity (SKNA) and electrocardiogram (ECG) using conventional ECG electrodes. This method (neuECG) can be used to adequately estimate sympathetic tone.nnnMETHODSnWe recorded neuECG signals from the skin of 56 human subjects. The signals were low-pass filtered to show the ECG and high-pass filtered to show nerve activity. Protocol 1 included 12 healthy volunteers who underwent cold water pressor test and Valsalva maneuver. Protocol 2 included 19 inpatients with epilepsy but without known heart diseases monitored for 24 hours. Protocol 3 included 22 patients admitted with electrical storm and monitored for 39.0 ± 28.2 hours. Protocol 4 included 3 patients who underwent bilateral stellate ganglion blockade with lidocaine injection.nnnRESULTSnIn patients without heart diseases, spontaneous nerve discharges were frequently observed at baseline and were associated with heart rate acceleration. SKNA recorded from chest leads (V1-V6) during cold water pressor test and Valsalva maneuver (protocol 1) was invariably higher than during baseline and recovery periods (P < .001). In protocol 2, the average SKNA correlated with heart rate acceleration (r = 0.73 ± 0.14, P < .05) and shortening of QT interval (P < .001). Among 146 spontaneous ventricular tachycardia episodes recorded in 9 patients of protocol 3, 106 episodes (73%) were preceded by SKNA within 30 seconds of onset. Protocol 4 showed that bilateral stellate ganglia blockade by lidocaine inhibited SKNA.nnnCONCLUSIONnSKNA is detectable using conventional ECG electrodes in humans and may be useful in estimating sympathetic tone.

Signal transducer and activator of transcription 3–stimulated hypoxia inducible factor-1α mediates estrogen receptor-α–induced mesenchymal stem cell vascular endothelial growth factor production

OBJECTIVEnVascular endothelial growth factor, a critical factor in angiogenesis, mediates stem cell paracrine protective effects on ischemic myocardium. Studies on the role of sex in stem cell function have demonstrated that female mesenchymal stem cells produce greater vascular endothelial growth factor and provide better cardiac protection compared with male mesenchymal stem cells. The purpose of this study was to determine the mechanisms by which estrogen affects mesenchymal stem cell function as a potential therapeutic measure during ex vivo expansion, before therapeutic use.nnnMETHODSnA single-step purification method using adhesion to cell culture plastic was adopted to isolate mesenchymal stem cells from wild-type, estrogen receptor-alpha knockout, estrogen receptor-beta knockout, and signal transducer and activator of transcription 3 knockout mice. Mesenchymal stem cells were treated with or without 17beta-estradiol, estrogen receptor-alpha agonist (propyl pyrazoletriol), and estrogen receptor-beta agonist (diarylpropionitrile).nnnRESULTSn17beta-estradiol significantly increased mesenchymal stem cell vascular endothelial growth factor production in a dose-dependent manner. Both estrogen receptor-alpha and estrogen receptor-beta were expressed in mesenchymal stem cells. Administration of 17beta-estradiol or estrogen receptor-alpha agonist (not estrogen receptor-beta agonist) elevated mesenchymal stem cell vascular endothelial growth factor, hypoxia inducible factor-1alpha expression, and signal transducer and activator of transcription 3 activation. However, these effects were neutralized in estrogen receptor-alpha knockout mesenchymal stem cells, not estrogen receptor-beta knockout. Signal transducer and activator of transcription 3 knockout abolished estrogen receptor-alpha-induced hypoxia inducible factor-1alpha and subsequent vascular endothelial growth factor production.nnnCONCLUSIONn17beta-estradiol-induced vascular endothelial growth factor production from mesenchymal stem cells appears to be mediated through estrogen receptor-alpha-activated signal transducer and activator of transcription 3-mediated hypoxia inducible factor-1alpha expression.

Atrioesophageal Fistula After Surgical Unipolar Radiofrequency Atrial Ablation for Atrial Fibrillation

Atrial fibrillation is the most common arrhythmia in the United States. Procedural treatment options such as the MAZE procedure and radiofrequency ablation are available with reasonable success rates. However, there are risks inherent to these procedures, with atrioesophageal fistula being a rare but devastating complication. We report a patient with atrioesophageal fistula who presented with neurologic symptoms 20 days after her initial MAZE procedure, followed by a quick decline within 24 hours of presentation.

MEK mediates the novel cross talk between TNFR2 and TGF-EGFR in enhancing vascular endothelial growth factor (VEGF) secretion from human mesenchymal stem cells

BACKGROUNDnBone marrow mesenchymal stem cells (MSCs) may mediate their beneficial effects by paracrine mechanisms. Recently, we reported that tumor necrosis factor-alpha (TNF-alpha) increased the release of vascular endothelial growth factor (VEGF) from human MSCs and augmented transforming growth factor-alpha (TGF-alpha)-stimulated VEGF secretion. However, it is unknown whether TNF-alpha stimulates VEGF production via TNF receptor 1 (TNFR1) or 2 (TNFR2) and the mechanism by which TNF-alpha augments TGF-alpha (a ligand of epidermal growth factor receptor, EGFR) stimulated VEGF production. We hypothesized that the ablation of TNFR2 would decrease TNF-alpha-stimulated and/or TGF-alpha- stimulated VEGF production via MEK-dependent mechanisms.nnnMETHODSnMSCs transfected with TNFR1, TNFR2, or GAPDH siRNA were stimulated with TNF-alpha and/or TGF-alpha for 24 h. VEGF levels in the supernatant were determined by enzyme-linked immunosorbent assay (ELISA). A Western blot analysis was performed to measure the activation of MEK and ERK and the expression of TNFR1 and TNFR2.nnnRESULTSnTNF-alpha or TGF-alpha increased VEGF secretion in cells transfected with GAPDH or TNFR1 siRNA. The combination of TNF-alpha and TGF-alpha increased VEGF production. TNF-alpha and/or TGF-alpha stimulation increased phospho-MEK and phospho-ERK in cells transfected with TNFR1 siRNA. Conversely, the effects of TNF-alpha and/or TGF-alpha on MSC VEGF production were significantly decreased, and MEK/ERK activation was negated in cells transfected TNFR2 siRNA.nnnCONCLUSIONnTNFR2 plays a vital role in the effects of TNF-alpha and TGF-alpha on MSC VEGF production. The activation of MEK was implicated in this novel cross talk between TNFR2 and TGF-alpha-EGFR in regulating the production of VEGF in human MSCs.

Long-term results with cryopreserved arterial allografts (CPAs) in the treatment of graft or primary arterial infections.

OBJECTIVEnOur purpose was to evaluate our results with CPAs in patients with infected grafts or primary arterial infection with emphasis on long-term durability of these grafts.nnnMETHODSnTo evaluate the long-term durability of CPAs, clinical outcomes were analyzed following their use for either graft or primary arterial infections at a single institution over a 9-y period (2000-2009). The 30-d mortality rate, 90-d mortality rate, and the cause of early mortality were determined in each case. Among those surviving 90 d, the grafts were evaluated for subsequent failure.nnnRESULTSnFrom 2000 through 2009, 51 patients with either infected prosthetic grafts (35) or primary arterial infections (15) received CPAs. One patient had infection of a previously placed thoracic allograft. Forty-three graft infections involved either the thoracic or abdominal aorta. Eleven patients presented with fulminant sepsis with systemic inflammatory response syndrome (SIRS), seven of whom died postoperatively. Eight patients presented with aorto-enteric, esophageal, or bronchial fistulae with infected prosthetic grafts. The 30-d mortality rate was 25.5% (11 deaths) seven of which occurred in patients with SIRS. The 90-d mortality rate was 41.4%. There were 10 graft failures, seven occurring in patients with aorto-enteric or bronchial fistulae all of whom had recurrent hemorrhage. The other three graft failures were due to anastomotic hemorrhage in the early postoperative period. Among those surviving 90 d, the mean follow-up was 46.4 mo (range 1-112 mo). No aneurysmal degeneration of the CPAs was noted. Only one subsequent allograft graft failure was noted among those surviving more than 90 d.nnnCONCLUSIONSnCPAs are a suitable option in dealing with cardiovascular infections. Patients with enteric or bronchial fistulae are a difficult group to treat perhaps because of ongoing contamination of the allograft. The operative mortalities are largely determined by patient comorbidities (SIRS). Subsequent degeneration or infection of the CPAs is rare.

Role of Tumor Necrosis Factor Receptor 1 in Sex Differences of Stem Cell Mediated Cardioprotection

BACKGROUNDnMesenchymal stem cells (MSCs) hold great therapeutic potential for the repair and regeneration of ischemic tissue, possibly through the release of beneficial paracrine factors. Sex differences have been observed in the paracrine function of MSCs. Female stem cells produce lower proinflammatory cytokines and higher levels of growth factors compared with their male counterparts. Ablation of tumor necrosis factor receptor 1 (TNFR1) increases protective growth factor production by male, but not by female, MSCs. We therefore hypothesized the following: (1) that female MSCs would improve myocardial recovery compared with male MSCs after ischemia-reperfusion injury (I/R); and (2) that MSCs isolated from TNFR1 knock out male, but not female, mice, would improve postischemic myocardial recovery compared with their wild type (WT) counterparts.nnnMETHODSnMale adult Sprague-Dawley rat hearts were subjected to I/R by Langendorff isolated heart preparation. The MSCs were harvested from adult mice and cultured under normal conditions. Immediately prior to ischemia, one million MSCs were infused into the coronary circulation. Cardiac functional parameters were recorded continuously.nnnRESULTSnPretreatment with MSCs from either sex significantly increased postischemic myocardial recovery as evidenced by improved left ventricular developed pressure, contractility, and rate of relaxation. Infusion with female MSCs was associated with a greater degree of myocardial recovery after I/R compared with male MSCs. The TNFR1 deficiency increased the degree of myocardial recovery associated with male MSCs, but not with female MSCs. No additional cardioprotection was observed when TNFR1 was ablated in female MSCs.nnnCONCLUSIONnSex differences influence the cardioprotective effects of both WT and TNFR1 ablated MSCs.

Sensor to detect endothelialization on an active coronary stent

BackgroundA serious complication with drug-eluting coronary stents is late thrombosis, caused by exposed stent struts not covered by endothelial cells in the healing process. Real-time detection of this healing process could guide physicians for more individualized anti-platelet therapy. Here we present work towards developing a sensor to detect this healing process. Sensors on several stent struts could give information about the heterogeneity of healing across the stent.MethodsA piezoelectric microcantilever was insulated with parylene and demonstrated as an endothelialization detector for incorporation within an active coronary stent. After initial characterization, endothelial cells were plated onto the cantilever surface. After they attached to the surface, they caused an increase in mass, and thus a decrease in the resonant frequencies of the cantilever. This shift was then detected electrically with an LCR meter. The self-sensing, self-actuating cantilever does not require an external, optical detection system, thus allowing for implanted applications.ResultsA cell density of 1300 cells/mm2 on the cantilever surface is detected.ConclusionsWe have developed a self-actuating, self-sensing device for detecting the presence of endothelial cells on a surface. The device is biocompatible and functions reliably in ionic liquids, making it appropriate for implantable applications. This sensor can be placed along the struts of a coronary stent to detect when the struts have been covered with a layer of endothelial cells and are no longer available surfaces for clot formation. Anti-platelet therapy can be adjusted in real-time with respect to a patients level of healing and hemorrhaging risks.