We developed a tissue-engineered vascular graft (TEVG) for use in children and present results of a U.S. Food and Drug Administration (FDA)–approved clinical trial evaluating this graft in patients with single-ventricle cardiac anomalies. The TEVG was used as a Fontan conduit to connect the inferior vena cava and pulmonary artery, but a high incidence of graft narrowing manifested within the first 6 months, which was treated successfully with angioplasty. To elucidate mechanisms underlying this early stenosis, we used a data-informed, computational model to perform in silico parametric studies of TEVG development. The simulations predicted early stenosis as observed in our clinical trial but suggested further that such narrowing could reverse spontaneously through an inflammation-driven, mechano-mediated mechanism. We tested this unexpected, model-generated hypothesis by implanting TEVGs in an ovine inferior vena cava interposition graft model, which confirmed the prediction that TEVG stenosis resolved spontaneously and was typically well tolerated. These findings have important implications for our translational research because they suggest that angioplasty may be safely avoided in patients with asymptomatic early stenosis, although there will remain a need for appropriate medical monitoring. The simulations further predicted that the degree of reversible narrowing can be mitigated by altering the scaffold design to attenuate early inflammation and increase mechano-sensing by the synthetic cells, thus suggesting a new paradigm for optimizing next-generation TEVGs. We submit that there is considerable translational advantage to combined computational-experimental studies when designing cutting-edge technologies and their clinical management.

Cardiovascular complications are a leading cause of death in patients with type 2 diabetes mellitus (T2DM). Diastolic dysfunction is one of the earliest manifestations of diabetes-induced changes in left ventricular (LV) function, and results from a reduced rate of relaxation and increased stiffness. The mechanisms responsible for increased stiffness are not completely understood. Chronic hyperglycemia, advanced glycation endproducts (AGEs), and increased levels of proinflammatory and profibrotic cytokines are molecular pathways known to be involved in regulating extracellular matrix (ECM) synthesis and accumulation resulting in increased LV diastolic stiffness. Experiments were conducted using a genetically-induced mouse model of T2DM generated by a point mutation in the leptin receptor resulting in nonfunctional leptin receptors (db/db murine model). This study correlated changes in LV ECM and stiffness with alterations in basal activation of signaling cascades and expression of profibrotic markers within primary cultures of cardiac fibroblasts from diabetic (db/db) mice with nondiabetic (db/wt) littermates as controls. Primary cultures of cardiac fibrobroblasts were maintained in 25 mM glucose (hyperglycemic-HG; diabetic db/db) media or 5 mM glucose (normoglycemic-NG, nondiabetic db/wt) media. The cells then underwent a 24-hour exposure to their opposite (NG; diabetic db/db) media or 5 mM glucose (HG, nondiabetic db/wt) media. Protein analysis demonstrated significantly increased expression of type I collagen, TIMP-2, TGF-β, PAI-1 and RAGE in diabetic db/db cells as compared to nondiabetic db/wt, independent of glucose media concentration. This pattern of protein expression was associated with increased LV collagen accumulation, myocardial stiffness and LV diastolic dysfunction. Isolated diabetic db/db fibroblasts were phenotypically distinct from nondiabetic db/wt fibroblasts and exhibited a profibrotic phenotype in normoglycemic conditions.

Temporal pattern of left ventricular structural and functional remodeling following reversal of volume overload heart failure. J Appl Physiol 111: 1778 -1788. First published September 1, 2011 doi:10.1152/japplphysiol.00691.2011.-Current surgical management of volume overload-induced heart failure (HF) leads to variable recovery of left ventricular (LV) function despite a return of LV geometry. The mechanisms that prevent restoration of function are unknown but may be related to the timing of intervention and the degree of LV contractile impairment. This study determined whether reduction of aortocaval fistula (ACF)-induced LV volume overload during the compensatory stage of HF results in beneficial LV structural remodeling and restoration of pump function. Rats were subjected to ACF for 4 wk; a subset then received a load-reversal procedure by closing the shunt using a custom-made stent graft approach. Echocardiography or in vivo pressure-volume analysis was used to assess LV morphology and function in sham rats; rats subjected to 4-, 8-, or 15-wk ACF; and rats subjected to 4-wk ACF followed by 4-or 11-wk reversal. Structural and functional changes were correlated to LV collagen content, extracellular matrix (ECM) proteins, and hypertrophic markers. ACF-induced volume overload led to progressive LV chamber dilation and contractile dysfunction. Rats subjected to shortterm reversal (4-wk ACF ϩ 4-wk reversal) exhibited improved chamber dimensions (LV diastolic dimension) and LV compliance that were associated with ECM remodeling and normalization of atrial and brain natriuretic peptides. Load-independent parameters indicated LV systolic (preload recruitable stroke work, Ees) and diastolic dysfunction (tau, arterial elastance). These changes were associated with an altered ␣/␤-myosin heavy chain ratio. However, these changes were normalized to sham levels in long-term reversal rats (4-wk ACF ϩ 11-wk reversal). Acute hemodynamic changes following ACF reversal improve LV geometry, but LV dysfunction persists. Gradual restoration of function was related to normalization of eccentric hypertrophy, LV wall stress, and ECM remodeling. These results suggest that mild to moderate LV systolic dysfunction may be an important indicator of the ability of the myocardium to remodel following the reversal of hemodynamic overload.hemodynamics; cardiac remodeling/hypertrophy; collagen THE INCIDENCE OF HEART FAILURE (HF) is increasing due to an aging population and improved management of diseases that are precursors to ventricular dysfunction. The successes of therapeutic advances over the past decades have dramatically decreased mortality rates, such that the focus has now shifted towards reducing morbidities (12). As a result, cardiac remodeling has become a primary therapeutic target in patients with heart failure. Strategies to prevent or reverse adverse left ventricular (LV) remodeling include pharmacotherapy, surgical interventions, and device-based-therapies such as left ventricular assist devices (LVAD) and cardiac resynchro...

Previous studies from our laboratory showed that coronary arterioles from type 2 diabetic mice undergo inward hypertrophic remodeling and reduced stiffness. The aim of the current study was to determine if coronary resistance microvessels (CRMs) in Ossabaw swine with metabolic syndrome (MetS) undergo remodeling distinct from coronary conduit arteries. Male Ossabaw swine were fed normal (n = 7, Lean) or hypercaloric high-fat (n = 7, MetS) diets for 6 mo, and then CRMs were isolated and mounted on a pressure myograph. CRMs isolated from MetS swine exhibited decreased luminal diameters (126 ± 5 and 105 ± 9 μm in Lean and MetS, respectively, P < 0.05) with thicker walls (18 ± 3 and 31 ± 3 μm in Lean and MetS, respectively, P < 0.05), which doubled the wall-to-lumen ratio (14 ± 2 and 30 ± 2 in Lean and MetS, respectively, P < 0.01). Incremental modulus of elasticity (IME) and beta stiffness index (BSI) were reduced in CRMs isolated from MetS pigs (IME: 3.6 × 10(6) ± 0.7 × 10(6) and 1.1 × 10(6) ± 0.2 × 10(6) dyn/cm(2) in Lean and MetS, respectively, P < 0.001; BSI: 10.3 ± 0.4 and 7.3 ± 1.8 in Lean and MetS, respectively, P < 0.001). BSI in the left anterior descending coronary artery was augmented in pigs with MetS. Structural changes were associated with capillary rarefaction, decreased hyperemic-to-basal coronary flow velocity ratio, and augmented myogenic tone. MetS CRMs showed a reduced collagen-to-elastin ratio, while immunostaining for the receptor for advanced glycation end products was selectively increased in the left anterior descending coronary artery. These data suggest that MetS causes hypertrophic inward remodeling of CRMs and capillary rarefaction, which contribute to decreased coronary flow and myocardial ischemia. Moreover, our data demonstrate novel differential remodeling between coronary micro- and macrovessels in a clinically relevant model of MetS.

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PPAR␥ agonists are synthetic ligands for the peroxisome proliferatoractivated receptor-␥ (PPAR␥). These agents have insulin-sensitizing properties but can cause fluid retention, thereby limiting their usefulness in patients at risk for cardiovascular disease. The side effect etiology is unknown, but the nature of presentation suggests modulation of renal salt and water homeostasis. In a well-characterized cell culture model of the principal cell type [Madin-Darby canine kidney (MDCK)-C7], PPAR␥ agonists inhibit vasopressin-stimulated Cl Ϫ secretion with agonist dose-response relationships that mirror receptor transactivation profiles. Analyses of the components of the vasopressin-stimulated intracellular signaling pathway indicated no PPAR␥ agonist-induced changes in basolateral membrane conductances, intracellular cAMP, protein kinase A, or total cellular adenine nucleotides. The PPAR␥ agonist-induced decrease in anion secretion is the result of decreased mRNA of the final effector in the pathway, the apically located cystic fibrosis transmembrane regulator (CFTR). These data showing that CFTR is a target for PPAR␥ agonists may provide new insights into the physiology of PPAR␥ agonist-induced fluid retention.

BackgroundHospital length of stay (HLOS) is a commonly used measure of hospital quality and is influenced by clinical and non-clinical factors. To reduce HLOS, it is key to identify factors placing patients at increased risk of lengthy HLOS and discharge delays.MethodsThis was a retrospective cohort study of patients age ≥ 18 admitted to four level 1 trauma centers between 1/1/2015 and 3/31/2018 with traumatic brain injury (TBI). The primary outcome was discharge delay, defined as discharge ≥24 h after case management notes indicated the patient was ready for discharge. The independent variables of interest were primary insurance provider and discharge destination. Chi-square, Fisher exact, and unadjusted and adjusted logistic regression analyses were used to assess associations between discharge delay and the two primary independent variables, as well as other patient demographic and clinical characteristics. Complications developing during the delay period were also examined.ResultsA total of 1543 patients with TBI were included. The median age was 61 years, and the median HLOS was 5 days. Approximately half of patients were discharged home (54%). The most common insurance providers were Medicare (35%) and commercial/private (35%). Two-hundred ten (14%) patients experienced a discharge delay. The median delay period was 3 days, and the most common reasons for delay were insurance authorization (52%) and lack of accepting bed (41%). Compared to being discharged home, patients discharged to a skilled nursing facility (adjusted odds ratio (AOR) = 10.35) or intermediate care facility (AOR = 10.64) had the highest odds of discharge delay. Compared to Medicare patients, uninsured/self-pay patients (AOR = 2.98) and those with Medicaid (AOR = 2.83) or commercial/private insurance (AOR = 2.22) had higher odds of delay. Thirty-two patients (15% of those delayed) experienced at least one complication during the delay, some of which were clinically severe.ConclusionsA substantial portion of TBI patients in this study experienced discharge delays, and discharge destination and primary insurance provider were significant drivers of these delays. Evaluation of a facility’s quality of care should consider the specific causes of these delays.

Wilson K, Guggilam A, West TA, Zhang X, Trask AJ, Cismowski MJ, de Tombe P, Sadayappan S, Lucchesi PA. Effects of a myofilament calcium sensitizer on left ventricular systolic and diastolic function in rats with volume overload heart failure. Am J Physiol Heart Circ Physiol 307: H1605-H1617, 2014. First published September 26, 2014 doi:10.1152/ajpheart.00423.2014.-Aortocaval fistula (ACF)-induced volume overload (VO) heart failure (HF) results in progressive left ventricular (LV) dysfunction. Hemodynamic load reversal during pre-HF (4 wk post-ACF; REV) results in rapid structural but delayed functional recovery. This study investigated myocyte and myofilament function in ACF and REV and tested the hypothesis that a myofilament Ca 2ϩ sensitizer would improve VOinduced myofilament dysfunction in ACF and REV. Following the initial sham or ACF surgery in male Sprague-Dawley rats (200 -240 g) at week 0, REV surgery and experiments were performed at weeks 4 and 8, respectively. In ACF, decreased LV function is accompanied by impaired sarcomeric shortening and force generation and decreased Ca 2ϩ sensitivity, whereas, in REV, impaired LV function is accompanied by decreased Ca 2ϩ sensitivity. Intravenous levosimendan (Levo) elicited the best inotropic and lusitropic responses and was selected for chronic oral studies. Subsets of ACF and REV rats were given vehicle (water) or Levo (1 mg/kg) in drinking water from weeks 4 -8. Levo improved systolic (% fractional shortening, end-systolic elastance, and preload-recruitable stroke work) and diastolic (, dP/ dt min) function in ACF and REV. Levo improved Ca 2ϩ sensitivity without altering the amplitude and kinetics of the intracellular Ca 2ϩ transient. In ACF-Levo, increased cMyBP-C Ser-273 and Ser-302 and cardiac troponin I Ser-23/24 phosphorylation correlated with improved diastolic relaxation, whereas, in REV-Levo, increased cMyBP-C Ser-273 phosphorylation and increased ␣-to-␤-myosin heavy chain correlated with improved diastolic relaxation. We concluded that Levo improves LV function, and myofilament composition and regulatory protein phosphorylation likely play a key role in improving function. myofilament dysfunction; myofilament Ca 2ϩ sensitization; levosimendan; myosin-binding protein-C; troponin I MITRAL REGURGITATION (MR) is the most and second most common valve lesion in the United States and Europe, respectively, affecting Ͼ2 million Americans (10, 16). The pathophysiological consequences of MR include chronic left ventricular (LV) hemodynamic volume overload (VO) followed by LV chamber dilation, progressive LV contractile dysfunction, and heart failure (HF). Despite the clinical importance of VO, few models mimic the pathophysiological progression of chronic VO with and without hemodynamic load reduction. The aortocaval fistula (ACF) model of VO HF in the rodent mimics increased hemodynamic preload observed in human disease, irrespective of etiology. In this model, chronically increased LV preload leads to progressive LV pump failure, which is classified into t...