Abnormal left atrial body stiffness is predicted by appendage size: impact of appendage occlusion on left atrial mechanics assessed by pressure-volume analysis.

Atrial cardiomyopathy has been recognized as having important consequences for cardiac performance and clinical outcomes. The pathophysiological role of the left atrial (LA) appendage and the effect of percutaneous left atrial appendage occlusion (LAAO) upon LA mechanics is incompletely understood. We evaluated if changes in LA stiffness due to endocardial LAAO can be detected by LA pressure-volume (PV) analysis and whether stiffness parameters are associated with baseline characteristics. Patients undergoing percutaneous endocardial LAAO (n = 25) were studied using a novel PV analysis using near-simultaneous three-dimensional LA volume measurements by transesophageal echocardiography (TEE) and direct invasive LA pressure measurements. LA stiffness (dP/dV, change in pressure with change in volume) was calculated before and after LAAO. Overall LA stiffness significantly increased after LAAO compared with baseline (median, 0.41-0.64 mmHg/mL; P ≪ 0.001). LA body stiffness after LAAO correlated with baseline LA appendage size by indexed maximum depth (Spearman's rank correlation coefficient Rs = 0.61; P < 0.01). LA stiffness change showed an even stronger correlation with baseline LA appendage size by indexed maximum depth (Rs = 0.70; P < 0.001). We found that overall LA stiffness increases after endocardial LAAO. Baseline LA appendage size correlates with the magnitude of increase and LA body stiffness. These findings document alteration of LA mechanics after endocardial LAAO and suggest that the LA appendage modulates overall LA compliance.NEW & NOTEWORTHY Our study documents a correlation of LA appendage remodeling with the degree of chronically abnormal LA body stiffness. In addition, we found that LA appendage size was the baseline parameter that best correlated with the magnitude of a further increase in overall LA stiffness after appendage occlusion. These findings offer insights about the LA appendage and LA mechanics that are relevant to patients at risk for adverse atrial remodeling, especially candidates for LA appendage occlusion.

MRI monitoring of transplanted neonatal porcine islets labeled with polyvinylpyrrolidone-coated superparamagnetic iron oxide nanoparticles in a mouse model.

Islet transplantation is a potential treatment option for certain patients with type 1 diabetes; however, it still faces barriers to widespread use, including the lack of tools to monitor islet grafts post-transplantation. This study investigates whether labeling neonatal porcine islets (NPI) with polyvinylpyrrolidone-coated superparamagnetic iron oxide nanoparticles (PVP-SPIO) affects their function, and whether this nanoparticle can be utilized to monitor NPI xenografts with magnetic resonance imaging (MRI) in a mouse model. In vitro, PVP-SPIO-labeled NPI in an agarose gel was visualized clearly by MRI. PVP-SPIO-labeled islets were then transplanted under the kidney capsules of immunodeficient nondiabetic and diabetic mice. All diabetic mice that received transplantation of PVP-SPIO-labeled islets reached normoglycemia. Grafts appeared as hypo-intense areas on MRI and were distinguishable from the surrounding tissues. Following injection of spleen cells from immunocompetent mice, normoglycemic recipient mice became diabetic and islet grafts showed an increase in volume, accompanied by a mixed signal on MRI. Overall, this study demonstrates that PVP-SPIO did not affect the function of NPI that PVP-SPIO-labeled islets were easily seen on MRI, and changes in MRI signals following rejection suggest a potential use of PVP-SPIO-labeled islets to monitor graft viability.

Impact of donor and prolonged cold ischemia time of neonatal pig pancreas on neonatal pig islet transplant outcome.

BACKGROUND: Genetically modified pigs (GMP) have been developed to alleviate the shortage of donors in human islet transplantation and rejection. In this study, we characterized and compared the islets from GalTKO, GalTKO/hCD46, GalTKO/hCD46/hCD39, and wild-type (WT) neonatal pigs. METHODS: Islets were isolated from GMP and WT pig pancreases that have been packaged with ice pack for at least 24 hours. The difference in gene expression and function of islets were evaluated by microarray analysis and transplantation of islets under the kidney capsule of streptozotocin-induced diabetic immune-deficient mice, respectively. Blood glucose levels of these mice were monitored weekly post-transplantation for >100 days, and islet grafts were collected and evaluated for the presence of endocrine cells. RESULTS: The genes involved in extracellular components, cell adhesion, glucose metabolism, and inflammatory response are differentially expressed between GMP and WT pig islets. Variation in the ability of pig islets in correcting the diabetic state of the mouse recipients appears to be dependent on the pig donor. In addition, prolonged cold ischemia time had a negative effect on the transplant outcome. All normoglycemic mice were able to respond well to glucose challenge despite the initial differences in the ability of islet transplants to reverse their diabetic state. Islet xenografts of normoglycemic mice contained abundant insulin- and glucagon-positive cells. CONCLUSION: The effect of GMP and WT neonatal pig islet transplants on hyperglycemia in mice appears to be dependent on the pig donor, and prolonged cold ischemia time negatively affects the neonatal pig islet transplant outcome.

Comparison of devices used in carotid artery stenting: A vascular quality initiative analysis of commonly used carotid stents and embolic protection devices.

BACKGROUND: Data regarding efficacy of various stent and embolic protection device (EPD) combinations to prevent stroke during carotid artery stenting (CAS) is limited. We compared post-procedure inpatient neurologic outcomes across various carotid stent-EPD platforms recorded in the Vascular Quality Initiative (VQI) registry. METHODS: We analyzed 13,786 consecutive CAS procedures in the VQI registry performed between January 1, 2005 and December 31, 2015. The most commonly used stent-EPD combinations (n = 5407) were included in the analysis. Post-procedure inpatient neurologic outcomes included (1) ipsilateral stroke/transient ischemic attack (TIA) and (2) any stroke/TIA. Multivariate generalized estimating equation regression analysis was performed, adjusting for age, sex, tobacco use, coronary artery disease, congestive heart failure, prior stroke/TIA, hypertension, history of carotid revascularization, and presence of a second ipsilateral stenosis >70%, to determine whether risk of outcomes differed according to device. RESULTS: Of 13,786 CAS procedures, Xact-Emboshield (n = 2,438, 17.6%), Precise-Angioguard (n = 1,480, 10.7%), Acculink-Accunet (n = 829, 6.01%), and Acculink-Emboshield (n = 660, 4.8%) were the most commonly used combinations, accounting for a total of 5,407 procedures. Inpatient event rates for ipsilateral stroke/TIA and any stroke/TIA were 1.9 and 2.7% in the Accunet-Acculink, 3.0 and 3.2% in Acculink-Emboshield, 3.2 and 4.1% in Precise-Angioguard and 2.2 and 3.0% in Xact-Emboshield. There was no evidence of difference in risk of ipsilateral stroke/TIA or any stroke/TIA across device combinations (P = 0.15 and P = 0.16, respectively). CONCLUSION: CAS with current carotid stent-EPD combinations is associated with low rates of inpatient stroke/TIA. There is no statistically significant difference in rates of inpatient stroke/TIA across device combinations.

First update of the International Xenotransplantation Association consensus statement on conditions for undertaking clinical trials of porcine islet products in type 1 diabetes--Chapter 3: Porcine islet product manufacturing and release testing criteria.

In the 2009 IXA consensus, the requirements for the quality and control of manufacturing of porcine islet products were based on the U.S. regulatory framework where the porcine islet products fall within the definition of somatic cell therapy under the statutory authority of the U.S. Food and Drug Administration (FDA). In addition, porcine islet products require pre-market approval as a biologic product under the Public Health Services Act and they meet the definition of a drug under the Federal Food, Drug, and Cosmetic Act (FD&C Act). Thus, they are subject to applicable provisions of the law and as such, control of manufacturing as well as reproducibility and consistency of porcine islet products, safety of porcine islet products, and characterization of porcine islet products must be met before proceeding to clinical trials. In terms of control of manufacturing as well as reproducibility and consistency of porcine islet products, the manufacturing facility must be in compliance with current Good Manufacturing Practices (cGMP) guidelines appropriate for the initiation of Phase 1/2 clinical trials. Sponsors intending to conduct a Phase 1/2 trial of islet xenotransplantation products must be able to demonstrate the safety of the product through the establishment of particular quality assurance and quality control procedures. All materials (including animal source and pancreas) used in the manufacturing process of the porcine islet products must be free of adventitious agents. The final porcine islet product must undergo tests for the presence of these adventitious agents including sterility, mycoplasma (if they are cultured), and endotoxin. Assessments of the final product must include the safety specifications mentioned above even if the results are not available until after release as these data would be useful for patient diagnosis and treatment if necessary. In addition, a plan of action must be in place for patient notification and treatment in case the sterility culture results are positive. In terms of the characterization of porcine islet products and product release criteria, the information on the porcine islet products should be acquired from a sample of the final product to be used for transplantation and must include the morphology of the islets, specific identity, purity, viability, and potency of the product. In addition, information on the quantity of the islet products should also be provided in a standardized fashion and this should be in terms of islet equivalents and/or cell numbers. The current consensus was created to provide guidelines that manufacturing facilities may find helpful in the manufacture of and the release criteria for porcine islet products including encapsulated islets and combined islet products. Our intent with the above recommendations is to provide a framework for individual porcine islet manufacturing facilities to ensure a high level of safety for the initiation of Phase 1/2 clinical trials on porcine islet xenotransplantation.

Use of regadenoson for measurement of fractional flow reserve.

OBJECTIVE: To compare the use of regadenoson to adenosine for measurement of fractional flow reserve (FFR). BACKGROUND: FFR is an accepted method to assess the functional significance of intermediate coronary artery stenoses and uses adenosine to induce maximal hyperemia. The use of the selective A2a receptor agonist regadenoson for FFR is not established. METHODS: Fifty-seven patients undergoing clinically indicated FFR assessment of intermediate coronary stenoses were included. For the initial assessment of FFR, hyperemia was achieved by a standard intravenous adenosine infusion (140 mcg/kg/min). After a washout period of 10 min, FFR was reassessed using regadenoson as a single 0.4 mg intravenous bolus. FFR measurements were recorded at baseline and following maximal hyperemia with both agents. RESULTS: Mean age was 57 ± 8 years and 47 were male. Sixty coronary lesions were evaluated and were located in the left anterior descending in 34, the left circumflex in 9, right coronary in 15, and left main coronary artery in 2. Mean ( ± SD) FFR following adenosine and regadenoson was 0.79 ( ± 0.09) and 0.79 (±0.09), respectively, P = NS. Time to FFR nadir was shorter with regadenoson compared to adenosine, 36.6 ± 24 versus 66 ± 0.19 sec, P < 0.0001, respectively. No patients experienced any significant side effects related to regadenoson. CONCLUSIONS: Regadenoson is a viable alternative to intravenous adenosine for achieving maximal hyperemia during FFR assessment. Compared to adenosine, regadenoson has a similar hemodynamic response, achieves more rapid hyperemia, is easier to use, and has an excellent side-effect profile.

Tackle and impact detection in elite Australian football using wearable microsensor technology.

The effectiveness of a wearable microsensor device (MinimaxX(TM) S4, Catapult Innovations, Melbourne, VIC, Australia) to automatically detect tackles and impact events in elite Australian football (AF) was assessed during four matches. Video observation was used as the criterion measure. A total of 352 tackles were observed, with 78% correctly detected as tackles by the manufacturer's software. Tackles against (i.e. tackled by an opponent) were more accurately detected than tackles made (90% v 66%). Of the 77 tackles that were not detected at all, the majority (74%) were categorised as low-intensity. In contrast, a total of 1510 "tackle" events were detected, with only 18% of these verified as tackles. A further 57% were from contested ball situations involving player contact. The remaining 25% were in general play where no contact was evident; these were significantly lower in peak Player Load™ than those involving player contact (P < 0.01). The tackle detection algorithm, developed primarily for rugby, was not suitable for tackle detection in AF. The underlying sensor data may have the potential to detect a range of events within contact sports such as AF, yet to do so is a complex task and requires sophisticated sport and event-specific algorithms.

Detecting elevated left ventricular end diastolic pressure from simultaneously measured femoral pressure waveform and electrocardiogram.

Objective.Instantaneous, non-invasive evaluation of left ventricular end-diastolic pressure (LVEDP) would have significant value in the diagnosis and treatment of heart failure. A new approach called cardiac triangle mapping (CTM) has been recently proposed, which can provide a non-invasive estimate of LVEDP. We hypothesized that a hybrid machine-learning (ML) method based on CTM can instantaneously identify an elevated LVEDP using simultaneously measured femoral pressure waveform and electrocardiogram (ECG).Approach.We studied 46 patients (Age: 39-90 (66.4 ± 9.9), BMI: 20.2-36.8 (27.6 ± 4.1), 12 females) scheduled for clinical left heart catheterizations or coronary angiograms at University of Southern California Keck Medical Center. Exclusion criteria included severe mitral/aortic valve disease; severe carotid stenosis; aortic abnormalities; ventricular paced rhythm; left bundle branch and anterior fascicular blocks; interventricular conduction delay; and atrial fibrillation. Invasive LVEDP and pressure waveforms at the iliac bifurcation were measured using transducer-tipped Millar catheters with simultaneous ECG. LVEDP range was 9.3-40.5 mmHg. LVEDP = 18 mmHg was used as cutoff. Random forest (RF) classifiers were trained using data from 36 patients and blindly tested on 10 patients.Main results.Our proposed ML classifier models accurately predict true LVEDP classes using appropriate physics-based features, where the most accurate demonstrates 100.0% (elevated) and 80.0% (normal) success in predicting true LVEDP classes on blind data.Significance.We demonstrated that physics-based ML models can instantaneously classify LVEDP using information from femoral waveforms and ECGs. Although an invasive validation, the required ML inputs can be potentially obtained non-invasively.

Long-term survival of neonatal porcine islets in nonhuman primates by targeting costimulation pathways.

We evaluated the ability of neonatal porcine islets to engraft and restore glucose control in pancreatectomized rhesus macaques. Although porcine islets transplanted into nonimmunosuppressed macaques were rapidly rejected by a process consistent with cellular rejection, recipients treated with a CD28-CD154 costimulation blockade regimen achieved sustained insulin independence (median survival, >140 days) without evidence of porcine endogenous retrovirus dissemination. Thus, neonatal porcine islets represent a promising solution to the crucial supply problem in clinical islet transplantation.

Instantaneous detection of acute myocardial infarction and ischaemia from a single carotid pressure waveform in rats.

Aims: Myocardial infarction (MI) is one of the leading causes of death worldwide. It is well accepted that early diagnosis followed by early reperfusion therapy significantly increases the MI survival. Diagnosis of acute MI is traditionally based on the presence of chest pain and electrocardiogram (ECG) criteria. However, around 50% of the MIs are without chest pain, and ECG is neither completely specific nor definitive. Therefore, there is an unmet need for methods that allow detection of acute MI or ischaemia without using ECG. Our hypothesis is that a hybrid physics-based machine learning (ML) method can detect the occurrence of acute MI or ischaemia from a single carotid pressure waveform. Methods and results: We used a standard occlusion/reperfusion rat model. Physics-based ML classifiers were developed using intrinsic frequency parameters extracted from carotid pressure waveforms. ML models were trained, validated, and generalized using data from 32 rats. The final ML models were tested on an external stratified blind dataset from additional 13 rats. When tested on blind data, the best ML model showed specificity = 0.92 and sensitivity = 0.92 for detecting acute MI. The best model's specificity and sensitivity for ischaemia detection were 0.85 and 0.92, respectively. Conclusion: We demonstrated that a hybrid physics-based ML approach can detect the occurrence of acute MI and ischaemia from carotid pressure waveform in rats. Since carotid pressure waveforms can be measured non-invasively, this proof-of-concept pre-clinical study can potentially be expanded in future studies for non-invasive detection of MI or myocardial ischaemia.

The addition of evolocumab to maximal tolerated statin therapy improves walking performance in patients with peripheral arterial disease and intermittent claudication (Evol-PAD study).

OBJECTIVE: To test the hypothesis that in patients with peripheral arterial disease (PAD) and claudication, treated with maximal tolerated statin therapy, the addition of a monthly subcutaneous injection of evolocumab for 6 months improves treadmill walking performance. BACKGROUND: Lipid lowering therapy improves walking parameters in patients with PAD and claudication. Evolocumab decreases cardiac and limb adverse events in patients with PAD; however, the effect of evolocumab on walking performance is not known. METHODS: We performed a double-blind, randomized, placebo-controlled study to compare maximal walking time (MWT) and pain free walking time (PFWT) in patients with PAD and claudication treated with monthly subcutaneous injections of evolocumab 420 mg (n = 35) or placebo (n = 35). We also performed measurements of lower limb perfusion, brachial flow mediated dilatation (FMD), carotid intima media thickness (IMT), and serum biomarkers of PAD disease severity. RESULTS: After six-months of treatment with evolocumab MWT increased by 37.7 % (87.5 ± 24 s) compared to 1.4 % (-21.7 ± 22.9 s) in the placebo group, p = 0.01. PFWT increased by 55.3 % (67.3 ± 21.2 s) in the evolocumab group compared to 20.3 % (8.5 ± 20.3 s) in the placebo group, p = 0.051. There was no difference in lower extremity arterial perfusion measurements. FMD increased by 42.0 ± 73.9 % (1.01 ± 0.7 %) in the evolocumab group and decreased by 16.29 ± 20.06 % (0.99 ± 0.68 %) in the placebo group (p < 0.001). IMT decreased by 7.16 ± 4.6 % (0.06 ± 0.04 mm) in the evolocumab group and increased by 6.68 ± 4.9 % (0.05 ± 0.03 mm) in the placebo group, (p < 0.001). CONCLUSIONS: The addition of evolocumab to maximal tolerated statin therapy improves maximal walking time in patients with PAD and claudication, increases FMD, and decreases IMT. CONDENSED ABSTRACT: Peripheral arterial disease (PAD) impairs quality of life by causing lower extremity intermittent claudication, rest pain, or amputation. Evolocumab is a monthly injectable monoclonal antibody medication that reduces cholesterol. In this study, we randomly treated patients with PAD and claudication, and on background statin therapy, with evolocumab or placebo, and found that evolocumab improves walking performance on a treadmill test by increasing maximal walking time. We also found that evolocumab decreases plasma MRP-14 levels, a marker of PAD severity.

Devices to treat peripheral chronic total occlusions.

Chronic total occlusions occur in approximately 40% of patients with peripheral vascular disease and are a difficult lesion subset to treat by endovascular approaches. The challenge lies in the difficulty in placing a wire across the site of occlusion and remaining in an intraluminal position. Conventional percutaneous transluminal balloon angioplasty for chronic total occlusions involves advancing a stiff wire through the site of obstruction, has the chance for vessel dissection and perforation, and is associated with high rates of procedural failure. Several mechanical devices have thus been developed to treat peripheral chronic total occlusions. In this article, we provide a review of the currently available devices that may increase the procedural success of treating peripheral chronic total occlusions.

Yield, cell composition, and function of islets isolated from different ages of neonatal pigs.

The yield, cell composition, and function of islets isolated from various ages of neonatal pigs were characterized using in vitro and in vivo experimental models. Islets from 7- and 10-day-old pigs showed significantly better function both in vitro and in vivo compared to islets from 3- and 5-day-old pigs however, the islet yield from 10-day-old pigs were significantly less than those obtained from the other pigs. Since islets from 3-day-old pigs were used in our previous studies and islets from 7-day-old pigs reversed diabetes more efficiently than islets from other groups, we further evaluated the function of these islets post-transplantation. B6 rag-/- mouse recipients of various numbers of islets from 7-day-old pigs achieved normoglycemia faster and showed significantly improved response to glucose challenge compared to the recipients of the same numbers of islets from 3-day-old pigs. These results are in line with the findings that islets from 7-day-old pigs showed reduced voltage-dependent K+ (Kv) channel activity and their ability to recover from post-hypoxia/reoxygenation stress. Despite more resident immune cells and immunogenic characteristics detected in islets from 7-day-old pigs compared to islets from 3-day-old pigs, the combination of anti-LFA-1 and anti-CD154 monoclonal antibodies are equally effective at preventing the rejection of islets from both age groups of pigs. Collectively, these results suggest that islets from various ages of neonatal pigs vary in yield, cellular composition, and function. Such parameters may be considered when defining the optimal pancreas donor for islet xenotransplantation studies.

Mouse pancreatic islets are resistant to indoleamine 2,3 dioxygenase-induced general control nonderepressible-2 kinase stress pathway and maintain normal viability and function.

Islet transplantation is a promising treatment for diabetes. However, it faces several challenges including requirement of systemic immunosuppression. Indoleamine 2,3-dioxygenase (IDO), a tryptophan degrading enzyme, is a potent immunomodulatory factor. Local expression of IDO in bystander fibroblasts suppresses islet allogeneic immune response in vitro. The aim of the present study was to investigate the impact of IDO on viability and function of mouse islets embedded within IDO-expressing fibroblast-populated collagen scaffold. Mouse islets were embedded within collagen matrix populated with IDO adenovector-transduced or control fibroblasts. Proliferation, insulin content, glucose responsiveness, and activation of general control nonderepressible-2 kinase stress-responsive pathway were then measured in IDO-exposed islets. In vivo viabilities of composite islet grafts were also tested in a syngeneic diabetic animal model. No reduction in islet cells proliferation was detected in both IDO-expressing and control composites compared to the baseline rates. Islet functional studies showed normal insulin content and secretion in both preparations. In contrast to lymphocytes, general control nonderepressible-2 kinase pathway was not activated in islets cocultured with IDO-expressing fibroblasts. When transplanted to diabetic mice, syngeneic IDO-expressing composite islet grafts were functional up to 100 days tested. These findings collectively confirm normal viability and functionality of islets cocultured with IDO-expressing cells and indicate the feasibility of development of a functional nonrejectable islet graft.

Factors Associated With the Use of Bare Metal Stents in Patients With ST Elevation Myocardial Infarction.

BACKGROUND: Drug eluting stents (DES) are used in the majority of patients undergoing percutaneous coronary intervention (PCI). Factors associated with the use of bare metal stents (BMS) for patients undergoing primary PCI for ST elevation myocardial infarction (STEMI) have not been adequately explored. The objective of this study was to evaluate factors associated with BMS use in STEMI patients undergoing primary PCI. METHODS: Patients undergoing primary PCI for STEMI between January 2008 and February 2015 were retrospectively identified. Patients who received both a DES and BMS were included in the DES group and patients receiving balloon angioplasty only were excluded. Baseline demographics, angiographic variables, procedure related variables and in-hospital events were collected. Multivariate analysis was performed to identify factors associated with BMS use. RESULTS: Eight hundred and sixty-five patients underwent primary PCI for STEMI during the study period. Seventy-two patients (8.3%) received balloon angioplasty only and were excluded, yielding 793 patients for the study cohort. Three hundred fifty-two patients (44%) received BMS and 441 patients (56%) received DES. Patients receiving DES had a higher prevalence of diabetes mellitus, prior myocardial infarction, prior PCI, left anterior descending artery culprit location and Medicaid Insurance compared to those receiving BMS. Patients receiving BMS had a higher prevalence of cardiogenic shock and right coronary artery culprit location. Unadjusted in-hospital mortality was significantly higher for patients receiving BMS compared to patients receiving DES, 11.1% vs 3.2%, respectively, p < 0.0001. Multivariate predictors of BMS use were cardiogenic shock (OR 30.3; 95% CI 11.25 to 81.73) and diabetes mellitus (OR 2.99; 95% CI 1.04 to 8.64). CONCLUSION: In a contemporary series of patients undergoing primary PCI for STEMI, BMS were used in 44% of patients and independent factors associated with BMS use were cardiogenic shock and diabetes mellitus.

Intrinsic frequency method for instantaneous assessment of left ventricular-arterial coupling after transcatheter aortic valve replacement.

BACKGROUND: Aortic stenosis (AS) is the most common cause for valve replacement in the United States. The pathophysiology of AS involves obstruction to the left ventricular (LV) outflow and reduced arterial compliance. The intrinsic frequency (IF) method is a system-based approach for hemodynamic monitoring of the LV-arterial system and involves determination of ω1 and ω2, which represent the dynamics of LV systolic and vascular function, respectively. Total frequency variation of the systemic circulation is the difference between these IFs (Δω = ω1- ω2). OBJECTIVE: Our goal in this study was to investigate whether Δω, obtained from the ascending aortic pressure waveform, can be indicative of LV-arterial coupling after transcatheter aortic valve replacement (TAVR). APPROACH: Thirty patients undergoing elective TAVR for severe, symptomatic AS were included. We applied the IF method to assess the immediate effects of TAVR on LV-arterial coupling. MAIN RESULTS: Mean age was 86 ± 4 years, 50% were male with a mean aortic valve area of 0.7 cm2 and mean ejection fraction (EF) of 59 ± 7%. The results showed a significant decrease in Δω (47.6 to 9.5 bpm, p < 0.00001) and a significant increase in ω2 (51.9 to 84.6 bpm, p < 0.00001) immediately post TAVR. SIGNIFICANCE: These preliminary findings indicate that the IF method can be used to evaluate improvements in LV hemodynamics immediately following TAVR. Use of the IF method may have implications for patients undergoing TAVR with impaired LV systolic function.

Epithelial cells within the human pancreas do not coexpress mesenchymal antigens: epithelial-mesenchymal transition is an artifact of cell culture.

Pancreatic mesenchymal stem cells (MSCs) may be derived from human beta-cells undergoing reversible epithelial-mesenchymal transition (EMT), suggesting that they could be a potential source of new beta-cells. In this study we sought to determine the origin of pancreatic MSCs in the nonendocrine pancreas. Double immunofluorescent (IF) staining and flow cytometry were used to assess the cell phenotype of nonendocrine pancreas tissue following islet procurement, during in vitro expansion of MSCs, and after differentiation. IF staining of paraffin-embedded pancreatic biopsy sections was used to assess cell phenotype in vivo. In this study we demonstrated that: (1) pancreatic epithelial cells do not express MSC antigens in vivo; (2) following islet isolation EpCAM- and CK19-positive epithelial cells coexpressed the MSC antigens CD44 (32+/-8% and 38+/-10%) and CD29 (85+/-4% and 64+/-4%); (3) during in vitro expansion the number of single-positive epithelial and double-positive epithelial/MSCs decreased whereas the number of single-positive MSCs increased and (4) differentiated MSCs do not revert to a true epithelial cell phenotype in our culture conditions, as epithelial cell surface markers (EpCAM, CK19 and E-Cadherin) are not reexpressed, although the MSC phenotype is altered. This study demonstrates that MSCs may be derived in vitro via a pancreatic epithelial cell undergoing EMT, however it is more likely that a small percentage of MSCs that reside in the adult pancreas are proliferating whereas the epithelial cells are negatively selected by the experimental culture conditions.

Sertoli cell line lacks the immunoprotective properties associated with primary Sertoli cells.

Sertoli cells are important for maintenance of the immune privileged environment of the testis and prolong survival of cotransplanted cells. The objective of the current study was to examine the immunoprotective properties of a mouse Sertoli cell line (MSC-1) in order to identify a Sertoli cell line that could be used to aid in investigation of the immunoprotective abilities of Sertoli cells. BALB/c islets were cotransplanted with 0-9 million primary BALB/c Sertoli cells or MSC-1 cells into diabetic C3H or BALB/c mice and protection of grafted islets was examined by monitoring blood glucose levels and immunohistochemical analysis. Additionally, expression of potential immunoprotective factors in MSC-1 cells was examined. Cotransplantation of islets with 3 million primary Sertoli cells significantly prolonged islet allograft survival (61.1 +/- 6.9 days; p < 0.05) compared with control mice that received allogeneic islets alone (26.9 +/- 2.1 days). Grafts collected from normoglycemic C3H mice at 100 days posttransplant contained insulin-positive beta-cells adjacent to allogeneic Sertoli cells arranged in tubule-like structures. In contrast, cotransplantation of islet allografts with MSC-1 cells did not prolong islet survival (average 29.8 +/- 3.3 days) regardless of the number of MSC-1 cells transplanted and the rejected grafts contained very few beta-cells and randomly arranged MSC-1 cells. The lack of islet cell survival was not due to detrimental effects of MSC-1 cells because syngneic islets cotransplanted with MSC-1 cells were functional throughout the study. MSC-1 cells were found to express known Sertoli cell-expressed, immunoprotective factors, clusterin, Fas ligand, and transforming growth factor-beta1, suggesting additional factors may be involved in Sertoli cell immune privilege. These data indicate the MSC-1 cell line lacks the immunoprotective properties associated with primary Sertoli cells. Further study of this cell line could be useful in examining the mechanisms that enable Sertoli cells to provide immune privilege.

Monotherapy with anti-LFA-1 monoclonal antibody promotes long-term survival of rat islet xenografts.

Previously we demonstrated that anti-LFA-1 monoclonal (mAb) could promote long-term survival of discordant porcine islet xenografts in mice. The aim of this study, therefore, was to determine whether a shortterm administration of anti-LFA-1 mAb would promote long-term survival of concordant rat islet xenografts in mice, and whether combining short-term administration of anti-LFA-1 mAb therapy with an immunosuppressive drug, rapamycin, would facilitate islet xenograft survival. Streptozotocin-induced diabetic BALB/c mice were transplanted with 500 Wistar-Furth rat islets under the kidney capsule and were either left untreated or treated with short-term administration of rapamycin (0.2 mg/kg) alone, anti-LFA-1 mAb (0.2 mg/ dose) alone, or a combination of rapamycin and anti-LFA-1 mAb using the same doses. All untreated mice rejected their grafts by 24 days posttransplantation with a mean graft survival time of 18.8 +/- 2.5 days posttransplantation (n = 5). All mice treated with rapamycin alone had prolonged islet graft survival but eventually rejected their islet grafts by 81 days posttransplantation. In contrast, the majority of the mice (27/ 28) treated with anti-LFA-1 mAb alone maintained long-term normoglycemia (>100 days). Rapamycin in combination with anti-LFA-1 mAb proved equally effective with 29 of 30 mice maintaining normoglycemia for more than 100 days posttransplantation. Low levels of mouse anti-rat antibodies, as well as a decrease in the degree of mononuclear cell infiltration of the islet graft, closely correlated with long-term islet xenograft survival. These results demonstrate that monotherapy with anti-LFA-1 mAb is highly effective in promoting long-term survival of rat islet xenografts and that combination of anti-LFA-1 mAb with rapamycin does not facilitate nor abrogate the induction of long-term xenograft survival by anti-LFA-1 mAb therapy in BALB/c mice. Our study indicates that immunomodulation through mAb therapy could form a significant component of future antirejection therapies in clinical islet xenotransplantation.

Prolonged survival of microencapsulated neonatal porcine islet xenografts in immune-competent mice without antirejection therapy.

Several studies have demonstrated that in vitro culture of islets prolonged islet graft survival in immune-competent mice without administration of antirejection drugs. However, we recently showed that in vitro cultured microencapsulated neonatal porcine islets (NPI) were rejected in immune-competent mice not receiving antirejection therapy. The aim of this study was to determine whether culture of microencapsulated NPI in vivo could promote long-term survival of microencapsulated NPI in immune-competent mice without administration of antirejection drugs. Microencapsulated NPI that were cultured in vitro for 7 and 50 days or transplanted initially in immune-deficient C.B.-17 SCID-BEIGE mice for 100 days (in vivo cultured) were characterized and transplanted into streptozotocin-induced diabetic immune-competent BALB/c mice. Day 50 in vitro cultured and day 100 in vivo cultured microencapsulated NPI showed significantly higher insulin and DNA content, indicating maturation of NPI compared to day 7 in vitro cultured microencapsulated NPI. Interestingly, in vivo cultured microencapsulated NPI expressed lower levels of porcine antigens compared to day 7 and day 50 in vitro cultured microencapsulated NPI. Transplantation of day 7 in vitro cultured microencapsulated NPI did not reverse diabetes in immune-competent BALB/c mouse recipients. In contrast, transplantation of day 50 in vitro cultured and in vivo cultured microencapsulated NPI into diabetic immune-competent BALB/c mice resulted in the immediate reversal of hyperglycemia within 2 days posttransplantation. However, all recipients of day 50 in vitro cultured microencapsulated NPI eventually rejected their grafts by day 15 posttransplantation, while 6 of 10 BALB/c mouse recipients of in vivo cultured microencapsulated NPI maintained normoglycemia for 100 days posttransplantation. These results show that in vivo culture of NPI in immune-deficient mice results in the modulation of NPI, which allows for their long-term survival in immune-competent mice without antirejection therapy.