A Retrospective Cohort Study on Predictors for Rehospitalizations With Recurrence of Atrial Fibrillation Post-Catheter Ablation for Atrial Fibrillation.

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is increasing in prevalence due to an aging population. Although medications for rhythm and rate control remain the first-line treatment options for many patients, difficulties can include arrhythmia relapse and drug side effects. Catheter ablation or radiofrequency is an alternative treatment modality that can isolate where ectopic arrhythmic sites originate. Several previous studies have examined post-ablation complications and hospitalization rates for arrhythmia recurrence. However, many of these studies used patient data from before 2015. We examined the following data using recent records: pre-procedural patient characteristics, rates of post-procedural hospitalizations with documented recurrence of AF, and patient risk factors associated with these recurrences.

Limited Scleroderma-Induced Pulmonary Arterial Hypertension Resulting in Impaired Postoperative Respiratory Function.

Limited scleroderma falls under the umbrella of systemic sclerosis, an autoimmune disease that presents with multiorgan dysfunction that includes pulmonary arterial hypertension. We examine a case of pulmonary arterial hypertension in an elderly nonsmoker with a history of limited scleroderma.  The patient presented with abdominal tenderness and was diagnosed with a sigmoid colonic stricture. She underwent laparoscopic bowel resection. During and after her surgery, she suffered from worsening respiratory function and decompensated, developing a large pleural effusion that led to a thoracentesis and a prolonged hospital course. Patients with scleroderma can develop acute symptoms involving several organ systems, including the colonic tract and lungs, as seen in our patient. A thorough workup and continuous close management and monitoring are necessary to avoid further complications in these patients, especially in the postoperative period.

Eosinophilic Gastroenteritis Presenting As Unexplained Chronic Abdominal Pain.

A 27-year-old Caucasian female was hospitalized three times over a four-month period for recurrent, intermittent abdominal pain associated with nausea and diarrhea. No signs or symptoms of gastrointestinal (GI) bleeding were present. A stool occult blood test and stool enteric pathogen tests were negative. A complete blood count (CBC) revealed a peripheral blood eosinophil count of 1080 cells /µL without any inflammatory reaction. An upper endoscopy showed grossly normal-appearing esophageal and duodenal mucosa; however, a gastric mucosal biopsy showed an eosinophil infiltration of ≥20 eosinophils/high power field (HPF). Based on these findings, she was diagnosed with eosinophilic gastroenteritis (EGE). A definitive diagnosis of EGE should be confirmed with both an analysis of gastrointestinal mucosal biopsy and an elevated peripheral blood eosinophil count. Specifically, histological evaluation of the mucosal tissue must show an eosinophilic infiltration rate of 20 eosinophils/HPF. The diagnosis should be followed by an extensive review of the patient's allergic disease history.

A Rare Case of Immune-Mediated Primary Adrenal Insufficiency With Cytotoxic T-Lymphocyte Antigen-4 Inhibitor Ipilimumab in Metastatic Melanoma of Lung and Neck of Unknown Primary.

Immunotherapy with checkpoint inhibitors such as ipilimumab, a cytotoxic T-lymphocyte antigen-4 (CTLA-4) inhibitor, and nivolumab, a programmed death-1 (PD-1) inhibitor, has significantly improved the survival of patients with metastatic melanoma. The immune-related endocrinopathies of these treatments have been well documented, such as hypothyroidism, hyperthyroidism, primary adrenal insufficiency (PAI), insulin-dependent diabetes, and hypophysitis. We report the onset of PAI in a patient with metastatic melanoma to the lung and neck of unknown primary origin who was treated with ipilimumab. The patient's symptoms resolved with steroid replacement. After the completion of 16 cycles of another checkpoint inhibitor, nivolumab, full remission was achieved.

Magnetic Resonance Imaging of Shear Stress and Wall Thickness in Tissue-Engineered Vascular Grafts.

OBJECTIVES: Tissue-engineered vascular grafts (TEVGs) have demonstrated potential for treating congenital heart disease (CHD); however, quantitative imaging for tracking functional and structural remodeling of TEVGs has not been applied. Therefore, we evaluated the potential of magnetic resonance (MR) imaging for assessing TEVG wall shear stress (WSS) and wall thickness in a large animal model. METHODS: Cell-seeded (n = 3) or unseeded (n = 3) TEVGs were implanted as inferior vena cava interposition grafts in juvenile lambs. Six months following implantation, two-dimensional phase-contrast MR imaging was performed at 3 slice locations (proximal, middle, and distal) to assess normalized WSS (i.e., WSS-to-cross sectional area). T2-weighted MR imaging was performed to assess TEVG wall thickness. Histology was qualitatively assessed, whereas immunohistochemistry was semiquantitatively assessed for smooth muscle cells (αSMA), macrophage lineage cells (CD11b), and matrix metalloproteinase activity (MMP-2 and MMP-9). Picrosirius Red staining was performed to quantify collagen content. RESULTS: TEVG wall thickness was significantly higher for proximal, middle, and distal slices in unseeded versus cell-seeded grafts. Significantly higher WSS values existed for proximal versus distal slice locations for cell-seeded TEVGs, whereas no differences in WSS existed between slices for unseeded TEVGs. Additionally, no differences in WSS existed between cell-seeded and unseeded groups. Both groups demonstrated elastin formation, without vascular calcification. Unseeded TEVGs possessed greater content of smooth muscle cells when compared with cell-seeded TEVGs. No differences in macrophage, MMP activity, or collagen content existed between groups. CONCLUSION: MR imaging allows for in vivo assessment of functional and anatomical characteristics of TEVGs and may provide a nonionizing approach that is clinically translatable to children undergoing treatment for CHD.

Angiotensin II receptor I blockade prevents stenosis of tissue engineered vascular grafts.

We previously developed a tissue-engineered vascular graft (TEVG) made by seeding autologous cells onto a biodegradable tubular scaffold, in an attempt to create a living vascular graft with growth potential for use in children undergoing congenital heart surgery. Results of our clinical trial showed that the TEVG possesses growth capacity but that its widespread clinical use is not yet advisable due to the high incidence of TEVG stenosis. In animal models, TEVG stenosis is caused by increased monocytic cell recruitment and its classic ("M1") activation. Here, we report on the source and regulation of these monocytes. TEVGs were implanted in wild-type, CCR2 knockout ( Ccr2-/-), splenectomized, and spleen graft recipient mice. We found that bone marrow-derived Ly6C+hi monocytes released from sequestration by the spleen are the source of mononuclear cells infiltrating the TEVG during the acute phase of neovessel formation. Furthermore, short-term administration of losartan (0.6 g/L, 2 wk), an angiotensin II type 1 receptor antagonist, significantly reduced the macrophage populations (Ly6C+/-/F480+) in the scaffolds and improved long-term patency in TEVGs. Notably, the combined effect of bone marrow-derived mononuclear cell seeding with short-term losartan treatment completely prevented the development of TEVG stenosis. Our results provide support for pharmacologic treatment with losartan as a strategy to modulate monocyte infiltration into the grafts and thus prevent TEVG stenosis.-Ruiz-Rosado, J. D. D., Lee, Y.-U., Mahler, N., Yi, T., Robledo-Avila, F., Martinez-Saucedo, D., Lee, A. Y., Shoji, T., Heuer, E., Yates, A. R., Pober, J. S., Shinoka, T., Partida-Sanchez, S., Breuer, C. K. Angiotensin II receptor I blockade prevents stenosis of tissue engineered vascular grafts.

Oversized Biodegradable Arterial Grafts Promote Enhanced Neointimal Tissue Formation.

Most tissue-engineered arterial grafts are complicated by aneurysmal dilation secondary to insufficient neotissue formation after scaffold degradation. The optimal graft would form an organized multilayered structure with a robust extracellular matrix that could withstand arterial pressure. The purpose of the current study was to determine how oversizing a biodegradable arterial scaffold affects long-term neotissue formation. Size-matched (1.0 mm, n = 11) and oversized (1.6 mm, n = 9) electrospun polycaprolactone/chitosan scaffolds were implanted as abdominal aortic interposition grafts in Lewis rats. The mean lumen diameter of the 1.6 mm grafts was initially greater compared with the native vessel, but matched the native aorta by 6 months. In contrast, the 1.0 mm grafts experienced stenosis at 6 and 9 months. Total neotissue area and calponin-positive neotissue area were significantly greater in the 1.6 mm grafts by 6 months and similar to the native aorta. Late-term biomechanical testing was dominated by remaining polymer, but graft oversizing did not adversely affect the biomechanics of the adjacent vessel. Oversizing tissue-engineered arterial grafts may represent a strategy to increase the formation of organized neotissue without thrombosis or adverse remodeling of the adjacent native vessel by harnessing a previously undescribed process of adaptive vascular remodeling.

Role for the EWS domain of EWS/FLI in binding GGAA-microsatellites required for Ewing sarcoma anchorage independent growth.

Ewing sarcoma usually expresses the EWS/FLI fusion transcription factor oncoprotein. EWS/FLI regulates myriad genes required for Ewing sarcoma development. EWS/FLI binds GGAA-microsatellite sequences in vivo and in vitro. These sequences provide EWS/FLI-mediated activation to reporter constructs, suggesting that they function as EWS/FLI-response elements. We now demonstrate the critical role of an EWS/FLI-bound GGAA-microsatellite in regulation of the NR0B1 gene as well as for Ewing sarcoma proliferation and anchorage-independent growth. Clinically, genomic GGAA-microsatellites are highly variable and polymorphic. Current data suggest that there is an optimal "sweet-spot" GGAA-microsatellite length (of 18-26 GGAA repeats) that confers maximal EWS/FLI-responsiveness to target genes, but the mechanistic basis for this remains unknown. Our biochemical studies, using recombinant Δ22 (a version of EWS/FLI containing only the FLI portion), demonstrate a stoichiometry of one Δ22-monomer binding to every two consecutive GGAA-repeats on shorter microsatellite sequences. Surprisingly, the affinity for Δ22 binding to GGAA-microsatellites significantly decreased, and ultimately became unmeasureable, when the size of the microsatellite was increased to the sweet-spot length. In contrast, a fully functional EWS/FLI mutant (Mut9, which retains approximately half of the EWS portion of the fusion) showed low affinity for smaller GGAA-microsatellites but instead significantly increased its affinity at sweet-spot microsatellite lengths. Single-gene ChIP and genome-wide ChIP-sequencing (ChIP-seq) and RNA-seq studies extended these findings to the in vivo setting. Together, these data demonstrate the critical requirement of GGAA-microsatellites as EWS/FLI activating response elements in vivo and reveal an unexpected role for the EWS portion of the EWS/FLI fusion in binding to sweet-spot GGAA-microsatellites.

Objective characterization of airway dimensions using image processing.

OBJECTIVES: With the evolution of medical and surgical management for pediatric airway disorders, the development of easily translated techniques of measuring airway dimensions can improve the quantification of outcomes of these interventions. We have developed a technique that improves the ability to characterize endoscopic airway dimensions using common bronchoscopic equipment and an open-source image-processing platform. METHODS: We validated our technique of Endoscopic Airway Measurement (EAM) using optical instruments in simulation tracheas. We then evaluated EAM in a large animal model (Ovis aries, n = 5), comparing tracheal dimensions obtained with EAM to measurements obtained via 3-D fluoroscopic reconstruction. The animal then underwent resection of the measured segment, and direct measurement of this segment was performed and compared to radiographic measurements and those obtained using EAM. RESULTS: The simulation tracheas had a direct measurement of 13.6, 18.5, and 24.2 mm in diameter. The mean difference of diameter in simulation tracheas between direct measurements and measurements obtained using EAM was 0.70 ± 0.57 mm. The excised ovine tracheas had an average diameter of 18.54 ± 0.68 mm. The percent difference in diameter obtained from EAM and from 3-D fluoroscopic reconstruction when compared to measurement of the excised tracheal segment was 4.98 ± 2.43% and 10.74 ± 4.07% respectively. Comparison of these three measurements (EAM, measurement of resected trachea, 3-D fluoroscopic reconstruction) with repeated measures ANOVA demonstrated no statistical significance. CONCLUSIONS: Endoscopic airway measurement (EAM) provides equivalent measurements of the airway with the improved versatility of measuring non-circular and multi-level dimensions. Using optical bronchoscopic instruments and open-source image-processing software, our data supports preclinical and clinical translation of an accessible technique to provide objective quantification of airway diameter.

TGF-ß receptor 1 inhibition prevents stenosis of tissue-engineered vascular grafts by reducing host mononuclear phagocyte activation.

Stenosis is a critical problem in the long-term efficacy of tissue-engineered vascular grafts (TEVGs). We previously showed that host monocyte infiltration and activation within the graft drives stenosis and that TGF-ß receptor 1 (TGF-ßR1) inhibition can prevent it, but the latter effect was attributed primarily to inhibition of mesenchymal cell expansion. In this study, we assessed the effects of TGF-ßR1 inhibition on the host monocytes. Biodegradable TEVGs were implanted as inferior vena cava interposition conduits in 2 groups of C57BL/6 mice (n = 25/group): unseeded grafts and unseeded grafts with TGF-ßR1 inhibitor systemic treatment for the first 2 wk. The TGF-ßR1 inhibitor treatment effectively improved TEVG patency at 6 mo compared to the untreated control group (91.7 vs. 48%, P < 0.001), which is associated with a reduction in classic activation of mononuclear phagocytes. Consistent with these findings, the addition of rTGF-ß to LPS/IFN-γ-stimulated monocytes enhanced secretion of inflammatory cytokines TNF-α, IL-12, and IL-6; this effect was blocked by TGF-ßR1 inhibition (P < 0.0001). These findings suggest that the TGF-ß signaling pathway contributes to TEVG stenosis by inducing classic activation of host monocytes. Furthermore, blocking monocyte activation by TGF-ßR1 inhibition provides a viable strategy for preventing TEVG stenosis while maintaining neotissue formation.-Lee, Y.-U., de Dios Ruiz-Rosado, J., Mahler, N., Best, C. A., Tara, S., Yi, T., Shoji, T., Sugiura, T., Lee, A. Y., Robledo-Avila, F., Hibino, N., Pober, J. S., Shinoka, T., Partida-Sanchez, S., Breuer, C. K. TGF-ß receptor 1 inhibition prevents stenosis of tissue-engineered vascular grafts by reducing host mononuclear phagocyte activation.

Rational design of an improved tissue-engineered vascular graft: determining the optimal cell dose and incubation time.

AIM: We investigated the effect of cell seeding dose and incubation time on tissue-engineered vascular graft (TEVG) patency. MATERIALS & METHODS: Various doses of bone marrow-derived mononuclear cells (BM-MNCs) were seeded onto TEVGs, incubated for 0 or 12 h, and implanted in C57BL/6 mice. Different doses of human BM-MNCs were seeded onto TEVGs and measured for cell attachment. RESULTS: The incubation time showed no significant effect on TEVG patency. However, TEVG patency was significantly increased in a dose-dependent manner. In the human graft, more bone marrow used for seeding resulted in increased cell attachment in a dose-dependent manner. CONCLUSION: Increasing the BM-MNC dose and reducing incubation time is a viable strategy for improving the performance and utility of the graft.

Effect of cell seeding on neotissue formation in a tissue engineered trachea.

BACKGROUND: Surgical management of long segment tracheal disease is limited by a paucity of donor tissue and poor performance of synthetic materials. A potential solution is the development of a tissue-engineered tracheal graft (TETG) which promises an autologous airway conduit with growth capacity. METHODS: We created a TETG by vacuum seeding bone marrow-derived mononuclear cells (BM-MNCs) on a polymeric nanofiber scaffold. First, we evaluated the role of scaffold porosity on cell seeding efficiency in vitro. We then determined the effect of cell seeding on graft performance in vivo using an ovine model. RESULTS: Seeding efficiency of normal porosity (NP) grafts was significantly increased when compared to high porosity (HP) grafts (NP: 360.3 ± 69.19 × 10(3) cells/mm(2); HP: 133.7 ± 22.73 × 10(3) cells/mm(2); p<0.004). Lambs received unseeded (n=2) or seeded (n=3) NP scaffolds as tracheal interposition grafts for 6 weeks. Three animals were terminated early owing to respiratory complications (n=2 unseeded, n=1 seeded). Seeded TETG explants demonstrated wound healing, epithelial migration, and delayed stenosis when compared to their unseeded counterparts. CONCLUSION: Vacuum seeding BM-MNCs on nanofiber scaffolds for immediate implantation as tracheal interposition grafts is a viable approach to generate TETGs, but further preclinical research is warranted before advocating this technology for clinical application.

Cilostazol, Not Aspirin, Prevents Stenosis of Bioresorbable Vascular Grafts in a Venous Model.

OBJECTIVE: Despite successful translation of bioresorbable vascular grafts for the repair of congenital heart disease, stenosis remains the primary cause of graft failure. In this study, we investigated the efficacy of long-term treatment with the antiplatelet drugs, aspirin and cilostazol, in preventing stenosis and evaluated the effect of these drugs on the acute phase of inflammation and tissue remodeling. APPROACH AND RESULTS: C57BL/6 mice were fed a drug-mixed diet of aspirin, cilostazol, or normal chow during the course of follow-up. Bioresorbable vascular grafts, composed of poly(glycolic acid) mesh sealed with poly(l-lactide-co-ε-caprolactone), were implanted as inferior vena cava interposition conduits and followed up for 2 weeks (n=10 per group) or 24 weeks (n=15 per group). Both aspirin and cilostazol suppressed platelet activation and attachment onto the grafts. On explant at 24 weeks, well-organized neotissue had developed, and cilostazol treatment resulted in 100% graft patency followed by the aspirin (67%) and no-treatment (60%) groups (P<0.05). Wall thickness and smooth muscle cell proliferation in the neotissue of the cilostazol group were decreased when compared with that of the no-treatment group at 24 weeks. In addition, cilostazol was shown to have an anti-inflammatory effect on neotissue at 2 weeks by regulating the recruitment and activation of monocytes. CONCLUSIONS: Cilostazol prevents stenosis of bioresorbable vascular graft in a mouse inferior vena cava implantation model up to 24 weeks and is accompanied by reduction of smooth muscle cell proliferation and acute inflammation.

Regenerative implants for cardiovascular tissue engineering.

A fundamental problem that affects the field of cardiovascular surgery is the paucity of autologous tissue available for surgical reconstructive procedures. Although the best results are obtained when an individual's own tissues are used for surgical repair, this is often not possible as a result of pathology of autologous tissues or lack of a compatible replacement source from the body. The use of prosthetics is a popular solution to overcome shortage of autologous tissue, but implantation of these devices comes with an array of additional problems and complications related to biocompatibility. Transplantation offers another option that is widely used but complicated by problems related to rejection and donor organ scarcity. The field of tissue engineering represents a promising new option for replacement surgical procedures. Throughout the years, intensive interdisciplinary, translational research into cardiovascular regenerative implants has been undertaken in an effort to improve surgical outcome and better quality of life for patients with cardiovascular defects. Vascular, valvular, and heart tissue repair are the focus of these efforts. Implants for these neotissues can be divided into 2 groups: biologic and synthetic. These materials are used to facilitate the delivery of cells or drugs to diseased, damaged, or absent tissue. Furthermore, they can function as a tissue-forming device used to enhance the body's own repair mechanisms. Various preclinical studies and clinical trials using these advances have shown that tissue-engineered materials are a viable option for surgical repair, but require refinement if they are going to reach their clinical potential. With the growth and accomplishments this field has already achieved, meeting those goals in the future should be attainable.

Scaffolding for challenging environments: materials selection for tissue engineered intestine.

Novel therapies are crucially needed for short bowel syndrome. One potential therapy is the production of tissue engineered intestine (TEI). The intestinal environment presents significant challenges to the selection of appropriate material for tissue engineering scaffolds. Our goal was to characterize different scaffold materials to downselect to that best suited for TEI production. To investigate this, various tubular scaffolds were implanted into the peritoneal cavity of adult rats and harvested at multiple time-points. Harvested scaffolds were examined histologically and subjected to degradation studies and mechanical evaluation. We found that poly(glycolic acid) (PGA)-nanofiber and PGA-macrofiber scaffolds exhibited early robust tissue infiltration. Poly(ɛ-caprolactone) (PCL)-nanofiber, poly(l-lactic acid) (PLLA)-nanofiber, poly(d-lactic acid-co-glycolic acid) (PDLGA)-nanofiber and polyurethane (PU)-nanofiber experienced slower tissue infiltration. Poly(ɛ-caprolactone-co-lactic acid) (PLC) nanofiber had poor tissue infiltration. Significant weight loss was observed in PGA-nanofiber (92.2%), PGA-macrofiber (67.6%), and PDLGA-nanofiber (76.9%) scaffolds. Individual fibers were no longer seen by scanning electron microscopy in PLC-nanofiber and PGA-nanofiber scaffolds after 1 week, PGA-macrofiber scaffolds after 2 weeks, and PDLGA-nanofiber scaffolds after 4 weeks. In conclusion, PGA-macrofiber and PDLGA appear to be the most appropriate materials choices as TEI scaffolds due to their biocompatibility and degradation. Future experiments will confirm these results by analyzing cell-seeded scaffolds in vitro and in vivo.